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Facade retrofit: enhancing energy performance in existing buildings

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Facade retrofit: enhancing energy performance in existing buildings

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FACADE RETROFIT:
ENHANCING ENERGY PERFORMANCE IN EXISTING BUILDINGS

by

Andrea Soledad Martinez Arias

A Thesis Presented to the
FACULTY OF THE USC SCHOOL OF ARCHITECTURE
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
MASTER OF BUILDING SCIENCE

December 2013

Copyright 2013 Andrea Soledad Martinez Arias
i

ACKNOWLEDGEMENTS
I would like to deeply thank my faculty members. My sincere acknowledgement starts with Professor
Douglas Noble, who not only provided me with unconditional support, but also with tremendous
encouragement to explore this important and candent topic in our field. His advice, supervision, and
personal guidance were fundamental for the development of this research. His critical feedback was crucial
to the completion of this study.

I also sincerely thank Professor Marc Schiler for his critical and deep review of the building science
principles contained in this work. Not only is his expertise in energy, thermal, daylighting and
environmental factors affecting this study, but his always willingness to help in clarifying key elements in
the process. He served with charisma and sincerity, gestures that makes him an outstanding model to
follow.

A special acknowledgement goes to Professor Rachel Berney. She helped and provided me with the most
valuable learning in the methods and processes for doing research. Her warm and candid responses were
the basis in the development of my critical thinking of the problem, a coherent progression of the process,
and a clear completion of the whole thesis. She is an outstanding example of professionalism in research
and professorate.

I would like to extend my acknowledgment to Kevin Devine for having given me access to the building, and
to Jose Torres for having patiently explained all the building’s operations; Chuck Khuen, principal of
Weather Analytics for facilitating real weather data for the energy analysis; Deepa Chandrashekaran,
William Vicent and Andres Fergadiotti for their help with energy simulation models. To my dear friends,
Melisa and Carolina, I thank for the hard time I gave them editing my second language.

Finally, my deepest dedication of this work is for my family. My husband and son are my reason for living
and the source of love and inspiration I needed to battle every day. And all my extended family, which at
the distance of my home country brought me the best of the encouragement and wishes.
ii

ABSTRACT
Buildings in the United States are responsible for over 40% of the energy used (US Department of Energy
2013a, Architecture 2030 2013a) in the country. During the life span of buildings less than 20% of energy
consumption is for extraction of raw materials, materials sourcing and construction, and over 80% of the
total energy consumption occurs during building operation (United Nations Environment Programme and
World Resources Institute 2010). That energy, supplied by mechanical means, is wasted due to poor
building performance in building facades, such as leaking windows, deficient insulation, or defects in
construction. Retrofit strategies not only rescue embodied energy contained in buildings already built, but
also save energy in their operational phase.

A special focus of this thesis is the exploration of mid-20th century buildings. Since many of them were
built with an emphasis on mechanical-conditioned spaces, they are excellent candidates for a new life
reconsidering a passive approach. As the first part of the exploration, a general typology of facade retrofits
is defined, examining existing cases worldwide. Building retrofits range from partial to total, presenting
different combinations. Most of the existing cases of facade retrofits have been made as urgent response
to facade failure mitigation. Since the cases vary in a wide range - from low-e film application in windows to
whole building retrofit - this thesis typologizes these cases prior to testing through simulation modeling and
in a case study.

A specific case study focuses on alternative and passive energy solutions applied to an existing building in a
mild climate. The building is a 12-story office building in Los Angeles area built in 1972 with a curtain wall
façade. The goal of the thesis is to examine different scenarios for facade upgrading in the building using
energy simulation modeling and drawing upon what was learned from the typological analysis of existing
cases. Two energy software packages- eQuest and Design Builder- are explored in the case study building
to evaluate selected facade solution alternatives. As the first part of the exploration, current building
energy consumption and a survey of the components of the facade have been collected and transferred to
the computer model. After calibrating the model, five different schemes are explored: (1) replacing existing
windows for double, triple or quadruple glass, (2) adding interior and exterior insulation (3) adding
iii

overhangs and fins to fenestrations, (4) re-skinning with more glazed area, and (5) attaching a double glazed
skin to the existing original facade.

