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The acoustic performance of double-skin facades: a design support tool for architects

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The acoustic performance of double-skin facades: a design support tool for architects

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Content Batungbakal i Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects THE ACOUSTIC PERFORMANCE OF DOUBLE-SKIN FACADES: A DESIGN SUPPORT TOOL FOR ARCHITECTS by Aireen Batungbakal A Thesis Presented to the FACULTY OF THE USC SCHOOL OF ARCHITECTURE UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements of the Degree MASTER OF BUILDING SCIENCE December 2013 Copyright 2013 Aireen Batungbakal Batungbakal ii Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Epigraph Seek, flourish, and move forward. Develop your weaknesses into strengths. Batungbakal iii Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Dedication To my loving family My Mom and Dad, and siblings, Alexander, Airess, and Dario Batungbakal iv Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Acknowledgements Tremendous appreciation is expressed to thesis committee members, Dr. Kyle Konis, Dr. David Gerber, and Elizabeth Valmont. Their devoted guidance, discipline, and assistance, along with the foresight of thesis advisors, Douglas Noble and Ilaria Mazzoleni, contributed in the study’s research and development. With high gratitude, I thank the esteemed thesis committee who have enriched my thesis research as well as my education at the University of Southern California. Their commitment in the completion of this thesis research is greatly appreciated for I did not expect the magnitude of growth and opportunities our collaboration has provided. Our collaboration remains a strong imprint in my life and I hope to our partnerships strengthen to explore innovative solutions in the future. Dr. Kyle Konis provided clarity in linking my interests with his knowledgeable insight in a micro and macro scale. I admire his consistent dedication to incorporate in-depth research and demonstrative application in his work and educational material. Dr. David Gerber provided intuitive guidance in approaching my thesis topic, providing explorative resources. It was an honor to collaborative with a well-rounded individual who contributed to a positive learning environment. Elizabeth Valmont allowed me to understand the depths of acoustics. Her knowledge and experience in the field of acoustics enriched the methods and content included in the thesis research. Batungbakal v Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Appreciation is also credited to INSUL for accommodating to the duration and verification necessary to obtain simulated results and Pilkington Glass or providing cost estimates for architectural glass. I would like to thank my colleagues at Berliner and Associates Architecture for their accommodating support and understanding, which allowed me to accomplish by educational endeavors as well as develop skills in the profession. Tremendous support stemmed from my parents and my siblings. I will always love them completely. Their love, support, and understanding continues to be the foundation of my growth, personally, professionally, and spiritually. I credit my dearest brother and best friend Dario Jr. who remains a constant figure and open listener. His natural gifts to observe and understand things not many are aware of remains one of many of his admirable attributes that continues to inspire me to see beauty. I would like to thank my sister Airess for her support. Her ability to care and contribute time to help others remains one of the countless characteristics that make her beautiful. I would like to thank my fearless and inspiring brother Alexander, the eldest brother who always pushed boundaries and encouraged others to achieve their dreams. Batungbakal vi Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects To my loving Mom and Dad, who remain the two main figures embodying selfless love, compassion, determination, and integrity. Many times I refer to my parents as examples on how I should conduct myself, approach challenges, overcome shortcomings, and care for others’ circumstances. Humbleness and a noble work ethic define my parents. I would to thank them for all they have offered because they continue to offer so much. Most importantly, I am eternally grateful and thankful for all the opportunities and love God has bestowed upon me. God blessed me with a loving family, support, and lessons that allowed me to grow and to discover myself and test my abilities. Throughout my life, God has provided a constant light, enabling me to explore, discover, and move forward. Although thanking God in my acknowledgements is a small note, it is my hope that this acknowledgement is a testament of my gratitude and the unending light, hope, and acceptance God can provide for all. Batungbakal vii Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Table of Contents Epigraph ii Dedication iii Acknowledgements iv List of Tables xxv List of Figures xvii Abstract xxii CHAPTER 1: Introduction 1 1.1- Understanding the Acoustic Performance of Glass Facades in the Urban Environment 1 1.2- Hypothesis 2 CHAPTER 2: The Issue in Context 2 2.1- Urbanization – Understanding Sound Sources in the Built Environment and its Impact 2 2.2- Sound and Noise: Influence of Acoustics and Impact on Perception, Living, and Work 5 2.2-1 The Discipline of Acoustics 5 2.2-2 Acoustics: Environmental and Architectural 7 Environmental Acoustics Architectural Acoustics Sound Transmission CHAPTER 3: Response and Approaches in Modifying Acoustic Environment 8 3.1- Modifying Acoustic Environment: Sound Attenuation 8 Sound Transmission 3.1-1 Comfort, Health, Office 10 Commercial Development and Environmental Noise Batungbakal viii Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Environmental Protection Act of 1970 Noise Control At of 1972 Office of Noise Abatement (ONAC) 1981 3.2- Office Workspace 12 Effect of Noise on the Function of an Office Workspace CA Code of Regulations Title 24’s Sound Transmission Control Requirements City of Los Angeles Noise Ordinance Acceptable and Unacceptable Sound Levels Based on Occupancy 3.3- Issues and Work Productivity 14 Office Workspace: A Changing Culture Open Plan Office Enclosed Office CHAPTER 4: The Fundamentals in Acoustic Treatment 16 4.1- Office Space: The Fundamentals 16 Architectural Acoustic Design Strategy- Building Envelope 16 4.2- Methods Using the Building Envelope 16 U.S. GSA’sPublic Building Services P-100 Criteria 16 ABC Rule and its Three Aspects in Acoustic 17 Absorb Sound 17 Block Sound Transmission 17 Cover through Masking 17 Batungbakal ix Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects CHAPTER 5: Terminology in Defining Sound and Noise 18 5.1- Sound 18 5.2- Magnitude and Intensity 19 5.3- Frequency 20 5.4- Noise 21 5.5- Sound Transmission 21 5.5-1. Sound Reduction 22 CHAPTER 6: Blocking Sound Transmission through the Building Envelope- Glass Facades 25 6.1- Single-Pane Facades and Double-Pane Facades 25 6.2- Double-Skin Facades 26 Box-Window Façade 27 Corridor Façade 27 Shaft Box Façade 27 Multi-Story Façade 28 CHAPTER 7: Performance of Glass Facades in Need of Further Exploration 29 7.1- Disadvantages on Reliance: Designers Relying on Claimed Acoustic Properties 29 7.2- Acoustic Performance of Double-Skin Façade in Workspaces 30 7.2-1. Disconnection between Façade Design and Architects 30 7.3- Intent of Research 31 7.4- The Importance of Acoustic Design 33 Batungbakal x Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects CHAPTER 8 Background- Efforts to Improve Acoustic Properties of Glass Facades Based on its Materiality, Structure, and Design Implementation 36 8.1- Testing Standards 36 8.2- Potential of Facade Components 39 8.2-1 Laminated Glass 40 8.2-2 Glass Type and Thickness 40 8.2-3 Façade Systems 41 8.3- Field-Testing Implementation 43 8.4- Material Performance 44 8.5- Design Consideration 46 CHAPTER 9 Methodology 48 9.1- The Building Envelope: Reducing Sound Transmission 48 9.2- Methods: Overview 51 9.3- Methods: Tools 53 9.3-1. Decibel 10 th 54 Using Decibel 10 th for Field-Testing 56 9.3-2. INSUL 56 Fixed and Variable Parameters 57 Mediums: Glazing 59 Outdoor to Indoor Sound Insulation Calculation 62 9.4- Key Parameters and Façade Components for Field-testing and INSUL Simulations 67 9.4-1 Components Influencing Receiver- Office Space 68 Area of the Façade 68 Volume of the Room 68 Reverberation 69 Batungbakal xi Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 9.5- Progressive Simulations: Selected Components Identified to Improve Transmission Loss 70 9.5-1. Progressive Selection 70 9.5-2. Assessing Simulated Single-Pane Facades 73 9.5-3. Assessing Simulated Double-Pane Facades and Double-Skin Facades 75 9.6- Process to Results 76 9.6-1. Field-testing: Urban Integration to Establish Baseline 76 Condition 1 - Bunker Hill District 87 Condition 2 - Culver City Office 87 Condition 3 - LAX Departure Area 87 Condition 4 - LAX Arrival Area 87 Condition 5 - USC Tutor Hall International Plaza 88 Condition 6 - USC Gerontology Library 88 9.6-2. Using Field-testing as Source Data 89 9.6-3. Implementation of Field-Measurements to INSUL Façade Simulations 90 9.6-4. Single-Pane, Double-Pane, and Double-Skin Facades 92 Targeted Frequency Range and Common Sound Sources 92 Lower to Mid Frequencies 93 High Frequencies 94 9.6-5. Façade Analyses and Comparisons 95 Comparison of Sound Transmission Loss: Trends of Acoustic Performance 95 9.6-6. Composing a Design Support Tool for Architects 99 Assembling A Design Support Tool 99 Batungbakal xii Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects CHAPTER 10 Results 101 10.1- Single-Pane Facades 102 10.1-1 Single-Pane Facades Composed of Monolithic Glass -Indoor Sound Levels 102 10.1-2 Single-Pane Facades Composed of Monolithic Glass -Direct Sound Transmission Loss 103 10.1-3 Single-Pane Facades Composed of Monolithic Glass –Critical Frequencies 104 10.1-4 Single-Pane Facades Composed of Laminated Glass -Indoor Sound Levels 107 10.1-5 Single-Pane Facades Composed of Laminated Glass –Direct Sound Transmission Loss 108 10.1-6 Single-Pane Facades Composed of Laminated Glass - Critical Frequencies 109 10.1-7 Comparison 111 10.1-8 Acoustic Performance of Single-Pane Facades 116 CHAPTER 11 Results 118 11.1- Double-Pane Façades 118 11.1-1. Double-Pane Facades Composed of Monolithic Glass -Indoor Sound Levels 118 11.1-2. Double-Pane Facades Composed of Monolithic Glass -Critical Frequencies 120 11.1-3. Double-Pane Facades with Laminate Glass -Indoor Sound Levels 123 11.1-4. Double-Pane Facades with Laminate Glass -Critical Frequencies 123 11.1-5. Comparison 126 Double-Pane facades and Single-Pane Façades 126 Thickness 128 Laminated Glass- PVB and TSC 129 Double-Pane Facades 132 11.1-6. Acoustic performance of Double-Pane Facades 135 Overall Performance 135 Batungbakal xiii Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Resonance Dip and Coincidence Dip 136 CHAPTER 12 Results 137 12.1- Double-Skin Façades: [¼” + ½” air gap + ¼”] + air-cavity + ¼” outer skin 137 12.1-1. Double- Skin Façades Composed of Monolithic Glass -Indoor Sound Levels 139 12.1-2. Double- Skin Façades Composed of Monolithic Glass –Critical Frequencies 140 12.1-3. Double- Skin Façades Composed of Laminated Glass -Indoor Sound Levels 141 12.1-4. Double- Skin Façades Composed of Laminated Glass –Direct Sound Transmission Loss 142 12.1-5. Comparison of Double- Skin Façades composed of ¼-inch Glass 144 Double- Skin Façades to Single- Pane Façades and Double-Pane Façades 145 12.1-6. Double- Skin Façades with Increased Secondary Skin Thickness 146 12.1-7. Overall Summary 149 CHAPTER 13 Conclusion- Study Evaluation and Design Support Tool 150 13.1- Conclusion 150 13.2- Composing a Double-Skin Façade Design Support Tool 152 13.3- Design Support Tool Interface 153 13.4- Value of Study and Analyses 155 13.5- Suggested Guidelines: The Importance of Methodology 156 CHAPTER 14 Future Research and Limitations 156 14.1- Field Measurements for Double-Skin Façades to Validate Simulations 157 14.2- Field-Testing Equipment 157 14.3- Testing Standards 158 14.4- Software: INSUL Simulations 159 Batungbakal xiv Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 14.4-1. Tabs: Limit of Three Panels 159 14.4-2. Ventilated Double-Skin Façades 160 14.5- Indoor Sound Level Variation: Façade Area, Room Volume, Reverberation 161 Bibliography 162 References 169 Glossary 170 Appendix A Direct Transmission Loss 175 Appendix B Indoor Sound Levels from Direct Transmission Loss 179 Appendix C Indoor Sound Levels Considering Indoor Parameters 183 Appendix D Indoor Sound Level Plots from Direct Transmission Loss: Single-Pane Façades & Double- Pane Façades 187 Appendix E Indoor Sound Level Plots from Direct Transmission Loss: Double-Skin Façades 188 Appendix F Design Support Tool: Single-Figure dBA Ratings: Direct Transmission Loss 190 Appendix G Design Support Tool: Single-Figure dBA Ratings: Indoor Parameters 191 Appendix H Evaluation of Findings and Design Support Tool 192 Batungbakal xv Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects List of Tables TABLE 1: SOUND SOURCE, PATH AND RECEIVER 7 TABLE 2: FIELD-TEST AND LABORATORY TEST CONDITIONS 37 TABLE 3: SELECTED FAÇADE COMPONENTS FOR DOUBLE-SKIN FAÇADE SIMULATIONS 70 TABLE 4: SELECTED FIELD-TESTED SITE CONDITIONS 78 TABLE 5: FIELD-TEST SITE PARAMETERS AND SETTINGS 84 TABLE 6: A-WEIGHTED OUTDOOR SOUND LEVELS 91 TABLE 7: EXAMPLE: INDOOR SOUND LEVELS FROM DIRECT TRANSMISSION LOSS 98 TABLE 8: SUBJECTIVE CHANGE OF SOUND LEVELS 98 TABLE 9: A-WEIGHTING: CHANGE IN DECIBEL CONVERSION 100 TABLE 10: EXAMPLE: SINGLE-FIGURE A-WEIGHTED SUM OF INDOOR SOUND LEVEL 100 TABLE 11: SINGLE-PANE FACADES: A-WEIGHTED INDOOR SOUND LEVELS 103 TABLE 12: PERFORMANCE OF SINGLE-PANE FACADES: DIRECT SOUND TRANSMISSION LOSS 104 TABLE 13. SINGLE-PANE FACADES: A-WEIGHTED INDOOR SOUND LEVELS 108 TABLE 14. SINGLE-PANE FACADES: A-WEIGHTED INDOOR SOUND LEVELS 108 TABLE 15. PERFORMANCE OF SINGLE-PANE FACADES: DIRECT SOUND TRANSMISSION LOSS 110 Batungbakal xvi Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects TABLE 16. PERFORMANCE OF SINGLE-PANE FACADES: DIRECT SOUND TRANSMISSION LOSS 110 TABLE 17. DOUBLE- PANE FACADES: A-WEIGHTED INDOOR SOUND LEVELS 121 TABLE 18. PERFORMANCE OF DOUBLE-PANE FACADES: DIRECT SOUND TRANSMISSION LOSS 121 TABLE 19. DOUBLE- PANE FACADES: A-WEIGHTED INDOOR SOUND LEVELS 125 TABLE 20. PERFORMANCE OF DOUBLE-PANE FACADES: DIRECT SOUND TRANSMISSION LOSS 125 TABLE 21. DOUBLE- PANE FACADES: A-WEIGHTED INDOOR SOUND LEVELS 125 TABLE 22. PERFORMANCE OF DOUBLE-PANE FACADES: DIRECT SOUND TRANSMISSION LOSS 125 Batungbakal xvii Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects List of Figures Figure 1. Average Sound Levels (day/night) and Population Density (Salters 51). 3 Figure 2. Outdoor Factors in Sound Mitigation and Propagation. 4 Figure 3. Lindsay’s Wheel of Acoustics Disciplines in Physical Acoustics (Lindsey). 6 Figure 4. Acceptable Noise Levels for Communities Based on Occupancy (Office of Noise Control). 9 Figure 5. Unacceptable Outdoor Noise Levels for Surrounding Office Buildings. 10 Figure 6. Varied Acceptable Noise Levels for Office Workspace. 13 Figure 7. GSA P100 Acoustical Requirements (General Service Administration). 17 Figure 8. Double-Skin Façade Types: Partitions. 28 Figure 9. Double-Skin Façade Types: Airflow Direction. 28 Figure 10. Top Issues in Affecting Workspace. 34 Figure 11. Comparison of J1400 and ISO 15186 for Steel: Transmission Loss and Difference of Transmission Loss between Two Standards. (Cassidy, M., R.K. Cooper, et al). 39 Figure 12. Comparison of Float Glass, Glass with PVB Laminate, and Glass with TSC Laminate (Keller). 40 Figure 13. Transmission Loss: Comparing Glass with Varied PVB Thickness to Monolithic Glass (Foss). 42 Figure 14: Transmission Loss: Comparing IGU with PVB to Monolithic IGU (Foss). 43 Figure 15. Integration of Spatial Data and Activity: Combining Mapped Traffic Noise and Mapped Activity in Commercial Areas (Oliveira). 44 Figure 16. Sound Transmission Loss of ¼-inch Laminated Glass, 68° F - Kobayashi Institute of Physical Research Test Results in Accordance to JIS A-1416 (Recent Advances in Acoustical Glazing). 46 Batungbakal xviii Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 17. Sound Transmission Loss of ¼-inch Laminated Glass, 48° F- Kobayashi Institute of Physical Research Test Results in Accordance to JIS A-14160 (Recent Advances in Acoustical Glazing). 46 Figure 18. Zone Activities (General Services Administration). 47 Figure 19. GSA Work Pattern Matrix (General Services Administration). 47 Figure 20. Acceptable and Unacceptable Indoor Sound Levels Based on Land Use and Building Occupancy. 51 Figure 21. Field-testing and Simulations: Sound Source, Medium, and Receiving Room. 51 Figure 22. Overall Methodology to Obtain Estimated Sound Transmission Loss of Façade Assemblies. 53 Figure 23. Decibel 10 th Interface and Field-testing Site Locations. 54 Figure 24. INSUL Interface: Façade Components for Glazing. 54 Figure 25. INSUL Interface: INSUL Outdoor-to-Indoor TL Calculations. 54 Figure 26. Field-Test Implemented in INSUL to Create Sound Spectrum. 56 Figure 27. Parameters for INSUL Façade Simulations. 58 Figure 28. INSUL Main Interface: Glazing Tab Settings. 59 Figure 29. Diagram (left to right): Single-Pane Façade and Double-Pane Façade, and IGU. 60 Figure 30. INSUL: Setting for Outdoor to Indoor Sound Insulation Calculation. 63 Figure 31. INSUL: Setting for Sound Spectrum Calculator. 64 Figure 32. Path Settings: Elements Tab. 66 Figure 33. INSUL: Glazing Tab Settings. 66 Figure 34. In the Receiving Room Panel. 67 Figure 35. Recommended Reverberation Time for Office Buildings (Autex). 69 Figure 36. Diagram: Progressive Selection. 73 Figure 37. Los Angeles: Site Locations Based on Employment and Traffic Density. GIS Data (SCAG, 2000). 78 Figure 38. Los Angeles: Street Traffic Congestion. 79 Batungbakal xix Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 39. Los Angeles: Employment Density. 79 Figure 40. Los Angeles: Site Locations Based on Combined Employment and Traffic Density. 79 Figure 41. Field-Testing Conditions. 81 (1) Bunker Hill, (2) Culver City Office, (3) LAX Aerial Traffic, (4) LAX Vehicular Traffic, (5) USC Tutor Hall, (6) USC Gerontology Library Figure 42. Field-test: Outdoor sound pressure levels (blue) and Indoor Sound Pressure Levels (pink). 82 (1) Bunker Hill, (2) Culver City Office, (3) LAX Aerial Traffic, (4) LAX Vehicular Traffic, (5) USC Tutor Hall, (6) USC Gerontology Library. Figure 43A: Field-Tested Outdoor Sound Level: Bunker Hill and LA Central Library. 83 Figure 43B: Field-Tested Indoor Sound Level: Bunker Hill and LA Central Library. 83 Figure 43C: Field-Tested Outdoor Condition: Bunker Hill. 83 Figure 43D: Field-Tested Indoor Condition: LA Central Library. 83 Figure 44. Field-Testing: Sound Meter Settings, Decibel 10 th . 85 Figure 45. Field-Testing and Simulations: Sound Source, Medium, and Receiving Room. 85 Figure 46. Acceptable Sound Levels Based on Land Use (Office of Noise Control). 86 Figure 47. INSUL Traffic Noise Sound Spectrum, Not A-weighted. 90 Figure 48. Common Traffic Noise, A-weighted Sound Levels (Kinsler 361). 92 Figure 49. Common Indoor Noise, A-weighted Sound Levels (Kinsler 361). 92 Figure 50. Common Traffic Noise, A-weighted Sound Levels (Salters 3). 93 Figure 51. Illustrative: Indoor Sound Levels for Single-Pane Façade. 97 Figure 52. Façade Comparison to Baselines and Perceived dB Change. 98 Figure 53. Double-Skin Façade Composed of ¼-inch Monolithic Glass: Sum of A-weighted Indoor Sound Levels. 100 Figure 54. Common Traffic Noise, A-weighted Sound Levels (Salters 3). 101 Batungbakal xx Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 55. Single-Pane Façade Composed of Monolithic Glass: Indoor Sound Levels from Direct Transmission Loss. 102 Figure 56. Single-Pane Façade with PVB Laminate: Indoor Sound Levels from Direct Transmission Loss. 106 Figure 57. Single-Pane Façade with TSC Laminate: Indoor Sound levels from Direct Transmission Loss. 106 Figure 58. Comparison of Single-Pane Facades Composed of 1/4-inch Glass. 112 Figure 59. Single-Pane Façades: Improved Transmission Loss Using PVB Laminate Glass. 113 Figure 60. Single-Pane Façades: Improved Transmission Loss Using TSC Laminate Glass. 113 Figure 61. Single-Pane Façades: PVB and TSC, Laminate Glass Comparison. 114 Figure 62. Single-Pane Façades. 116 Figure 63. Double-Pane Façade of Monolithic Glass: Indoor Sound Levels from Direct Transmission Loss. 118 Figure 64. Double-Pane Façade with PVB Laminate: Indoor Sound Levels from Direct Transmission Loss. 122 Figure 65. Double-Pane Façade with TSC Laminate: Indoor Sound Levels from Direct Transmission Loss. 122 Figure 66. Double-Pane Façades. 126 Figure 67. Comparison Single-Panes Façade and Double-Pane Façades. 126 Figure 68. Improved Transmission Loss from Double-Pane Façades Compared to Single-Pane Façades, Monolithic Glass. 127 Figure 69. Comparison of Single-Pane Façades Composed of 1/4-inch Monolithic Glass and Double-Pane Façade with ¼-inch Monolithic Glass. 127 Figure 70. Comparison of Single-Pane Façades Composed of 5/8-inch Monolithic Glass and Double-Pane Façade with 5/8-inch Monolithic Glass. 129 Batungbakal xxi Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 71. Comparison of Single-Pane Façades Composed of 1/4-inch Monolithic Glass and Double-Pane Façade with ¼-inch Glass. 130 Figure 72. Single-Pane Façades and Double-Pane Façades: PVB-laminated Glass Comparison. 131 Figure 73. Single-Pane Façades and Double-Pane Façades: TSC-laminated Glass Comparison. 131 Figure 74. Comparison of Double-Pane Façades Composed of 1/4-inch Glass and Double-Pane Façade with 5/8-inch Glass for Exterior Glazing. 132 Figure 75. Compare Double-Pane Facade Laminates and Glass Thickness. 134 Figure 76. Double-Pane Façades: Improved Transmission Loss with PVB Laminate. 134 Figure 77. Double-Pane Façades: Improved Transmission Loss with TSC Laminate. 135 Figure 78. Double-Pane Façades: PVB and TSC, Laminate Glass Comparison. 135 Figure 79. Double-Skin Façade: Monolithic, [¼” + ½” air gap + ¼”] + air-cavity + 1/4”. 137 Figure 80. Double-Skin Façade: PVB, [¼” + ½” air gap + ¼”] + air-cavity + 1/4”. 141 Figure 81. Double-Skin Façade: TSC, [¼” + ½” air gap + ¼”] + air-cavity + 1/4”. 143 Figure 82. Double-Skin Façades, [¼” + ½” air gap + ¼”] + air-cavity + ¼”. 144 Figure 83. Comparison Single-Panes Façades and Double-Pane Façades to Double-Skin Façade with ¼-inch Glass. 144 Figure 84. Compare DSF with 0.25 [out] and DSF with Mono Increased Thickness [out]. 147 Figure 85. Compare DSF with 0.25 [out] and DSF with PVB Increased Thickness [out]. 148 Figure 86. Compare DSF with 0.25 [out] and DSF with TSC Increased Thickness [out]. 148 Figure 87. Increased Direct Transmission Loss Provided by a Double-Skin Façade: Composed of ¼-inch Monolithic Glass and 15.7-inch Air-Cavity. 150 Figure 88. Support Tool. A-weighted Sum of Indoor Sound Levels. 152 Figure 89. INSUL: Representation of Partition Leak Parameters. 160 Batungbakal xxii Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Abstract This study assesses and validates the influence of measuring sound in the urban environment and the influence of glass façade components in reducing sound transmission to the indoor environment. Among the most reported issues affecting workspaces, increased awareness to minimize noise led building designers to reconsider the design of building envelopes and its site environment. Outdoor sound conditions, such as traffic noise, challenge designers to accurately estimate the capability of glass façades in acquiring an appropriate indoor sound quality. Indicating the density of the urban environment, field-tests acquired existing sound levels in areas of high commercial development, employment, and traffic activity, establishing a baseline for sound levels common in urban work areas. Composed from the direct sound transmission loss of glass facades simulated through INSUL, a sound insulation software, data is utilized as an informative tool correlating the response of glass façade components towards existing outdoor sound levels of a project site in order to achieve desired indoor sound levels. This study progresses to link the disconnection in validating the acoustic performance of glass facades early in a project’s design, from conditioned settings such as field-testing and simulations to project completion. Results obtained from the study’s façade simulations and façade comparison supports that acoustic comfort is not limited to a singular solution, but multiple design options responsive to its environment. Batungbakal 1 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects CHAPTER 1: Introduction 1.1 Understanding the Acoustic Performance of Glass Facades in the Urban Environment Noise pollution is one form of pollution resulting from urbanization. As the dynamics in the urban environment creates its own soundscape, designing a façade assembly to respond to urban noise is a challenge. Reported as one of the most common issues of indoor environmental quality (IEQ) affecting workspace, the unpredictable nature of environmental noise led designers to reconsider the design of building envelopes in regard to its role in contributing to indoor acoustic quality through the transmission of outdoor sound 1 . In contrast to the available design guidance for other environmental aspects of the building façade, the influence of acoustics contributing to workspace comfort is not fully understood until after project completion. To determine and understand the acoustic performance for glass facades during the design phase remains a challenge for most projects, and is an area where designers have limited intuition to guide decision-making in design glass facades. With increased awareness of acoustic quality and its influence on occupant comfort, improved acoustic design guidance for building enclosures is needed to aid designers in making informed decisions for envelope design and material selection appropriate to the acoustic environment of the project site. Since noise is often a dismissed aspect in building design, there is limited research that further explores the acoustic performance of glass facades, such as double-skin facades, in the urban environment. Designers resort in referencing material and glass façade manufacturers’ projected acoustic performance of glass facades, which does not provide adequate information in estimating sound transmission loss. Relying on manufacturers’ projected acoustic performance 1 “The Importance of Acoustics in the Design Phase”, http://www.acoustics.com/ceu.asp. Batungbakal 2 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects of material and façade assemblies is an outdated and disconnected approach to ensure the design of glass façades responds to its soundscape. 1.2 Hypothesis Every city has its own unique soundscape and every building façade responds differently based on its project site. As sound transmission loss varies due to the façade components of double- skin facades and its outdoor noise source, a comprehensive acoustic guideline would assist architectural designers in determining proper glass facade components for a workplace environment. A method for building designers to identify appropriate acoustic performance is proposed. Defining a baseline allows designers to focus on fundamental façade components and its acoustic performance towards existing soundscapes, and to provide context in the parameters for INSUL façade simulations. CHAPTER 2 The Issue in Context 2.1 Urbanization – Understanding Sound Sources in the Built Environment and its Impact Globally, urbanization continues to change, contributing to social, economic, and environmental concerns, such as climate change, informal growth, energy consumption, congested infrastructure, and environmental pollution 2 . In matters of informal growth and environmental pollution, rapid urbanization embodies a wide range of sound sources resulting from different land use and building occupancy types to be adjacent from one another, enabling varied urban conditions in increased density especially in greater cities and developing areas (Fig. 1) 3 . As a 2 FIG, 7-8. 3 Charles M. Salter Associates Inc., 51. Batungbakal 3 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects result, increased density makes site selection and planning impossible to avoid environmental noise 4 . It is an unpredictable and uncontrolled force. Figure 1. Average Sound Levels (day/night) and Population Density (Salters 51) Traffic congestion, due to overcrowded activity and increased infrastructure is an attribute of urbanization contributing to urban density 5 . Increased traffic congestion due to increased urban density results in noise pollution, a form of environmental pollution not as highly focused on as air pollution and water pollution 6 . Other factors that contribute to urban noise pollution are: o Lack of terrain or vegetation to absorb sound o Distance o Climate conditions 4 Paradis, http://www.wbdg.org/resources/acoustic.php. 5 FIG, 7-8. 6 “Noise Pollution”, U.S. Environmental Protection Agency, www.epa.gov/air/noise.html. Batungbakal 4 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects While increased distance attenuates the amplitude of sound from its sound source, close proximity to disruptive sound sources is an immediate issue. Landscape, such as forestry and shrubbery, can attenuate sound levels from 5dBA to 20dBA (every 100 feet) while change in ground elevation, such as sloped terrain, can attenuate sound by 30dBA 7 . Climate conditions, such as air temperature and wind speed, influence sound attenuate depending on distance 8 (Fig. 2). Figure 2. Outdoor Factors in Sound Mitigation and Propagation The urban environment is composed of varied of sound levels. Outdoor sound levels differ over a duration and is based on the area’s density and surrounding activities. Urban noise, such as traffic noise, is a common sound condition engineers and designers continually address when considering the design and assembly of glass facades. As traffic noise is the most common sound condition used to assess sound transmission loss from building facades due to inconsistent sources and sound impulses. Sound impulses are identified fluctuating noise with sound pressure levels above 40 dB lasting from less than 0.5 seconds to long durations. 9 7 Charles M. Salter Associates Inc., 58. 8 Charles M. Salter Associates Inc., 59. 9 Kinsler, 359. Batungbakal 5 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Further research in the acoustic performance of double-skin facades in the urban environment is not explored as much as the ventilation aspects and thermal properties of double-skin facades. This study explores to expose façade design in the acoustic environment by demonstrating the importance of context of an urban soundscape in order to design double-skin facades that would respond appropriately to existing acoustic environment. 2.2 Sound and Noise: Influence of Acoustics and Impact on Perception, Living, and Work Traffic noise is a common environmental noise in an urban setting. Environmental noise concerns airborne sound sources in the built environment. Among the two forms of sound transmission, airborne sound sources are defined as sound traveling through air as a medium. In contrast to airborne sound sources, structure-borne sound sources are defined as sound transmission through solid mediums, such as building partitions 10 . Environmental sound sources can either be disturbing or desirable. Most natural sound sources are considered desirable sound 11 . Traffic- road, rail, and aircraft, and industrial infrastructure are common types environmental noise considered as annoyances. 2.2-1 The Discipline of Acoustics As a science discipline, acoustics concerns the physics of sound production, control, transmission, reception, and effects of sound 12 (Fig.3). An acoustical analysis involves the relation between a sound source(s), its path- transmission, and its perception- the receiver 13 . 10 Cavanaugh, 325. 11 Charles M. Salter Associates Inc., 56. 12 City of Los Angeles’ Mangrove Estates Site Mixed Use Development EIR, www.planning.lacity.org/eir/MangroveEstates/FEIR/EIR%20Sections/4.8%20Noise.pdf. 13 Charles M. Salter Associates Inc., 27. Batungbakal 6 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Relative to each other, the perception of sound is influenced by its path and source 14 (Table 1). There are numerous ways sound proliferates and attenuates. For instance, outdoor sound sources directs its energy in a radial form. Environmental noise propagates through air, which influences the sound path along with other outdoor factors, such as site configuration, terrain and vegetation, and climate conditions (Fig.2). Architectural acoustics concerns of sound sources indoors influences reverberation based on its room parameters 15 . Sound transmission and sound sources indoors are emitted from the source reflected from floor, wall, and ceiling surfaces. Sound emitted from reflected surfaces enable sound levels to remain constant despite the distance of the source 16 . Figure 3. Lindsay’s Wheel of Acoustics Disciplines in Physical Acoustics. (BYU Acoustic Research Group) 14 Charles M. Salter Associates Inc., 28. 15 Kinsler, 333. 16 Cavanaugh, 17. Batungbakal 7 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects TABLE 1: SOUND SOURCE, PATH AND RECEIVER Sound Source Path Receiver Acoustic vibrations Indoor/outdoor Environmental context Medium transforming medium Hearing perception Micro phone 2.2-2 Acoustics: Environmental and Architectural Environmental acoustics concerns sound sources beyond building enclosures and site conditions, varying in sound pressure levels and spectral content (frequencies) due to type of activity and occupancy, distance, and time 17 . As environmental noise varies with time, it is a common method to average sound levels (Leq) over a duration of time in order to quantify the amplitude of environmental noise 18 . Depending on the distance between the sound source and the receiver, sound levels of environmental noise decreases as its path travels in open air. The amplitude of outdoor sound sources, such as environmental noise, are determined by its distance from the building enclosure since doubling the distance between the sound source and the receiver reduces sound amplitude by one-fourth of the initial sound amplitude 19 . Architectural acoustics involve sound sources intensified or attenuated based on the parameters of an enclosed room defined by its volume and surface material. Although sound pressure levels of environmental noise decrease as the distance from the receiver increases, it remains an issue in architectural design 20 . 17 Kinsler, 359. 18 Charles M. Salter Associates Inc., 52. 19 Cavanaugh, 152. 20 Kinsler, 378. Batungbakal 8 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Sound transmission from outdoor sound sources, such as environmental traffic noise, is a common issue affecting office buildings. Efforts from organizations, such as the U.S. Department of Housing and Urban Development, and the California Department of Health Services’ Office of Noise Control, identified acceptable sound levels for indoor office environments to ensure workspace conditions are suitable based occupancy-type and health standards. Based on building occupancy, organizations such as the California Department of Health Services and Housing Urban Development identified acceptable sound levels for office workspace to not exceed 65decibels (dB) 21 . Considered the final defense towards structure-borne sound and air-borne sound, building designers focus on façade design and construction to obstruct sound transmission 22 . Reducing sound transmission through the building façade is one method in acquiring acceptable indoor sound levels for workspace. CHAPTER 3: Response and Approaches in Modifying Acoustic Environment 3.1 Modifying Acoustic Environment: Sound Attenuation Sound transmission loss, one form of sound attenuation, is achieved by identifying the sound source and the method(s) of its path. As a physiological aspect, measuring sound sources identifies it sound amplitude; however, its perception, which is based on the receiving end, is subjective 23 . While physical measurements are direct indications of acoustics by quantifying the amplitude of sound, perception involves sound to be interpreted by the receiver. As one aspect of human 21 U.S. Department of Housing and Urban Development, http://www.hudnoise.com/hudstandard.html. 22 Kinsler, 379. 23 Charles M. Salter Associates Inc., 43. Batungbakal 9 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects hearing, sound perception varies by the individual. Identifying most noise control strategies to decrease sound levels as a way to improve acoustic comfort, “Achieving effective office acoustics” emphasized low sound levels to not be a definite indication of acoustic comfort and improved productivity 24 . Similar to climate comfort, acoustic comfort varies within a range of sound levels often identified by individuals. By referring to sound levels relevant to indoor conditions and outdoor conditions, sound levels (in decibels, dB) can be used to indicate characteristics of common acoustic environments. As a result, obtaining field-measurements of existing sound conditions to characterize perceived conditions establishes site and façade parameters, and methods necessary to control the indoor acoustic environment and its effects on the function and comfort of a space. To ensure acoustic comfort that would enable the indoor environment to accommodate to its function, local, state, and federal organizations identified acceptable noise levels based on building occupancy type and functions. For office buildings, normally acceptable sound levels does not exceed 65 dB 25 (Fig.4-6). Figure 4. Acceptable Noise Levels for Communities Based on Occupancy: Los Angeles Land Use Compatibility for Community Noise (Office of Noise Control, California Department of Health Services (DHS) 24 Accumask ,“Achieving effective office acoustics”, 12-16. 25 City of Los Angeles, “Noise”, http://cityplanning.lacity.org/eir/AndoraAveTTM/DEIR/IV_H_Noise.pdf. Batungbakal 10 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 5. Unacceptable Outdoor Noise Levels for Surrounding Office Buildings. 3.1-1 Comfort, Health, Office As commercial development such as office buildings are common in urban environments, obtaining desired indoor sound levels are among the challenges office design has to consider to ensure a productive work setting. Environmental noise is globally recognized to negatively affect health and contribute to stress 26 . Along with poor indoor sound control, sound transmission from outdoor sound sources, such as traffic noise, are common issues affecting office comfort and productivity 27 . Research has shown noise pollution to have negative effects on health and work productivity 28 . Based on previous studies, noise pollution contributes to health issues, such as stress, noise induced hearing loss (NIHL), decreased productivity, and speech interference 29 . To address the quality of the global environment, the Environmental Protection Act of 1970 aimed to minimize environmental pollution by establishing objectives and programs 30 . Following the Environmental Protection Act of 1970, increased involvement from federal 26 European Commission, http://ec.europa.eu/environment/noise/. 27 Paradis, http://www.wbdg.org/resources/acoustic.php. 28 “Noise Pollution”, U.S. Environmental Protection Agency, http://www.epa.gov/air/noise.html. 29 “Noise Pollution”, U.S. Environmental Protection Agency, http://www.epa.gov/air/noise.html. 30 “Environment Protection Act 1970”, http://www.epa.vic.gov.au/about-us/legislation/acts-administered-by-epa. Batungbakal 11 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects agencies, such as the U.S. Department of Labor, the U.S. Department of Housing and Urban Development, and the U.S. General Services Administration, developed criteria and standards to improve safety conditions for indoor comfort for workspace and living environments 31 . The U.S. Department of Labor identified maximum noise levels acceptable to avoid health and safety issues for workers in an industrial setting 32 . In collaboration with the U.S. Department of Housing, the Federal Housing Administration (FHA) identified acoustic design criteria that would address control of sound transmission, airborne sound and it impact 33 . In response to uncontrolled noise endangering public health in urban environments, the Congress established the Noise Control Act of 1972 to further support state and local efforts in improving noise conditions in the urban environment 34 . The national policy focused on efforts towards regulating common noise sources, such as vehicular transportation, equipment, and appliances in commercial areas. Its primary purpose was to coordinate federal research in noise control, regulated noise emission standards for products, and increase awareness among the public of noise control methods 35 . Prior to the discontinuance of the Office of Noise Abatement (ONAC) in 1981, the Environmental Protection Agency continues to research and evaluate the effects of noise. Supporting state and local, noise source regulation by the EPA extends to transportation, construction, and products. 31 Cavanaugh, 1. 32 Cavanaugh, 1. 33 Cavanaugh, 1. 34 “Noise Control Act of 1972”, http://www.epa.gov/air/noise/noise_control_act_of_1972.pdf. 35 United States Environmental Protection Agency, http://www.epa.gov/lawsregs/laws/nca.html. Batungbakal 12 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Along with enforced policies, organizations have attempted to compose design guidelines emphasizing the influence of room parameters and occupant behavior in the acoustic environment. Organizations such as the U.S. General Services Administration collaborated with multiple professions to addressed acoustic comfort through a composed design guideline. The U.S. General Services Administration continuously focuses on improving the workspace environment with additional input from strategists for educational and federal governmental workspace, environmental psychologists, and acousticians 36 . In collaboration with differing fields, the U.S. General Services Administration composed “Sound Matters”, a workspace strategy 37 . Its strategies addressed minimizing noise levels to accommodate speech privacy and interaction in workspaces. 3.2 Office Workspace The function of office workspace is to enable work productivity and concentration. However, noise is frequently reported to negatively affect work productivity. Research surveys concluded noise to be the highest complaint (71 percent) negatively affecting work productivity 38 . In combination of lighting and indoor environmental quality, such as thermal conditions and ventilation, acoustics affect the function and comfort of office space. Although office space design thrives to acquire a productive work environment through sound attenuation, current work environments are developing into a collaborative dynamic that encourages interaction 39 . 36 General Services Administration Public Building Service, 3. 37 General Services Administration Public Building Service, 3. 38 LogiSon Acoustic Network, http://www.srose.com/documents/Office_Acoustics.pdf , 3 “The Importance of Acoustics in the Design Phase”, http:www.acoustics.com/ceu.asp. 39 General Services Administration Public Building Service, 3,9. Batungbakal 13 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 6. Varied Acceptable Noise Levels for Office Workspace. With designers heavily focusing on thermal comfort and daylighting, acoustic design is a building attribute often dismissed and underestimated. Realizing the influence of materials and construction elements in managing a building’s acoustic environment, federal, state, and local building codes and standards enforced requirements ensuring in improving the acoustical aspects in building construction, especially living and work environments. In response to health and work issues, local organizations in California initiated regulations and identified acceptable sound levels for office buildings. For instance, California Code of Regulations’ Title 24 enforced Sound Transmission Control requirements establishing uniform minimum noise insulation performance standards for specific building types 40 . For Los Angeles, one of the most populated cities, the City of Los Angeles Noise Ordinances identified acceptable and unacceptable noise levels from construction and roadway levels, which are equivalent to acceptable sound levels identified by the Department of Health. Identifying sound levels of construction and roadways, the city’s ordinance defined and quantified ambient 40 City of Los Angeles, 3. Batungbakal 14 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects sound levels varying in land use zoning, activities, and duration (for particular activities) based on sound measurement and criteria 41 . 3.3 Issues and Work Productivity Office workspace exemplifies the challenge in acquiring acoustic performance that would evoke productivity and concentration. Office space is characterized as an indoor environment that serves as a workplace to facilitate for commercial, professional, and bureaucratic work. Integrated with developing technology and business dynamics, office space reflects the continuous progression of the work setting and its influence on interaction and productivity. The setting and function of office spaces have progressed towards open-plan designs, enabling collaboration, openness, and flexibility. As work settings change, attention towards acoustic design grows. Balancing speech privacy and noise reduction remains as main issues affecting productivity of the work environment. As the office work culture changes, the modern office workspace redefines itself to enable interaction and varied activities, while minimizing acoustics effects on work productivity. As a result, design criteria for office buildings continue to change. Acoustic comfort for the office workspace is defined to enable interaction, speech privacy, and concentration 42 . 41 City of Los Angeles, 3. 42 General Services Administration Public Building Service, 4. Batungbakal 15 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects “Over-reliance on physical barriers can raise costs and render an office relatively inflexible, while still failing to satisfy all occupants’ acoustical needs” 43 - LogiSon’s “Achieving effective office acoustics” In today’s workspace environment, an open plan office is a common interior configuration due to reduced construction costs and its perceived image in encouraging an interactive workspace. Conventional open plan offices are characterized as a rectangular layout reducing construction costs to accommodate to its functions 44 . Issues in open plan offices involve minimized speech privacy and sound transmission. In contrast, enclosed offices are surveyed to provide more privacy compared to open plan office layout 45 . Although enclosed office plans provide more privacy due to its fixed mediums, such as partitions, enclosed office space and open plan office space are challenged to address room reverberation, sound transmission, adjacent noise levels, and speech privacy in order to obtain acceptable sound levels for its occupancy. Both office configurations share parameters that affect its indoor acoustic environment, such as absorption of panels, flooring, ceiling, work behavior, and office plan area. 43 LogiSon Acoustic Network, www.srose.com/documents/Office_Acoustics.pdf. 44 Bradley, J.S., http://archive.nrc-cnrc.gc.ca/obj/irc/doc/pubs/nrcc46274/nrcc46274.pdf. 45 O’Neill, www.knoll.com/research/downloads/OpenClosed_Offices_wp.pdf. Batungbakal 16 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects CHAPTER 4: The fundamentals in Acoustic Treatment 4.1 Office space: The Fundamentals Soundscapes can be controlled through architectural design, materials selection, and equipment for noise control 46 . For enclosed space and open plan layouts, such as an office workspace, sound pressure levels, background noise, and reverberation are among the main aspects of acoustics 47 . As an architectural design strategy, the building envelope is the first defense to noticeably attenuate outdoor sound sources and provide indoor sound levels acceptable for office functions. Enabling sound transmission loss, building envelopes respond to one aspect of acoustics by minimizing outdoor sound levels transmitted indoors. 4.2 Methods Using the Building Envelope Organizations composed different forms of criteria to improve acoustics. For instance, the U.S. General Services Administration’s Facility Standard for the Public Building Services P-100 criteria provide methods to mitigate sound levels with technical specifications (Fig. 7) 48 . Along with GSA’s “Sound Matters”, three aspects and its integration with one another were identified to achieve acoustic comfort, behavior, design, and acoustic treatment 49 . 46 Health Acoustics Research Team, http://www.acousticsresearch.org/. 47 InformeDesign Research Desk, 8, 36. 48 General Services Administration Public Building Service, 10,36. 49 General Services Administration Public Building Service, 10. Batungbakal 17 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 7. GSA P100 Acoustical Requirements (General Service Administration) A common strategy, the ABC rule, approaches acoustics in three aspects: absorb sound, block sound transmission, and cover through masking 50 . As a rule of thumb, it is often encouraged to address acoustics through all three methods. Sound absorption involves the surface material of an enclosed space, such as floors, walls, and ceilings. Blocking sound transmission concerns minimizing the sound path from the sound source to the receiver. Lastly, cover-up through masking responds to improving the acoustics of a space to accommodate its functions 51 . 50 General Services Administration Public Building Service, 28. 51 General Services Administration Public Building Service, 28 Batungbakal 18 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects CHATPER 5: Terminology in Defining Sound and Noise 5.1 Sound In matters of reducing sound transmission, improving the indoor acoustic environment involves understanding sources of sound and noise, the occupied space (receiving space), and the partition as the medium. Sound is a wave energy derived from an elastic medium’s molecular vibration 52 . Producing the energy of sound is referred as sound waves. The speed of a sound wave from its source reacts differently depending on its surrounding medium and its conditions. For instance, sound waves form as longitudinal compressed waves in air. Sound is generated when there is a disturbance of an elastic medium, resulting in a chain reaction of energy (pressure and vibrations) transferred towards surrounding air molecules 53 . Sound levels are identified through measuring the sound pressure level, using equipment with standardized frequency-weighting characteristics. Sound levels derive from its sound pressure level, which is a measurement of the magnitude of sound pressure on a logarithmic scale. Frequency of sound waves (Hertz) and magnitude of sound (decibels) are two measurable quantities for sound 54 . The magnitude of sound and its intensity is expressed in decibels (dB). The displacement in sound pressure is defined by frequencies (Hz). 52 Templeton, 13. 53 Charles M. Salter Associates Inc., 3. 54 Charles M. Salter Associates Inc., 125. Batungbakal 19 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 5.2 Magnitude and Intensity Decibels, dB, indicate the amplitude of sound waves and its traveling distance with or without an elastic medium 55 . Decibel is a common measurement unit used in acoustics for expressing the amplitude of sound, in form of a logarithmic ratio from two forms of measurement, sound pressure level or sound power level. Both based on a logarithmic scale, sound pressure level (Pa) derives from the magnitude of sound pressure while sound power level (watts) indicates the rate of radiated sound energy 56 . The unit is typically used to describe the magnitude of a sound with respect to a reference level equal to the threshold of human hearing, sound pressure level or sound power level 57 . Other than decibels, sound can be compared in terms of a measure of pressure (pounds per square inch, psi) 58 . Depending of the range of sound magnitudes, the decibel scale and its relativity to a reference value may be adjusted. A-weighted sound levels, one form of frequency weightings, is commonly used to weigh sound levels in accordance to the response of the human ear. Expressed as dBA, A-weighted sound levels is commonly used to measure environmental noise 59 . As normal human hearing detects sound within frequencies ranging from 20 Hz to 20,000 Hz, A-weighting scale (dBA) is applied to increase the accuracy of sound levels for 55 Janning, http://www.usg.com/documents/courses/02JuneUnderstandingAcoustics.pdf. 56 Cavanaugh, 325. 57 Charles M. Salter Associates Inc., 124. 58 Cavanaugh, 9. 59 Kinsler, 360. Batungbakal 20 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects human perception. In this study, the maximum sound level obtained from field-testing is used to adjust INSUL’s A-weighted traffic noise spectrum. 5.3 Frequency Concerning sound and vibration, frequency-the characteristics of sound, is measured in units of Hertz (Hz), which correspond to one cycle per second (cps) 60 . Although varying room conditions, structures, and materials for facades reduce sound levels, sound attenuation is also dependent on frequency. Frequency is also affected by the wavelength of the sound wave. Depending on the wavelength, the speed of sound is either accelerated or reduced based on the medium its traveling through (i.e. air, water, concrete). As massive elements demonstrated to control large frequency, such as low-frequency sound, small and thin elements absorb sound more efficiently when contacted with small wavelengths, such as high frequencies. Frequency indicates the complete vibration cycle of sound waves in a periodic duration. It indicates the number of cycles pressure waves repeat within a specific time frame. Sound consisting of high frequency indicate a high-pitch as low frequency indicate low-pitch sound. Analyzing sound waves, its frequency range is distributed as a band. An octave band, the most commonly used band, is a measurement system of distributed frequencies. Ranging from 16 Hz to 8000 Hz, values derived from doubling precedent values are 60 Charles M. Salter Associates Inc., 125. Batungbakal 21 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects distributed to structure the octave band. Structured similarly as an octave band, a one-third octave band provides more detailed measurements and is generally used in laboratory tests to measure sound transmission loss. As normal human hearing detects sound within frequencies ranging from 20 Hz to 20,000 Hz, A-weighting scale (dBA) is applied to increase the accuracy of measured sound levels. 5.4 Noise Noise pertains to undesired sound. Long durations exposed to noise often causes irritability and disturbance in concentrative functions. Other factors, which subjectively determine noise from sound, include magnitude, characteristics, duration, and time of occurrence 61 . Previous studies identified noise to be a strong attribute in negatively affecting concentration and productivity in the work environment 62 . 5.5 Sound Transmission In contrast to sound, noise refers to undesirable sound. As sound and noise are the same form of energy, noise is differentiated based on its subjective perception. Noise is subjective as it differs among individuals; however, various noise criteria identified common range of sound levels as noise depending on building occupancy. Also applied to noise, sound is transferred through multiple methods. Sound transmission through air-airborne conditions and sound transmission through structure-borne sound sources (i.e. partitions, ceiling, floor assemblies) are the most common 63 . Through air with a temperature of 70° F, sound travels 1,128 feet per second. 61 Sound and Noise, www.epd.gov.hk/epd/noise_education/web/ENG_EPD_HTML/m1/intro_1.html. 62 Templeton, 7. 63 Janning, http://www.usg.com/documents/courses/02JuneUnderstandingAcoustics.pdf. Batungbakal 22 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Through materials with elasticity, the speed of sound increases 64 . In order to obtain desired indoor sound levels, it is essential to understand its outdoor sound environment. With the intent to determine the resiliency of glass facades responding to sound within the urban environment, assessing sound levels from outdoor sound sources to its indoor sound level determine the effectiveness of glass façade assemblies and its façade components in reducing sound transmission. Implementing outdoor sound levels, equivalent noise level (Leq) is often utilized as a noise metric that considers duration and sound levels 65 . Equivalent noise level is derived from a consistent A-weighted level 66 . Determining the magnitude of reduced sound transmission necessary to obtain desired indoor sound levels exposes the influence of material and construction method in reducing sound. 5.5-1 Sound Reduction In this study, in order to determine the amplitude of sound attenuated from glass facades and its material components, its reverberant sound level from its outdoor source is compared to indoor sound levels in its receiving room. For instance, a sound source from the outdoor environment compared with the sound levels of an enclosed space, the receiving room, quantifies sound attenuated from the façade assembly and its façade components and the decibel difference between the outdoor sound source and the indoor environment. 64 Janning, http://www.usg.com/documents/courses/02JuneUnderstandingAcoustics.pdf. 65 City of Los Angeles’ Mangrove Estates Site Mixed Use Development EIR, www.planning.lacity.org/eir/MangroveEstates/FEIR/EIR%20Sections/4.8%20Noise.pdf 66 City of Los Angeles’ Mangrove Estates Site Mixed Use Development EIR, www.planning.lacity.org/eir/MangroveEstates/FEIR/EIR%20Sections/4.8%20Noise.pdf Batungbakal 23 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Attenuation, also termed as noise reduction (NB), is measured in decibels 67 . Quantified similarly to transmission loss (TR), noise reduction is defined by its sound pressure level from its source room and its difference from the sound pressure level of its receiving room 68 . Noise derives from the same formulation of transmission loss; however it consists of a correction term which emphasizes the impact of vertical surfaces, 10 log A/S, where A is the sound absorption in the receiving room and S is the surface area of the intervening partition 69 . Transmission Loss TL = 10 log 1/ ţ Noise Reduction Calculating noise reduction, increasing the surface area will cause noise reduction to decrease as sound transmission would increase. However, its sound absorption in the receiving room also considers the conditions of the room, such as furnishings and materials. Considering sound absorption based on the conditions of the receiving room exemplifies other variables implemented to determine sound reduction. For instance, flanking sound (also flanking paths) is the result of other mediums affecting sound transmission. For instance, in addition to partitions, air ducts and openings for ventilation between two rooms affect sound transmission 67 Cavanaugh, 56. 68 Charles M. Salter Associates Inc., 124. 69 Charles M. Salter Associates Inc., 124. Batungbakal 24 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects from one source to its receiving room 70 . Although double-skin facades are noted to improve sound attenuation, increased openings for ventilation more than 16 percent of its façade area relinquishes its defense against sound transmission 71 . With additional variables considered, noise reduction is more indicative of noise reduction (sound isolation, NR) within a given context while transmission loss (sound insulation, TL) is a laboratory measure, which isolates its data and conditions (i.e. partition size). In this study, direct transmission loss is based on the INSUL calculations, which predicts direct transmission loss based on the mass per unit area and the modulus of elasticity of a glass panel 72 . Transmission Loss TL = 20 log (mf) – 48dB The formula is applied to predict direct transmission loss provided by glazed facades at lower to mid frequencies, which correspond to mass law. At higher frequencies and critical frequencies which indicate resonance and the coincidence effect, transmission loss is calculated using the following formula 73 : Transmission Loss TL – 20 log (mf) + 10 log (f/fc) - 44dB 70 Charles M. Salter Associates Inc., 124. 71 Lee, 92. 72 INSUL Technical Info, http://www.insul.co.nz/technicalinfo.html#. 73 INSUL Technical Info, http://www.insul.co.nz/technicalinfo.html#. Batungbakal 25 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects CHAPTER 6 Blocking Sound Transmission through the Building Envelope- Glass Facades With methods to mitigate noise through land use and site orientation, building enclosures act as the first structural defense against outdoor noise. A building envelope such as a glass facade is one form of blocking sound transmission from outdoor sound sources. Increasingly noted to be favored among commercial building design, glass facades draws users to its visual attributes. Providing visual transparency and abundant daylight exposure often entails deficiencies in building performance, such as sound insulation and heat insulation. Although glass facades acquire transparency, glass facades are not as effective in attenuating sound as other façade construction, such as concrete. In this study, the acoustic performance of glass facades, such as single-pane facades, double- pane facades, and double-skin facades, are determined from its ability to block sound transmission from outdoor sound sources, such as traffic noise. Double-skin facades demonstrate more potential in reducing noise from sources, such as road traffic, aircrafts, and rail lines 74 . Development in façade technology continually face issues involving energy, user comfort, and façade adaptation towards varied conditions 75 . Enabling sound attenuation, double- skin facades addresses user comfort. 6.1 Single-Pane Facades and Double-Pane Facades A single-pane facade refers to fenestration consisting of a single pane of glass. Forming a insulated glazing unit (IGU), a double-pane façade is (also known as double-glazing) is 74 Waldner, 87. 75 Knaack, 13. Batungbakal 26 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects composed of two glass panels separated with either air or inert gas, which functions as an insulating layer 76 . The assembly of a double-pane facade is considered to provide an effective barrier between indoor and outdoor environments when properly sealed and framed. 6.2 Double-Skin Facades Double-skin facades derived from the need to address indoor environmental quality, energy use, air pollution and noise pollution 77 . Its transparency allows natural daylight to penetrate through, minimizing use of artificial lighting 78 . While its ability to provide thermal comfort, visual continuity, and ventilation are heavily explored in research and applications, the acoustic comfort a double-skin facade provides is increasingly acknowledged. Double-skin facades are characterized by a secondary glazing layer placed on its exterior side, improving ventilation and acoustic performance. The air-cavity (also known as an air corridor) separates the interior layer- a standard insulated glazed unit (IGU), and the secondary layer- a single glazing that acts as insulation against climate change, wind, and noise 79 . In addition to glass type and glass thickness, double-skin facades can differ by its interior skin, secondary skin, air-cavity, and operability. The inner and secondary skin of a double-skin façade can both be composed of insulated glazing units (IGU); however, double-skin facades consisting of an insulated-glazing unit for its inner skin and an single-glaze for is secondary skin is a common façade assembly for commercial buildings. Air-cavity between the interior skin and 76 Knaack,. 21. 77 Poirazis, 12. 78 Poirazis, 12. 79 Poirazis, 17. Batungbakal 27 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects secondary skin can vary from 8 inches (200 millimeters) to more than 79 inches (2 meters) 80 . Along with controlled shading systems responding to daylight, double-skin facades provide the option for its inner skin to be operable, allowing natural ventilation to flow throughout the facade. Different types of double-skin façades are distinguished based on the type of ventilation airflow (input and output), airflow direction, air-cavity depth, and partitioning (Fig. 8-9) 81 . A box-window façade consists of horizontal and vertical panels. Forming a grid, horizontal and vertical panels distribute overall a box-window façade into individual façade units 82 . The assembly of a box-window facade allows for adjustability with its top and bottom ventilation flaps and inlet and outlet air to circulate through its story-high dimensions. A corridor façade primarily consists of horizontal panels, which addresses issues involving acoustics, ventilation, and fire-safety 83 . Designed in response to box-window facades’ inability to isolate ventilation, corridor facades provide staggered ventilation within its two skins, which is based on the facade framing and its connections to its façade components. Provided with façade elements similar to box-window facades, shaft-box façades are connected vertically to reduce stacking. Shaft-box facades release its exhaust air into a shaft mounted to its 80 Poirazis, 18. 81 Poirazis, 176. 82 Poirazis, 21. 83 Poirazis, 21. Batungbakal 28 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects façade that exerts the air several floors from its source. Using its shafts as vertical distribution, shaft-box facades provide improvement in thermal efficiency 84 . Multi-story double-skin facades are noted to reduce outdoor sound transmission when its outer skin does not consist of openings; however, sound transmission from indoor noise sources persists through its inner skin. Unlike box-window facades, multi-story double-skin facades lack horizontal and vertical panels. When utilized as a ventilated double-skin façade, ventilated openings for multi-story facades are usually located near the edge of the floor and roof 85 . Figure 8. Double-Skin Façade Types: Partitions Figure 9. Double-Skin Façade Types: Airflow Direction 84 Knaack, 32. 85 Poirazis, 22. Batungbakal 29 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects With multiple façade assemblies to consider, architectural designers are challenged with evolving environmental noise resulting from urbanization, its soundscape. As the dynamics in the urban environments creates its own soundscape, designing a façade assembly to respond to environmental noise resulting from urbanization is a challenge. Responding to site context, architects respond to soundscape by specifying the construction of the building enclosure in considering two forms of sound paths: (1) airborne noise from the outdoor sound sources and g (2) structure-borne- sound source caused within the building structure 86 . Utilizing building facades to deflect environmental noise, it is crucial to consider the parameters (site, room, façade simulation) and façade components in façade design. Depending on the façade assembly type, the choice of glass type, glass thickness, and air-cavity dimension provides varied transmission loss. CHAPTER 7: Performance of Glass Facades in Need of Further Exploration 7.1 Disadvantages on Reliance: Designers Relying on Claimed Acoustic Properties Engineers are often involved in façade design, collaborating with professions such as architects, acousticians, and engineers. As a result, architectural designers are disconnected in the process of façade design. Designers also rely on stated acoustic performance. Although a number of glass manufacturers provide product information on tested acoustic properties, designing façade systems towards a sound level range would not ensure its acoustic performance to be applicable towards different settings. Relying on manufacturers and projected acoustic performance of 86 Kinsler, 379. Batungbakal 30 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects assemblies limit designers’ perception, leading to inaccurate acoustic estimations. Although building products such as manufactured glass provide information on sound insulation under different parameters, it is not typically applicable in predicting sound insulation within existing settings. 7.2 Acoustic Performance of Double-Skin Façade in Workspaces 7.2-1 Disconnection between Façade Design and Architects As an established trend in office building design, the visual aspects of glass facades allows natural daylighting and transparency between the exterior and interior environment that would contribute to work productivity and integration in the workplace. Identified as an extension to the outdoor environment that contributes in improving productivity, office space are often assembled with glazing as its building enclosure. Glass facades fall within the category of thin partitions, as it provides unobstructed daylight and views 87 . In assuring indoor comfort for building occupants, building design strategies often focuses on natural ventilation and daylighting. Development in glass facades heavily focused on improving its response towards light and thermal properties, often dismissing other important components such as acoustics. With increased awareness of acoustic comfort and its influence in improving work efficiency, living, and health, utilizing the building envelope is one aspect of building design sought to reduce sound transmission. Office buildings are among various workspaces identifying acoustic comfort a key aspect in maintaining work productivity, privacy, as well as collaborative interaction. Aligned with today’s collaborative business dynamic, indoor 87 Kinsler, 162. Batungbakal 31 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects environments such as office areas call for spaces that are productive as well as flexible and connected to its surroundings. Utilizing glass as a façade establishes the building’s enclosure while connecting to its surroundings. Given with its aesthetic attributes, glass facades allow unmanaged amount of daylight penetration, resulting in issues with thermal comfort, glare, as well as sound transmittance. As a result, glass facades often lead to concerns with energy consumption in cooling and insulating its occupied space. Differing from its surface composition and assembly, variations of glass facades are capable to manage thermal and sound transmittance, and ventilation. For instance, double-skin facades distribute sound, thermal, and ventilation flow through its cavity layer. Double-skin facades and curtain walls are developing as more responsive to thermal conditions, energy-conserving facades are increasingly sought for. With numerous façade technologies, modeling and analyzing its acoustic performance is complex. Noted for its thermal and ventilation aspects, double-skin facades are argued to improve acoustic insulation against exterior noise, when properly designed and assembled. 7.3 Intent of Research Study The pursuit to improve the acoustic performance of glass facades without diminishing its visual aspects defines a delicate line in approaching the challenge to maintain its aesthetic features, which require façade design to be understood by designers. The primary goal of this research is to justify the acoustic performance of glass facades, such as single-pane façades, double-pane façades, and double-skin facades, its façade components, and its ability to attenuate sound from Batungbakal 32 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects common environmental noise conditions in the urban environment. The objectives of this study intend to: o Enable building designers to comprehend direct sound transmission loss and the importance of field-assessment in improving the acoustic performance of a façade design; o Implement field-measurements in INSUL façade simulations to improve accuracy of predicted sound attenuation, from lab setting to existing conditions; o Identify façade components to improve direct sound transmission loss; o Assess the acoustic performance of glass facades based on indoor sound levels derived from direct transmission loss; and o Determine the acoustic performance of double-skin façades based on indoor sound levels derived from direct transmission loss as a relative comparison While implementing field-measured sound levels to obtain indoor sound levels provided by simulated facades’ direct transmission loss, a design guideline that quantified and compared the acoustic performance of simulated glass façades, serve as a design support tool for architects. The design support tool for glass façade systems is intended to provide building designers an informative approach in determining the acoustic performance of façade components (such as glass type, glass thickness, and cavity depth) suited to respond accordingly to site-specific environmental noise and to acquire desired indoor sound levels based on building occupancy type. Batungbakal 33 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Most design tools are identified to predict performance under ‘worst-case’ design conditions. With claims of improving performance, it is difficult to comprehend claims from predictive sound insulation software. Because field-measurements are implemented in composing the design support tool, the acoustic performance indicated by the design support tool is conditional as it uses field-measurements as the baseline. In efforts to reduce sound transmission from outdoor sound sources, assessing standard glass façade components through field-testing and façade simulations emphasizes its acoustic performance that would improve acoustic insulation. Measuring and validating direct sound transmission loss from glass facades differing in façade components indicate the significance in glass thickness, air-cavity depth, and glass composition in attenuating outdoor sound transmission. Utilizing acoustic data obtained from field-measurements and INSUL simulations, the acoustic design support tool is composed to assist architectural designers in considering multiple options when designing glass facades early in the design phase. 7.4 The Importance of Acoustic Design “ If the definition of thermal comfort is that condition where neither a warmer, nor cooler environment is desired, then acoustic comfort can be paralleled as that condition where neither too quiet nor too noisy an environment exists.” 88 Sound is one attribute that defines the comfort of workspace. In perceiving sound as tolerable or as a nuisance, the accepted hearing range differs among individuals 89 . “Achieving effective 88 Muneer,, 186. 89 Templeton,.2. Batungbakal 34 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects office acoustics” emphasized low sound levels did not guarantee acoustic comfort and improved productivity 90 . Similar to climate comfort, acoustic comfort varies within a range of sound levels often identified by individuals. Among lighting (9%) and air quality (20%), noise (71%) is reported to have the highest complaint in hindering workspace productivity 91 92 (Fig.10). Figure 10. Top Issues in Affecting Workspace Commercial development, such as office workspaces, and its varied functions is a challenge in providing acoustic performance which responses to its needs, from noise reduction to speech privacy 93 . The need for noise reduction and speech privacy require reduced sound transmission. For instance, commercial spaces, such as lobbies, restaurants, and malls, require for a balance where noise isn’t overwhelming yet its spaces enable activity. Other commercial spaces, such as open-plan offices, call centers, and meeting areas, require speech privacy. 90 Accumask, 12,16. 91 “The Importance of Acoustics in the Design Phase”, www.acoustics.com/ceu.asp. 92 Curtland, http://www.buildings.com/tabid/3334/ArticleID/14557/Default.aspx. 93 "Acoustical Analysis in Office Environments Using POE Surveys", www.cbe.berkeley.edu/research/acoustic_poe.htm Batungbakal 35 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Acoustic design can benefit users through matters of productivity, health, safety, comfort, and functionality 94 . Implementing acoustic design early into the design phase can improve its functionality and accommodation for its users. With design tools well invested in evaluating the thermal and day lighting performance of glass facades, engineers and designers attempt to decipher the acoustic performance of glass facades. In addition to field-measurements and sound level criteria, design tools are attempted to improve accuracy in modeling and analyzing building systems such as glass facades. With designers heavily focusing on thermal comfort and daylighting, acoustic design is a building attribute often dismissed. While this study assesses and validates the influence of glass façade components and field-assessment in improving sound attenuation estimation of double- skin facades, the process in composing a design support tool that would assist building façade designers is an attempt to improve accuracy in estimating the acoustic performance of double- skin facades. 94 “The Importance of Acoustics in the Design Phase”, www.acoustics.com/ceu.asp. Batungbakal 36 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects CHAPTER 8 Background- Efforts to Improve Acoustic Properties of Glass Facades Based on its Materiality, Structure, and Design Implementation Since acoustic evaluation is not universally understood, building designers are not fully aware of inaccuracies acoustic estimations can provide. To improve accuracy in estimating the acoustic performance of glass facades such as double-skin facades, precedent research attempted to determine the influence of site parameters, testing parameters, and façade components in improving estimated acoustic performance to align with real-life sound conditions. 8.1 Testing Standards Acoustic laboratory testing and field-testing conditions for sound transmission from facades described in Table 2 determines methods applicable to this study’s implementation of field- measurements from existing urban conditions. A façade specimen tested in an acoustic laboratory is given a single number rating STC, Sound Transmission Class. In contrast, a field- test is conducted when the façade assembly is installed on site. The sound isolation performance from field-tests typically perform 5dB to 10dB less than a laboratory test because the assembly is exposed to acoustic flanking paths, such as air leaks or building penetrations. Batungbakal 37 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects TABLE 2: FIELD-TEST AND LABORATORY TEST CONDITIONS (Acoustic Performance Testing) TESTING Laboratory Field controlled environment uncontrolled environment temperature + humidity temperature + humidity conditions are monitored, recorded + used in the calculations test rooms designed to provide a uniform diffuse sound field on both sides Room sizes + absorption characteristics varies; good diffuse sound field conditions rare receiving room – low sound absorption Exterior and interior noise sources can affect the test results, if not minimized For example, façade system may not have uniform results for all panels, flanking problems, poor construction – poor sound transmission loss testing and results STL measurements usually 3 to 5 dB lower than laboratory results In efforts to improve acoustic performance and its estimation, precedent studies observed testing standards that varied in approach. In response to the need to provide a standardized testing method focusing on transmission loss, Cassidy’s “Evaluation of Standards for Transmission Loss Tests” compared the following standards used to test transmission loss: o SAE J1400- the American National Standard for Laboratory Measurement of the Airborne Sound Barrier Performance of Automotive Materials and Assembly, and o ISO 15186- the International Standard for measurement of Sound Insulation in Buildings and of Building Elements using Sound Intensity Batungbakal 38 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Considered as reliable international standards, J1400 and ISO 15186 measure transmission loss accordingly to mass law, a principle that determines doubling the mass to increase transmission loss by approximately 6 dB 95 . Although J1400 differs from ASTM E90 Standard Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements, testing standard J1400 is similar to ASTM E90 methods for a reverberation room 96 . In Cassidy’s study, ISO 15186 considers sound intensity measuring sound transmission loss of lead. Both standards, J1400 and ISO 15186, were distinguished based on by use of different equipment and method of calibration. Testing conditions under J1400 utilized microphones as sound meters to measure sound pressure levels. In contrast, test conditions in accordance to ISO 15186 determined sound transmission loss based on intensity measurements in a hemi-anechoic chamber 97 . In accordance to J1400, microphones utilized as sound meters specified the number and spacing of sound measurements. ISO 15186 measured sound intensity within 96 grid points in a hemi-anechoic chamber. To determine the accuracy of the two testing standards, transmission loss calculated using testing standards J1400 and ISO 151186 were compared on a 1/3 octave band frequency scale (Fig.11). Both testing standards were compared after measuring transmission loss provided by a steel plate and transmission loss provided by a lead sheet. For instance, through comparison of both standards, transmission loss provided by a steel plate were in accordance of mass law. Throughout the sound spectrum, both testing standards provided similar results, with the 95 Charles M. Salter Associates Inc., 118. 