These possibilities for the first step in the energy demand derived from facade interventions are explored in
this thesis, which considers the results of the energy simulations and recorded energy consumption data.
Each façade retrofit scenario is evaluated individually and combined with the most effective from each
type. The thesis approach is based on the belief that building facade retrofits represent a unique
opportunity to have a major impact on total energy use of existing buildings. Further research will expand
this thesis results beyond the purely energy perspective.

iv

LIST OF CONTENT
Acknowledgements ..................................................................................................................................i
Abstract ................................................................................................................................................... ii
List of Figures .......................................................................................................................................... vi
List of Tables ............................................................................................................................................ x
Introduction............................................................................................................................................ 1
Chapter 1: Context of building facade retrofit ...................................................................................... 3
Old buildings, part of the problem… part of the solution .............................................................. 4
Scenario in the United States.......................................................................................................... 5
The role of building envelope ......................................................................................................... 9
Chapter 2: Research Background ........................................................................................................ 12
For how long does a building live? ............................................................................................... 13
Retrofit related terms and Building Energy Retrofit Definitions ................................................. 15
Building Energy Retrofit Process ................................................................................................... 18
Retrofit Trends .............................................................................................................................. 19
Building energy retrofit opportunities and challenges ................................................................ 30
Opportunities in retrofitting existing buildings ..................................................................... 30
Challenges and constraints .................................................................................................... 37
Chapter 3: Research scope, Objectives, Methods and Procedures .................................................. 38
Scope ............................................................................................................................................. 39
Objective ........................................................................................................................................ 40
Methodology ................................................................................................................................. 40
Software .................................................................................................................................. 41
Procedure in the case study .......................................................................................................... 41
Chapter 4: Typologies of facade retrofit ............................................................................................ 44
1. Single Skin .................................................................................................................................. 48
2. Sunshades .................................................................................................................................. 49
3. Over-cladding ............................................................................................................................ 53
4. Recladding ................................................................................................................................. 56
v

5. Double Skins .............................................................................................................................. 59
Chapter 5: Case study .......................................................................................................................... 61
General description ................................................................................................................ 62
Occupancy schedule profile ................................................................................................... 63
Envelope profile ...................................................................................................................... 64
HVAC SYSTEM OF THE BUILDING ........................................................................................... 72
Building’s energy consumption profile .................................................................................. 74
Summary of energy consumption in the building ................................................................. 75
Chapter 6: Simulation and testing ...................................................................................................... 77
eQuest simulation model .............................................................................................................. 78
Calibration............................................................................................................................... 79
Typology applied to Schemes ................................................................................................ 93
Single schemes compilation ................................................................................................. 114
Cascading Analysis ................................................................................................................ 116
Design Builder simulation model ................................................................................................ 122
Chapter 7: Data analysis ................................................................................................................... 128
Chapter 8: ConclusionS and future work .......................................................................................... 139
APPENDIX 1. Glass study for case study ........................................................................................... 143
APPENDIX 2. RESFEN and CONFEM tests ......................................................................................... 145
APPENDIX 3. Data loggers ................................................................................................................. 151
APPENDIX 4. eQuest test for quadruple glass .................................................................................. 156
Bibliography........................................................................................................................................ 158

vi

LIST OF FIGURES

Figure 01. Energy-related CO2 emissions............................................................................................. 6
Figure 02. Energy consumption in the US ............................................................................................ 6
Figure 03. Use of gas and coal in buildings in the US (Rocky Mountain Institute 2013b) .................. 7
Figure 04. Building energy end use in the US ....................................................................................... 7
Figure 05. Energy end-use in residential and commercial buildings in the US ................................... 8
Figure 06. Commercial Sector Energy Consumption table .................................................................. 9
Figure 07. Graphic comparison between skeleton and skin of buildings and automobiles ............. 10
Figure 08. Procedures for envelope failures ...................................................................................... 11
Figure 09. Commercial Building Median Lifetimes ............................................................................ 13
Figure 10. Ville Savoye current and condition previous to restoration ............................................ 14
Figure 11. Lifetime of building systems .............................................................................................. 14
Figure 12. Different kinds of retrofits in buildings. ............................................................................. 16
Figure 13. Building facade retrofit related terms diagram ................................................................. 17
Figure 14. Planning process of retrofit ............................................................................................... 18
Figure 15. A retrofit approach diagram .............................................................................................. 19
Figure 16. Energy and CO
2.
average values for US commercial buildings ......................................... 23
Figure 17. LEED-EBOM Scale. .............................................................................................................. 24
Figure 18. Goals of Net Zero Energy Initiative for Commercial Buildings .......................................... 25
Figure 19. The 2030 Challenge. .......................................................................................................... 25
Figure 20. the Retrofit Ramp-up initiative in the US. ......................................................................... 28
Figure 21. Main events related to building retrofit development. ................................................... 29
Figure 22. Embodied CO
2
contained in materials. ............................................................................. 31
Figure 23. Estimated building stock by 2035...................................................................................... 32
Figure 24. Total number of building by vintage in the US .................................................................. 33
Figure 25. Commercial sector characteristics .................................................................................... 34
Figure 26. Energy savings and payback .............................................................................................. 35
Figure 27. Diagram with the main scope of the thesis ...................................................................... 39
vii

Figure 28. Methodology of the thesis ................................................................................................ 40
Figure 29. Section of the ddatabase of facade retrofit cases ............................................................ 46
Figure 30. Empire State building retrofit information ....................................................................... 48
Figure 31. Willis tower retrofit information ....................................................................................... 49
Figure 32. CIC Camden building retrofit information ........................................................................ 50
Figure 33. German air traffic control office ........................................................................................ 50
Figure 34. Aidlin Darling Architects building ...................................................................................... 51
Figure 35. GSA Building retrofit information ...................................................................................... 52
Figure 36. Mayor’s Towers retrofit information ................................................................................ 53
Figure 37. New York County Family court .......................................................................................... 54
Figure 38. CIS Chief office in Manchester........................................................................................... 55
Figure 39. 35 Newhall Street building retrofit information ............................................................... 56
Figure 40. Sparkasse Vorderpfalz building information..................................................................... 57
Figure 41. The Lighthouse International Headquarters retrofit information ................................... 57
Figure 42. Cathay Bank retrofit information ...................................................................................... 58
Figure 43. 100 Park Avenue building retrofit project ........................................................................ 59
Figure 44. Different views of the case study building ......................................................................... 62
Figure 45. Building orientation and typical floor ................................................................................ 63
Figure 46. Facade elevation. ............................................................................................................... 63
Figure 47 Detail of original facade components. .............................................................................. 65
Figure 48. Facades modularity and WWR. ......................................................................................... 66
Figure 49. Maximum and minimum dry bulb temperature for Marina del Rey ............................... 69
Figure 50. Cooling and heating degree days ...................................................................................... 71
Figure 51. Views of the building’s systems ........................................................................................ 72
Figure 52. Refrigeration, Hot water, and Fan Elements Diagram. ..................................................... 73
Figure 53. Real energy consumption for the building in 2009. ......................................................... 74
Figure 54. Diagram of simulations taking retrofit typology. .............................................................. 78
Figure 55. Description of the calibration process in eQuest. ............................................................ 79
Figure 56. eQuest basic geometry ...................................................................................................... 80
Figure 57. Wall showed by type and construction in eQuest. ........................................................... 80
viii