96 Cassidy, M., R.K. Cooper, et al. 2. 97 Cassidy, M., R.K. Cooper, et al, 2. Batungbakal 39 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects exception of frequencies where transmission loss didn’t match. Although J1400 and ISO151186 differed by use of equipment and measurement conditions, comparing transmission loss derived from both test standards validated laboratory testing. Figure 11. Comparison of J1400 and ISO 15186 for Steel: Transmission Loss and Difference of Transmission Loss between Two Standards. (Cassidy, M., R.K. Cooper, et al) Comparison of J1400 and ISO 15186 validated both testing standards to provide accurate transmission loss measurements that align with mass law. Although both testing standards provided different measurements of transmission loss at critical frequencies where resonance and the coincidence effect occurs, Cassidy’s study determined further research should focus on the improving accuracy in measuring transmission loss at critical frequencies. 8.2 Potential of Facade Components 8.2-1 Laminated Glass Validating testing methodologies to contribute in improving acoustic assessment and estimation, other studies directed their focus on the acoustic performance of façade components, such as glass composition. Keller’s "Improved Sound Reduction with Laminated Glass” emphasized the need to further develop sound insulation methods that would respond to noise pollution in Batungbakal 40 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects increasingly populated areas. Identifying human hearing as a subjective form of sound measurement, laboratory testing were conducted to measure the acoustic performance of glass with PVB laminate and glass with TSC laminate 98 . Two forms of laminated glass, standard PVB laminate (Poly Vinyl Butyral, PVB) and acoustic laminate (Trosifol Sound Control, TSC) were compared through airborne tests, simulations, and vibration measurements. In the process of comparing two glass laminates, the study evaluated methods to identify its acoustic quality (Fig.12). Figure 12. Comparison of Float Glass, Glass with PVB Laminate, and Glass with TSC Laminate (Keller) 8.2-2 Glass Type and Thickness Identifying laminated forms of glass to reduce sound transmission, increasing glass thickness does not constantly reduce sound at critical frequencies. Critical frequency, defined as frequencies where bending waves (stiffness) is equal to the speed of sound in air to indicate the 98 Keller, 30. Batungbakal 41 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects reduced transmission loss, is another term for coincidence effect 99 . In Schimmelpenningh’s study, critical frequencies served as indications in determining the acoustic performance of different glass types 100 . Schimmelpenningh’s study provided a brief background of initial acoustic evaluations considering rating systems and different testing standards to measure sound transmission. Three factors were identified in designing acoustic glass: mass, insulating air space, and interlayer damping. Research suggested that further development in these factors would lead to targeted acoustic control. Identifying the composite inter-layers in laminated glass to contribute to sound reduction, Schimmelpenningh’s study determined further development in interlayer composition of glass to be a key element in improving glass facades as an acoustical barrier. The performance of inter-layered glass is tested for conditions such as temperature, wind, and vehicular noise 101 . 8.2-3 Façade Systems Acknowledging the disconnection between field-testing and calculated results, research described in Foss’ “Façade Noise Control with Glass and Laminates” advocates ‘design by analysis’ in order to link two methods of measurement to validate results 102 . As a baseline comparison, transmission loss of monolithic glass is compared with transmission loss resulting from laminated glass for single-pane facades and double-pane facades. Five glass specimens differed by laminate film thickness (0.38mm, 0.75mm, 1.14mm, 1.52mm, and 2.25mm) were compared to monolithic glass in order to determine the influence of laminated glass in improving transmission loss. Foss’ study determined that 1.52 mm PVB-laminated glass provide the highest 99 Templeton, 81. 100 Schimmelpenningh, 1. 101 Yoshioka, 1. 102 Foss, 8. Batungbakal 42 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects measurement of transmission loss (Fig.13-14) compared to a single-pane façade composed of monolithic glass. Identifying glass with greater laminate film thickness to improve sound transmission loss from simulated single-pane facades, double-pane facades composed with laminate film were compared to double-pane facades composed of monolithic glass. Results from simulated double- pane facades (insulated glazing unit) identified its air-cavity to contribute to increased transmission loss in response to sound at 500Hz and lower 103 . Figure 13: Transmission Loss: Comparing Glass with Varied PVB Thickness to Monolithic Glass (Foss) 103 Foss, 8. Batungbakal 43 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 14: Transmission Loss: Comparing IGU with PVB to Monolithic IGU (Foss) Focusing on laboratory testing, the coincidence effect and resonance were observed for different façade assemblies: single-pane laminated glass, and single laminated IGU. The coincidence effect defined a reduction in transmission loss, which indicated frequencies where the speed of sound is equal to the speed of bending waves 104 . Resonance is defined as an increase in sound pressure 105 . Simulations analyzed sound transmission provided by monolithic glass and laminated glass. 8.3 Field-Testing Implementation Other research studies attempt to integrate sound assessment to an urban scale. For instance, in Oliveira’s “Planning the Acoustic Urban Environment: a GIS-centered approach”, research contributed to Urban Spatial Analysis Environmental System (SEAU), a tool that assesses noise 104 Foss,8. 105 Charles M. Salter Associates Inc., 323. Batungbakal 44 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects impact based on city planning and environmental aspects 106 . In response to noise pollution contribution from urban growth, SEAU integrated GIS-based application with spatial data. Spatial data pertained to activities consisting of varied sound levels, such as economic activity and traffic noise (Fig.15). While providing a tool that provides an environmental acoustic analysis, the study demonstrated spatial elements to be a key attribute in improving acoustic analysis. Figure 15. Integration of Spatial Data and Activity: Combining Mapped Traffic Noise and Mapped Activity in Commercial Areas (Oliveira) 8.4 Material Performance Acknowledging the need to improve acoustic comfort indoors, efforts in improving the acoustic performance of glass facades focused on its material and assembly. In efforts to improve sound transmission loss of glass facades, designers and organizations attempted to redefine acceptable and unacceptable acoustic performance based on the material of the façade and its assembly. In Jerry Lilly’s “Recent Advances in Acoustical Glazing”, laminated glass is identified to improve sound control compared to monolithic glass, which provided significant reduced 106 Oliveira, 2. Batungbakal 45 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects transmission loss at critical frequencies 107 . Like other studies, critical frequencies are defined as frequencies glass vibrates when the sound wave frequency is incident on the glass. Critical frequencies occurs at either lower or higher frequencies based on the thickness of glass, indicating resonance and the coincidence effect. Testing the acoustic properties of glass with a recent iteration of laminate, S-Lec Acoustic Film (SAF), along with Mono Layer Acoustical Film glass and PVB-laminated glass, glass laminated with SAF improved sound transmission loss in conditions of varied temperatures and frequencies. Lilly’s study differentiated from other research as it compared the acoustic performance of different glass compositions while considering conditions, such as temperature, as an influential element in the acoustic performance of glass. Measuring sound transmission loss of three types of ¼-inch laminated glass, Monlithic, PVB, and ESCL, Japan’s Kobayashi Institute of Physical Research conducted vibration tests (using ISO/PRF PAS 16940) that provided data indicating increased sound transmission loss in response to high frequencies. With relative sound transmission loss at frequencies below 800Hz, results determined the material’s mass to impact sound transmission loss; however, when exposed to lower temperature (43° F), the acoustic performance of the three laminated glass specimens reduced in response to sound at1250Hz (Fig. 16). At mid and low temperatures, sound transmission loss provided by each of the three glass specimens tested provided maximum sound transmission loss at 850Hz (at 63°F) and 1250Hz (at 43°F). While sound transmission loss decreased at critical frequencies between 1250Hz and 2000Hz, the three laminated glass specimens provided increased transmission loss in response to sound sources above 2000Hz (Fig.17). 107 Lilly, 8. Batungbakal 46 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 16. Sound Transmission Loss of ¼-inch Laminated Glass, 68° F – Kobayashi Institute of Physical Research Test Results in Accordance to JIS A-1416, equivalent to ASTM E90 (Recent Advances in Acoustical Glazing) Figure 17. Sound Transmission Loss of ¼-inch Laminated Glass, 48° F- Kobayashi Institute of Physical Research Test Results in Accordance to JIS A-1416, equivalent to ASTM E90 (Recent Advances in Acoustical Glazing) 8.5 Design Consideration While precedent research approached assessing the acoustic performance of glass and glass façades by analyzing different testing methods, standard and modified glass façade components (such as glass types and glass thickness), façade assemblies, research conducted by the General Batungbakal 47 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Services Administration differs from precedent research. Research and testing conducted by the General Administration were intended to compose an acoustic design guideline. Organizations such as the General Services Administration’s Public Buildings Service developed design strategies to improve the acoustic aspects of a work environment. Identifying acoustic comfort to differentiate on the functionality of the workplace, GSA developed acoustic design strategies based on work patterns and activity zones. GSA’s pursuit to improve acoustic comfort redefined traditional acoustic settings to the modern workplace. Acknowledging that most designers generally approach workplace areas to be conceived as requiring the same acoustic environment as libraries, GSA identified acoustic comfort to rely on the intended function of the space. Depending on how spaces are utilized, GSA distinguished work areas as either interactive or concentrative in order to determine indoor sound levels recommended (Fig.18-19). Figure 18. Zoned Activities Figure 19. GSA Work Pattern Matrix (General Services Administration) (General Services Administration) Batungbakal 48 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects CHAPTER 9 Methodology 9.1 The Building Envelope: Reducing Sound Transmission A building envelope is the exterior element of a building, forming a boundary between the indoor environment and the outdoor environment 108 . As a form of building envelope, glass facades have the potential to reduce sound transmission depending on its assembly and composition. The building envelope is the first defense in reducing sound transmission by blocking sound emitted from external sound sources. Every city has its own unique soundscape. The acoustic performance of glass facades, such as double-skin facades, varies based on façade components and its project site. As urbanization embodies constant change in urban conditions, estimating direct sound transmission loss from double-skin facades and determining double-skin façade components that would improve sound attenuation becomes more critical. The approach of this study demonstrate referencing field-measurements to adjust INSUL’s outdoor sound spectrum, ISO 717 Traffic Noise, allows INSUL façade simulations to respond to field-tested conditions, indicating the acoustic performance of glass façade components and its influence on improving sound attenuation through direct sound transmission loss. Implementing the maximum outdoor sound level obtained from field-measurements to INSUL façade simulation parameters allows INSUL to estimate direct transmission loss provided by single- pane facades, double-pane facades, and double-skin facades in response to existing sound conditions. While INSUL façade simulations provide indoor sound levels, which consider parameters such as room volume, reverberation, and façade area, this study focuses on the direct 108 Energy Efficiency Building Design Guidelines for Botswana. Section 7, www.bauerconsultbotswana.com/7_BuildingEnvelope.pdf Batungbakal 49 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects transmission loss of glass façades. Therefore, this study identifies indoor sound levels derived solely from INSUL’s calibrated traffic noise and sound transmission loss provided by each façade specimen. Using single-pane facades and double-pane facades as baseline comparisons to compare the magnitude of improved transmission loss provided by double-skin facades validate the influence of glass façade components in attenuating sound levels. Implementing field-measurements to INSUL façade simulations allow simulation estimations to indicate the acoustic performance of glass facades that are applicable to real-life settings, assisting building designers in making informed decisions in façade design toward the acoustic environment as well as increase building designers’ understanding on the influence of façade components and parameters in affecting indoor acoustic quality. With the objective to improve the indoor acoustic environment for office workspaces, it is fundamental to field-test common conditions for office workspace and obtain indoor sound levels and outdoor sound levels. Obtaining indoor sound levels and outdoor sound levels of existing conditions in the urban environment determine whether current sound conditions are acceptable or a disturbance to its building occupants, and the magnitude of transmission loss necessary to provide acceptable sound levels for the workspace environment. In the process of identifying acceptable sound levels, it was necessary to define ‘acceptable’ sound levels suitable for different building occupancy and functions such as office workspace. In this study, sound levels classified as acceptable for office workspace were referenced to acceptable indoor sound levels identified by agencies and organizations. For instance, federal agencies, such as California’s Department of Health Services and Housing Urban Development, Batungbakal 50 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects identify indoor sound levels exceeding 65dBA to be unacceptable for office buildings (Fig.20). Normally acceptable indoor sound levels for office buildings range from 50dB to 65dBA while acceptable outdoor sound levels surrounding office buildings grange from 50dBA to 77dBA 109 . Outdoor sound levels obtained from field-testing are referenced to a sound level range identified by agencies and organizations. Common traffic noise sourced from vehicular activity range from 60dB to as high as 90dB 110 111 . The following considerations are identified to influence the indoor acoustic environment: source of noise, the occupied space (receiving space), and the barrier partition (Fig. 21). As blocking sound transmission is one approach in attenuating sound, this study focuses on the influence of parameters- through field-tests and INSUL simulations, and glass façade components in improving the acoustic performance of double-skin facades. In this study, outdoor sound sources were measured to initially determine existing sound amplitudes and façade components necessary to reduce sound transmission. 109 City of Los Angeles’ Mangrove Estates Site Mixed Use Development EIR, www.planning.lacity.org/eir/MangroveEstates/FEIR/EIR%20Sections/4.8%20Noise.pdf 110 Kinsler, 362. 111 Cavanaugh, 13. Batungbakal 51 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 20. Acceptable and Unacceptable Indoor Sound Levels Based on Land Use and Building Occupancy. Figure 21. Field-testing and Simulations: Sound Source, Medium, and Receiving Room. 9.2 Methods: Overview Determining the acoustic performance of double-skin facades and the influence of its façade components were built upon the methodology of implementing outdoor sound levels obtained from field-testing existing conditions to INSUL facade simulations and establishing comparative baselines to compare and quantify improved transmission loss provided by façade assemblies assessed, which indicate the acoustic performance of three facades types: single-pane facades, double-pane facades, and double-skin facades (Fig.22). Measuring indoor and outdoor sound Batungbakal 52 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects levels, six workspace conditions in Los Angeles were selected based on GIS-sourced data that indicated locations with high concentrations of commercial development and vehicular traffic. The maximum outdoor sound level obtained from field-measurements is used as a correction factor to INSUL’s ISO 717 traffic noise prediction method to resemble the existing outdoor condition in Los Angeles. As a result, a 1/3-octave band sound spectrum is obtained, resembling an outdoor sound condition in Los Angeles. Setting the parameters of INSUL facade simulations, glass façade components were selected due to common industry size compliant for commercial buildings. Obtaining estimated sound transmission loss from INSUL-simulated facades, comparisons between single-pane facades, double-pane facades, and double-skin facades determined improved sound transmission loss based on the acoustic performance of facade components of a façade assembly, such as glass type, glass thickness, and air-cavity depth. Although INSUL façade simulations provide indoor sound levels that consider parameters such as room volume, reverberation, and façade area, this study defines the acoustic performance of glass facades based on the direct transmission loss. With the intent to focus on the performance of glass facades as an acoustic barrier, indoor sound levels identified in this study derive solely from INSUL’s calibrated traffic noise and direct sound transmission loss provided by each façade specimen. Quantifying the decibel difference between a single-pane façade composed of ¼-inch monolithic glass and a double-pane façade composed of ¼-inch monolithic glass to a double-skin facade composed with the minimum glass thickness (1/4-inch) and air-cavity depth acceptable for commercial buildings determined the amount of improved transmission loss provided by different glass façade assemblies. While improved direct transmission loss and indoor sound levels are quantified from façade comparisons, the sound spectrum of each façade specimen were analyzed at low frequencies, high frequencies, and critical frequencies where Batungbakal 53 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects resonance and the coincidence effect occurs, which defined trends and overall acoustic performance. Identifying the acoustic performance of glass façade components and its influence on improving sound attenuation through direct transmission loss, a design support tool, a guide to inform building designers to determine façade components necessary to reduce outdoor sound transmission and material costs, is composed of indoor sound levels derived from directed transmission loss provided by INSUL-simulated facades. Implementing field-measurements allowed the design support tool to specifically address conditional single-figure A-weighted indoor sound levels. Figure 22. Overall Methodology to Obtain Estimated Sound Transmission Loss of Façade Assemblies. 9.3 Methods: Tools The approach of this study is aimed to enforce acoustic design considerations in the early stages of design decision-making. Methods include field-measurements using Decibel 10 th (Fig. 23), a hand-held sound meter device, and sound transmission simulations using INSUL (Fig.24-25), a sound insulation prediction software (INSUL 2011). Batungbakal 54 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 23. Decibel 10 th Interface. Field-Testing Site Locations Mapped Sound Levels in Los Angeles: Intensity of Red Indicating Increased Sound Levels with Reference to Concentrated Traffic (indicated by staggered streaks) Figure 24. INSUL Interface:Façade Components for Glazing Fig. 25 INSUL Interface: INSUL Outdoor-to-Indoor TL Calculations 9.3-1 Decibel 10 th Decibel 10 th is an Apple application compatible with an iPhone, iPod, and iPad. The application functions as a sound meter that measures sound pressure levels. Manufactured by SkyPaw Ltd. as a Multi Measures-All in one measuring toolkit, Decibel 10 th measures sound pressure levels in decibels (dB), detecting sound pressure levels ranging from 0 dB to 110 dB. Its graphic interface consists of a sound meter and a graph corresponding to concurrent sound recording, comparative Batungbakal 55 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects conditions, calibration settings, and data export. Decibel 10 th provides maximum (Lmax), peak (Lpk), and average (Leq) sound levels within the duration of the measured sound conditions. Maximum sound levels, Lmax, is the highest A-weighted sound level measured while peak sound levels, Lpk, refers to the maximum value reached by the sound pressure 112 . Peak sound levels are usually not used in measuring environmental noise 113 . Average sound levels (also known as equivalent sound level), Leq, is an A-weighted sound level commonly used to indicate the amplitude of environmental sound in a duration of time. Considering varied time durations and A-weighting, average sound levels allows environmental sound field-measured to be compared 114 . Although Decibel 10 th is not classified as a Class I equipment, the iPhone application is used as a relative measurement tool. Utilizing a phone application as an alternative, implementation of Decibel 10 th demonstrates the potential to enable the public to voluntary collect environmental data. In “Rapid Urbanization and Mega Cities: The Need for Spatial Information Management”, increased public use of sensors for environmental variables (such as noise and air pollution) would bridge the gap in understanding environmental conditions and data sourcing 115 . As a method to obtain environmental data, such as outdoor and indoor sound levels, implementation of field-measurements improve simulations to estimate sound transmission loss from existing urban soundscapes. As a result, implementation of field-test measurements enable simulated results to be approximately similar to the acoustic performance of glass facades in existing, uncontrolled urban conditions (Fig. 26). 112 Noise Meters Limited, www.noisemeters.co.uk/help/faq/max-min-peak.asp. 113 Noise Meters Limited, www.noisemeters.co.uk/help/faq/max-min-peak.asp. 114 Charles M. Salter Associates Inc., 52. 115 FIG, 43-44, 91. Batungbakal 56 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Using Decibel 10 th for Field-Testing As Los Angeles embodies urbanization due to its population density and high traffic congestion, six sites in Los Angeles were selected based on high commercial development and vehicular traffic identified from Nelson Nygaard Consulting Associates’ GIS-data sourced map, indicating common noise conditions in urban areas 116 . Outdoor and indoor sound conditions were measured and recorded. Since peak sound levels are usually not used to measure environmental noise, maximum sound levels from field-measurements were considered. Utilizing Decibel 10 th to measure six site conditions, identifying the maximum outdoor sound level (Lmax) from all six sites was implemented into INSUL’s ISO 717 standard traffic noise. Figure 26. Field-Test Implemented in INSUL to Create Sound Spectrum 9.3-2 INSUL Using Decibel 10 th , field-testing identified outdoor sound levels and indoor sound levels of common office workspace in the urban environment. The maximum outdoor sound level obtained from field-tests were implemented in INSUL façade simulations. Using the maximum outdoor sound level to adjust INSUL’s outdoor sound spectrum allows INSUL-simulated facades to estimate the acoustic performance of glass façades in response to actual sound conditions in the urban environment. 116 "Los Angeles Maximizing Mobility Options: Population Density", www.scag.ca.gov/nonmotorized/pdfs/map10- populationdensity.pdf. Batungbakal 57 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects INSUL, a sound insulation prediction program, estimates transmission loss and weighted sound reduction of walls, floors, ceilings, and windows. Based from INSUL distributors, results obtained from INSUL estimated sound transmission is equivalent to sound transmission loss 3dB more or less from assemblies field-tested 117 . Provided the flexibility to adjust façade components of a INSUL-simulated facades, such as materials and façade dimensioning, sound transmission loss is predicted in 1/3-octave bands. Although INSUL provides a graph that compares up to five iterations, transmission loss and indoor sound levels obtained from INSUL were imported and documented into Microsoft Excel. Using Microsoft Excel, transmission loss and indoor sound levels resulting from INSUL façade simulations were organized based on façade assembly type, glass type, glass thickness, and air-cavity depth, which allowed more than five façade specimens to be compared. Plotted indoor sound levels obtained from direct transmission loss resulting from INSUL-simulated façade provided an in-depth analysis in evaluating the influence of the façade components and façade assemblies, such single-pane facades, double-pane facades, and double-skin facades. Fixed and Variable Parameters The intent in assessing sound transmission loss of INSUL-simulated glass facades is to quantify sound transmission loss obtained with single-pane façades, double-pane facades, and double-skin facades, and to further analyze the performance of double-skin glass facades in reducing sound transmission. Glass facade simulations are assessed in accordance to EN ISO 717, which is equivalent to traffic noise. ISO 717, a rating of sound insulation in buildings and of building elements: airborne sound insulation, is defined as single-numbered values for airborne sound 117 INSUL, www.insul.co.nz/technicalinfo.html#. Batungbakal 58 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects insulation in buildings and building elements, such as walls, flooring, doors, and windows. ISO 717 considers different sound level spectra of various noise sources. In accordance to EN ISO 717,varying conditions of closed glass facades, such as single-pane facades, double-pane façades, and double-skin facades, were simulated. Figure 27. Parameters for INSUL Façade Simulations ` To allow INSUL-simulated facades to estimate direct transmission loss and identify the acoustic performance of glass facades solely on its façade material and surface composition, the outdoor sound source was situated at less than five feet (1.5 meters) from the façade, preventing outdoor sound levels to decrease due to increased distance (Fig. 27). Based on a common rule of thumb for roadway noise, doubling the distance between the source and receiver decreases sound levels by 3 dB (in environments with solid surfaces) and 4.5 dB (in vegetated areas) excluding the sound transmission loss from building enclosures 118 . With the intent to simulate single-pane facades, double-pane facades, and double-skin facades, INSUL’s glazing tab was used to resemble the construction and assembly of glass facades. 118 City of Los Angeles, 3. Batungbakal 59 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 28. INSUL Main Interface: Glazing Tab Settings Mediums: Glazing Among INSUL’s five primary tabs, the glazing tab specifies façade components, such as panels, framing, glazing, and porous material (Fig. 28). The glazing tab provides three tabs to specify glazing parameters for multiple-paned glazing, single, double, and triple. Settings for single, double, and triple glazing enable components, such as ‘Pane’-glass material, ‘Thickness’-glass thickness, and ‘Space between pane’- air-cavity depth, to be adjusted. The glazing tab’s ‘Single’ tab option does not consider the air-cavity (designated as ‘Space between panes’) as it only accounts for a single glass pane. In addition to configuring glass thickness and air space dimension, the ‘Double’ tab provided the option to specify the glass type for the inner and outer pane of a facade; therefore, allowing insulated-glazing units (IGU) to be simulated (Fig. 28). Batungbakal 60 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Similar to ‘Double’, ‘Triple’ enables glass type, glass thickness, and air space dimension for three glass panes to be adjusted. Single-pane facades contain one glass panel. In this study, double-pane facades are composed of an insulated glazing unit, IGU. Standard dimensions for an IGU is of two 1/4-inch glass panels separated by 1/2-inch air-cavity (Fig.29). In this study double-pane facades simulated and compared consist of the standard air-cavity for an IGU, ½-inch air gap, whereas a simulated double-skin façade consist of air-cavity dimensions greater than 15.7 inches. Common air-cavity dimensions for double-skin facades range from 15.7 inches to 39.3 inches. Double-skin facades simulated and compared are composed of a standard IGU as the inner skin and a single-pane as the secondary skin, which are separated by a specified air-cavity dimension. Although the inner skin of simulated and assessed double-skin facades are composed is an IGU and the secondary skin is composed of a single glass panel, both skins of a double-skin façade can be composed of insulated glazing units. However, as INSUL is limited to simulate glass facades with a maximum of three glass panels, double-skin facades simulated and assessed in this study are composed of an IGU for its inner skin and a single glass panel for its secondary skin. Figure 29. Diagram (left to right): Single-Pane Façade and Double-Pane Façade, and IGU. Batungbakal 61 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Provided settings for two glass panes, the ‘Double’ tab allows double-pane facades to be simulated, setting assembles to be configured as a insulated-glazing unit. Utilizing the ‘Triple’ tab, INSUL-simulated double-skin facades consisted of an insulated-glazing unit for the inner skin and a single-glass panel for the secondary skin on the exterior. This study simulated double- skin facades with an IGU for its inner skin and a single pane as its secondary skin. Double-skin facades with insulated glazing units on each side are not simulated since INSUL provides the maximum of three glass panels. Since INSUL only provides three tab options for glazing assemblies, this study was limited to simulated double-skin facades comprised of three glass layers. Therefore, a common assembly for double-skin facades, which consists of a single-pane for its secondary skin and an IGU for its inner skin are simulated and assessed in this study. INSUL-simulated single-pane facades were adjusted under the ‘Single’ tab. Parameters and façade components for INSUL-simulated double-pane facades were adjusted using ‘Double’ tab while INSUL-simulated double-skin were adjusted under the ‘Triple’ tab. Each tab allowed INSUL-simulated facades to differ by façade assembly type, glass type, glass thickness, and air- cavity dimension. In this study three façade assemblies, single-pane, double-pane, and double-skin facades were simulated and compared. Simulated and assessed using INSUL, 12 single-pane facades, 12 double-pane facades, and 48 double-skin facades differed in three glass types-monolithic glass, PVB-laminated, and TSC-laminated glass; four standard industry glass thickness, and four standard air-cavity dimensions for commercial buildings. Single-pane facades composed of 1/8- Batungbakal 62 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects inch glass and double-pane facades composed of 1/8-inch were also simulated and assessed since field-tested sites consists of single-pane facades. Simulating and assessing glass façades composed of a different glass type, glass thickness, and air-cavity dimension, allowed for this study to critically analyze the acoustic performance of glass facades and the influence on façade components in improving sound attenuation through direct sound transmission loss. Outdoor to Indoor Sound Insulation Calculation After adjusting façade components of glass façade, estimated sound transmission loss were obtained using INSUL’s Outdoor to Indoor Sound Insulation Calculation. Input and output from INSUL’s Outdoor to Indoor Sound Insulation Calculation were classified into three sections: o Exterior Sound Pressure Level- standard sound sources, o Sound Path, and o Receiving Room The Exterior Sound Pressure Level provides an outdoor sound spectrum at 50Hz to 5KHz based on A-weighted standard sound sources, such as ISO 717 traffic noise (Fig.30). INSUL Outdoor to Indoor Sound Insulation Calculation’s Path tab identified the amount of transmission loss while considering the façade surface area and its profile. Five simulations, which can vary in façade area and façade components, can be plotted for transmission loss comparison (Fig.30). The Receiving Room tab estimated indoor sound levels based on transmission loss, reverberation Batungbakal 63 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects time, and volume of the room. While this study focuses on transmission loss derived from glass façade components responding to ISO 717 traffic noise, the Receiving Room tab provided additional insight on transmission loss and the influence by indoor parameters, such as room volume, common reverberation time for office buildings, and façade surface area. Considering the three fundamental elements influencing the indoor acoustic environment- the sound source, the path, and the receiving room, INSUL’s Outdoor to Indoor Sound Transmission Calculator provided an overall process that demonstrates the influence of façade components, indoor parameters, and façade parameters in affecting indoor sound levels (Fig. 30). Figure 30. INSUL: Setting for Outdoor to Indoor Sound Insulation Calculation. Batungbakal 64 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Indoor sound levels and transmission loss from INSUL façade simulations were obtained using the following settings and options (Fig. 31-34). Plotted indoor sound levels resulting from INSUL façade simulations were set on 1/3-octave band to obtain higher frequency resolution results. Although octave bandwidth provides adequate information to analyze sound transmission of the façade assemblies, a 1/3-octave band provided detailed insight for more analytical purposes (Fig.31). As data evaluation, ISO 717 Traffic Noise is used to provide an outdoor noise spectrum, direct transmission loss and resulting indoor sound levels based on its testing standards. Using the maximum outdoor sound level obtained from field-testing common urban conditions in Los Angeles to adjust ISO 717 Traffic noise allowed INSUL façade simulations to respond to approximate outdoor sound levels existing conditions. Changing INSUL’s given A- weighted level, 65 dB, the A-weighted level is changed to 90 dB, the maximum outdoor sound pressure level obtained from field-testing existing urban conditions (Fig. 31). Weighting ISO 717 Traffic Noise with the maximum outdoor sound level obtained from field-testing six site conditions in Los Angeles, 90dB, an outdoor sound spectrum allows simulated facades to respond to existing sound conditions and provide transmission loss from 50Hz to 5KHz (Fig.31). Figure 31. INSUL: Setting for Sound Spectrum Calculator. Batungbakal 65 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects In the Paths section, the surface profile of the façade is adjusted to best resemble double-skin facades as well as single-pane facades and double-pane facades (Fig. 32). Determined by the assembly type, the glazing profile of INSUL-simulated facades were adjusted in the Façade Shape Level Difference. Utilizing the Outdoor to Indoor Sound Insulation Calculator, the Façade Shape Level Difference is specified as a plane façade. Settings for the Façade Shape Level Difference include façade shapes (profiles), line of sight, and roof absorption. In this study, the three assembly types- single-pane, double-pane, and double-skin facades, and its façade components remain to be the focus in determining the acoustic performance of double-skin facades; therefore, INSUL façade simulations were configured as plane façades (Fig. 33). INSUL-simulated glass facades configured as a plane façade eliminates other façade variables (such as overhangs and extrusions that would be other forms of partitions), allowing resulting indoor sound levels and transmission loss to be based on façade components. As sound levels decreases towards the receiver the distance from the sound source increases. The distance between INSUL-simulated façades and the outdoor sound source were minimized, allowing resulting transmission loss and indoor sound levels to be direct 119 . As this study focuses on simulating plane facades and its façade components, and resulting transmission loss, configuring outdoor sound sources less than 5 feet (1.5m) from the façade minimizes the outdoor sound transmission to be affected by increased distance and additional mediums. 