Figure 58. EQuest zone Groups for shell 1 and 2. ............................................................................... 81
Figure 59. HVAC Systems Definition perimeter zones ........................................................................ 82
Figure 60. Error obtained in EPW to DOE format conversion process. .............................................. 84
Figure 61. Comparison between an .epw files ................................................................................... 84
Figure 62. Temperature comparison (dew point) for three possible locations in eQuest. .............. 89
Figure 63. Differences in energy prediction from different weather options in eQuest.................. 90
Figure 64. Comparison between actual data and eQuest model for electricity and gas. ................ 92
Figure 65. Baseline end-uses (percentage and KBtu/yr) ................................................................... 93
Figure 66. End uses related and not related to facade interventions. .............................................. 94
Figure 67. Simulation diagram in eQuest. .......................................................................................... 94
Figure 68. Comparison for different daylighting control within eQuest. .......................................... 96
Figure 69. Results for different alternatives of single glass ............................................................... 99
Figure 70. Results for different alternatives of double glass ........................................................... 101
Figure 71. Results for different alternatives of triple glass .............................................................. 103
Figure 72. Results for different alternatives of quadruple glass ...................................................... 105
Figure 73. Summary of all options for glazing replacements ........................................................... 106
Figure 74. Solar Tool’s calculation of overhangs and fins. ............................................................... 107
Figure 75. Results for different alternatives of sunshade devices .................................................. 109
Figure 76. Results for different alternatives of over cladding .......................................................... 111
Figure 77. Percentage of savings of all single retrofits options ....................................................... 115
Figure 78. Results of total savings for cascading analysis 1 ............................................................. 117
Figure 79. Results of total savings for cascading analysis 2 ............................................................. 119
Figure 80. Comparison of total energy and end-uses for double and triple glass. ......................... 121
Figure 81. Design Builder model of the building .............................................................................. 122
Figure 82. Definition of building as a block and zones for core and perimeter .............................. 123
Figure 83. Calibration in Design Builder for electricity and gas. ....................................................... 124
Figure 84. Double skin configuration in Design Builder ................................................................... 125
Figure 85. Multi-story double skin façade model in Design Builder................................................ 126
Figure 86. Full-story double skin with incorporation of vents in Design Builder. ........................... 126
Figure 87. Total energy use for double skin façade retrofit using Design Builder .......................... 127
ix

Figure 88. Table 1. EPA’s ENERGY STAR Performance Ratings, ...................................................... 130
Figure 89. Site and Source energy consumption of the case study building. ................................. 131
Figure 90. Relation between R-value and WWR for curtain walls .................................................. 132
Figure 91. 3M product on-line simulator ......................................................................................... 134
Figure 92. Comparison between ¼”single clear and single reflective glass .................................... 144
Figure 93. RESFEN using Single clear glass in aluminum frame ....................................................... 146
Figure 94. RESFEN using triple super insulated glass (cod.451 U-value: 0.18 and SHGC: 0.40) ..... 146
Figure 95. RESFEN using triple super insulated glass (cod.452, U-value: 0.18 and SHGC: 0.26) .... 147
Figure 96. results using user-defined performance factors of glass in RESFEN .............................. 148
Figure 97. COMFEN results ............................................................................................................... 150
Figure 98. Location of data loggers in the building .......................................................................... 151
Figure 99. Temperatures from data loggers .................................................................................... 152
Figure 100. Detail of temperatures for two days ............................................................................. 153
Figure 101. Temperature in façades of the building ........................................................................ 154
Figure 102. Temperatures in the core of the building ...................................................................... 155
Figure 103. View and results of different types of quadruple glass in eQuest ............................... 156