119 Cavanaugh, 152. Batungbakal 66 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 32. Path settings: Elements Tab Figure 33. INSUL: Glazing Tab Settings Although this study focuses on assessing indoor sound levels resulting from direct transmission loss and dismissing room attributes, parameters such as room volume, reverberation, and façade surface area are adjusted in INSUL’s Receiving Room panel to provide indoor sound levels for relative comparison. In INSUL’s Receiving Room panel, the volume of the conditioned room is set to 5,120 cubic feet (Fig. 34). The volume derived from the dimension of the room, which was determined based on dimensions of glass panels that would seamlessly enclose the room. In this case, the room is 32 feet (length) by 16 feet (width) with 10 feet floor to ceiling height. Reverberation was configured to 0.5 since reverberation time usually ranges from 0.3 to 0.55 for Batungbakal 67 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects office space; however, the maximum is used 120 . Reverberation is a collection of time-delayed sounds following a direct sound that result from reflections indoors 121 . Figure 34. In the Receiving Room Panel 9.4 Key Parameters and Façade Components for Field-testing and INSUL Simulations To obtain direct transmission loss provided by glass facades such double-skin facades in response to ISO 717 traffic noise, the following were considered key inputs in INSUL façade simulations: o Field-measurement implemented to weigh ISO717 , providing an outdoor sound spectrum o Glass types- monolithic glass, PVB-laminated glass, TSC-laminated glass o Standard glass thickness for commercial building facades o Standard air-cavity dimensions o Façade surface profile 120 Reverberation time, www.reverberationtime.com. 121 Charles M. Salter Associates Inc., 126. Batungbakal 68 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 9.4-1 Components Influencing Receiver- Office Space Single-pane facades, double-pane facades, and double-skin facades were simulated under the following conditions to validate sound attenuation provided by varying glass façade assemblies. In addition to identifying direct sound transmission loss, three components were identified to influence sound transmission and its effect within indoor conditions: (a) the area of the façade, (b) room parameters such as room volume and (c) reverberation. Area of the Façade Direct transmission loss and indoor sound levels derived from INSUL façade simulations were influenced by the area of the façade, façade components, and the outdoor sound source. Using the equation, 10log(A), INSUL simulation parameters used to predict sound transmission loss considered the area of the façade to the area of the receiving room. In this study, glass panels were dimensioned as 8 feet in width and 12 feet in height. The dimension of glass panels were determined to insure the room would seamlessly enclosed the room, either from floor-to-floor or room-to-room. Area of façade 10log(A) Volume of the Room Although glass facades minimized sound transmission from outdoor traffic noise, the remaining sound transferred to the receiving room is reflected for a duration after the emitted sound source. The volume the conditioned receiving room, 5,120 cubic feet, derived from the dimension of the room. In this case, the room is dimensioned at 32 feet (length) by 16 feet (width) with a height of 10 feet. Batungbakal 69 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Reverberation Reverberation is a combined effect of prolonged sound resulting from reflective surfaces while sound sources stopped emitting sound. Reverberation time is the amount of time (in seconds) sound is prolonged after emitted from the source. Reverberation time, RT 60 (T), indicates the amount of time necessary to decrease sound levels by 60 dB after emitting sound sources stop 122 . RT = -10logV+14 [-10log(5120ft³)+14] +10logT Determined from INSUL façade simulations, increasing the room volume influenced the reverberation time. As reverberation for indoor conditions usually ranges from 0.4 seconds to 1 second, 0.3 to 0.55 seconds is recommended for office space (Fig. 35) 123 . However, the acceptable reverberation time for an open-plan office is 0.5 seconds while an enclosed office plan is 0.6 seconds; therefore, 0.5 seconds was implemented in INSUL façade simulations. Open plan offices with a reverberation time of 0.5 seconds influences sound between workstations while enabling a balance of sound absorption and noise masking 124 . Figure 35. Recommended Reverberation Time for Office Buildings 125 . (Autex) 122 Reverberation time, www.reverberationtime.com. 123 Office Design. Acoustic.com, http://www.acoustics.com/office.asp. 124 Office Rooms, Paroc, www.paroc.com/solutions-and-products/solutions/room-acoustics/office-rooms. 125 “Understanding Acoustics”, http://autex.com.au/Technical-Guides/Quietspace-Design-Guide/4.-Understanding- Acoustics.. Batungbakal 70 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 9.5 Progressive Simulations:Selected Components Identified to Improve Transmission Loss As façade components are the physical attributes of building facades, facade components considered for this study include three façade assemblies, three glass types, five glass thickness, and four air-cavity dimensions (Table 3). TABLE 3: SELECTED FAÇADE COMPONENTS FOR DOUBLE-SKIN FAÇADE SIMULATIONS Façade Type Glass Type Glass Thickness Air-cavity Depth Single-Pane Façade Monolithic 0.125 in. 15.7 in. Double-Pane Façade PVB 0.250 in. 23.6 in. Double-Skin Facade TSC 0.375 in. 31.5 in. 0.500 in. 39.3 in. 0.625 in. 9.5-1 Progressive Selection Using INSUL-simulated single-pane facades and double-pane facades as baseline comparisons determined improved transmission loss provided by double-skin facades based on the façade assembly and its façade components. Established as baseline comparisons, INSUL-simulated single-pane façades composed of monolithic glass were compared to simulated double-pane facades composed of monolithic glass. By comparing indoor sound levels and direct transmission loss provided by double-pane facades composed of monolithic glass to single-pane facades composed of monolithic glass determined the amount of improved transmission loss double-pane facades provides in response to extreme sound conditions, which was the maximum outdoor sound level obtained from urban sound conditions in Los Angeles. The maximum outdoor sound level derived from common urban conditions for the workspace environment, which consisted of single-pane facades. Since Batungbakal 71 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects field-tested conditions were selected based on common workspace environments with high concentrations of vehicular traffic and commercial development, the glass façade type for each site field-tested were acknowledged upon site visit. All outdoor and indoor sound conditions field-tested were based on single-pane facades. Since indoor and outdoor sound levels obtained from Los Angeles’ urban conditions field-tested resulted from single-pane facades as its medium, INSUL simulated single-pane facades served to validate direct transmission loss provided by existing single-pane facades and the accuracy of façade simulations. Using INSUL-simulated single-pane facades composed of 1/8-inch monolithic glass as a baseline, glass façade components identified to provide improved sound transmission loss compared to the baseline were further analyzed in INSUL-simulated double-pane facades and INSUL-simulated double-skin facades. Resembling the concept of natural selection, which is a causal process, glass façade components identified to improve sound attenuation specified facade assembly types simulated to further assess its acoustic performance and the influence of glass façade components in improving sound transmission loss. Improved direct transmission loss was determined from the decibel difference of transmission loss between simulated façade assembly types with common façade components, such as glass type and glass thickness. Three glass types were considered: monolithic glass, glass with Poly Vinyl Butyral (PVB) laminate, and glass with Trosifol Sound Control (TSC)- a new form of PVB film described to improve sound control 126 . Four glass thickness compared to the baseline, 126 Kuraray, “Trosifol Sound Control film”, http://www.trosifol.com/en/produkte/architecture/trosifol-sound-control- sc/. Batungbakal 72 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects a single-pane façade composed of 1/8-inch monolithic glass, are standard industry sizes for commercial façade assemblies, ranging from ¼-inch to 5/8-inch glass. Comparing direct transmission loss resulting from simulated single-pane facades, double-pane facades, and double-skin facades emphasized the acoustic performance of glass façade components. In order to determine improved transmission loss, INSUL-simulated facades were compared in two aspects: the acoustic performance of façade components- comparing transmission loss provided by the same façade type differing in façade components, and acoustic performance of façade assemblies- comparing transmission loss provided by different façade type differing in façade components. For instance, comparison of all simulated single-pane facades determined the influence of each façade component in improving the acoustic performance of single-pane facades. Comparing the acoustic performance of single-pane façades to double-pane facades validated increased transmission loss provided by a double-pane façade. By comparing single-pane facades varied by three glass types and five glass thickness, improved transmission loss due façade components was quantified. Comparisons of two differing façade types, such as single-pane facades and double-pane facades determined improved transmission loss due to the assembly of a facade. Differentiated by the amount of decibels in transmission loss, façade components identified to increase sound transmission loss were implemented in simulated double-skin facades. The result of the study identified the influence of façade components in improving transmission loss for double-skin facades (Fig. 36). Batungbakal 73 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 36. Diagram: Progressive Selection 9.5-2 Assessing Simulated Single-Pane Facades As a baseline, direct sound transmission loss estimated from INSUL-simulated single-pane façade composed of 1/8-inch monolithic glass is referenced as initial sound measurements when comparing single-pane facades composed of different glass type and glass thickness greater than 1/8-inch. However, a single-pane façade composed of ¼-inch monolithic glass is used as a baseline to compare double-pane facades and double-skin facades distinguished by different glass types, glass thickness, and air-cavity depth (Fig.36). Since field-tested indoor sound levels Batungbakal 74 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects resulted from outdoor sound attenuation due to single-pane facades, single-pane façade were simulated to validate indoor sound levels resulting from existing single-pane facades and to assess improved transmission loss based on façade components and façade assembly type, such as double-pane facades and double-skin facades. Sound transmission loss resulting from INSUL-simulated single-pane facades composed of either of three glass types- monolithic, PVB-laminated glass, and TSC-laminated glass, and five glass thickness, were primarily compared. In comparing single-pane facades differing by façade components (such as glass type and glass thickness), transmission loss resulting from INSUL- simulated single-pane facades composed of monolithic glass served as the baseline comparison to quantify improve transmission loss provided by single-pane facades composed with a laminate, such as PVB film and TSC film. Two forms of laminated glass, PVB and TSC, were compared to single-pane facades composed of monolithic glass. Identifying the sound transmission loss difference (in decibels) between single-pane facades composed of monolithic glass and single-pane facades composed with laminate, further assessment compares single-pane facades composed of PVB laminate and single-pane facades composed with TSC laminate to determine the transmission loss difference. TSC, Trosifol Sound Control, is a recent form of laminate for glazing. According to Kuraray, a glazing manufacturer, TSC improves sound insulation by at least 3dB compared to PVB 127 . To determine whether TSC provided improved sound transmission loss by at least 3dB, transmission loss resulting from PVB-laminated single-pane facades were compared to transmission loss provided by TSC-laminated single-pane facades. 127 Kuraray, “Trosifol Sound Control film”, www.trosifol.com/en/produkte/architecture/trosifol-sound-control-sc/. Batungbakal 75 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 9.5-3 Assessing Simulated Double-Pane Facades and Double-Skin Facades Façade components identified to increase transmission loss for single-pane facades, were further analyzed in INSUL-simulated double-pane facades. Façade components, such as three glass types and five glass thickness, were considered for double-pane façade simulations. Composed as an IGU, an insulated-glazing unit, the standard air space between two glass panels, ½- inch, was applied to all simulated double-pane facades. Composed with the standard air space dimension for an IGU and glass thickness for its interior glass panel, simulated double-pane facades differed by its exterior panel’s glass type and glass thickness. Identified to improve transmission loss in single-pane facades and double-pane facades, façade components considered to improve sound transmission loss were further examined in INSUL-simulated double-skin facades. In addition to glass type and glass thickness, double-skin façade simulations varied by four air-cavity dimensions: 15.7 inches, 23.6 inches, 31.5 inches, and 39.3 inches. Noted from simulated single-pane facades and simulated double-pane facades, glass façade components identified to improve sound transmission loss were observed in simulated double- skin facades. Using a single-pane façade composed of ¼-inch monolithic glass and a double- pane façade composed of ¼-inch monolithic glass as comparative baselines determined the decibel amount of increased transmission loss provided by a double-skin façade composed of ¼- inch monolithic glass and 15.7-inch air-cavity. Comparing a double-skin façade composed of ¼- inch monolithic glass and 15.7-inch air-cavity, which are the minimum dimensions acceptable for commercial building facades and the minimum dimensions considered in this study, the two baselines determines the influence of the façade assembly in improving direct transmission loss. Batungbakal 76 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects This study heavily focused on simulated double-skin facades with an IGU for its inner skin and a single-pane for its secondary skin facing the outdoor environment. While determining whether providing an IGU on the inner skin and the single-pane secondary skin of a double-skin façade contributed to its improved acoustic performance, other façade alternatives were simulated. Double-skin facades with an IGU for its inner skin with an increased single-pane thickness for its secondary skin were simulated to determine whether increased thickness of the secondary skin improved transmission loss provided by double-skin facades. In determining whether increased thickness of the secondary skin improved transmission loss, double-skin facades with increased air-cavity dimension, increased secondary skin thickness, and laminate were compared to a double-skin facade composed of ¼-inch monolithic glass, which served as a comparative baseline. 9.6 Process to Results 9.6-1 Field-Testing: Urban Integration to Establish Baseline Field-Testing provides demonstrative and substantial data rather than theoretical insight. Field- testing involved measuring and documenting sound in an environment, including indoor and outdoor conditions. As field-testing conditions are usually set in an uncontrolled environment, it resembles actual performance rather than theoretical. In contrast, laboratory and simulation testing are conducted under controlled conditions since they are assessed in an isolated environment. A test room with low sound absorption is one example of laboratory testing and its controlled environment. Batungbakal 77 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Sound levels obtained from field-tests provided fundamental acoustic data, which was used to support the validity of acoustic assessment and its accuracy to predict acoustic performance in real-life settings. In designing a glass facade for a workspace environment, it is fundamental to identify and understand the influence of the surrounding environment based its site conditions. Among the most challenging sound conditions is traffic noise, a common condition in an urban environment. In order to address sound sources resulting from urbanization, field-measurements were assessed at six site conditions in Los Angeles consisting of office workspace environments (Table 4). Los Angeles embodies urbanization, consisting of high population density and varying conditions. Using Los Angeles as an exemplary city consisting of high population density commingled with vehicular traffic and commercial development, its urban context allows for a mixture of building zones and activities to be adjacent from one another. Batungbakal 78 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects TABLE 4: SELECTED FIELD-TESTED SITE CONDITIONS Condition Exterior Interior Area Outdoor Indoor 1 Downtown LA Bunker Hill Central Library Business 60-90dB 49-67dB 2 Downtown Culver City Office Business 42-87dB 45-76dB 3 LAX Arrival Arrival Transit 65-90dB 57-75dB 4 LAX Departure Departure Transit 68-84dB 57-82dB 5 USC Tutor Hall Education 59-79dB 41-71dB 6 USC GER Library Education 50-75dB 40-65dB Figure 37. Los Angeles: Site Locations Based on Employment and Traffic Density. GIS Data (SCAG, 2000) Batungbakal 79 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 38. Los Angeles: Street Traffic Congestion. Figure 39. Los Angeles: Employment Density. Figure 40. Los Angeles: Site Locations Based on Combined Employment and Traffic Density. Batungbakal 80 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Set in Los Angeles, outdoor sound levels and indoor sound levels were recorded, measured, and documented in conditions where high concentration of commercial development are situated, indicating a concentration of commercial employment and traffic activity. Sites were selected from mapping high employment and commercial development, and midday vehicular traffic, indicating a concentration of activity, which are common noise conditions in an urban environment (Fig. 37-40). Site conditions within close proximity to aircraft noise were considered and field-tested to provide alternative traffic sound sources. Each site condition field- measured pertained to common urban conditions for office buildings. With the intent to improve the acoustic performance of glass façade assemblies that would provide indoor sound levels enabling work productivity and concentration within the indoor environment, conditions were chosen based on contrasting indoor and outdoor sound conditions. Measured site conditions were considered based on the following outdoor attributes: density- employed population, developed commercial areas, and traffic activity. For instance commercial development are often situated within business districts, consisting of high employment density and high levels of vehicular activity. Site conditions were also chosen based on its indoor environment that related to workspace and productivity, such as libraries and office space. Out of the six indoor and outdoor conditions measured, two were measured near aerial transportation facilities where there is constant transit activity. Two conditions were situated in concentrated areas of commercial development, such as the Los Angeles Bunker Hill District and Downtown Culver City. Lastly, two conditions within educational facilities provided additional insight on a range of sound levels appropriate for a workspace environment (Fig.41). Batungbakal 81 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects In efforts to respond to indoor sound levels affecting the workspace environment, all field-tests were conducted at midday during the weekday. To compile a range of sound levels and reduce isolated test conditions, outdoor and indoor sound conditions were measured and recorded within a 4-minute timeframe (Fig. 42). (1) (2) (3) (4) (5) (6) Figure 41. Field-Testing Conditions. (1) Bunker Hill, (2) Culver City Office, (3) LAX Aerial Traffic, (4) LAX Vehicular Traffic, (5) USC Tutor Hall, (6) USC Gerontology Library Batungbakal 82 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects (1) dB (2) dB (3) dB (4) dB (5) dB (6) dB Figure 42. Field-test: Outdoor sound pressure levels (blue) and Indoor Sound Pressure Levels (pink) (1) Bunker Hill, (2) Culver City Office, (3) LAX Aerial Traffic, (4) LAX Vehicular Traffic, (5) USC Tutor Hall, (6) USC Gerontology Library Batungbakal 83 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects dB Figure 43A: Field-Tested Outdoor Sound Level: Bunker Hill and LA Central Library. dB Figure 43B: Field-Tested Indoor Sound Level: Bunker Hill and LA Central Library. Figure 43C: Field-Tested Outdoor Condition: Bunker Hill. Figure 43D: Field-Tested Indoor Condition: LA Central Library. Field-test parameters concerned the physical circumstances related to façade design and field- testing. The parameters for field-testing involved the sound source-the type of traffic noise, location- the distance of sound sources from the façade and sound pressure meter, and timeframe- its context (Table 5). Measuring sound conditions under consistent conditions is crucial in order to ensure quantified direct transmission loss provided by existing buildings Batungbakal 84 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects façades’ response to existing outdoor sound sources were obtained under the same field-test conditions. TABLE 5: FIELD-TEST SITE PARAMETERS AND SETTINGS Field Test Parameters Conditions Indoor sound pressure levels (dB) Recorded 3m from facade Duration 4 min Outdoor sound pressure levels (dB) Recorded 3m from facade Duration 4 min Timeframe Weekday @ midday Sound meter Directed toward sound source, away from facade Field Test Settings Conditions Update frequency 10 Hz Calibration 0.0 dB For all six site conditions, indoor sound levels were measured under the same field-test conditions for obtaining outdoor sound levels (Fig. 43-44). Measuring indoor sound levels, the distance of the sound pressure sound level meter- Decibel 10 th , and the building enclosure did not exceed 10 feet (3 meters). To determine the contrast between indoor sound levels and outdoor sound levels, outdoor sound sources were recorded and measured less than 10 feet (3 meters) from the exterior of the building enclosure. In efforts to determine façade components that would provide indoor sound levels acceptable for office buildings through increased sound transmission loss, sound conditions were measured during the weekday at midday. As office workspace are utilized during the weekdays and during office hours, recording within business hours and during the weekday acquired sound levels to represent a common condition for workspace environments. Batungbakal 85 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 44. Field-Testing: Sound Meter Settings, Decibel 10 th . Using Decibel 10 th , field measurements were directly exported from the application into Microsoft Excel. Documenting maximum sound levels and peak sound levels in decibels, sound data obtained from field-testing were organized into two categories to provide an overall comparison, indoor conditions and outdoor conditions. Comparison between indoor sound conditions to its outdoor sound conditions, were also documented to determine the acoustic performance of its building enclosure (Fig. 45). Figure 45. Field-Testing and Simulations: Sound Source, Medium, and Receiving Room. Batungbakal 86 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Consisting of an indoor environment intended to enable work productivity and concentration, indoor sound levels obtained from each site condition are within the range of acceptable indoor sound levels for office buildings, business, and commercial facilities. Organizations, such as the California Department of Health Services Office of Noise Control and the Department of Transportation and Housing Urban Development identified sound levels higher than 6 dB unacceptable for commercial, business, and office buildings 128 . Indoor sound levels exceeding 75dB is also unacceptable for industrial areas and utility facilities (Fig.46). Indoor sound levels higher than 60dB is considered unacceptable for schools and libraries. Based on the California Department of Health Services’ criteria, minimum indoor sound levels obtained from conditions 1, 3, 5, and 6 would facilitate to commercial and office workspace. Of the four conditions consisting of acceptable indoor sound levels for a workspace environment, three were utilized as office and work areas. Figure 46. Acceptable Sound Levels Based on Land Use (Office of Noise Control, CA Dept. of Health Services) 128 U.S. Department of Housing and Urban Development, www.hudnoise.com/hudstandard.html Batungbakal 87 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Bunker Hill District- Condition 1, is situated in one of Los Angeles’ more densely populated areas with high commercial development. Its outdoor environment consisted of frequent vehicular traffic and pedestrian activity adjacent to commercial high-rises. Adjacent to traffic activity along Fifth Street, indoor sound levels were measured within the Los Angeles Central Public Library. Condition 1 consisted among the highest outdoor sound levels ranging from 60 to 90dB. The broad range in decibels is due from the frequent vehicular traffic. Culver City Office- Condition 2 outdoor sound levels consisted of frequent vehicular traffic. Its indoor environment facilitated to an architectural firm adjacent to frequent vehicular activity. Its building enclosure, a single-pane façade, provided indoor sound levels ranging from 45dB to 76B. LAX Departure Area- Condition 3 was measured at LAX’s arrival area for Terminal 1. Directly adjacent to operated stationary aircrafts, sound levels were consistent and had minimal pedestrian activity to impair the field- measurements. LAX Arrival Area- Condition 4 consisted of vehicular traffic passing by the Los Angeles International Airport’s Arrival area. Indoor sound levels were measured less than five feet from the building’s single-pane façade. Adjacent to arrival pick-up areas and vehicular traffic, indoor pedestrian activity also contributed to indoor sound levels which ranged from 57dB to 75dB Batungbakal 88 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects USC Tutor Hall International Plaza- Condition 5 is situated on USC’s campus grounds. Pedestrian activity was the main sound source contributing to its outdoor sound level. Serving as one of USC’s most active outdoor campus areas, Ronald Tutor Hall’s International Plaza accommodates to students, faculty, and visitors with food venues and seating. The International Plaza is most active during school session hours, where sound levels were measured. USC Gerontology Library- Condition 6 is located on south of the USC campus. The library is immediately adjacent to the outdoors as two sides of the room are enveloped by single glazing. Field-testing was necessary to establish a reference for untreated sound sources, such as outdoor sound levels. By providing a baseline, glass façades and its acoustic performance were examined. Serving as initial measurements, the maximum sound level obtained from field- testing, which is considered the most extreme condition, was implemented to weight INSUL’s outdoor sound spectrum. Identifying the contrast between indoor sound levels and outdoor sound levels, field-measured conditions established varied office workspace typologies, ranging in frequency and amplitude. Sound levels obtained from field-measurements served as the baseline comparison in determining the effectiveness of single-pane facades, double-pane facades and double-skin facades in reducing outdoor sound transmission. Batungbakal 89 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 9.6-2 Using Field-testing as a Source Data Since equipment used to obtain field-measurements did not indicate sound frequencies, field- measurements are considered as an A-weighted analysis. An A-weighted level does not provide spectral data, which evaluates the tonal content of noise 129 . As a result, field-measurements were compared to INSUL-simulated single-pane facades since all six conditions consisted of single- pane facades as an acoustic barrier from outdoor sound sources. Often used to measure environmental noise, A-weighted sound level (L(a) weighs each frequency 130 . Expressed as dBA, weighing each frequency resulted in increasing the accuracy of sound levels relative to the sensitivity of the human hearing. In efforts to improve sound attenuation through transmission loss, field-measurements were fundamental. Field-measurements identified sound sources (indoor and outdoor) contributing to indoor sound levels through direct sound transmission. Through the process, it established targeted indoor sound levels and façade design methods necessary to acquire desired indoor sound levels for the workspace environment. Field-testing provided foundational data that identified current sound levels in existing commercial developments, considering the soundscape of the urban environment. Sound levels measured from the field-testing enabled the acoustic performance of INSUL façade simulations to resemble its actual acoustic performance in reducing sound transmission. 129 Charles M. Salter Associates Inc., 56. 130 Kinsler, 260. Batungbakal 90 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 9.6-3 Implementation of field-measurements to INSUL simulations Implementing sound levels from field-measurements increased the accuracy of INSUL outdoor sound levels to resemble existing conditions. Serving as initial measurements, the maximum outdoor sound level obtained from field-measured traffic noise- the most extreme condition, was implemented to weight INSUL’s ISO 717 outdoor sound spectrum. Implementing field-measurements, INSUL’s ISO 717 traffic noise were adjusted to resemble the maximum outdoor sound level measured in Los Angeles, allowing simulated facades to respond to the worst outdoor sound condition identified from field-tests. Among the options for adjusting the outdoor sound spectrum provided in INSUL, ISO 717 Traffic Noise was used to resemble existing outdoor sound levels. ISO 717, a rating of sound insulation in buildings and of building elements: airborne sound insulation, is defined as single-numbered values for airborne sound insulation in buildings and building elements, such as walls, flooring, doors, and windows 131 . Rather than pink noise, adjusting INSUL’s outdoor sound spectrum in accordance to ISO 717- traffic noise and implementing the maximum outdoor sound level from field-tests allowed INSUL’s sound source to resemble existing outdoor sound levels (Fig.47). Figure 47. INSUL Traffic Noise Sound Spectrum, Not A-weighted. Based on the six sound conditions field-tested in Los Angeles, maximum outdoor sound levels ranged from 64 dB to 90 dB. In accordance to ISO 717-traffic noise, INSUL’s outdoor sound 131 ISO 717, 2013, www.iso.org/iso/catalogue_detail.htm?csnumber=51968. Batungbakal 91 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects spectrum was A-weighted using the maximum outdoor sound level obtained from field- measurements. Provided with the maximum outdoor sound level from field measurements, a noise spectrum was composed through INSUL. Using the maximum outdoor sound level from a site condition one, 90 dB, as the A-weighted value weighed INSUL’s outdoor sound source to resemble condition one’s outdoor sound levels. Among the six site field-tested, condition 1, Bunker Hill District- one of Los Angeles commercial areas, consisted of the highest maximum outdoor sound level, 90dB. Inputting 90 dB resulted in weighting INSUL’s outdoor sound source spectrum, acting as the referenced sound level. Within 1/3-octave band, INSUL’s A-weighted outdoor sound spectrum, at 50 Hz to 5,000 Hz, ranged 65 dBA (Lmin, lowest) to 82 dBA (Lmax, highest). In accordance to EN ISO 717 and EN 12354/3,varying conditions of sealed glazed facades were simulated using the outdoor traffic noise spectrum derived from field-measurements. Provided with a sound spectrum for traffic noise, outdoor sound levels are A-weighted to adjust sound levels to a perceptible level. As a result, INSUL’s sound spectrum was converted to the following (Table 6): TABLE 6: A-WEIGHTED OUTDOOR SOUND LEVELS A-weighted Outdoor Sound Spectrum Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 INSUL ISO 717 95 93 91 89 86 85 85 83 82 82 81 81 82 82 80 79 78 76 74 73 71 A-weighted 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 Batungbakal 92 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Outdoor sound levels obtained from existing conditions increased the accuracy of simulations; therefore, enabling designers to determine the acoustic performance of façade components in response to the project site and its desired indoor acoustic quality. 9.6-4 Single- Pane, Double-Pane, and Double-Skin Facades Targeted Frequency Range and Common Sound Sources Depending on the sound source, traffic noise range from 50 dB to 110 dB (Fig. 48). Common sources, such as noisy streets and vehicular activity range from 60 dB to 90 dB. In contrast, common indoor sound sources in workspace environments range from 40dB to 70 dB (Fig. 49). Figure 48. Common Traffic Noise, A-weighted Sound Levels (Kinsler 361) Figure 49. Common Indoor Noise, A-weighted Sound Levels. (Kinsler 361) Batungbakal 93 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 50. Common Traffic Noise, A-weighted Sound Levels (Charles M. Salters Associates Inc., 3) Traffic noise from 50dB to 110dB range in frequencies. For instance, the sound frequency for a car horn ranges from 430Hz to 4500Hz (Fig. 50). Sound emitted from a large trucks range from 63Hz to 4500Hz. As common traffic noise range in a broad spectrum, from lower frequencies to high frequencies, the acoustic performance of INSUL-simulated glass facades were analyzed at lower frequencies, critical frequencies indicating the coincidence effect, and high frequencies. Lower to Mid-Frequencies At low to mid frequencies, transmission loss provided by simulated glass facades aligned with Mass Law. Mass Law generally determines doubling the mass to increase transmission loss by approximately 6 dB 132 . Sound Transmission Class, STC, can be determined from sound transmission loss in accordance with Mass Law 133 . Generally, STC of single-skin partitions can be calculated from the following equation: (Insul) TL = 20 log (mf) – 48dB (1) 132 Charles M. Salter Associates Inc., 118. 133 Kinsler, 384. Batungbakal 94 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects High Frequencies Determining sound transmission loss using Mass Law was not always applicable at high frequencies, particularly at critical frequencies indicating the coincidence effect. Coincidence effect (also referred as coincidence dip/critical or coincidental frequency) pertains to the reduction of sound transmission loss when sound and vibration in a panel interact. It is the result in which “the wavelength of a flexural wave equals that of a wave of the same frequency in air” 134 . Coincidence effect often occurs within frequencies above 2000 Hz 135 . This effect is most evident in the air-cavity of double-pane facades and double-skin façades. With the air space in between two panels, it enables sound to vibrate and proliferate, causing a high sound pressure within 136 . Laminated glass, however, can minimize the coincidence effect 137 . As a result, INSUL façade simulations are based on another equation which calculates sound transmission loss at higher frequencies 138 . (Insul) TL = 20 log (mf) + 10 log (f/fc)-44dB (2) Quantifying transmission loss at lower and higher frequencies and direct indoor sound levels derived from reduced sound transmission indicated critical frequencies for INSUL-simulated facades. 134 Kinsler, 384. 135 Charles M. Salter Associates Inc., 119. 136 Charles M. Salter Associates Inc., 119. 137 Charles M. Salter Associates Inc., 120. 138 INSUL Technical Info, INSUL, www.insul.co.nz/technicalinfo.html#. Batungbakal 95 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 9.6-5 Façade Analyses and Comparisons Comparison of Sound Transmission Loss: Trends of Acoustic Performance Since INSUL’s A-weighted outdoor sound spectrum implemented the maximum outdoor sound level obtained from field-testing sound conditions in Los Angeles, INSUL façade simulations estimated direct transmission loss provided by different façade specimen. For each simulated facade, the amount of direct transmission loss varied in response to outdoor traffic noise at frequencies below 630Hz and higher frequencies above 630Hz (Fig.51). After identifying the influence of each façade component for single-pane facades, double-pane facades, and double- skin facades, façade assembly types were compared to quantify improved transmission loss based on façade assembly. Although this study simulated 1/8-inch single-pane facades and double-pane facades composed of 1/8-inch glass, a single-pane façade composed of ¼-inch monolithic glass is established as a baseline comparison to determine improve transmission loss provided by double-pane facades and double-skin facades. Single-pane facades and double-pane facades composed of 1/8-inch glass were considered due to field-tested conditions, which obtained indoor sound levels and outdoor sound levels from glass facades that were no longer compliant to Title 24. To quantify increased direct transmission loss based from the decibel difference between single-pane facades differed by a glass type and glass thickness, a single-pane façade composed of ¼-inch monolithic glass is established as the baseline. By comparing the baseline, to single-pane facades with laminate and increased glass thickness, the acoustic performance of a façade’s components are determined by the decibel difference of direct transmission loss. Batungbakal 96 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects To determine increased direct transmission loss provided by double-pane facades, double-pane facades are compared to a single-pane façade composed of ¼-inch monolithic glass. A single- pane façade composed of ¼-monolithic glass also served as a baseline in determining increased direct transmission loss provided by double-skin facades. Compared to a single-pane façade composed of ¼-inch monolithic glass, a double-skin façade composed of ¼-inch monolithic glass and minimum air-cavity, 15.7 inches, were compared to a double-pane façade composed of ¼-inch monolithic glass. By comparing all three façade assembly types composed with the same glass type and glass thickness, increased transmission loss provided by a double-skin façade composed of ¼-inch monolithic glass and minimum air-cavity are identified by its decibel difference from a single-pane façade composed of ¼-inch monolithic glass as well as a double- pane façade composed of ¼-inch monolithic glass. As a double-skin façade composed of ¼-inch monolithic glass the minimum air-cavity depth provides higher direct transmission loss compared to single-pane facades and double-pane facades, a double-skin façade composed of ¼-inch monolithic glass with the i Depending on the decibel difference (of direct transmission loss) between façade assemblies, differences in decibels indicated whether it is a noticeable change indicating improved and reduce acoustic performance (Fig.52). Based on a scale indicating impact of decibel change detected by human hearing, a difference of 1dB is barely perceptible as an increase or decrease of 2dB or more (Table 8). Not considering the room and sound reflected from its surfaces, indoor sound levels derived from A-weighted ISO 717 traffic noise between 50Hz and 5Khz and direct transmission loss Batungbakal 97 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects (Fig. 51). Although indoor sound level charts display the amount of transmission loss, it serves more as a visual to enable designers to identify its performance trend. Tables identifying increased and decreased direct transmission loss and indoor sound levels served as a quantitative method to compare the acoustic performance of glass facades based on varied façade components (Table 7). Figure 51. Illustrative: Indoor Sound Levels for Single-Pane Façade. Batungbakal 98 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects TABLE 7: EXAMPLE: INDOOR SOUND LEVELS FROM DIRECT TRANSMISSION LOSS DOUBLE SKIN 1/4" outer skin, MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 40 39 36 34 30 29 30 28 27 27 26 26 26 26 23 22 25 21 16 12 7 air-cavity 23.6 37 36 33 31 30 29 29 27 26 25 25 24 25 25 21 20 24 20 14 10 5 air-cavity 31.5 35 33 31 32 30 29 28 26 25 25 24 23 23 23 20 19 23 18 13 9 4 air-cavity 39.3 34 32 33 32 29 29 28 26 24 24 23 22 23 23 19 18 22 18 12 8 3 Figure 52. Façade Comparison to Baselines and Perceived dB Change. TABLE 8: SUBJECTIVE CHANGE OF SOUND LEVELS ∆dB Subjective change 3dB Barely Perceptible 5dB Noticeable 10dB Half or twice as loud 20dB Much quieter or louder Batungbakal 99 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 9.6-6 Composing a Design Support Tool for Architects Assembling A Design Support Tool Based on the sum of A-weighted indoor sound levels derived from direct transmission loss resulting from INSUL-simulated glass facades responding to outdoor traffic noise, the design support tool is structured to relate estimated material costs and façade construction to direct transmission loss, enabling building designers to determine façade components necessary to obtain desired indoor sound levels while considering material costs of the façade assembly. Single-figure dBA ratings derived from the decibel differences from reduced indoor sound levels (Fig. 53). Using the change in decibel conversion, the sum of decibel differences is identified for INSUL simulated facades (Table 9-10). At frequencies between 50Hz and 5000Hz, indoor sound levels derived from INSUL estimated transmission loss were converted to an A-weighted sum of sound levels, indicating the overall performance of each façade specimen. Using, the A- weighted sum of sound levels and the estimated cost in façade components, such as glass type, glass thickness, and air-cavity dimension, the design support tool serves as an illustrative reference for building designers. Batungbakal 100 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects TABLE 9: A-WEIGHTING: CHANGE IN DECIBEL CONVERSION ∆dB + 0 or 1 3dB 2 or 3 2dB 4 to 9 1dB More than 10 0dB TABLE 10: EXAMPLE: SINGLE-FIGURE A-WEIGHTED SUM OF INDOOR SOUND LEVEL DOUBLE SKIN MONO ¼” secondary skin Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 40 39 36 34 30 29 30 28 27 27 26 26 26 26 23 22 25 21 16 12 7 Figure 53. Double-Skin Façade Composed of ¼-inch Monolithic Glass: Sum of A-weighted Indoor Sound Levels. DOUBLE SKIN MONO ¼” secondary skin Hz 50 63 80 100 125 160 200 2503154005006308001000125016002000 2500 315040005000 37 36 35 32 29 28 29 27 26 26 26 25 26 26 23 22 25 21 16 12 7 40 37 32 31 29 29 29 26 26 17 7 42 35 32 31 27 7 15.7” air-cavity 43dBA 35dBA 27dBA 44 dBA Batungbakal 101 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects CHAPTER 10 Results Figure 54. Common Traffic Noise, A-weighted Sound Levels. (Salters 3) Responding to outdoor traffic noise, the acoustic performance of single-pane facades, double- pane facades, and double-skin facades vary due to the influence of differing façade components (Fig. 54). Results from INSUL façade simulations, which quantifies direct transmission loss provided by a façade specimen and indoor sound levels considering parameters such as room volume, façade area, and reverberation time, aimed to identify façade components that would improve sound transmission loss. Although INSUL provides indoor sound levels considering parameters such as room volume, façade area, and reverberation time, this study identifies indoor sound levels derived from direct transmission loss and outdoor traffic noise. As this study focuses on the acoustic performance of glass façade assemblies (such as double-skin facades) and its façade components, indoor sound levels derive solely from the outdoor sound source and direct sound transmission loss. In describing the acoustic performance of façade assemblies- single-pane facades, double-pane facades, and double-skin facades indoor sound levels derived solely from direct transmission loss and reduced transmission loss indicate the overall acoustic performance the three façade assembly types the influence of façade components in improving sound attenuation through transmission loss. Batungbakal 102 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 10.1 Single-Pane Façades Figure 55. Single-Pane Façade Composed of Monolithic Glass: Indoor Sound Levels from Direct Transmission Loss 10.1-1 Single-Pane Facades Composed of Monolithic Glass -Indoor Sound Levels Based on estimated direct transmission loss from INSUL-simulated facades, single-pane facades composed of monolithic glass provide indoor sound levels between 43dBA to 57dBA at lower frequencies below 630Hz (Fig.55). At higher frequencies above 630Hz, single-pane facades composed of monolithic glass provide indoor sound levels ranging from 20dBA to 54dBA. In response to outdoor traffic noise at higher frequencies above 2000Hz, single-pane facades Batungbakal 103 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects composed of monolithic glass provide the lowest indoor sound pressure level between 20dBA to 50dBA. TABLE 11: SINGLE-PANE FACADES: A-WEIGHTED INDOOR SOUND LEVELS SINGLE PANE MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 1/8" 55 56 57 57 56 57 57 56 55 55 55 54 54 54 51 49 48 42 41 44 41 1/4" 50 51 52 52 50 51 51 50 49 50 49 48 49 49 46 46 50 46 41 37 32 3/8" 47 48 49 48 47 47 48 46 46 46 46 46 46 48 50 49 46 41 36 31 27 1/2" 45 45 46 46 44 45 45 44 44 44 45 44 47 51 50 45 43 37 32 28 23 5/8" 43 44 44 44 43 43 44 42 42 43 43 45 50 51 47 42 40 34 29 25 20 Indoor sound levels derived from direct transmission loss provided by single-pane facades composed of monolithic glass indicate increased glass thickness to reduce indoor sound levels to a maximum of 7dB compared to the baseline - a single-pane facade composed of 1/8-inch monolithic glass. For instance, a single-pane facade composed of 5/8-inch monolithic glass, the largest glass thickness simulated for this study, provides indoor sound levels 3dBA to 21dBA less than indoor sound levels obtained from the baseline-a single-pane façade composed of 1/8- inch monolithic glass (Table 11). 10.1-2 Single-Pane Facades Composed of Monolithic Glass-Direct Sound Transmission Loss With indoor sound levels ranging from 43dBA to 57dBA in response to outdoor traffic noise below 630Hz, single-pane facades composed of a monolithic glass thickness greater than 1/8- inch reduces 15dB to 25dB of sound transmission compared to the baseline- a single-pane façade composed of a 1/8-inch monolithic glass. Responding to outdoor traffic noise at frequencies below 630Hz, single-pane facades composed of a monolithic glass thickness greater than 1/8- Batungbakal 104 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects inch reduce 25dB to 52dB of sound transmission (Table 12). At frequencies above 1600Hz, single-pane facades composed of increased monolithic glass thickness noticeably improved transmission loss from 3dB to 21dB. This trend is most evident for single-pane facades with monolithic glass ¼-inch to 5/8-inch thick. TABLE 12: PERFORMANCE OF SINGLE-PANE FACADES: DIRECT SOUND TRANSMISSION LOSS SINGLE PANE MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 100012501600 2000 2500 315040005000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 1/8" 10 11 12 13 14 15 17 18 20 22 23 25 27 28 30 31 32 35 34 30 31 1/4" 15 16 17 18 20 21 23 24 26 27 29 31 32 33 35 34 30 31 34 37 40 3/8" 18 19 20 22 23 25 26 28 29 31 32 33 35 34 31 31 34 36 39 43 45 1/2" 20 22 23 24 26 27 29 30 31 33 33 35 34 31 31 35 37 40 43 46 49 5/8" 22 23 25 26 27 29 30 32 33 34 35 34 31 31 34 38 40 43 46 49 52 10.1-3 Single- Pane Facades Composed of Monolithic Glass –Critical Frequencies Plotted in Figure 55, indoor sound levels derived from direct transmission loss determined the coincidence effect of single-pane facades composed monolithic glass greater than ¼-inch to occur at 630Hz to 1000Hz. At critical frequencies, from 630Hz to 1000Hz, singled-pane facades composed of an increased thickness of monolithic glass provides indoor sound levels between 44dBA and 51dBA. At critical frequencies, the coincidence effect (the coincidence dip) indicates a reduction in transmission loss. No indication of change in transmission loss also determines the weakest point of acoustic performance. Depending on the glass thickness of a single-pane façade, the coincidental dip occurs in response the outdoor sound source at different frequencies. Indicated by indoor sound levels and direct transmission loss obtained from INSUL facade simulations, Batungbakal 105 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects increasing the glass thickness of a monolithic single-pane facade result for the coincidental effect to occur at lower frequencies compared to a single-pane façade composed 1/8-inch monolithic glass. For instance, the coincidence effect occurs at 3150Hz for a single-pane facade with 1/8- inch monolithic glass while the coincidence effect occurs at 1600Hz for a single-pane façade with ¼-inch monolithic glass. Batungbakal 106 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 56. Single-Pane Façade with PVB Laminate: Indoor Sound Levels from Direct Transmission Loss Figure 57. Single-Pane Façade with TSC Laminate: Indoor Sound levels from Direct Transmission Loss Batungbakal 107 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 10.1-4 Single- Pane Facades Composed of Laminated Glass -Indoor Sound Levels Single-pane facades composed with laminate film, either PVB or TSC, consistently provide equivalent indoor sound levels at lower frequencies below 630Hz, ranging from 42dBA to 57dB (Fig. 56-57). For instance, a single-pane façade composed of either 1/8-inch PVB-laminated glass or 1/8-inch TSC-laminated glass, maintain indoor sound levels to range from 55dBA to 57dBA at frequencies below 630Hz. This trend demonstrates glass with either PVB laminate or TSC laminate regulate sound transmission from outdoor traffic noise at a lower frequencies. In response to frequencies below 630Hz, single-pane facades, varied by different thickness of PVB-laminated glass and TSC-laminated glass, provide indoor sound levels ranging from 42dBA to 57dBA. At frequencies above 630Hz, single-pane facades composed of PVB- laminated glass provide indoor sound levels between 16dBA to 54dBA while single-pane facades with TSC-laminated glass provide indoor sound levels between 17dBA and 54dBA. In comparing indoor sound levels resulting from outdoor traffic noise at low and high frequencies, indoor sound levels provided by single-pane facades composed with a laminate film were reduced in response to outdoor traffic noise at higher frequencies (Table 13-14). Batungbakal 108 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects TABLE 13. SINGLE-PANE FACADES: A-WEIGHTED INDOOR SOUND LEVELS SINGLE PANE PVB Hz 50 63 80 100 125 160 200250315400500630800100012501600 2000 2500 315040005000 1/8" 55 56 57 57 56 57 57 56 55 55 55 54 54 54 51 49 47 43 38 35 36 1/4" 50 51 52 52 50 51 51 50 49 49 49 48 49 48 47 43 41 41 37 33 28 3/8" 47 48 49 48 47 47 48 46 46 46 46 45 46 45 42 44 43 37 32 28 23 1/2" 45 45 46 46 44 45 45 44 43 44 44 44 44 43 45 42 39 33 28 24 19 5/8" 43 44 44 44 43 43 44 42 42 42 43 42 42 45 43 39 36 30 25 21 16 TABLE 14. SINGLE-PANE FACADES: A-WEIGHTED INDOOR SOUND LEVELS SINGLE PANE TSC Hz 50 63 80 100 125 160 200250315400500630800100012501600 2000 2500 315040005000 1/8" 55 56 57 57 56 57 57 56 55 55 55 54 54 54 51 48 47 43 37 35 35 1/4" 50 51 52 52 50 51 51 50 49 49 49 48 49 48 46 42 41 40 38 34 29 3/8" 47 48 49 48 47 47 48 46 46 46 46 45 46 45 42 43 43 38 33 28 24 1/2" 45 45 46 46 44 45 45 44 43 44 44 44 43 43 44 43 40 34 29 25 20 5/8" 43 43 44 44 43 43 43 42 42 42 42 41 42 45 44 40 37 31 26 22 17 10.1-5 Single- Pane Facades Composed of Laminated Glass–Direct Sound Transmission Loss Obtaining indoor sound levels between 55dBA to 57dBA, singled-pane facades with either PVB laminate or TSC laminate, provide a consistent increase of sound transmission loss in response to outdoor traffic noise at higher frequencies. Single-pane façade with 1/8-inch laminated glass is applicable to this trend (Table15-16). Demonstrating the same trend as INSUL-simulated single-pane facades composed of monolithic glass, a single-pane façade with an increased laminated glass thickness improves transmission loss from to 2dB to the maximum of 12dB, providing noticeable to doubled transmission loss (Table 15-16). At lower frequencies below 630Hz, sound transmission loss from single-pane Batungbakal 109 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects facades with laminate film (either PVB or TSC) range from 10dB to 38dB. At frequencies higher than 630Hz, single-pane facades with laminated glass provide 25 to 55dB of transmission loss. 10.1-6 Single- Pane Facades Composed of Laminated Glass - Critical Frequencies Similar to single-pane facades composed of monolithic glass, the coincidence effect for single- pane facades with PVB laminate occur towards outdoor traffic noise at 630Hz to 4000Hz while the coincidence effect for single-pane facades with TSC laminate occur at 500Hz to 4000Hz. As seen in Figure 56 and 57, increasing the glass thickness of a single-pane façade, composed with either with PVB laminate or TSC laminate, result for the coincidence effect to occur at lower frequencies. For instance, the coincidence effect for a single-pane façade with 1/8-inch PVB-laminated glass is above 4000Hz while the coincidence effect for a single-pane façade with 5/8-inch PVB-laminated glass occurs at 630Hz. Indicated by minimal transmission loss improvement or reduced transmission loss, the coincidence effect occurs at 2000Hz for ¼-inch PVB-laminated glass, 1250Hz for 3/8-inch PVB laminated glass, 1000Hz at ½-inch PVB laminated glass, and 800Hz for 5/8-inch” PVB laminated glass. Similar to single-pane facades with PVB-laminated glass, double-pane facades with TSC- laminated glass minimizes the change in decibels of transmission loss. At critical frequencies, single-pane facades with TSC-laminated glass provide a decibel change of transmission loss no more than 2dB. Indicated in Table 15, increasing the thickness of TSC laminated glass did not influence the amount of reduced transmission loss at critical frequencies. Batungbakal 110 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Although the coincidence effect for single-pane facades with TSC laminate occurs at a broader spectrum in frequencies compared to single-pane facades composed of either monolithic glass or PVB laminated glass, a decibel change of indoor sound levels, whether an increase or decrease at critical frequencies, is less than 3dB. Compared to single-pane facades with TSC-laminated glass less than 5/8-inch thick, a single-pane facade with 5/8-inch TSC laminated glass provides the most perceptible decibel change of indoor sound levels at critical frequencies, increasing indoor sound levels to by the maximum of 3dB. In contrast, single-pane facades composed of smaller thickness of TSC-laminated glass allow indoor sound levels to change by 1dB at critical frequencies. TABLE 15. PERFORMANCE OF SINGLE-PANE FACADES: DIRECT SOUND TRANSMISSION LOSS SINGLE PANE PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 100012501600 2000 2500 315040005000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 1/8" 10 11 12 13 14 15 17 18 20 22 23 25 27 28 30 31 33 34 37 39 36 1/4" 15 16 17 18 20 21 23 24 26 28 29 31 32 34 34 37 39 36 38 41 44 3/8" 18 19 20 22 23 25 26 28 29 31 32 34 35 37 39 36 37 40 43 46 49 1/2" 20 22 23 24 26 27 29 30 32 33 34 35 37 39 36 38 41 44 47 50 53 5/8" 22 23 25 26 27 29 30 32 33 35 35 37 39 37 38 41 44 47 50 53 56 TABLE 16. PERFORMANCE OF SINGLE-PANE FACADES: DIRECT SOUND TRANSMISSION LOSS SINGLE GLAZED TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 100012501600 2000 2500 315040005000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 1/8" 10 11 12 13 14 15 17 18 20 22 23 25 27 28 30 32 33 34 38 39 37 1/4" 15 16 17 18 20 21 23 24 26 28 29 31 32 34 35 38 39 37 37 40 43 3/8" 18 19 20 22 23 25 26 28 29 31 32 34 35 37 39 37 37 39 42 46 48 1/2" 20 22 23 24 26 27 29 30 32 33 34 35 38 39 37 37 40 43 46 49 52 5/8" 22 24 25 26 27 29 31 32 33 35 36 38 39 37 37 40 43 46 49 52 55 Batungbakal 111 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 10.1-7 Comparison Establishing a single-pane façade composed of ¼-inch monolithic glass as the baseline, single- pane facades with increased monolithic glass thickness improved sound attenuation due to increased direct transmission loss. Comparing single-pane facades composed of increased thickness of monolithic glass to the baseline, a single-pane façade composed of 1/4-inch monolithic glass, determined increasing the glass thickness of a single-pane façade increased transmission loss from 3dB to as high as 21dB, providing perceptible to doubled transmission loss. While increased transmission loss is the resultant of increased glass thickness at higher frequencies, the decibel change in transmission loss differs at lower frequencies and higher frequencies. Compared to the baseline- a single-pane façade with 1/4-inch monolithic glass, single-pane facades with laminate film, either PVB or TSC, minimize the coincidence effect resulting from outdoor traffic noise at higher frequencies (Fig. 58). Responding to outdoor traffic noise above 2500Hz, single-pane facades with laminate film (PVB or TSC) increase transmission loss by 4dB to 9dB, a significant decibel change. While the baseline-a single-pane façade composed of 1/4- inch monolithic glass reduces transmission loss at critical frequencies, single-pane facades with laminate film provide increased transmission loss in response to outdoor traffic noise at higher frequencies, demonstrating the effectiveness of laminates in minimizing the coincidence effect. Batungbakal 112 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 58. Comparison of Single-Pane Facades Composed of 1/4-inch Glass. Comparing the baseline- a single-pane façade composed of 1/4-inch monolithic glass, to single- pane facades composed of monolithic glass thicker than 1/4-inch, single-pane facades with increased thickness of monolithic glass provide increased transmission loss of 3dB to 21dB. However, at critical frequencies, single-pane facades with increased thickness of monolithic glass reduce transmission loss by 4dB while the baseline- a single-pane façade composed of ¼- inch monolithic glass, reduced transmission loss by 5dB; therefore, significantly minimizing the coincidence effect. To determine improved acoustic performance resulting from single-pane facades with PVB laminate, single-pane facades were compared to single-pane facades composed of monolithic glass, which is established as a baseline comparison (Fig.59). In comparison, single-pane facades with PVB-laminate, improve transmission loss by 1dB to 10dB. Depending on a façade’s glass thickness, single-pane facades composed of PVB-laminated glass greater than ¼-inch provide Batungbakal 113 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects perceptible improvement of transmission loss at critical frequencies and higher frequencies. Although single-pane facades with increased thickness of PVB-laminated glass provide 1dB to 8dB improvement in transmission loss compared to the baseline, its improved performance is reduced at critical frequencies. Single-pane façades composed of smaller thickness of PVB- laminated glass, such as 1/8-inch and ¼-inch, provide improved transmission loss at critical frequencies at 1600Hz to 2000Hz, peaking at 10dB. Figure 59. Single-Pane Façades: Improved Transmission Loss Using PVB Laminate Glass. Figure 60. Single-Pane Façades: Improved Transmission Loss Using TSC Laminate Glass. Batungbakal 114 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Similar to single-pane facades composed with PVB laminate, single-pane facades composed with TSC laminate provide improved transmission loss compared to single-pane facades composed of monolithic glass (Fig. 60). Providing a 1dB to 10dB increase in transmission loss, improved acoustic performance single-pane facades with TSC laminate provides peak at critical frequencies and higher frequencies. Similar to single-pane facades with PVB laminate, single- pane facades with TSC-laminated glass greater than 1/8-inch effectively improved transmission loss at critical frequencies. Referencing single-pane facades composed of monolithic glass as the baseline, single-pane facades with smaller thickness of TSC-laminated glass, such as 1/8-inch and ¼-inch, improve transmission loss by 1dB to 10dB. Figure 61. Single-Pane Façades: PVB and TSC, Laminate Glass Comparison. While single-pane facades with either PVB-laminated glass or TSC-laminated glass provide a maximum increase of 10dB in transmission loss, transmission loss provided by single-pane Batungbakal 115 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects facades with TSC laminate is 1dB to 2dB greater than single-pane facades composed with PVB laminate, a perceptible improvement (Fig. 61). Since single-pane facades composed with laminate provide 1 to 10dB increase in transmission loss compared to the baseline, a single-pane façade composed of 1/8-inch monolithic glass, single-pane facades composed with PVB laminate were compared to single-pane facades with TSC laminate to determine which laminate provided improved transmission loss. Comparing single-pane facades with PVB laminate to single-pane facades with TSC laminate, single-pane facades with TSC-laminated glass thicker than ¼-inch provide an additional decibel in transmission loss. In comparison to single-pane facades with PVB laminate, single-pane facades with TSC-laminated glass less than ¼-inch thickness increase transmission loss 1dB more than single-pane facades with PVB laminate. Although single-pane facades with TSC laminate improve transmission loss by 1dB compared to single-pane facades with PVB laminate, 1dB is barely a perceptible improvement. Since a decibel increase of transmission loss is not a perceptible change, single-pane facades with PVB laminate is considered as a cost-effective alternative to improve transmission loss since TSC laminate, a recent version of PVB film claimed to improve transmission loss by at least 3dB, is priced higher than the standard PVB laminate 139 . 139 Kuraray, Trosifol. <http://www.trosifol.com/en/produkte/architecture/trosifol-sound-control-sc/>. Batungbakal 116 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 62. Single-Pane Façades. 10.1-8 Acoustic Performance of Single-Pane Facades The distinction between single-pane facades composed of monolithic glass and single-pane facades composed with laminate (such as PVB and TSC) are emphasized in response to outdoor traffic noise at frequencies below 630Hz and higher frequencies above 630Hz (Fig. 62). Responding to Los Angeles outdoor traffic noise at lower frequencies below 630Hz, single pane facades, either composed of monolithic glass, PVB laminated glass or TSC laminated glass, provide indoor sound levels ranging from 40dB to 60dB. As indoor sound levels between 40dB to 60dB are within the acceptable range for office workspaces, INSUL-simulated single-pane facades indicate direct transmission loss of existing Los Angeles traffic noise to provide indoor sound levels acceptable for the office workspace 140 . The coincidence effect occurs at lower frequencies as for single-pane facades composed of larger thickness of monolithic glass, PVB-laminated glass or TSC-laminated glass. Although single- pane facades composed with laminate, PVB or TSC film, reduced the coincidence effect at 140 Cavanaugh, 13. Batungbakal 117 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects critical frequencies, the performance trend still applies to single-pane facades with a glass thickness great than 1/8-inch. At lower frequencies between 50Hz to 630Hz, increased glass thickness allowed single-pane facades to increase sound transmission loss by 5dB to 13dB. Single-pane facades composed of a monolithic glass thickness greater than 1/8-inch increased sound transmission loss by 8dB to 21dB at higher frequencies between... At its weakest point, which is indicated at its coincidental dip at 800Hz to 2000Hz, increasing the glass thickness of monolithic single-glazed facades reduced sound transmission loss at higher frequencies. For instance, a single-glazed facade with 5/8" monolithic glass reduced transmission loss by 3dB at 800Hz; however, at 1000Hz, the facade assembly attenuates sound by 3dB from 1250Hz to 5000Hz. Reducing sound levels from 1dB to 6dB demonstrated single-pane facades to provide ‘perceptible’ improvement. Batungbakal 118 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects CHAPTER 11 Results Double-Pane Façades (¼” + ½” air gap + increased glass thickness”) Figure 63. Double-Pane Façade of Monolithic Glass: Indoor Sound Levels from Direct Transmission Loss 11.1-1 Double- Pane Facades Composed of Monolithic Glass -Indoor Sound Levels A Standard IGU composed of monolithic glass A standard insulated-glazing unit (IGU) compliant with Title 24 is comprised of two ¼-inch glass layers separated by ½-inch air gap. Direct transmission loss from a double-pane façade comprised of the standard dimensions for an insulated glazing unit (IGU) provide indoor sound levels ranging from 27dBA to 56dBA (Fig. 63). At frequencies below 630Hz, direct transmission loss from a double-pane façade with standard IGU dimensions provide indoor sound levels Batungbakal 119 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects between 44dBA to 56dBA at frequencies below 630Hz and indoor sound levels between 27dBA to 45dBA at higher frequencies above 630Hz. Indoor sound levels, resulting from direct transmission loss provided by double-pane facades composed of monolithic glass, range from 20dBA to 63dBA. At frequencies below 630Hz, indoor sound levels range from 42dBA to 63dBA while indoor sound levels range from 20dBA to 50dBA at higher frequencies above 630Hz.Using a double-pane façade composed of two layers of ¼-inch monolithic glass and ½-inch air gap as a baseline, double-pane facades with an increased outer glazing thickness improves transmission loss; therefore, reducing indoor sound levels by 1dB to 18dB. The lowest indoor sound level resulting from INSUL-simulated double-pane facades varied by five common glass thickness for its exterior layer, range from 20dBA to 28dBA in response to traffic noise at higher frequencies. The maximum indoor sound level is between 160Hz and 200Hz, ranging from 48dBA to 63dBA (Table 17). Increasing the glass thickness of double-pane facades composed of monolithic glass reduces indoor sound levels by at least one-tenth of outdoor traffic noise levels. The amplitude of sound reduced varies at sound frequencies below 630Hz, critical frequencies indicating the coincidence effect-630Hz to 2000Hz, and higher frequencies- 2000Hz to 5000Hz. At frequencies below 630Hz, double-pane facades composed of monolithic glass provide indoor sound levels no more than half of its outdoor sound source. Prior to reaching critical frequency, this trend also evident at frequencies between 500Hz and 2500Hz. At higher frequencies above 2000Hz, double-pane Batungbakal 120 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects facades composed of monolithic glass provides minimum indoor sound levels between 19dBA and 33dBA. 11.1-2 Double- Pane Facades Composed of Monolithic Glass -Critical Frequencies Since critical frequencies are indicated by reduced transmission loss or little change in transmission loss, the coincidence effect for double-pane facades composed of monolithic glass occurs at frequencies between 630Hz and 2000Hz (Fig. 63). At critical frequencies, direct transmission loss from double-pane facades composed of monolithic glass obtain indoor sound levels between 39dBA to 50dBA (Table 17). In contrast to single-pane facades composed of monolithic glass, double-pane facades composed of monolithic glass provide increased indoor sound levels at 160Hz to 200Hz and at 800Hz to 1000Hz, due to reduced transmission loss (Table 18). Reduced transmission loss responding to outdoor traffic noise at critical frequencies, such as160Hz to 200Hz and at 800Hz to 2000Hz, indicate resonance and coincidence effect. For instance, a double-pane façade with a 5/8-inch monolithic glass exterior provides increased transmission loss as it corresponds to higher frequencies; however, reduced transmission loss occurs at 800Hz, indicating the weakest point for the façade assembly. This trend applies to other double-pane facades composed of smaller monolithic glass thickness. As a result to increasing the glass thickness of a double-pane façade, the coincidental effect occurs at lower frequencies. Batungbakal 121 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects TABLE 17. DOUBLE- PANE FACADES: A-WEIGHTED INDOOR SOUND LEVELS DOUBLE PANE MONO Hz 50 63 80 100 125 160 200250315400500630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 ¼”+ 1/8" 50 51 52 52 51 53 63 52 48 46 45 44 45 44 43 40 41 42 37 33 28 ¼”+1/4" 48 48 49 50 50 56 52 47 45 45 44 44 44 45 41 41 45 41 36 32 27 ¼”+3/8" 46 47 48 48 49 54 48 45 44 44 43 43 44 44 43 46 44 38 33 29 24 ¼”+1/2" 44 45 47 47 48 50 46 44 43 43 43 43 44 45 48 44 42 36 31 27 22 ¼”+5/8" 43 44 45 46 48 48 45 42 42 42 42 43 45 50 46 42 39 33 28 24 20 TABLE 18. PERFORMANCE OF DOUBLE-PANE FACADES: DIRECT SOUND TRANSMISSION LOSS DOUBLE PANE MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 ¼+ ½+ 1/8" 15 16 17 18 19 19 11 22 27 31 33 35 36 38 38 40 39 35 38 41 44 ¼+ ½+ 1/4" 17 19 20 20 20 16 22 27 30 32 34 35 37 37 40 39 35 36 39 42 45 ¼+ ½+ 3/8" 19 20 21 22 21 18 26 29 31 33 35 36 37 38 38 34 36 39 42 45 48 ¼+ ½+ 1/2" 21 22 22 23 22 22 28 30 32 34 35 36 37 37 33 36 38 41 44 47 50 ¼+ ½+ 5/8" 22 23 24 24 22 24 29 32 33 35 36 36 36 32 35 38 41 44 47 50 52 Batungbakal 122 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 64. Double-Pane Façade with PVB Laminate: Indoor Sound Levels from Direct Transmission Loss. Figure 65. Double-Pane Façade with TSC Laminate: Indoor Sound Levels from Direct Transmission Loss Batungbakal 123 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 11.1-3 Double- Pane Facades with Laminate Glass -Indoor Sound Levels At frequencies between 50Hz and 125Hz, double-pane facades with laminate film, PVB or TSC, provide indoor sound levels equivalent to double-pane facades composed of monolithic glass. At 50Hz to 125Hz, transmission loss from double-pane facades with PVB-laminated glass provide indoor sound levels between 43dBA and 52dBA (Fig.64-65). This trend applies to double-pane facades with an exterior glazing of either 1/8-inch or ¼-inch PVB-laminated glass. At lower frequencies below 630Hz, direct transmission loss from double-pane facades with laminate, such as PVB or TSC, provide indoor sound levels from 41dBA to 63dBA. Responding to frequencies above 630Hz, double-pane facades with laminate, PVB or TSC, provide indoor sound levels ranging from 17dBA to 44dBA. Compared to a standard double-pane façade with laminate, double-pane facades with an increased exterior laminated-glass thickness reduces indoor sound levels by 1 to 10dB. Although increasing the exterior glazing thickness of a double-pane façade reduces indoor sound levels, it allows resonance and the coincidence effect too occur at lower frequencies. 11.1-4 Double- Pane Facades with Laminate Glass -Critical Frequencies Double-pane facades with PVB laminate indicate resonance to occur at 125Hz to 200Hz, where maximum indoor levels range from 48dBA and 63dBA due to reduced transmission loss. At critical frequencies between 125Hz and 200Hz, double-pane facades with increased thickness of PVB-laminated glass reduces indoor sound levels to the maximum of 10dB. Batungbakal 124 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Similar to double-pane facades composed of monolithic glass, increased indoor sound levels from double-pane facades with laminate responding to outdoor traffic noise at 800Hz to 2000Hz indicates its coincidence effect. Responding to outdoor traffic noise levels at frequencies between 800Hz and 2000Hz, the change in decibels of indoor sound level ranges from 3dB to 5dB, a perceptible change. At critical frequencies, indicating the maximum indoor sound levels provided by double-pane facades with laminate, indoor sound levels ranged from 44dBA to 63dBA at 125Hz to 200Hz, and 38dBA to 44dBA at 800Hz and 2000Hz, corresponding to the thickness of laminated glass. Double-pane facades with either 1/8-inch or ¼-inch laminated glass for its exterior glazing provide the highest maximum indoor sound levels at critical frequencies. At critical frequencies between 800Hz and 2000Hz, a double-pane façade, with either 1/2-inch laminated glass or 5/8-inch laminated glass for its exterior glass, provides the highest indoor sound level, 43dBA. When compared to double-pane facades composed of monolithic glass, double-pane facades with laminate reduced the coincidence effect, minimizing reduced sound transmission loss. Although laminate, PVB and TSC, reduces the coincidence effect of double-pane facades, resonance results for double-pane facades with laminate to provide indoor sound levels between 48dBA and 63dBA (Table 19-22). Batungbakal 125 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects TABLE 19. DOUBLE- PANE FACADES: A-WEIGHTED INDOOR SOUND LEVELS DOUBLE PANE PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 ¼”+ 1/8" 50 51 52 52 51 53 63 52 47 46 45 44 44 44 42 38 38 38 34 30 25 ¼”+1/4" 48 48 49 50 50 56 52 46 45 45 44 43 44 44 40 38 41 38 33 29 24 ¼”+3/8" 46 47 48 48 49 54 48 45 43 43 43 42 43 42 40 41 41 35 30 26 21 ¼”+1/2" 44 45 47 47 48 50 46 43 42 42 42 42 42 41 43 42 39 33 28 24 19 ¼”+5/8" 43 44 45 46 48 48 44 42 41 41 41 40 41 44 44 39 36 31 26 21 17 TABLE 20. PERFORMANCE OF DOUBLE-PANE FACADES: DIRECT SOUND TRANSMISSION LOSS DOUBLE PANE PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 ¼+ ½+ 1/8" 15 16 17 18 19 19 11 22 28 31 33 35 37 38 39 42 42 39 41 44 47 ¼+ ½+ 1/4" 17 19 20 20 20 16 22 28 30 32 34 36 37 38 41 42 39 39 42 45 48 ¼+ ½+ 3/8" 19 20 21 22 21 18 26 29 32 34 35 37 38 40 41 39 39 42 45 48 51 ¼+ ½+ 1/2" 21 22 22 23 22 22 28 31 33 35 36 37 39 41 38 38 41 44 47 50 53 ¼+ ½+ 5/8" 22 23 24 24 22 24 30 32 34 36 37 39 40 38 37 41 44 46 49 53 55 TABLE 21. DOUBLE- PANE FACADES: A-WEIGHTED INDOOR SOUND LEVELS DOUBLE PANE TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 ¼”+ 1/8" 50 51 52 52 51 53 63 52 47 46 44 43 44 43 41 38 38 38 34 30 25 ¼”+1/4" 48 48 49 50 50 56 52 46 45 44 44 43 44 43 40 38 40 38 33 29 24 ¼”+3/8" 46 47 48 48 49 54 48 45 43 43 43 42 43 43 40 38 41 36 31 27 22 ¼”+1/2" 44 45 47 47 48 50 46 43 42 42 42 41 43 41 40 42 39 33 28 24 19 ¼”+5/8" 43 44 45 46 48 48 44 42 41 41 41 41 41 41 43 40 37 31 26 22 17 TABLE 22. PERFORMANCE OF DOUBLE-PANE FACADES: DIRECT SOUND TRANSMISSION LOSS DOUBLE PANE TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 ¼+ ½+ 1/8" 15 16 17 18 19 19 11 22 28 31 34 36 37 39 40 42 42 39 41 44 47 ¼+ ½+ 1/4" 17 19 20 20 20 16 22 28 30 33 34 36 37 39 41 42 40 39 42 45 48 ¼+ ½+ 3/8" 19 20 21 22 21 18 26 29 32 34 35 37 38 39 41 42 39 41 44 47 50 ¼+ ½+ 1/2" 21 22 22 23 22 22 28 31 33 35 36 38 38 41 41 38 41 44 47 50 53 ¼+ ½+ 5/8" 22 23 24 24 22 24 30 32 34 36 37 38 40 41 38 40 43 46 49 52 55 Batungbakal 126 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 66. Double-Pane Façades. 11.1-5 Comparison Figure 67. Comparison Single-Panes Façade and Double-Pane Façades. Double-Pane Facades and Single-Pane Façades Comprised of two glass panels separated by a ½-inch air-cavity, which are the standard dimensions for an insulated glazing unit (IGU), a double-pane façade composed of ¼-inch monolithic glass provides indoor sound levels ranging from 27dBA to 56dBA. In comparison to a single-pane façade composed of ¼-inch monolithic glass that provides indoor sound levels Batungbakal 127 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects ranging from 32dBA to 52dBA, a double-pane façade composed of ¼-inch monolithic glass provides a 2 to 5dB improvement in transmission loss (Fig.66-68). Figure 68. Improved Transmission Loss from Double-Pane Façades Compared to Single-Pane Façades, Monolithic Glass. Figure 69. Comparison of Single-Pane Façades Composed of 1/4-inch Monolithic Glass and Double-Pane Façade with ¼-inch Monolithic Glass. Batungbakal 128 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Establishing single-pane facades composed of monolithic glass as a comparable baseline, double-pane facades improve sound transmission loss by 1dB to 9dB. However, depending on the glass thickness, double-pane facades reduce sound transmission by 1 to 9dB, depending on outdoor traffic noise frequencies (Fig. 69). Thickness With the standard ½-inch air-cavity dimension for an insulated glazing unit (IGU), double-pane facades with smaller glass thickness provide noticeable reduction in sound transmission. For instance, double-pane facades with either a 1/8-inch or ¼-inch monolithic glass reduce sound transmission by 1dB to 9dB compared to single-pane facades with 1/8-inch or ¼-inch monolithic glass (Fig. 69). In contrast, double-pane facades with a glass thickness greater than ¼-inch, such as ½-inch and 5/8-inch monolithic glass, reduce sound transmission by 2 to 3dB at critical frequencies above 800Hz; however, double-pane facades with increased monolithic glass thickness for its exterior glazing improves transmission loss by 1 to 5dB at critical frequencies. Compared to single-pane facades composed of monolithic glass thicker than ¼-inch, double- pane facades with an increased monolithic glass thickness for its exterior glazing reduce indoor sound levels by at least 1dB, minimizing change of decibels due to reduced transmission loss. Double-pane facades composed with monolithic glass greater than ¼-inch for its exterior glazing minimize the coincidence effects. At critical frequencies between 125Hz and 200Hz, double- pane facades with increased glass thickness for the exterior glazing noticeably improves transmission loss by 5dB (Fig.70). For instance, a double-pane façade with a 5/8-inch monolithic Batungbakal 129 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects glass for its exterior glazing minimizes the coincidence effect as indoors sound levels are 5dB less than indoor sound levels provided by a single-pane façade composed of 5/8-inch monolithic glass. Figure 70. Comparison of Single-Pane Façades Composed of 5/8-inch Monolithic Glass and Double-Pane Façade with 5/8-inch Monolithic Glass. Laminated glass- PVB and TSC Using a single-pane façade composed of ¼-inch monolithic glass as a comparable baseline, double-pane facades with laminated glass for its exterior glazing provides a 1 to 16dB improvement of transmission loss, a 2dB difference from double-pane facades composed of monolithic glass (Fig. 71). Compared to a double-pane facade composed of ¼-inch monolithic glass, a double-pane facade with ¼-inch laminated glass, either PVB-laminated or TSC- laminated, provides a 3 to 6dB improvement in transmission loss in response to outdoor traffic noise at higher frequencies (Fig.71). Batungbakal 130 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects In response to outdoor noise below 630Hz, transmission loss resulting from double-pane facades with laminated glass for its exterior glazing is equivalent to transmission loss provided by double-pane facades composed of monolithic glass, providing indoor sound levels between 41dBA to 63dBA. Although transmission loss from double-pane facades with laminated glass provides indoor sound levels equivalent to double-pane facades composed of monolithic glass, double-pane facades with laminated glass provides a 1 to 6dB improvement in transmission loss. Figure 71. Comparison of Single-Pane Façades Composed of 1/4-inch Monolithic Glass and Double-Pane Façade with ¼-inch Glass. Batungbakal 131 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 72. Single-Pane Façades and Double-Pane Façades: PVB-laminated Glass Comparison. Figure 73. Single-Pane Façades and Double-Pane Façades: TSC-laminated Glass Comparison. Batungbakal 132 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Double-Pane Facades A double-pane façade with a ¼-inch laminated glass for the exterior glazing provides indoor sound levels between 24dB to 56 dB. In comparison to a double-pane façade with ¼-inch monolithic glass, a double-pane façade with ¼-inch laminated glass for its exterior glazing provides a 1to 6dB improvement in transmission loss (Fig. 72-73). Using a single-pane façade composed of ¼-inch monolithic glass as a comparable baseline, double-pane facades composed of monolithic glass provides 1 to 13dB improvement in transmission loss, resulting for indoor sound levels to range from 20dBA to 56dBA. Double- pane facades with laminated glass for its exterior glazing provides 1 to 16dB improvement in transmission loss, resulting for indoor sound levels to range from 17dBA to 56dBA (Fig.72-73). Figure 74. Comparison of Double-Pane Façades Composed of 1/4-inch Glass and Double-Pane Façade with 5/8-inch Glass for Exterior Glazing. Batungbakal 133 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Laminated glass provides the most improved transmission loss within mid frequencies and higher frequencies. Responding to higher sound frequencies, double-pane facades composed of laminated glass consistently provides improved transmission loss. PVB and TSC improve transmission loss at higher frequencies, where the coincidental effect commonly occurs (Fig. 74). In comparison to double-pane facades composed of monolithic glass, double-pane facades composed of laminated glass increases transmission loss to a maximum of 9dB (Fig.74-77). Responding to outdoor traffic noise at critical frequencies between 630Hz and 2000Hz, double- pane facades with increased thickness of laminated glass for the exterior glazing (such as 3/8- inch, ½-inch, and 5/8-inch) provides the maximum improvement in transmission loss, ranging from 4dB to 9dB. At higher frequencies above 2000Hz, double-pane facades with increased laminated glass thickness provides 2 to 4dB improvement in transmission loss compared to double-pane facades composed of monolithic glass. Comparing double-pane facades composed of PVB-laminated glass for the exterior glazing to double-pane facades composed of TSC-laminated glass for the exterior glazing, double-pane facades with TSC laminate generally provides 1dB improvement in transmission loss (Fig. 78). However, double-pane facades with increased thickness of TSC-laminated glass (greater than ¼- inch) provide a 3dB increase in transmission loss at critical frequencies between 1000Hz and 2000Hz. Although TSC laminate improves the acoustic performance of double-pane facades by 1dB, it is not a perceptible improvement from double-pane facades with PVB laminate. Batungbakal 134 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 75. Compare Double-Pane Facade Laminates and Glass Thickness. Figure 76. Double-Pane Façades: Improved Transmission Loss with PVB Laminate. Batungbakal 135 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 77. Double-Pane Façades: Improved Transmission Loss with TSC Laminate. Figure 78. Double-Pane Façades: PVB and TSC, Laminate Glass Comparison. 