x

LIST OF TABLES
Table 1. Retrofit schemes for case study ........................................................................................... 43
Table 2. Typology of façade retrofit ................................................................................................... 47
Table 3. Number of cases by typology and year ................................................................................ 60
Table 4. Instantaneous heat transfer ................................................................................................. 69
Table 5. Cumulative heat transfer ....................................................................................................... 70
Table 6. Energy Intensity Use comparison to benchmarks ............................................................... 75
Table 7. Weather data summary and temperature range for CZ9 .................................................... 86
Table 8. Weather data summary and temperature range for Los Angeles ...................................... 86
Table 9 Weather data summary and temp.range for Marina del Rey 2009 ..................................... 87
Table 10. Daylighting control options in eQuest ................................................................................ 95
Table 11. Detail of different alternatives of shading ....................................................................... 107
Table 12. Best single schemes for cascading analysis 1. .................................................................. 116
Table 13. Single schemes for cascading analysis 2 ........................................................................... 118
Table 14. Energy Consumption per sf of office floorspace by vintage ............................................ 129
Table 15. Energy expenditures per sf of office floorspace by function and class ........................... 130
Table 16. Comparison of three types of single glass types .............................................................. 143

1

INTRODUCTION
With the concepts of global warming and climate change becoming such popular phrases, sometimes they
dull the urgency and the need to take action. However, buildings in the United States are responsible for
over 40% of the energy used (US Department of Energy 2013a, Architecture 2030 2013a) in the country.
The high CO2 level in the environment warns us of the chance of altering the natural balance, where
buildings are at the top of the list of inefficient energy users. Among scientists, James Hansen (2008), one
of the first to define the effects of Global Warming in the 1980s, has emphasized the need to reduce from
the current levels of CO2 “if humanity wishes to preserve a planet similar to that on which civilization
developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest
that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm.” (Hansen, James, Sato,
Makiko, and Kharecha, Pushker 2008)

Alternative and passive technologies for buildings using solar, geothermal or wind power are ways to
address global warming using renewable sources instead of burning coal. However, these technologies are
slow to be adopted. With these kinds of solutions, the need for burning carbon for electricity generation
decreases, and eventually allows forests and soil to be used towards cleaning the air. As half of the
electricity in U.S. is generated at coal-fired plants , reduction of electric usage and/or shifting generation to
renewable sources could make an important contribution in the battle against CO2 increment generated by
burning coal.

The first question is: Why have buildings become so demanding of energy to ameliorate indoor spaces?
Some answers can be found in history, where new paradigms and new technologies started to change the
way buildings were conceived. The introduction of mechanical conditioning systems by Willis Carrier in
early 20
th
century created a demand for buildings with active systems instead of passive ones. In the
context of cheap energy, traditional concerns of efficient envelope and durable construction materials were
displaced to a second level of importance. As a consequence, we have inherited buildings prone to feature
leaks in windows, and with poor insulation and deficient construction techniques. All these deficiencies
make the envelope a more effective thermal transmitter than environment-conditions protector.
2

During the last few decades the focus has been in the design of more efficient buildings in new
construction, but new buildings are a very small part of the built environment. If we focus in terms of
impact, old buildings are already present in our cities and they are an opportunity on which to focus urgent
mitigations. Although thinking in net-zero energy is not a much-explored alternative in existing buildings,
taking further steps from the current status is needed.

Currently, the building sector is highly conscious of building more efficient buildings as part of the
commitment to reduce energy consumption in a context of economic and environmental crisis. However,
energy reduction cannot be a goal if the quality of indoor space is not improved. The concept of green
building has been defined as “a holistic approach to design, construction, and demolition that minimizes the
building’s impact on the environment, the occupants and the community”. Therefore, any action oriented
to reduce energy is also committed to improve the quality of the spaces where all of us spend most part of
our lives: inside buildings. Regarding this point, the U.S. Environmental Protection Agency (EPA) has
quantified that Americans spend about 90% of their day indoors, where the air quality is sometimes worse
than outside (Environmental Protection Agency 2008).

Energy efficiency is not a new idea; it has long been sought by government and companies and also by final
consumers. All actors related to the built environment are attempting to put actions on the architectural
horizon considering existing buildings a crucial part of the solution. The concept of building retrofit in an
energy perspective is a new manifestation in the current energy crisis scenario. A new specific field of
research is using integrated building maintenance and repair to reduce energy use in “dying” buildings and
“rebirth” them. Researchers have indicated that no policy is focused to explore this promising topic in
energy retrofit yet; it is a promising field estimated to become more common in the next 10 to 15 years
(Pike Research 2010, 1).