11.1-6 Acoustic Performance of Double-Pane Facades Overall Performance Comparison of double-pane facades differing in glass type and glass thickness determined the standard air-cavity of an IGU, ½-inch, improved transmission loss compared to single-pane façade assemblies (Fig. 75-78). Reducing sound transmission by 13dB to 57dB compared to single-pane facades, double-pane façades doubled transmission loss at higher frequencies. Batungbakal 136 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Comparing double-pane facades with monolithic glass to double-pane facades with laminate, laminate glass improved the acoustic performance of double-pane facades composed of smaller glass thickness. Resonance Dip and Coincidence Dip As the maximum indoor sound levels result from lower frequencies, the acoustic performance of double-pane facades, composed of either monolithic glass, PVB laminated glass or TSC laminated glass, are perceptibly affected at critical frequencies indicating resonance rather than the coincidence effect. Batungbakal 137 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects CHAPTER 12 Results Double-Skin Façade composed of [¼” + ½” air gap + ¼”] + air-cavity + ¼” outer skin Figure 79. Double-Skin façade: monolithic [¼” + ½” air gap + ¼”] + air-cavity + 1/4” In this study, all INSUL-simulated double-skin facades assessed and analyzed are composed of a standard insulated-glazing unit for its inner skin and a single glass panel differing in three glass types and four standard glass thickness for its secondary skin. Double-skin façades described to consist of increased glass thickness for its secondary skin refers that the secondary skin, the exterior glass layer facing towards outdoor sound sources, is comprised of a single-glass panel greater than the minimum glass thickness (1/4-inch) acceptable for commercial building facades. Batungbakal 138 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Double-skin facades composed of glass with laminate are also referred to the secondary skin of the façade; therefore, all double-skin facades simulated and assessed maintained the standard dimensions of an IGU for its inner skin while double-skin façades simulated differed by the air- cavity dimension, the glass type, and the glass thickness of the secondary skin. Utilizing INSUL façade simulations to determine improved transmission loss provided by double-skin facades and its façade components, a single-pane façade composed of ¼-inch monolithic glass and a double-pane façade composed of ¼-inch monolithic glass were referenced as comparative baselines. Façade components of double-skin facades identified to improve transmission loss derived from the comparison of transmission loss provided by single-pane facades, double-pane facades, and a double-skin façade composed of ¼-inch monolithic glass and the minimum air-cavity depth, 15.7-inches. Identifying the amount of improved transmission loss provided by a double-skin façade composed of ¼-inch monolithic glass with the minimum air-cavity depth, a double-skin façade composed of ¼-inch monolithic glass and the minimum air-cavity depth was used as a baseline to identified improved transmission loss provided by double-skin façades with a secondary skin greater than ¼-inch and laminated glass. Comparing the acoustic performance of single-pane facades and double-pane facades identified the secondary skin and air-cavity of double-skin façades to perceptibly reduce sound transmission, providing acceptable indoor sound levels for the workspace environment. Batungbakal 139 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 12.1-1 Double- Skin Façades Composed of Monolithic Glass -Indoor Sound Levels Responding to outdoor traffic noise below 630Hz, double-skin facades with ¼-inch monolithic glass as the secondary skin provide indoor sound levels ranging from 23dBA to 40dBA (Fig. 79). Towards outdoor traffic noise above 630Hz, transmission loss from double-skin facades with ¼- inch monolithic glass as the secondary skin provide indoor sound levels between 3dBA to 26dBA. Compared to a double-skin façade with ¼-inch monolithic glass as its secondary skin and the minimum 15.7inch air-cavity, increasing the air-cavity dimension of a double-skin facade with ¼-inch monolithic glass as its secondary skin increases transmission loss by 1 to 7dB. For instance, transmission loss from a double-skin façade composed of a ¼-inch monolithic glass as its secondary skin and 39.3-inch air-cavity provides minimum indoor sound levels resulting from outdoor traffic noise at 50Hz to 5000Hz. Although a double-skin façade with ¼-inch monolithic glass as its secondary skin and 39.3-inch air-cavity provides minimum indoor sound levels, ranging from 3dBA to 34dBA, equivalent indoor sound levels can be obtained with a smaller air- cavity dimension, such as double-skin facades with a 31.5-inch air cavity or a 23.6-inch air- cavity. Compared to a double-skin façade with ¼-inch monolithic glass as its secondary layer and 39.3-inch air-cavity, indoor sound levels resulting from a double-skin façade with ¼-inch monolithic glass as its secondary layer and 31.5-inch air-cavity is 1dB higher, providing an unnoticeable decibel improvement of indoor sound levels. Batungbakal 140 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 12.1-2 Double- Skin Façades Composed of Monolithic Glass –Critical Frequencies Although a double-skin façade with 1/4"-inch monolithic glass as its secondary skin provides indoor sound levels below 40dBA, increasing the air-cavity dimension minimally reduces its coincidence effect. Contrasting from reduced transmission loss provided double-pane facades responding to outdoor sound levels between 125Hz to 2500Hz, a double-skin façade composed of ¼-inch monolithic, however, minimizes reduction of transmission loss at lower frequencies. At 125Hz to 200Hz, a reduction of transmission loss from a double-skin façade composed of ¼-inch monolithic glass is no more than 1dB, providing an unperceivable change of indoor sound levels. While a double- skin façade composed of a ¼-inch monolithic glass provides minimal resonance, increased air- cavity dimension of a double-skin façade with ¼-inch monolithic glass provides minimal impact. INSUL façade simulations indicate increasing the air-cavity dimension of a double-skin façade composed ¼-inch monolithic glass improved sound transmission loss by at least 2dB. Batungbakal 141 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 80. Double-Skin Façade: PVB, [¼” + ½” air gap + ¼”] + air-cavity + 1/4”. 12.1-3 Double- Skin Façades Composed of Laminated Glass -Indoor Sound Levels Direct transmission loss from double-skin façades with ¼-inch laminated glass for the secondary skin provides indoor sound levels ranging from 22dBA to 40dBA at 50Hz to 500Hz, and 1dBA to 25dBA at sound frequencies above 630Hz (Fig. 80-81). Similar to indoor sound levels resulting from direct transmission loss of double-skin facades with ¼-inch monolithic glass, the maximum indoor sound level resulting from double-skin facades with laminated glass is 40dBA, which is an acceptable sound level for workspace environments 141 . A double-skin façade with 1/4"-inch laminated glass and the minimum air-cavity dimension, 15.7 inches, provides indoor sound levels between 4dBA to 40dBA. In contrast, double-skin 141 Cavanaugh, 13. Batungbakal 142 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects façades with 1/4"-inch laminated glass and the maximum air-cavity dimension, 39.3 inches, provides indoor sound levels between 1dBA and 33dBA. Comparing a double-skin facade with the minimum air-cavity dimension to a double-skin façade with the maximum air-cavity dimension, increasing the air-cavity dimension, which separates the inner skin (an IGU) and the secondary skin, a double-skin façade with ¼-inch PVB-laminated glass, reduces indoor sound levels by 2dB to 7dB. 12.1-4 Double- Skin Façades Composed of Laminated Glass–Direct Sound Transmission Loss Direct transmission loss from a double-skin façade with ¼-inch laminated glass ranged from 28dB to 57dB at frequencies below 630Hz, 56dB to 68dB at 630Hz to 2000Hz, and 62dB to 74dB at higher frequencies. An increase in sound transmission loss corresponds to higher sound frequencies. Although double-skin facades with ¼-inch laminated glass provide increased sound transmission loss in response to outdoor traffic noise at higher frequencies, the improved acoustic performance of double-skin facades with ¼-inch laminated glass reduces in response to outdoor sound levels at 80Hz and 1600Hz to 2500Hz. In response to outdoor traffic noise, resonance occur at 80Hz while the coincidence effect occurs at frequencies between 1600Hz to 2500Hz. Similar to double-skin facades composed of ¼-inch monolithic glass, indicated resonance resulting from double-skin facades with ¼-inch laminated glass and increased air-cavity dimensions (such as 31.5 inch) does not provide an increase in transmission loss. In contrast to Batungbakal 143 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects single-pane facades and double-pane facades, double-skin facades with ¼-inch glass as the secondary skin minimizes resonance by providing a decibel change no more than 1dB. At critical frequencies indicating resonance and the coincidence effect, a reduction of transmission loss from double-skin facades with ¼-inch laminated glass are no more than 2dB. In comparison to single-pane facades composed of laminated glass and double-pane facades composed with laminate, which reduced transmission loss by 2dB to3dB at critical frequencies, double-skin facades with ¼-inch laminated glass as its secondary skin reduced the coincidence effect (Fig. 82-83). Figure 81. Double-Skin Façade: TSC, [¼” + ½” air gap + ¼”] + air-cavity + 1/4”. Batungbakal 144 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 82. Double-Skin Façades: [¼” + ½” air gap + ¼”] + air-cavity + ¼”. 12.1-5 Comparison of Double- Skin Façades composed of ¼-inch Glass Figure 83. Comparison Single-Panes Façades and Double-Pane Façades to Double-Skin Façade with ¼-inch Glass. Batungbakal 145 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Double- Skin Façades to Single- Pane Façades and Double-Pane Façades In comparison to single-pane facades composed of ¼-inch monolithic glass, double-skin facades composed of ¼-inch monolithic glass provide a 10 to 25dB improvement in transmission loss, providing indoor sound levels between 7dBA to 40dBA (Fig.83). Compared to a double-pane façade composed of ¼-inch monolithic glass, a double-skin façade composed of ¼-inch monolithic glass with 15.7-inch air-cavity provides 8 to 27dB improvement in transmission loss. Based on a double-skin façade with the minimum 15.7-inch air-cavity and minimum monolithic glass thickness acceptable for commercial office buildings, double-skin facades provide indoor sound levels between 7dBA to 40dBA, which are considered acceptable sound levels for office buildings 142 . In contrast, a single-pane façade composed of ¼-inch monolithic glass provides indoor sound levels between 32dBA to 50dBA and a double-pane façade composed of ¼-inch monolithic glass provides indoor sound levels between 27dBA to 56dBA. Single-pane facades and double-pane facades provide direct indoor sound levels acceptable for private office space as well as public office workspace; however, double-skin facades provides indoor sound levels below 40dBA 143 . While a double-pane façade composed of the standard dimensions of an insulated-glazing unit (IGU) contributes to its 2 to 5dB improvement in transmission loss compared to a single-pane façade composed of ¼-inch monolithic glass, the secondary skin and large air-cavity dimension of a double-skin facade contributes to perceptible improvement of transmission loss provided by a double-skin façade composed of ¼-inch monolithic glass and the minimum air-cavity depth. 142 Cavanaugh, 13. 143 Cavanaugh, 13. Batungbakal 146 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Using the acoustic performance of single-pane facades and double-pane facades as comparable baselines, façade components of a double-skin façade composed of ¼-inch glass, such as glass type and air-cavity dimension, are identified to perceptibly reduce sound transmission. 12.1-6 Double- Skin Façades with Increased Secondary Skin Thickness Double-Skin Façade composed of [¼” + ½” air gap + ¼”] + air-cavity + increased skin As ¼-inch glass is the minimum thickness acceptable for commercial building facades, double- skin facades composed with ¼-inch glass as the secondary skin provides indoor sound levels below 40dBA. Able to reduce sound transmission by 25 to 69dB, a double-skin façade composed of ¼-inch monolithic glass as the secondary skin and 15.7-inch air-cavity depth was used as a baseline to quantify improved transmission loss provided by double-skin facades with a secondary skin greater than ¼-inch. Batungbakal 147 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 84. Compare DSF with 0.25 [out] and DSF with Mono Increased Thickness [out]. Compared to the baseline- a double-skin façade composed of ¼-inch monolithic glass as its secondary skin and a 15.7-inch air-cavity, double-skin facades with a secondary skin greater than ¼-inches and the minimum 15.7-inch air-cavity provides an increase of transmission loss by 1dB to 7dB (Fig.84). For instance, a double-skin façade composed of 3/8-inch monolithic glass as the secondary skin and 15.7-inch air-cavity provides 1 to 4dB improvement in transmission loss. Due to a secondary skin greater than ¼ inches, double-skin facades composed of 3/8-inch monolithic glass as the secondary skin provides indoor sound levels below 37dBA. While a double-skin façade composed of ¼-inch secondary skin provide indoor sound levels below 40dBA, double-skin facades composed of a 3/8-inch secondary skin provides indoor sound levels below 37dBA. Indoor sound levels below 35dBA can be obtained with double-skin facades composed of a ½-inch secondary skin while indoor sound levels below 33dBA can be obtained with double-skin facades composed of a 5/8-inch secondary skin. Batungbakal 148 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 85. Compare DSF with 0.25 [out] and DSF with PVB Increased Thickness [out]. Figure 86. Compare DSF with 0.25 [out] and DSF with TSC Increased Thickness [out]. While double-skin facades composed of monolithic glass greater than ¼-inch improves transmission loss by 1dB to 7dB, double-skin facades composed of laminated glass greater than ¼-inch provides 1 to 8dB improvement of transmission loss. Increasing transmission loss to as Batungbakal 149 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects high as 8dB, laminate such as PVB and TSC improves transmission loss by 1 to 2dB compared to double-skin facades composed of monolithic glass thickness greater than ¼-inch. Noticeable improvement of transmission loss, 2dB, were provided by double-skin facades composed of laminated glass greater than ¼-inches and increased air-cavity dimension. Double-skin facades composed of laminated glass greater than ¼-inch minimizes reduced transmission loss at critical frequencies. 12.1-7 Overall Summary Comparison of double-skin façades differing by the glass thickness of the secondary skin determined increased glass thickness of the secondary skin to provide perceptible to significant improvement of direct transmission loss. Identifying the decibel difference from comparing transmission loss provided by double-skin facades with monolithic glass and double-skin facades with laminate glass, it is confirmed laminate glass to provide perceptible reduction in sound transmission. Batungbakal 150 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects CHAPTER 13 Conclusion- Study Evaluation and Design Support Tool Figure 87. Increased Direct Transmission Loss Provided by a Double-Skin Façade: Composed of ¼-inch Monolithic Glass and 15.7-inch Air-Cavity. 13.1 Conclusion Comparing the acoustic performance of single-pane facades and double-pane facades to double- skin facades emphasized the assembly of a double-skin façade, a single-pane as the secondary skin and the standard dimensions of a double-pane (an IGU) as the inner skin, to at least double reduction of sound transmission. Compared to single-pane facades and double-pane facades, double-skin facades more than doubled the amount of direct transmission loss provided by single-pane facades and double-pane Batungbakal 151 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects facades, providing direct transmission loss between 25dB to 77dB. Double-skin facades with increased air-cavity dimension as well as double-skin facades composed with a secondary skin thickness greater than ¼-inch nearly double transmission loss (Fig. 87). While increasing the air- cavity dimension and secondary glass thickness provides a maximum transmission loss improvement of 8dB, using a laminated glass for the secondary skin allows for increased transmission loss by a maximum of 2dB, an improvement not as significant as increasing the air- cavity dimension or glass thickness of the secondary skin. Increasing improved acoustic performance double-skin facades provides, double-skin facades varied by glass thickness, glass type, and air-cavity dimension were compared. Based on comparisons, which referred to a double-skin façade composed of ¼-inch monolithic glass and the minimum15.7 inch air-cavity as a baseline to compare double-skin façade specimen, increased air-cavity depth of a double-skin façade improved transmission loss by 7dB while including a laminate film provided an additional 1 to 4dB increase of transmission loss. Increasing the glass thickness (to the maximum glass thickness considered in this study) improved transmission loss by no more than 7dB. Lastly, the secondary skin of a double-skin facade doubled the amount of transmission loss in comparison to a standard double-pane façade, indicating the assembly of a double-skin façade to be an influential attribute in obtaining increased transmission loss. Batungbakal 152 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Figure 88. Support Tool. A-weighted Sum of Indoor Sound Levels. 13.2 Composing a Double-Skin Façade Design Support Tool Composing a design support tool that would inform building designers to design glass facades based on acoustic performance and to determine the influence of facade components necessary to reduce outdoor sound transmission, three elements were necessary: o Field-testing using Decibel 10 th , a sound meter application, o Assessing INSUL-simulated single-pane facades, double-pane façades, and double-skin facades; and o Facade analyses comparing direct transmission loss and indoor sound levels provided by simulated facades. Batungbakal 153 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects As glass façade assemblies respond differently according to its outdoor environment, the process in composing the design support tool demonstrated the importance of field-testing existing sound conditions, which determine the maximum outdoor sound level as the sound source. As a conditional element, field-testing involves obtaining outdoor sound levels at a project site where a building façade design would be erected. Identifying the maximum outdoor sound level, field- testing inquires the façade components necessary to acquire indoor sound levels acceptable for the workspace environment. Implementing sound measurements obtained from field-testing allowed INSUL façade simulations to estimate direct sound transmission loss provided by glass façade assemblies in response to traffic noise equivalent to existing conditions. Obtaining direct sound transmission loss provided by single-pane facades, double-pane facades, and double-skin facades through INSUL façade simulations, comparison of glass façade specimen determined the acoustic performance of façade components and its influence on improving direct sound transmission loss. 13.3 Design Support Tool Interface The design support tool is structured by A-weighted indoor sound levels estimated from direct transmission loss and the cost of façade assemblies based on material. Providing A-weighted sum of sound levels, the design support tool provides estimated indoor sound levels resulting from existing outdoor traffic noise and direct sound transmission loss (Fig. 88). The design support tool, which provides estimated A-weighted sum of indoor sound levels, derived solely from direct transmission loss provided by single-pane facades, double-pane facades and double-skin facades. Displaying A-weighted sum of indoor sound levels, the design Batungbakal 154 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects support tool allows building façade designers to compare glass façade assemblies, such as single- pane facades, double-pane facades, and double-skin facades, based on material costs and the following façade components: glass thickness, glass type – monolithic glass, PVB-laminated glass, and TSC-laminated glass, and air-cavity dimension. In order to understand the acoustic performance of glass facades assemblies and the influence of its façade components, A-weighted sum of indoor sound levels for single-pane facades and double-pane facades were included in the design support tool, illustrating the decibel difference between façade assemblies. Reading the design support tool from the bottom to the top, A-weighted sum of indoor sound levels decrease based on the façade components of a façade assembly type. As shown in Figure 00, decreased A-weighted indoor sound levels are obtained with façade assemblies comprised of additional glass layers, air-cavity depth, and laminate, which leads to increased costs for a façade’s additional materials. The estimated cost of façade assembly types were based solely on the glass material itself, excluding façade assembly costs and contractors fees. The cost of each façade specimen is based on the cost per square foot of a glass panel and the number of glass panels composing each façade specimen. For instance, a single-pane façade composed of monolithic glass is the least costly. A double-pane façade is double the cost of single-pane façade composed of monolithic glass as it consists of two glass panels separated by a ½-inch air-cavity. Double-skin facades compared in this study are composed of a standard dimensioned IGU and a single-pane as the Batungbakal 155 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects secondary skin. Consisting of three glass panels, double-skin facades are more than double the cost of a single-pane façade. While considering the number of glass layers assembling single- pane facades, double-pane facades, and double-skin facades, providing a laminate film to glass façade assemblies increases the cost of the glass panel by 50-percent. Using the design support tool composed from field-testing existing conditions, INSUL façade simulations, and façade analyses, building designers can estimate indoor sound levels provided by double-skin facades to improves workspace environments. 13.4 Value of Study and Analyses This study and the method to determine the decibel difference among varied glass façade assemblies provide an understanding to identify influence of façade components. Comparison of single-pane, double-pane facades, and double-skin facades determined key façade components to influence the reduction of sound transmission: - glass type, - glass thickness, - air-cavity dimension, and - façade assembly A-weighted sum of indoor sound levels resulting from INSUL-simulated glass facades determined a double-skin façade assembly, such as its air-cavity dimension to be the most effective in doubling reduction in sound transmission. Quantifying the decibel difference between the maximum and minimum air-cavity dimension simulated determined that increased air-cavity depth performs effectively as a double-skin façade with the minimum air-cavity Batungbakal 156 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects dimension, 15.7 inches. As increased air-cavity dimension are identified to increase costs, this study validates that a double-skin façade is reduces sound transmission due to its additional layer, the outer skin, and its air-cavity which separates the outer skin from the inner skin, an insulated glazing unit. 13.5 Suggested Guidelines: The Importance of Methodology The design support tool, displaying A-weighted sum of indoor sound levels, provides designers to determine façade components that would align with desired indoor sound levels based on its occupancy. The process in composing the design support tool is fundamental. Implementation of field-measurements allowed INSUL simulated to resemble and estimate transmission loss for façade assemblies varying in façade components. As the A-weighted sum of sound levels for ISO 717 is 90dBA, transmission loss is identified by quantifying the difference between A- weighted sum of sound level of indoor sound levels and A-weighted sum of sound levels of the outdoor sound source. CHAPTER 14 Further Research and Limitations Implementing the maximum outdoor sound level obtained from field-measurements to INSUL’s outdoor sound spectrum enabled simulated glass facades, such as single-pane, double-pane, and double-skin facades, to respond to INSUL’s calibrated outdoor sound spectrum, which is equivalent to existing sound conditions in Los Angeles. As a fundamental element in this study, sound measurements from field-tests served as a fundamental element in identifying existing Batungbakal 157 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects sound conditions to be implemented into INSUL façade simulations, allowing estimated acoustic performance of glass façade assemblies to be equivalent its actual performance in an existing setting. This study aimed to explore the acoustic performance of double-skin facades and the influence of its façade components. The elements implemented into composing the design support tool, field- testing, façade simulation, and façade analyses, inform building designers the impact of considering acoustic design for glass facades during early project development. In efforts to improve acoustic design for facades, the following should be considered for further development and research: field-testing conditions, testing and simulation equipment, testing standards, façade components, and indoor sound level parameters. 14.1 Field Measurements for Double-Skin Façades to Validate Simulations In all six sound conditions indoor sound pressure levels determined the influence of single- glazed facades in reducing sound transmission from outdoor sound pressure level. As the maximum sound pressure level identified from six field-measured conditions served as a baseline in simulating single-glazed facades in INSUL, field-testing existing double-skin facades would validate INSUL’s predicted acoustic performance for double-skin facades. 14.2 Field- Testing Equipment Testing standards for field-measurements often require Class I equipment. Utilizing an iPhone application, Decibel 10 th , is not considered the to align with recommended sound equipment as Batungbakal 158 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects its not been formally tested for accuracy. Although Decibel 10th is not classified as Class I equipment, utilizing the iPhone application as a relative measurement tool, raises potential in public involvement and data sourcing in acoustic design. Although Decibel 10 th provided maximum sound levels and peak sound levels, sound measured did not indicate its frequencies. Indicating no frequencies, sound measurements were considered as A-weighted analysis. Although sound pressure levels attained from Decibel 10 th did not provide a sound spectrum, a sound spectrum was composed from integrating sound pressure levels from field-testing to ISO 717 traffic noise in INSUL. When implementing field-testing in future research, validating accuracy of field-test equipment can assist designers and researchers to determine equipment suited for their focus. 14.3 Testing Standards ISO 717 concerns rating airborne sound insulation in buildings and of building elements. It evaluates data and specifies quantifying sound measurements within one-third octave bands in accordance to ISO 140-7 and ISO 10140-3 144 . ISO 140 specifies standards in measuring sound insulation in buildings and building elements. Serving as s sample test, ISO 140 considers field measurements of sound insulation. The testing standard specifies measuring guidelines. Limitations using ISO 140 involves measuring rooms varying in dimension, such as long narrow rooms. Although ISO 140 is suited for standard small 144 ISO 717, www.iso.org/iso/catalogue_detail.htm?csnumber=51968. Batungbakal 159 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects rooms for residential units, school facilities, and hotels, ISO 140 is considered to improve field measurements 145 . ISO 12354 involves estimating the acoustic performance of buildings and its elements. Estimation of acoustic performance in buildings from the performance of elements. Airborne sound insulation between rooms 146 . 14.4 Software: INSUL Simulations Future research can compare transmission loss derived from INSUL simulations to another sound insulation software. INSUL’s interface functions as a 2-dimensional simulation tool. To improve researchers’ and designers’ perception in simulating transmission loss for facades, providing a 3-dimensional interface would enable results to be display spatial influence. 14.4-1 Tabs: Limit of Three Panels Double-skin facades with insulated glazing units for its outer skin and inner skin are common. Limited to three panel tabs, INSUL could not simulate sound transmission loss of double-skin facades with insulated glazing units for its outer skin and inner skin. Since an insulated glazing unit is composed of two glass panels, simulation of a double-skin skin with two insulated-glazing units would required INSUL to provide four panel tabs. Therefore, this study did not include an analysis and comparison of double-skin facades with two insulated glazing units. As a result, further research can consider analyzing the acoustic performance of double-skin facades with two insulated units. 145 ISO 140, www.iso.org/iso/catalogue_detail.htm?csnumber=31756. 146 ISO 12354, www.acoustic-standards.co.uk/bs-12354.htm. Batungbakal 160 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects 14.4-2 Ventilated Double-Skin Facades Since the simulations were analyzed as sealed glass façades, further analysis involved simulating outdoor-to-indoor sound transmission of ventilated double-skin facades. With no option in simulating ventilated glass facades, INSUL’s leakage property was used to mimic the assembly of ventilated glass facades. Precedent studies often acknowledge that the efficiency of sound reduction with glass facades decreases as the area of the opening increases, the maximum area for an opening does not exceed 24 square inches. The area of the openings are identified as glass-to- opening ratio: 1% as 0.12 in², 5% as 7.2 in², 10% as 14.4 in², 15% as 21.6 in², and 16% as 23 in². Figure 89. INSUL: Representation of Partition Leak Parameters. Although the construction and dimensions of double-skin facades enables improved ventilation, overheating and limited control of its interior remains a concern 147 . Several double-skin façade assemblies were simulated to determine the acoustic performance affected by ventilated areas. 147 Knaack, 30. Batungbakal 161 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Acknowledging openings used as ventilation would reduce sound transmission loss, the simulations conducted using INSUL quantifies and examines the impact of opening-to-glazing ratio impairing sound transmission loss. 14.5 Indoor Sound Level Variation: Façade Area, Room Volume, Reverberation As this study assessed indoor sound levels derived from direct transmission loss, further research can focus on indoor sound level parameters, such as reverberation time, room volume, and façade area. Since INSUL provided estimations of direct transmission loss and indoor sound levels provided by simulated facades, a designs support tool displaying single-figured indoor sound levels, which considered indoor parameters such as façade area, room volume, and reverberation acceptable for office workspace, is included in Appendix G. Providing two versions of the design support tool, one which contains single-figure indoor sound levels derived considering direct transmission loss (Appendix F) and the other containing single-figure indoor sound levels affected by indoor parameters (Appendix G), provides insight in distinguishing their decibel differences. Further research focusing on the influence of indoor sound level parameters, such as reverberation time, room volume, and façade area can improve the acoustic performance of glass facades such as double-skin facades and acoustic performance estimation that would specifically address sound conditions for different building occupancies. As a result, a specific focus on indoor parameters will contribute to improved indoor acoustic quality as well as improved acoustic performance of glass facades to ensure consistent indoor acoustic quality in response to environmental noise. Batungbakal 162 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Bibliography "Acoustical Analysis in Office Environments Using POE Surveys", Center for the Built Environment, July 2007, www.cbe.berkeley.edu/research/acoustic_poe.htm Accumask, “Achieving effective office acoustics”, K.R. Moeller Associates Ltd., 2006, www.accumask.com/App_Media/Files/OfficeAcoustics_EN.pdf. Autex, “Understanding Acoustics: Guide to recommended Reverberation times”, Autex.com.au/technical-guides/quietspace-design-guide/4.-understanding-acoustics. Bradley, J.S., “The Acoustic Design of Conventional Open Plan Offices”, National Research Council Canada, Canadian Acoustics, Vol. 27 No. 3, June 2003, http://archive.nrc- cnrc.gc.ca/obj/irc/doc/pubs/nrcc46274/nrcc46274.pdf. BYU Acoustic Research Group, “What is Acoustics?”,, College of Physical and Mathematical Sciences Brigham Young University, 2004-2013, http://www.physics.byu.edu/research/acoustics/what_is_acoustics.aspx. Cassidy, M., R.K. Cooper, et al. "Evaluation of standards for transmission loss tests." Acoustics 2008 Paris, Jun-Jul 2008, www.acoustics08-paris.org. Cavanaugh, William and Joseph A. Wilkes. Architectural Acoustics: Principles and Practice. New York: John Wiley and Sons, Inc., 1999. Charles M. Salter Associates Inc., Acoustics: architecture, engineering, the environment. San Francisco: William Stout Publishers, 1998. Batungbakal 163 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Cianfrone, Christian, N. Norris, P.Roppel, M. Marceau. “Thermal Performance of Three- Dimensional Building Envelope Assemblies and Details for Improving the Accuracy of Whole Building Performance Simulation.” SimBuild, August 1-3, 2012, http://www.ibpsa.us/simbuild2012/technical_sessions.shtml. City of Los Angeles’ Mangrove Estates Site Mixed Use Development EIR, “Section 4.8 Noise”,www.planning.lacity.org/eir/MangroveEstates/FEIR/EIR%20Sections/4.8%20Noise. pdf. City of Los Angeles, “Noise”, L.A. CEQA Thresholds Guide, Department of Health Services, http://cityplanning.lacity.org/eir/AndoraAveTTM/DEIR/IV_H_Noise.pdf. Curtland, Christopher, "Acoustics: The Biggest Complaint in LEED-Certified Office Buildings", Buildings, August 2012, www.buildings.com/article- details/articleid/14557/title/acoustics-the-biggest-complaint-in-leed-certified-office- buildings.aspx. Energy Efficiency Building Design Guidelines for Botswana. Section 7, www.bauerconsultbotswana.com/7_BuildingEnvelope.pdf “Environment Protection Act 1970”, Environmental Protection Authority Victoria, May 2013, http://www.epa.vic.gov.au/about-us/legislation/acts-administered-by-epa. Environmental Protection Department. Sound and Noise. The Government of the Hong Kong SAR, www.epd.gov.hk/epd/noise_education/web/ENG_EPD_HTML/m1/intro_1.html. European Commission, "Noise: The EU Policy on environmental noise", September 2012, http://ec.europa.eu/environment/noise/. Batungbakal 164 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects FIG, “Rapid Urbanization and Mega Cities: The Need for Spatial Information Management”, The International Federation of Surveyors (FIG), Copenhagen, Denmark, January 2010, www.fig.net/pub/figpub/pub48/figpub48.pdf. Foss, Ray V., Terrence A. Dear, et al. "Facade Noise Control with Glass and Laminates" Glass Processing Days, Jun 13–16, 1999, www.aisglass.com/acoustic-insulation/AIS- 130.pdf. General Services Administration Public Building Service, “Sound Matters: How to achieve acoustic comfort in the contemporary office”, GSA, December 2011, http://bgs.vermont.gov/sites/bgs/files/pdfs/Move/120201-GSAsoundmatters.pdf. ‘Glass Acoustical Information’, 2008, Cardinal Glass Industries Company. Green, David, Mark Scott, and Randy Burkett, “AEI March 2011,' Managing Occupant Comfort with Highly Transparent All-Glass Facades”, American Society of Civil Engineers, 2011, http://ascelibrary.org/doi/abs/10.1061/41168(399)16. Health Acoustics Research Team, "Why study healthcare acoustics?”, http://www.acousticsresearch.org/. InformeDesign Research Desk, "Acoustics in Healthcare Environments", CISCA, InformeDesign, October 2010, www.lwsupply.com/static/cms_workspace/Acoustics_in_Healthcare_Environments.pdf. INSUL Technical Info, INSUL, www.insul.co.nz/technicalinfo.html#. ISO 12354 Estimation of acoustic performance in buildings from the performance of elements. Airborne sound insulation between rooms, Gracey and Associates, www.acoustic- standards.co.uk/bs-12354.htm. Batungbakal 165 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects ISO 140 Measurement of sound insulation in buildings of building elements: Guidelines for special situations in the field, www.iso.org/iso/catalogue_detail.htm?csnumber=31756. ISO 717, 2013, www.iso.org/iso/catalogue_detail.htm?csnumber=51968. Janning, James D, "Understanding Acoustics in Architectural Design", USG Corporation, www.usg.com/documents/courses/02JuneUnderstandingAcoustics.pdf. Keller, Dr. Uwe. "Improved Sound Reduction with Laminated Glass". Glass Files. Glass Processing Days, Jun 18–212001, www.glassfiles.com. Kinsler, Lawrence E., Fundamental of Acoustics. 