3

CHAPTER 1: CONTEXT OF BUILDING FACADE RETROFIT
This research focus on how facade retrofits can decrease the use of energy in existing buildings. In this
chapter, an introduction of the topic is presented, including a description of the challenges of existing
buildings face and their important role to achieve energy reductions in the US context.

4

Old buildings, part of the problem… part of the solution
The building sector is responsible for using the largest amount of primary energy in the US (Architecture
2030 2013). Research indicates buildings are responsible for a third of the energy consumed worldwide,
with 15% of global greenhouse gas emissions that could become an alarming 70% within cities (Clinton
Climate Initiative 2012). It is urgent to recognize that with the forecast in world population growth with the
majority living in urban areas, solutions to decrease the consequent increments in energy consumption of
new buildings are urgent, but more necessary is to repair the inefficiencies in the existing ones for their
reuse.

Failure is not a problem in our existing building; it is a huge opportunity. As Edward Mazria, founder of
Architecture 2030, has declared that the challenge of building sector is to “rapidly transform the US and
global building sector from the major contributor of greenhouse gas emissions to a central part of the
solution to the global-warming crisis” (Architecture 2030 2013b). It is desirable to identify where the big
saving opportunities are in building remediation actions. It is an overwhelming task considering such
different sources and estimations, and what kind of factors are those sources taking in consideration.
However, a first approach should consider where in the building’s lifecycle the mayor energy uses are and
for which kinds of occupant needs that energy is used.

Buildings consume energy along their lifetimes from extraction of raw materials, materials sourcing,
construction, and operation to demolition. However, most of that energy is not consumed during the
construction stage, but during the period the building is used. This situation has been quantified by United
Nations as 20% of energy consumption for construction and 80% of the total energy consumption for
building operation (United Nations Environment Programme and World Resources Institute 2010). So, the
primary problem lies with building performance during its useful life. Our existing buildings waste energy
because they have deficient insulation, leaking windows, deficient heating and cooling systems, and poor
construction techniques; obligating people to use high amounts of energy for their heating and cooling
needs.

5

Regardless of whether the building is fed with renewable or fossil fuels, energy continues to leak away
through the fabric of buildings. Many of them are dependent on mechanical space conditioners, displacing
most of the traditional concerns of efficient envelope applied in the past such as appropriate sun
orientation, locally chosen material with suitable labor, natural ventilation or facade differentiation.

New buildings are certainly part of the solution; however they represent a small percentage of the building
stock. In Europe, for example, just 1.5% represents new construction in the non-domestic sector (Baker
2009, 3). European building sector accounts for about 40% of current energy consumption and 36% of
Europe’s CO2 emissions; and heating and cooling requirements are responsible for 25% of that energy use
(European Commission Energy 2010). Specialists have calculated that heating and cooling demand can be
reduced by 80%, ultimately shaving 20% off Europe’s energy demand, if deep refurbishments are applied to
the building stock. That could make Europeans achieve 6% of reduction of energy consumption levels to
2020 (Jones 2010). In Germany, for example, the focus is in reducing space heating requirements, which
account for 33% of the building energy consumption (Giebeler et al. 2005, 32).
Scenario in the United States
The context of energy consumption in the United States is no less challenging. Environment America
Research and Policy Center reports the U.S. as responsible for 10% of all the energy used in the world
(Environment America 2009, 2). On one hand, a large part of the energy consumed in buildings is due to
appliances and other equipment, on the other, operating mechanical equipment to maintain indoor
comfort standards also consumes substantial energy. The use of appliances to support comfortable living
currently results in high levels of energy consumption inside buildings, which shapes the way that
Americans live. Regarding this last point, the International Energy Agency –an international forum of 28
advanced economies in energy issues- estimates that no less than 90 gigawatts (GW) of power generating
capacity is running just to supply appliances with standby power, and without further measures this will be
107 GW by 2020 (Jones 2010). Experts have shown a steady increment of energy consumption patterns
over time in the United States. For example, even though China is the largest generator of greenhouse gas
emissions in the world, the United States is the world’s larger economy, representing the highest CO2
emissions per capita (Yudelson 2009, 7).
6

Figure 01. Energy-related CO2 emissions
(Yudelson 2009, 7)

The analysis of the main sectors of the use of energy in the US shows buildings with the major split.
Architecture 2030, a non-profit independent organization, re-distributed national energy consumption data
by different categories, that revealed a more detailed impact of buildings, which they have recognized as
hidden in separated sectors. So, buildings in the commercial, residential and industrial sector consume
nearly 50% of the energy in the country and 76% of all electricity.

Figure 02. Energy consumption in the US
(Architecture 2030 2013a)
7

In addition to the energy breakdown done by Architecture 2030, the Rocky Mountain Institute –an
independent, nonprofit organization advocate to the built environment, energy and resources- reaffirms
buildings as the major consumers of coal and gas in the US (Rocky Mountain Institute 2010a).

Figure 03. Use of gas and coal in buildings in the US (Rocky Mountain
Institute 2013b)

There exist several versions of energy consumption breakdowns for buildings in general. The US
Department of Energy (US DOE) energy end-use data reports that space conditioning (cooling and heating)
and lighting are the end uses that represent the greatest demand in buildings (fig 04). Since they represent
half of the energy in buildings in the US, they constitute an important focus for remediation actions to be
studied.

Figure 04. Building energy end use in the US
(US Department of Energy 2013a)
0% 50% 100%
coal
gas
68%
55%
32%
45%
buildings others
8

Those end-uses (heating, cooling and lighting) have some variations depending on the building type. Based
on data from the U.S. Department of Energy for both groups, energy use in residential and non-residential
buildings varies in the split. Commercial buildings use less energy in space heating than residential ones,
because operations usually do not extend at night. Also, lighting use in commercial buildings is two times
higher than residential ones (fig 05).

Figure 05. Energy end-use in residential and commercial buildings in the US
(US Department of Energy 2013, based on tables 2.4.2 for residential
buildings and table 2.4.3 for commercial buildings)

Buildings die in demolition, which creates opportunities for new construction. Through demolition-as a
product of nature or man- buildings lose all that embodied energy contained in their materials, which is
typically highly recoverable. Therefore, energy analysis should consider a whole life cycle for buildings,
from the extraction of materials to demolishing. The hope exists and is real, Mazria states, if we could
retrofit all the existing commercial and residential buildings in the U.S. before 2030, the U.S. would achieve
energy independence and consequently reduce its contribution to global warming (Architecture 2030
2013b).
Space
Heating
25%
Space
Cooling
13%
Water
Heating
12%
Lighting
12%
Electronic
s
8%
Refrigerat
ion
8%
Wet
Clean
6%
Cooking
5%
Computer
s
1%
Other
4%
Adjust to
SEDS
6%
Residential
Space
Heating
12%
Space
Cooling
12%
Water
Heating
6%
Lighting
25%
Electronics
8%
Refrigerati
on
4%
Ventilation
6%
Cooking
2%
Computers
4%
Other
13%
Adjust to
SEDS
8%
Commercial
9

The role of building envelope
The building skin has an important impact on building performance, because of the amount of energy used
for cooling, heating or lighting needs, and all relate to the performance of the envelope system. The
building envelope has been defined by the California Green Building Standards Code as “the ensemble of
exterior and demising partitions of a building that enclose conditioned space” (California Building Standards
Commission 2009, 11). At some point, building envelopes became no longer thermally protective,
especially since the post-war period where that function was replaced by mechanical means. One of the
characteristic features in those buildings is a single-thickness glass skin that allows high solar infiltration and
thermal transmission loads, involving high energy costs. Consequently, mechanical systems provide both
the cooling for excess of solar heat gain and lighting, and the heating lost for conduction through vertical
elements such as wall and windows (Fig 06).