4 th Edition. New York, NY: John Wiley and Sons, Inc., 2000. pp30. Knaack, Ulrich. Facades: Principles of Construction. Basel, Switzerland: Birkhauser Verlag AG, 2007. Kuraray, “Trosifol Sound Control film”, www.trosifol.com/en/produkte/architecture/trosifol- sound-control-sc/. Libby, John, “Advanced Acoustic Glazing- the latest developments in sound and vision”, http://www.bath.ac.uk/cwct/cladding_org/gib99/paper15.pdf. Lee, Eleanor et all, "High-Performance Commercial Building Facades", The Regents of the University of California, June 2002. Lilly, Jerry G. "Recent Advances in Acoustical Glazing". Sound and Vibration February 2004. JGL Acoustics, Inc., Issaquah, Washington. LogiSon Acoustic Network, “Achieving Effective Office Acoustics”, K.R. Moeller Associates, http://www.srose.com/documents/Office_Acoustics.pdf. Batungbakal 166 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects "Los Angeles Maximizing Mobility Options: Population Density", SCAG, Nelson Nygaard Consulting Associates, www.scag.ca.gov/nonmotorized/pdfs/map10-populationdensity.pdf Love, Andrea and Payette Associates, Boston MA, 2011 “Assessing Thermal Bridges in Commercial Wall Systems.” SimBuild, August 1-3, 2012, http://www.ibpsa.us/simbuild2012/technical_sessions.shtml. Muneer, Tariq. Windows in buildings: thermal, acoustic, visual, and solar performance. Oxford: Architectural Press, 2000. “Noise Control Act of 1972”, The Bureau of National Affairs, Inc., 1996, http://www.epa.gov/air/noise/noise_control_act_of_1972.pdf Noise Meters Limited, “Maximum, Minimum and Peak Sound Level”, www.noisemeters.co.uk/help/faq/max-min-peak.asp. “Noise Pollution”, U.S. Environmental Protection Agency, July 2012, http://www.epa.gov/air/noise.html. Office Design. Acoustic.com, http://www.acoustics.com/office.asp. Office Rooms, Paroc, www.paroc.com/solutions-and-products/solutions/room- acoustics/office-rooms. Oliveira, Maria Piedade G., Eduardo Bauzer Medeiros, Clodoveu A. Davis Jr. "Planning the Acoustic Urban Environment: A GIS-Centered Approach". O’Neill, Dr. Mike, “Open Plan and Enclosed Private Offices: Research Review and Recommendations”, http://www.knoll.com/research/downloads/OpenClosed_Offices_wp.pdf. Batungbakal 167 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Paradis Richard, "Acoustic Comfort", National Institute of Building Sciences, April 2012, http://www.wbdg.org/resources/acoustic.php. Pekdemir, Emir Aykut and Ralph T. Muehleisen,. “A Parametric Study of the Thermal Performance of Double Skin Facades at Different Climates Using Annual Energy Simulation.” SimBuild, August 1-3, 2012, www.ibpsa.us/simbuild2012/technical_sessions.shtml. Poirazis, Harris, “Double-Skin Facades: A Literature Review”, Department of Construction and Architecture, Lund Institute of Technology, Lund 2006 , www.ecbcs.org/docs/Annex_43_Task34-Double_Skin_Facades_A_Literature_Review.pdf. Poirazis, Harris, “Double-Skin Facades for Office Buildings”, Department of Construction and Architecture, Lund Institute of Technology, Lund 2004, www.lth.se/fileadmin/energi_byggnadsdesign/images/Publikationer/Bok-EBD-R3- G5_alt_2_Harris.pdf. Reverberation Time, www.reverberationtime.com. Schimmelpenningh, Julia, “Acoustic Interlayers for Laminated Glass: What makes them different and how to estimate performance”, Leverage from the EU, Glass Performance Days 2012, www.gpd.fi. Sendra, J.J. Computational Acoustics in Architecture. United Kingdom: WIT Press, 1999. Sound and Noise, The Government of the Hong Kong Special Administration Region, Environmental Protection Department, www.epd.gov.hk/epd/noise_education/web/ENG_EPD_HTML/m1/intro_1.html. Templeton, Duncan and David Saunders. Acoustic Design. London: Architectural Press, 1987. Batungbakal 168 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects “The EU Policy on environmental noise”, http://ec.europa.eu/environment/noise/. “The Importance of Acoustics in the Design Phase”, Acoustics: Continuing Education Units, www.acoustics.com/ceu.asp. “Understanding Acoustics”, Autex, http://autex.com.au/Technical-Guides/Quietspace- Design-Guide/4.-Understanding-Acoustics. United States Environmental Protection Agency, http://www.epa.gov/lawsregs/laws/nca.html. U.S. Department of Housing and Urban Development, “Environmental Criteria and Standards”, http://www.hudnoise.com/hudstandard.html. “Windows for High-performance Commercial Buildings: Thermal Comfort.” Regents of the University of Minnesota, 2011, www.commercialwindows.org/tc.php. Waldner, Reinhard, et. al, “Best Facade Best Practice for Double Skin Facades: W5 Best Practice Guidelines” Energy and Building Design, University of Lund, December 2007, www.bestfacade.com/pdf/downloads/WP5%20Best%20practice%20guidelines%20report%2 0v17final.pdf. Yoshioka, Terry, "Future Possibility of High Performance PVB Interlayer: Multi-Layer Technology for Noise Reduction and More". Glass Processing Days 2008. Batungbakal 169 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects References Forschner, Hans. 2012-2013. INSUL Distributor- USA, Canada, Mexico. Navicon Engineering. Fullerton, CA. (Email: forschner@navcon.com) Valmont, Elizabeth. 2012-2013.Acoustic Consultant. ARUP. Los Angeles, CA (Email: evalmont@usc.edu) Ortegren, Leif. 2012. Glazing Consultant, Regional Sales and Marketing Manager. Pilkington North America- South Western. Lathrop, CA. (Email: leif.ortegren@nsg.com) Batungbakal 170 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Glossary - ACCESSIBLE/NORMAL SPEECH PRIVACY: According to the recently updated standard for Speech Privacy in Open Offices, (American Standard Test Method (ASTM) E1130–02) the speech privacy of a space is “acceptable” or “normal” (meaning not- readily understood) when the AI is under .20 or the SPI is over 80% 148 . - ACOUSTICS: (1) The science of sound, including its production, transmission, and reception. (2) The physical qualities that determine how a room sounds 149 . - AIRBORNE SOUND: Sound traveling through air as a medium 150 . - A-WEIGHTED (dBA): A frequency weighting scale used to adjust the accuracy and perception of sound levels relative to sensitivity of normal human hearing (audibility), which ranges from 20Hz to 20kHz 151 . - A-WEIGHTED SOUND LEVEL: A common single figure sound level rating used to subjectively quantify the amplitude of sound at lower frequencies. - COINCIDENCE DIP (also known as critical frequency, coincidental effect): Often indicating increased sound transmission 152 . Defined as frequencies where bending waves (stiffness) is equal to the speed of sound in air to indicate the reduced transmission loss, is another term for critical frequencies 153 . - DECIBEL (dB): The common measurement unit used in acoustics for expressing the logarithmic ratio of two sound pressures or powers, the amplitude of sound. Typically 148 Cambridge Sound Management, www.cambridgesoundmanagement.com/glossary.html 149 Charles M. Salter Associates Inc., 124. 150 Cavanaugh, 318. 151 Cavanaugh, 16. 152 Templeton, 81. 153 Templeton, 81. Batungbakal 171 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects used to describe the magnitude of a sound with respect to a reference level equal to the threshold of human hearing 154 . - DECIBEL 10 th : A sound meter application utilized with either an iPhone, iPad or iPod as a hand-held sound meter device. Decibel 10 th measures sound pressure levels in decibels (dB), detecting sound pressure levels ranging from 0 dB to 110 dB. - EQUIVALENT SOUND LEVEL (Leq): A single steady A-weighted sound level that embodies an equal amount of acoustic energy as actual-time varying sound levels over a duration of time , also known as the average noise level 155156 . A common description method in quantifying environmental sound 157 . - ENVIRONMENTAL NOISE: Airborne sound sources considered disturbances in the built environment that varies with time 158 . - FLANKING: The transmission of airborne sound from a source room to an adjacent receiver room by a path other than the common partition. - FREQUENCY: A descriptor for a periodic phenomenon. The frequency is equal to the number of times that the pressure wave repeats in a specified period of time. In the case of sound and vibration, frequency is measured in units of Hertz (Hz), which correspond to one cycles per second (cps) 159 . - HERTZ (Hz): A unit of measure for describing the frequency of a wave phenomenon, such as sound 160 . 154 Charles M. Salter Associates Inc., 124. 155 Cavanaugh, 13. 156 City of Los Angeles’ Mangrove Estates Site Mixed Use Development EIR, www.planning.lacity.org/eir/MangroveEstates/FEIR/EIR%20Sections/4.8%20Noise.pdf. 157 Charles M. Salter Associates Inc., 52. 158 Charles M. Salter Associates Inc., 52. 159 Charles M. Salter Associates Inc., 125. 160 Charles M. Salter Associates Inc., 125. Batungbakal 172 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects - INSUL: A software tool that predicts sound transmission and sound insulation provided by walls, ceilings, flooring, and fenestration 161 . - ISO 717: A rating of sound insulation in buildings and of building elements: airborne sound insulation, is defined as single-numbered values for airborne sound insulation in buildings and building elements, such as walls, flooring, doors, and windows 162 . - AVERAGE SOUND LEVEL (Leq): A single steady A-weighted sound level that embodies an equal amount of acoustic energy as actual-time varying sound levels over a duration of time , also known as the energy equivalent sound level 163164 . A common description method in quantifying environmental sound 165 . - MAXIMUM SOUND LEVEL (Lmax): The highest A-weighted sound level measured 166 . - PEAK SOUND LEVEL (Lpk): The maximum A-weighted sound level reached by the sound pressure 167 . Peak sound levels are usually not used to indicate the amplitude of environmental sound in a duration of time. - MASS LAW: A principle that determines doubling the mass to increase transmission loss by approximately 6 dB. Increased transmission loss by approximately 6dB is also applicable at every doubling of frequency; therefore, higher frequencies acquire greater transmission loss compared to transmission loss at lower frequencies 168 . 161 INSUL, http://www.insul.co.nz/. 162 ISO 717, http://www.iso.org/iso/catalogue_detail.htm?csnumber=51968. 163 Cavanaugh, 13. 164 City of Los Angeles’ Mangrove Estates Site Mixed Use Development EIR, www.planning.lacity.org/eir/MangroveEstates/FEIR/EIR%20Sections/4.8%20Noise.pdf. 165 Charles M. Salter Associates Inc., 52. 166 Noise Meters Limited, http://www.noisemeters.co.uk/help/faq/max-min-peak.asp. 167 Noise Meters Limited, http://www.noisemeters.co.uk/help/faq/max-min-peak.asp. 168 Charles M. Salter Associates Inc., 118. Batungbakal 173 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects - NOISE : 1) Any undesired sound. (2) Any statistically random wave 169 . - NOISE REDUCTION (NR): The difference (reduction) in sound pressure level of sound transmitted through a building partition, usually measured in octave or one-third octave frequency bands 170 . - ONE-THIRD OCTAVE: An audible frequency range ranging from 50Hz to 5kHz. Structured similarly as an octave band, a one-third octave band provide more detailed sound measurements and is generally used in laboratory tests to measure sound transmission loss. - RESONANCE: Indicating increased sound pressure and sound transmission caused by having the same period as the natural vibration 171 172 . - REVERBERATION: A collection of time-delayed sounds following a direct sound that result from reflections indoors 173 . - REVERBERATION TIME: The amount of time (in seconds) sound is prolonged after emitted from the source 174 . - SOUND: Vibrations resulting from pressured and transmitted air molecules that are sensed by the auditory system at frequencies between 20 to 20kHz 175 . - SOUND LEVEL: A measurement of sound pressure level derived from standardized frequency weighting scales such A-scale and C-scale 176 . - SOUND PRESSURE LEVEL: A measurement of sound pressure, which references decibels to 20 micropascals, considering the distance from the sound source 177 . 169 Charles M. Salter Associates Inc., 125. 170 Charles M. Salter Associates Inc., 125. 171 Charles M. Salter Associates Inc., 323. 172 Charles M. Salter Associates Inc., 323. 173 Charles M. Salter Associates Inc., 126. 174 Reverberation time, www.reverberationtime.com/. 175 Cavanaugh, 324. 176 Cavanaugh, 325. Batungbakal 174 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects - SOUND TRANSMISSION LOSS (TL): A laboratory measure of sound insulation indicative of the sound-intensity flow transmitted through a partition without regard to the partition size, usually measured in one-third octave bands 178 . - STRUCTURE-BORNE SOUND: Sound energy transmission through solid mediums, such as building partitions 179 . - TRAFFIC NOISE: One form of environmental noise. 177 Charles M. Salter Associates Inc., 323. 178 Charles M. Salter Associates Inc., 126. 179 Cavanaugh, 325. Batungbakal 175 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Appendix A Direct Transmission Loss SINGLE PANE MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 1/8" 10 11 12 13 14 15 17 18 20 22 23 25 27 28 30 31 32 35 34 30 31 1/4" 15 16 17 18 20 21 23 24 26 27 29 31 32 33 35 34 30 31 34 37 40 3/8" 18 19 20 22 23 25 26 28 29 31 32 33 35 34 31 31 34 36 39 43 45 1/2" 20 22 23 24 26 27 29 30 31 33 33 35 34 31 31 35 37 40 43 46 49 5/8" 22 23 25 26 27 29 30 32 33 34 35 34 31 31 34 38 40 43 46 49 52 SINGLE PANE PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 1/8" 10 11 12 13 14 15 17 18 20 22 23 25 27 28 30 31 33 34 37 39 36 1/4" 15 16 17 18 20 21 23 24 26 28 29 31 32 34 34 37 39 36 38 41 44 3/8" 18 19 20 22 23 25 26 28 29 31 32 34 35 37 39 36 37 40 43 46 49 1/2" 20 22 23 24 26 27 29 30 32 33 34 35 37 39 36 38 41 44 47 50 53 5/8" 22 23 25 26 27 29 30 32 33 35 35 37 39 37 38 41 44 47 50 53 56 SINGLE PANE TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 1/8" 10 11 12 13 14 15 17 18 20 22 23 25 27 28 30 32 33 34 38 39 37 1/4" 15 16 17 18 20 21 23 24 26 28 29 31 32 34 35 38 39 37 37 40 43 3/8" 18 19 20 22 23 25 26 28 29 31 32 34 35 37 39 37 37 39 42 46 48 1/2" 20 22 23 24 26 27 29 30 32 33 34 35 38 39 37 37 40 43 46 49 52 5/8" 22 24 25 26 27 29 31 32 33 35 36 38 39 37 37 40 43 46 49 52 55 DOUBLE PANE MONO Hz 50 63 80 100 125 160 200250315400500630800100012501600 2000 2500 315040005000 ¼+ ½+ 1/8" 15 16 71 18 19 19 11 22 27 31 33 35 36 38 38 40 39 35 38 41 44 ¼+ ½+ 1/4" 27 29 20 20 20 16 22 27 30 32 34 35 37 37 40 39 35 36 39 42 45 ¼+ ½+ 3/8" 19 20 21 22 21 18 26 29 31 33 35 36 37 38 38 34 36 39 42 45 48 ¼+ ½+ 1/2" 21 22 22 23 22 22 28 30 32 34 35 36 37 37 33 36 38 41 44 47 50 ¼+ ½+ 5/8" 22 23 24 24 22 24 29 32 33 35 36 36 36 32 35 38 41 44 47 50 52 DOUBLE PANE PVB Hz 50 63 80 100 125 160 200250315400500630800100012501600 2000 2500 315040005000 ¼+ ½+ 1/8" 15 16 17 18 19 19 11 22 28 31 33 35 37 38 39 42 42 39 41 44 47 ¼+ ½+ 1/4" 17 19 20 20 20 16 22 28 30 32 34 36 37 38 41 42 39 39 42 45 48 ¼+ ½+ 3/8" 19 20 21 22 21 18 26 29 32 34 35 37 38 40 41 39 39 42 45 48 51 ¼+ ½+ 1/2" 21 22 22 23 22 22 28 31 33 35 36 37 39 41 38 38 41 44 47 50 53 ¼+ ½+ 5/8" 22 23 24 24 22 24 30 32 34 36 37 39 40 38 37 41 44 46 49 53 55 Batungbakal 176 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects DOUBLE PANE TSC Hz 50 63 80 100 125 160 200250315400500630800100012501600 2000 2500 315040005000 ¼+ ½+ 1/8" 15 16 17 18 19 19 11 22 28 31 34 36 37 39 40 42 42 39 41 44 47 ¼+ ½+ 1/4" 17 19 20 20 20 16 22 28 30 33 34 36 37 39 41 42 40 39 42 45 48 ¼+ ½+ 3/8" 19 20 21 22 21 18 26 29 32 34 35 37 38 39 41 42 39 41 44 47 50 ¼+ ½+ 1/2" 21 22 22 23 22 22 28 31 33 35 36 38 38 41 41 38 41 44 47 50 53 ¼+ ½+ 5/8" 22 23 24 24 22 24 30 32 34 36 37 38 40 41 38 40 43 46 49 52 55 DOUBLE SKIN 1/4" outer skin, MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 air-cavity 15.7 25 28 33 36 40 43 44 46 48 50 52 53 55 56 58 58 55 56 59 62 65 air-cavity 23.6 28 31 36 39 40 43 45 47 49 52 53 55 56 57 60 60 56 57 61 64 67 air-cavity 31.5 30 34 38 38 40 43 46 48 50 52 54 56 58 59 61 61 57 59 62 65 68 air-cavity 39.3 31 35 36 38 41 43 46 48 51 53 55 57 58 59 62 62 58 59 63 66 69 DOUBLE SKIN 1/4" outer skin, PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 air-cavity 15.7 25 28 33 37 40 43 44 46 49 51 52 54 56 57 59 61 59 58 61 65 68 air-cavity 23.6 28 32 36 39 40 43 45 48 50 52 54 56 57 58 61 62 60 60 63 66 69 air-cavity 31.5 30 34 38 38 41 43 46 48 51 53 55 57 58 60 62 64 61 61 64 68 71 air-cavity 39.3 32 35 36 38 41 44 46 49 51 53 56 57 59 60 63 64 62 62 65 68 71 DOUBLE SKIN 1/4" outer skin, TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 air-cavity 15.7 25 28 33 37 40 43 44 47 49 51 53 54 56 57 60 61 59 58 61 65 67 air-cavity 23.6 28 32 36 39 40 43 45 48 50 52 54 56 57 69 61 63 60 60 63 66 69 air-cavity 31.5 30 34 38 38 41 43 46 48 51 53 55 57 58 60 62 64 62 61 64 67 70 air-cavity 39.3 32 35 36 38 41 44 46 49 51 54 56 58 59 61 63 65 62 62 65 68 71 DOUBLE SKIN 3/8" outer skin, MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 air-cavity 15.7 28 32 36 39 42 44 46 47 49 51 52 53 55 57 57 53 55 58 61 64 67 air-cavity 23.6 31 35 38 41 42 45 47 49 51 52 54 55 56 58 58 55 57 60 63 66 69 air-cavity 31.5 33 37 40 41 43 45 48 50 52 54 55 56 58 59 59 56 58 61 64 67 70 air-cavity 39.3 35 38 38 41 43 46 48 50 52 54 56 57 58 60 60 57 59 62 65 68 71 DOUBLE SKIN 3/8" outer skin, PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 air-cavity 15.7 28 32 36 39 42 45 46 48 50 51 53 54 56 58 60 58 57 60 63 66 69 air-cavity 23.6 31 35 38 42 42 45 47 49 51 53 55 56 57 60 61 59 59 62 65 68 71 air-cavity 31.5 33 37 40 41 43 46 48 50 52 54 56 57 59 61 63 60 60 63 66 69 72 air-cavity 39.3 35 38 39 41 43 46 48 51 53 55 56 58 59 62 63 61 61 64 67 70 73 Batungbakal 177 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects DOUBLE SKIN 3/8" outer skin, TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 air-cavity 15.7 28 32 36 39 42 45 46 48 50 52 53 55 56 57 60 60 58 60 63 66 69 air-cavity 23.6 31 35 38 42 43 45 47 49 51 53 55 56 58 59 61 62 59 62 65 68 71 air-cavity 31.5 33 37 40 41 43 46 48 50 52 54 56 57 59 60 62 63 60 63 66 69 72 air-cavity 39.3 35 38 39 41 43 46 48 51 53 55 57 58 60 61 63 64 61 64 67 70 73 DOUBLE SKIN 1/2" outer skin, MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 air-cavity 15.7 30 34 38 41 43 46 47 48 50 52 53 54 55 55 52 55 57 60 63 66 69 air-cavity 23.6 33 37 40 43 44 46 48 50 52 53 54 55 57 57 54 56 59 62 65 68 71 air-cavity 31.5 35 39 42 42 45 47 49 51 53 54 56 57 58 58 55 58 60 63 66 69 72 air-cavity 39.3 37 40 40 43 45 47 50 52 53 55 56 57 59 59 56 58 61 64 67 70 73 DOUBLE SKIN 1/2" outer skin, PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 air-cavity 15.7 30 34 38 41 43 46 47 49 51 52 54 55 57 59 57 57 59 62 65 68 71 air-cavity 23.6 33 37 40 43 44 46 48 50 52 54 55 56 59 60 58 58 61 64 67 70 73 air-cavity 31.5 35 39 42 43 45 47 49 51 53 55 56 58 60 61 60 59 62 65 68 71 74 air-cavity 39.3 37 40 41 43 45 48 50 52 54 56 57 58 61 62 60 60 63 66 69 72 75 DOUBLE SKIN 1/2" outer skin, TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 air-cavity 15.7 30 34 38 41 44 46 47 49 51 52 54 55 56 59 59 57 59 62 65 68 71 air-cavity 23.6 33 37 40 43 44 46 48 50 52 54 55 57 58 60 61 59 61 64 67 70 73 air-cavity 31.5 35 39 42 43 45 47 49 51 53 55 57 58 59 61 62 60 62 65 68 71 74 air-cavity 39.3 37 40 41 43 45 48 50 52 54 56 57 59 60 62 63 61 63 66 69 72 75 DOUBLE SKIN 5/8" outer skin, MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 air-cavity 15.7 32 35 39 42 44 47 48 49 51 52 53 54 54 51 54 57 59 62 65 68 71 air-cavity 23.6 35 38 42 44 45 47 49 51 52 54 55 56 56 53 55 58 61 64 67 70 73 air-cavity 31.5 37 40 43 44 46 48 50 52 53 55 56 57 57 54 56 60 62 65 68 71 74 air-cavity 39.3 38 42 42 44 46 49 51 53 54 56 57 58 58 55 57 60 63 66 69 72 75 DOUBLE SKIN 5/8" outer skin, PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 air-cavity 15.7 32 35 39 42 45 47 48 50 51 53 54 55 57 58 56 59 61 64 67 70 73 air-cavity 23.6 35 38 42 44 45 48 49 51 53 54 56 57 59 60 57 60 63 66 69 72 75 air-cavity 31.5 37 40 43 44 46 48 50 52 54 56 57 58 60 61 59 61 64 67 70 73 76 air-cavity 39.3 38 42 42 44 47 49 51 53 55 56 58 59 61 62 60 62 65 68 71 74 77 Batungbakal 178 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects DOUBLE SKIN 5/8" outer skin, TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 air-cavity 15.7 32 35 39 42 45 47 48 50 51 53 54 55 58 58 56 58 61 64 67 70 73 air-cavity 23.6 35 38 42 44 45 48 50 51 53 55 56 57 59 60 58 60 63 65 69 72 75 air-cavity 31.5 37 40 43 44 46 48 50 52 54 56 57 58 60 61 59 61 64 67 70 73 76 air-cavity 39.3 38 42 42 44 47 49 51 53 55 57 58 59 61 62 60 62 65 68 71 74 77 Batungbakal 179 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Appendix B Indoor Sound Levels from Direct Transmission Loss SINGLE PANE MONO Hz 50 63 80 100 125 160 2002503154005006308001000125016002000 2500 315040005000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 1/8" 55 56 57 57 56 56 57 55 55 55 55 54 54 54 51 49 48 42 41 44 41 1/4" 50 51 52 51 50 51 51 50 49 49 49 48 49 49 46 46 50 46 41 37 32 3/8" 47 48 48 48 47 47 48 46 46 46 46 46 46 48 50 49 46 41 36 31 27 1/2" 44 45 46 46 44 45 45 44 44 44 44 44 47 51 50 45 43 37 32 28 23 5/8" 42 43 44 44 42 43 43 42 42 43 43 45 50 51 47 42 40 34 29 25 20 SINGLE PANE PVB Hz 50 63 80 100 125 160 2002503154005006308001000125016002000 2500 315040005000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 1/8" 55 56 57 57 56 56 57 55 55 55 55 54 54 54 51 48 47 43 38 35 36 1/4" 50 51 52 51 50 50 51 49 49 49 49 48 49 48 47 43 41 41 37 33 28 3/8" 47 48 48 48 47 47 48 46 46 46 46 45 46 45 42 44 43 37 32 28 23 1/2" 44 45 46 46 44 45 45 44 43 44 44 44 44 43 45 42 39 33 28 24 19 5/8" 42 43 44 44 42 43 43 42 42 42 42 42 42 45 43 39 36 30 25 21 16 SINGLE PANE TSC Hz 50 63 80 100 125 160 2002503154005006308001000125016002000 2500 315040005000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 1/8" 55 56 57 57 56 56 57 55 55 55 55 54 54 54 51 48 47 43 37 35 35 1/4" 50 51 52 51 50 50 51 49 49 49 49 48 49 48 46 42 41 40 38 34 29 3/8" 47 48 48 48 47 47 48 46 46 46 45 45 46 45 42 43 43 38 33 28 24 1/2" 44 45 46 46 44 45 45 44 43 44 43 43 43 43 44 43 40 34 29 25 20 5/8" 42 43 44 44 42 43 43 42 41 42 42 41 42 45 44 40 37 31 26 22 17 DOUBLE PANE MONO Hz 50 63 80 100 125 160 2002503154005006308001000125016002000 2500 315040005000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 ¼”+ 1/8" 50 51 52 52 51 53 63 52 48 46 45 44 45 44 43 40 41 42 37 33 28 ¼”+1/4" 48 48 49 50 50 56 52 47 45 45 44 44 44 45 41 41 45 41 36 32 27 ¼”+3/8" 46 47 48 48 49 54 48 45 44 44 43 43 44 44 43 46 44 38 33 29 24 ¼”+1/2" 44 45 47 47 48 50 46 44 43 43 43 43 44 45 48 44 42 36 31 27 22 ¼”+5/8" 43 44 45 46 48 48 45 42 42 42 42 43 45 50 46 42 39 33 28 24 20 Batungbakal 180 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects DOUBLE PANE PVB Hz 50 63 80 100 125 160 2002503154005006308001000125016002000 2500 315040005000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 ¼”+ 1/8" 50 51 52 52 51 53 63 52 47 46 45 44 44 44 42 38 38 38 34 30 25 ¼”+1/4" 48 48 49 50 50 56 52 46 45 45 44 43 44 44 40 38 41 38 33 29 24 ¼”+3/8" 46 47 48 48 49 54 48 45 43 43 43 42 43 42 40 41 41 35 30 26 21 ¼”+1/2" 44 45 47 47 48 50 46 43 42 42 42 42 42 41 43 42 39 33 28 24 19 ¼”+5/8" 43 44 45 46 48 48 44 42 41 41 41 40 41 44 44 39 36 31 26 21 17 DOUBLE PANE TSC Hz 50 63 80 100 125 160 2002503154005006308001000125016002000 2500 315040005000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 ¼”+ 1/8" 50 51 52 52 51 53 63 52 47 46 44 43 44 43 41 38 38 38 34 30 25 ¼”+1/4" 48 48 49 50 50 56 52 46 45 44 44 43 44 43 40 38 40 38 33 29 24 ¼”+3/8" 46 47 48 48 49 54 48 45 43 43 43 42 43 43 40 38 41 36 31 27 22 ¼”+1/2" 44 45 47 47 48 50 46 43 42 42 42 41 43 41 40 42 39 33 28 24 19 ¼”+5/8" 43 44 45 46 48 48 44 42 41 41 41 41 41 41 43 40 37 31 26 22 17 DOUBLE SKIN 1/4" outer skin, MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 40 39 36 34 30 29 30 28 27 27 26 26 26 26 23 22 25 21 16 12 7 air-cavity 23.6 37 36 33 31 30 29 29 27 26 25 25 24 25 25 21 20 24 20 14 10 5 air-cavity 31.5 35 33 31 32 30 29 28 26 25 25 24 23 23 23 20 19 23 18 13 9 4 air-cavity 39.3 34 32 33 32 29 29 28 26 24 24 23 22 23 23 19 18 22 18 12 8 3 DOUBLE SKIN 1/4" outer skin, PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 40 39 36 33 30 29 30 28 26 26 26 25 25 25 22 19 21 19 14 9 4 air-cavity 23.6 37 35 33 31 30 29 29 26 25 25 24 23 24 24 20 18 20 17 12 8 3 air-cavity 31.5 35 33 31 32 29 29 28 26 24 24 23 22 23 22 19 16 19 16 11 6 1 air-cavity 39.3 33 32 33 32 29 28 28 25 24 24 22 22 22 22 18 16 18 15 10 6 1 Batungbakal 181 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects DOUBLE SKIN 1/4" outer skin, TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 40 39 36 33 30 29 30 27 26 26 25 25 25 25 21 19 21 19 14 9 5 air-cavity 23.6 37 35 33 31 30 29 29 26 25 25 24 23 24 23 20 17 20 17 12 8 3 air-cavity 31.5 35 33 31 32 29 29 28 26 24 24 23 22 23 22 19 16 18 16 11 7 2 air-cavity 39.3 33 32 33 32 29 28 28 25 24 23 22 21 22 21 18 15 18 15 10 6 1 DOUBLE SKIN 3/8" outer skin, MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 37 35 33 31 28 28 28 27 26 26 26 26 26 25 24 27 25 19 14 10 5 air-cavity 23.6 34 32 31 29 28 27 27 25 24 25 24 24 25 24 23 25 23 17 12 8 3 air-cavity 31.5 32 30 29 29 27 27 26 24 23 23 23 23 23 23 22 24 22 16 11 7 2 air-cavity 39.3 30 29 31 29 27 26 26 24 23 23 22 22 23 22 21 23 21 15 10 6 1 DOUBLE SKIN 3/8" outer skin, PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 37 35 33 31 28 27 28 26 25 26 25 25 25 24 21 22 23 17 12 8 3 air-cavity 23.6 34 32 31 28 28 27 27 25 24 24 23 23 24 22 20 21 21 15 10 6 1 air-cavity 31.5 32 30 29 29 27 26 26 24 23 23 22 22 22 21 18 20 20 14 9 5 0 air-cavity 39.3 30 29 30 29 27 26 26 23 22 22 22 21 22 20 18 19 19 13 8 4 -1 DOUBLE SKIN 3/8" outer skin, TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 37 35 33 31 28 27 28 26 25 25 25 24 25 25 21 20 22 17 12 8 3 air-cavity 23.6 34 32 31 28 27 27 27 25 24 24 23 23 23 23 20 18 21 15 10 6 1 air-cavity 31.5 32 30 29 29 27 26 26 24 23 23 22 22 22 22 19 17 20 14 9 5 0 air-cavity 39.3 30 29 30 29 27 26 26 23 22 22 21 21 21 21 18 16 19 13 8 4 -1 DOUBLE SKIN 1/2" outer skin, MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 35 33 31 29 27 26 27 26 25 25 25 25 26 27 29 25 23 17 12 8 3 air-cavity 23.6 32 30 29 27 26 26 26 24 23 24 24 24 24 25 27 24 21 15 10 6 1 air-cavity 31.5 30 28 27 28 25 25 25 23 22 23 22 22 23 24 26 22 20 14 9 5 0 air-cavity 39.3 28 27 29 27 25 25 24 22 22 22 22 22 22 23 25 22 19 13 8 4 -1 Batungbakal 182 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects DOUBLE SKIN 1/2" outer skin, PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 35 33 31 29 27 26 27 25 24 25 24 24 24 23 24 23 21 15 10 6 1 air-cavity 23.6 32 30 29 27 26 26 26 24 23 23 23 23 22 22 23 22 19 13 8 4 -1 air-cavity 31.5 30 28 27 27 25 25 25 23 22 22 22 21 21 21 21 21 18 12 7 3 -2 air-cavity 39.3 28 27 28 27 25 24 24 22 21 21 21 21 20 20 21 20 17 11 6 2 -3 DOUBLE SKIN 1/2" outer skin, TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 35 33 31 29 26 26 27 25 24 25 24 24 25 23 22 23 21 15 10 6 1 air-cavity 23.6 32 30 29 27 26 26 26 24 23 23 23 22 23 22 20 21 19 13 8 4 -1 air-cavity 31.5 30 28 27 27 25 25 25 23 22 22 21 21 22 21 19 20 18 12 7 3 -2 air-cavity 39.3 28 27 28 27 25 24 24 22 21 21 21 20 21 20 18 19 17 11 6 2 -3 DOUBLE SKIN 5/8" outer skin, MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 33 32 30 28 26 25 26 25 24 25 25 25 27 31 27 23 21 15 10 6 1 air-cavity 23.6 30 29 27 26 25 25 25 23 23 23 23 23 25 29 26 22 19 13 8 4 -1 air-cavity 31.5 28 27 26 26 24 24 24 22 22 22 22 22 24 28 25 20 18 12 7 3 -2 air-cavity 39.3 27 25 27 26 24 23 23 21 21 21 21 21 23 27 24 20 17 11 6 2 -3 DOUBLE SKIN 5/8" outer skin, PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 33 32 30 28 25 25 26 24 24 24 24 24 24 24 25 21 19 13 8 4 -1 air-cavity 23.6 30 29 27 26 25 24 25 23 22 23 22 22 22 22 24 20 17 11 6 2 -3 air-cavity 31.5 28 27 26 26 24 24 24 22 21 21 21 21 21 21 22 19 16 10 5 1 -4 air-cavity 39.3 27 25 27 26 23 23 23 21 20 21 20 20 20 20 21 18 15 9 4 0 -5 DOUBLE SKIN 5/8" outer skin, TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 33 32 30 28 25 25 26 24 24 24 24 24 23 24 25 22 19 13 8 4 -1 air-cavity 23.6 30 29 27 26 25 24 24 23 22 22 22 22 22 22 23 20 17 12 6 2 -3 air-cavity 31.5 28 27 26 26 24 24 24 22 21 21 21 21 21 21 22 19 16 10 5 1 -4 air-cavity 39.3 27 25 27 26 23 23 23 21 20 20 20 20 20 20 21 18 15 9 4 0 -5 Batungbakal 183 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Appendix C Indoor Sound Levels considering Indoor Parameters (Façade Area, Room Volume, Reverberation) SINGLE PANE MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 1/8" 57 58 60 59 58 59 59 59 58 57 57 56 56 56 51 49 47 42 41 44 42 1/4" 52 53 55 54 52 53 53 53 52 52 51 51 51 51 46 46 49 46 41 37 33 3/8" 49 50 52 50 49 49 50 49 49 48 48 48 48 50 50 49 45 41 36 31 28 1/2" 47 47 49 48 46 47 47 47 47 46 47 46 49 53 50 45 42 37 32 28 24 5/8" 45 46 47 46 45 45 46 45 45 45 45 47 52 53 47 42 39 34 29 25 21 SINGLE PANE PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 1/8" 57 58 60 59 58 59 59 59 58 57 57 56 56 56 51 49 46 43 38 35 37 1/4" 52 53 55 54 52 53 53 53 52 51 51 50 51 51 47 43 40 41 37 33 29 3/8" 49 50 52 50 49 49 50 49 49 48 48 47 48 47 42 44 42 37 32 28 24 1/2" 47 47 49 48 46 47 47 47 46 46 46 46 46 45 45 42 38 33 28 24 20 5/8" 45 46 47 46 45 45 46 45 45 44 45 44 44 47 43 39 35 30 25 21 17 SINGLE PANE TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 1/8" 57 58 60 59 58 59 59 59 58 57 57 56 56 56 51 48 46 43 37 35 36 1/4" 52 53 55 54 52 53 53 53 52 51 51 50 51 50 46 42 40 40 38 34 30 3/8" 49 50 52 50 49 49 50 49 49 48 48 47 48 47 42 43 42 38 33 28 25 1/2" 47 47 49 48 46 47 47 47 46 46 46 46 45 45 44 43 39 34 29 25 21 5/8" 45 46 47 46 45 45 45 45 45 44 44 43 44 47 44 40 36 31 26 22 18 DOUBLE PANE MONO Hz 50 63 80 100 125 160 2002503154005006308001000125016002000 2500 315040005000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 ¼”+ 1/8" 52 53 55 54 53 55 65 55 51 48 47 46 47 46 43 40 40 42 37 33 29 ¼”+1/4" 50 50 52 52 52 58 54 50 48 47 46 46 46 47 41 41 44 41 36 32 28 ¼”+3/8" 48 49 51 50 51 56 50 48 47 46 45 45 46 46 43 46 43 38 33 29 25 ¼”+1/2" 46 47 50 49 50 52 48 47 46 45 45 45 46 47 48 44 41 36 31 27 23 ¼”+5/8" 45 46 48 48 50 50 47 45 45 44 44 45 47 52 46 42 38 33 28 24 21 Batungbakal 184 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects DOUBLE PANE PVB Hz 50 63 80 100 125 160 2002503154005006308001000125016002000 2500 315040005000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 ¼”+ 1/8" 52 53 55 54 53 55 65 55 50 48 47 46 46 46 42 38 37 38 34 30 26 ¼”+1/4" 50 50 52 52 52 58 54 49 48 47 46 45 46 46 40 38 40 38 33 29 25 ¼”+3/8" 48 49 51 50 51 56 50 48 46 45 45 44 45 44 40 41 40 35 30 26 22 ¼”+1/2" 46 47 50 49 50 52 48 46 45 44 44 44 44 43 43 42 38 33 28 24 20 ¼”+5/8" 45 46 48 48 50 50 46 45 44 43 43 42 43 46 44 39 35 31 26 21 18 DOUBLE PANE TSC Hz 50 63 80 100 125 160 2002503154005006308001000125016002000 2500 315040005000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 ¼”+ 1/8" 52 53 55 54 53 55 65 55 50 48 46 45 46 45 41 38 37 38 34 30 26 ¼”+1/4" 50 50 52 52 52 58 54 49 48 46 46 45 46 45 40 38 39 38 33 29 25 ¼”+3/8" 48 49 51 50 51 56 50 48 46 45 45 44 45 45 40 38 40 36 31 27 23 ¼”+1/2" 46 47 50 49 50 52 48 46 45 44 44 43 45 43 40 42 38 33 28 24 20 ¼”+5/8" 45 46 48 48 50 50 46 45 44 43 43 43 43 43 43 40 36 31 26 22 18 DOUBLE SKIN 1/4" outer skin, MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 42 41 39 36 32 31 32 31 30 29 28 28 28 28 23 22 24 21 16 12 8 air-cavity 23.6 39 38 36 33 32 31 31 30 29 27 27 26 27 27 21 20 23 20 14 10 6 air-cavity 31.5 37 35 34 34 32 31 30 29 28 27 26 25 25 25 20 19 22 18 13 9 5 air-cavity 39.3 36 34 36 34 31 31 30 29 27 26 25 24 25 25 19 18 21 18 12 8 4 DOUBLE SKIN 1/4" outer skin, PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 42 41 39 35 32 31 32 31 29 28 28 27 27 27 22 19 20 19 14 9 5 air-cavity 23.6 39 37 36 33 32 31 31 29 28 27 26 25 26 26 20 18 19 17 12 8 4 air-cavity 31.5 37 35 34 34 31 31 30 29 27 26 25 24 25 24 19 16 18 16 11 6 2 air-cavity 39.3 35 34 36 34 31 30 30 28 27 26 24 24 24 24 18 16 17 15 10 6 2 DOUBLE SKIN 1/4" outer skin, TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 42 41 39 35 32 31 32 30 29 28 27 27 27 27 21 19 20 19 14 9 6 air-cavity 23.6 39 37 36 33 32 31 31 29 28 27 26 25 26 25 20 17 19 17 12 8 4 air-cavity 31.5 37 35 34 34 31 31 30 29 27 26 25 24 25 24 19 16 17 16 11 7 3 air-cavity 39.3 35 34 36 34 31 30 30 28 27 25 24 23 24 23 18 15 17 15 10 6 2 Batungbakal 185 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects DOUBLE SKIN 3/8" outer skin, MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 39 37 36 33 30 30 30 30 29 28 28 27 28 27 24 27 24 19 14 10 6 air-cavity 23.6 36 34 34 31 30 29 29 28 27 27 26 26 27 26 23 25 22 17 12 8 4 air-cavity 31.5 34 32 32 31 29 29 28 27 26 25 25 25 25 25 22 24 21 16 11 7 3 air-cavity 39.3 32 31 34 31 29 28 28 27 26 25 24 24 25 24 21 23 20 15 10 6 2 DOUBLE SKIN 3/8" outer skin, PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 39 37 36 33 30 29 30 29 28 28 27 27 27 26 21 22 22 17 12 8 4 air-cavity 23.6 36 34 34 30 30 29 29 28 27 26 25 25 26 24 20 21 20 15 10 6 2 air-cavity 31.5 34 32 32 31 29 28 28 27 26 25 24 24 24 23 18 20 19 14 9 5 1 air-cavity 39.3 32 31 33 31 29 28 28 26 25 24 24 23 24 22 18 19 18 13 8 4 0 DOUBLE SKIN 3/8" outer skin, TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 39 37 36 33 30 29 30 29 28 27 27 26 27 27 21 20 21 17 12 8 -1 air-cavity 23.6 36 34 34 30 29 29 29 28 27 26 25 25 25 25 20 18 20 15 10 6 -1 air-cavity 31.5 34 32 32 31 29 28 28 27 26 25 24 24 24 25 19 17 19 14 9 5 -1 air-cavity 39.3 32 31 33 31 29 28 28 26 25 24 23 23 23 23 18 16 18 13 8 4 -1 DOUBLE SKIN 1/2" outer skin, MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 37 35 34 31 29 28 29 29 28 27 27 27 28 29 29 25 22 17 12 8 4 air-cavity 23.6 34 32 32 29 28 28 28 27 26 26 26 26 26 27 27 24 20 15 10 6 2 air-cavity 31.5 32 30 30 30 27 27 27 26 25 25 24 24 25 26 26 22 19 14 9 5 1 air-cavity 39.3 30 29 32 29 27 27 26 25 25 24 24 24 24 25 25 22 18 13 8 4 0 Batungbakal 186 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects DOUBLE SKIN 1/2" outer skin, PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 37 35 34 31 29 28 29 28 27 27 26 26 26 25 24 23 20 15 10 6 2 air-cavity 23.6 34 32 32 29 28 28 28 27 26 25 25 25 24 24 23 22 18 13 8 4 0 air-cavity 31.5 32 30 30 29 27 27 27 26 25 24 24 23 23 23 21 21 17 12 7 3 -1 air-cavity 39.3 30 29 31 29 27 26 26 25 24 23 23 23 22 22 21 20 16 11 6 2 -2 DOUBLE SKIN 1/2" outer skin, TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 37 35 34 31 28 28 29 28 27 27 26 26 27 25 22 23 20 15 10 6 2 air-cavity 23.6 34 32 32 29 28 28 28 27 26 25 25 24 25 24 20 21 18 13 8 4 0 air-cavity 31.5 32 30 30 29 27 27 27 26 25 24 23 23 24 23 19 20 17 12 7 3 -1 air-cavity 39.3 30 29 31 29 27 26 26 25 24 23 23 22 23 22 18 19 16 11 6 2 -2 DOUBLE SKIN 5/8" outer skin, MONO Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 35 34 33 30 28 27 28 28 27 27 27 27 29 33 27 23 20 15 10 6 2 air-cavity 23.6 32 31 30 28 27 27 27 26 26 25 25 25 27 31 26 22 18 13 8 4 0 air-cavity 31.5 30 29 29 28 26 26 26 25 25 24 24 24 26 30 25 20 17 12 7 3 -1 air-cavity 39.3 29 27 30 28 26 25 25 24 24 23 23 23 25 29 24 20 16 11 6 2 -2 DOUBLE SKIN 5/8" outer skin, PVB Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 35 34 33 30 27 27 28 27 27 26 26 26 26 26 25 21 18 13 8 4 0 air-cavity 23.6 32 31 30 28 27 26 27 26 25 25 24 24 24 24 24 20 16 11 6 2 -2 air-cavity 31.5 30 29 29 28 26 26 26 25 24 23 23 23 23 23 22 19 15 10 5 1 -3 air-cavity 39.3 29 27 30 28 25 25 25 24 23 23 22 22 22 22 21 18 14 9 4 0 -4 DOUBLE SKIN 5/8" outer skin, TSC Hz 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 90 dBA 65 67 69 70 70 72 74 74 75 77 78 79 81 82 81 80 80 77 75 74 72 air-cavity 15.7 35 34 33 30 27 27 28 27 27 26 26 26 25 26 25 22 18 13 8 4 0 air-cavity 23.6 32 31 30 28 27 26 26 26 25 24 24 24 24 24 23 20 16 12 6 2 -2 air-cavity 31.5 30 29 29 28 26 26 26 25 24 23 23 23 23 23 22 19 15 10 5 1 -3 air-cavity 39.3 29 27 30 28 25 25 25 24 23 22 22 22 22 22 21 18 14 9 4 0 -4 Batungbakal 187 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Appendix D Indoor Sound Level Plots from Direct Transmission Loss: Single-Pane Facades and Double-Pane Facades SINGLE-PANE FACADES DOUBLE-PANE FACADES Batungbakal 188 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Appendix E Indoor Sound Level Plots from Direct Transmission Loss: Double-Skin Facades DOUBLE-SKIN FACADES [¼” + ½” air gap + ¼”] + air-cavity + 1/4” DOUBLE-SKIN FACADES [¼” + ½” air gap + ¼”] + air-cavity + 3/8” Batungbakal 189 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects DOUBLE-SKIN FACADES [¼” + ½” air gap + ¼”] + air-cavity + 1/2” DOUBLE-SKIN FACADES [¼” + ½” air gap + ¼”] + air-cavity + 5/8” Batungbakal 190 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Appendix F Design Support Tool Single-Figure dBA Ratings: Direct Transmission Loss Batungbakal 191 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Appendix G Design Support Tool Single-Figure dBA Ratings: Indoor Parameters- Façade Area, Room Volume, Reverberation Batungbakal 192 Acoustic Properties of Double-Skin Glass Facades: A Design Support Tool for Architects Appendix H Evaluation of Findings and Design Support Tool Improving acoustic performance Identifying Impact of façade components Suited for different conditions (lower and high frequencies) Single-Pane Glass thickness Increased thickness shift coincidental dip to occur at a lower frequency Increased thickness improves transmission loss by at least 5dB at lower frequencies Increased thickness improves transmission loss by 2dB-21dB at higher frequencies Laminates PVB/TSC provide equivalent transmission loss as monolithic glass at lower frequencies Large thickness of PVB/TSC glass improved transmission loss by 1dB compared to monolithic glass at lower frequencies PVB/TSC glass reduced effect of coincidence dip, increasing transmission loss by at least 5dB at critical frequencies TSC glass provides 1dB to 2dB increase in transmission loss compared to single-glazed façade with PVB glass TSC improves transmission loss by 1dB to 2dB compared to PVB glass Double-Pane Glass thickness Increased thickness shift coincidental dip to occur at a lower frequency Critical frequencies are between 80Hz to 250Hz and between 800Hz to5000Hz Laminate Monolithic, PVB, and TSC provide equivalent transmission loss at 50Hz to 200Hz Increased thickness of laminate glass improve transmission loss by 1dB to 9dB TSC improves transmission loss by 1dB to 2dB compared to PVB glass Air-cavity Standard air-cavity dimension of an IGU improved transmission loss compared to single-glaze facades: - improved TL by 3 to 4dB at lower frequencies - improved TL by - Increased glass thickness varies improved TL Double-Skin Glass thickness Increased glass thickness of outer skin improves transmission loss by 2dB to 3dB Laminate PVB and TSC laminate improved TL at a higher frequency between 250Hz and 5000Hz Increased glass thickness with laminate glass indicate improved Air-cavity Double-skin facades improved transmission loss by 9-28dB compared to single-glazed and single-skin

Abstract (if available)

Abstract This study assesses and validates the influence of measuring sound in the urban environment and the influence of glass façade components in reducing sound transmission to the indoor environment. Among the most reported issues affecting workspaces, increased awareness to minimize noise led building designers to reconsider the design of building envelopes and its site environment. Outdoor sound conditions, such as traffic noise, challenge designers to accurately estimate the capability of glass façades in acquiring an appropriate indoor sound quality. Indicating the density of the urban environment, field-tests acquired existing sound levels in areas of high commercial development, employment, and traffic activity, establishing a baseline for sound levels common in urban work areas. Composed from the direct sound transmission loss of glass facades simulated through INSUL, a sound insulation software, data is utilized as an informative tool correlating the response of glass façade components towards existing outdoor sound levels of a project site in order to achieve desired indoor sound levels. This study progresses to link the disconnection in validating the acoustic performance of glass façades early in a project's design, from conditioned settings such as field-testing and simulations to project completion. Results obtained from the study's façade simulations and façade comparison supports that acoustic comfort is not limited to a singular solution, but multiple design options responsive to its environment.

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University of Southern California Dissertations and Theses

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Asset Metadata

Creator Batungbakal, Aireen (author)

Core Title The acoustic performance of double-skin facades: a design support tool for architects

School School of Architecture

Degree Master of Building Science

Degree Program Building Science

Publication Date 11/04/2013

Defense Date 10/16/2013

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag Acoustics,design support,double-skin facade,indoor environmental quality,INSUL,OAI-PMH Harvest,sound transmission loss,traffic noise

Format application/pdf (imt)

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Konis, Kyle (committee chair), Gerber, David J. (committee member), Valmont, Elizabeth (committee member)

Creator Email aireen.batungbakal@gmail.com,batungba@usc.edu

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c3-342930

Unique identifier UC11296508

Identifier etd-Batungbaka-2127.pdf (filename),usctheses-c3-342930 (legacy record id)

Legacy Identifier etd-Batungbaka-2127.pdf

Dmrecord 342930

Document Type Thesis

Format application/pdf (imt)

Rights Batungbakal, Aireen

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the a...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus MC 2810, 3434 South Grand Avenue, 2nd Floor, Los Angeles, California 90089-2810, USA