Figure 06. Commercial Sector Energy Consumption table
(US Department of Energy 2013, table 3.1.12)

In Boomer Buildings, Mitchell and Giurgola describe building failures through several cases of retrofits in
existing mid-century buildings. They describe that period of construction as a parallel to the baby boom
experienced after World War II. These boomer buildings have now become the predominant group of
buildings that use large amounts of energy. Mitchell and Giurgola state that inefficiencies were less
10

common in pre-war periods, when the envelope was more integrally incorporated as a load-bearing
component in the facade (Mitchell, Giurgola Architects 2005, 7).

A distinctive switch in the conception of the envelope in the middle of the 20
th
century is in part a result of
the new conception created by the Modernism, in which the low cost of energy and industrialized
processes dramatically affected how those buildings were conceived and built. Post-war buildings are heir
to Modernist construction principles, as such Le Corbusier’s idea of buildings mimicking industrial processes
such as in automobile manufacturing. Then, buildings were conceived using the concept of a load-bearing
chassis with a group of replaceable parts over that frame. In On Weathering: The Life of Buildings in Time,
Mostafavi and Leatherbarrow describe that a change in proportions in materials demanded new techniques
and connections in buildings at a time of a boom of industrial processes. Also, that a consequent problem
was that all those new processes of assembly were executed by an inexperienced labor force (Mostafavi
and Leatherbarrow 1993, 23-25)

Figure 07. Graphic comparison between skeleton and skin of buildings and
automobiles
This new conception of architecture of the mid-20
th
century resulted in building envelope inefficiencies.
Buildings from all ages are subject to present failures due to material defects, construction, design, or
natural disasters among others. When a building envelope system fails, that failure needs to be assessed to
determine whether a replacement or update is necessary. To recognize them, an audit with a forensic
• Buildings. Structural
frame and modular
envelope
• Automobiles. Chassis
and prefabricated shell
11

investigation of the building envelope components is recommended to thoroughly address a design
remediation. Some of the more common envelope failures are: thermal bridges (areas with high
conduction for heat lost in the facade); material failure (failure to achieve a reasonable service life, distress
in cladding panels which lead to financial consequences due to the need of replacement); lack of air
tightness; direct heat gain because of single pane glass, or moisture intrusion. (water leaks produced by
hurricanes or wind damage).

Figure 08. Procedures for envelope failures
procedures such as moisture intrusion investigation or the use of
thermography (Bet-r 2013) (Energy.gov 2012)

An extensive failure analysis precedes an adequate retrofit design process. In exhaustive diagnosis, some
testing as microscopy work, material compatibility testing, accelerated materials testing simulating weather
effects, and infrared thermography have been used by building forensics professionals (Fig 07). After all,
and as researchers have referred, the envelope constitutes the key system which can integrate mechanical
systems and lighting over the life of the building (Lawrence Berkeley National Laboratory 2013).

12

CHAPTER 2: RESEARCH BACKGROUND
The questions of this study are: How can we transform an inefficient and undervalued facade into an
efficient one? How long can we maintain them within efficient parameters? Are they capable of having
several life cycles? Is it possible that inefficient buildings could be considered to become net-zero buildings?
Most of those questions are difficult to address without having a big picture of this concept of building
retrofit and what the possibilities are. The intention of this chapter is to build the general background of
energy retrofit and how its concepts have inspired a new field of research.
13

For how long does a building live?
Depending on the point of view of the field of approach, life spans are specific. For example from a
commercial value perspective, buildings constitute assets with a useful life. In those quantifiable terms, for
tax purposes a building depreciates in its useful life expectancy. That depreciation is defined by the US
Internal Revenue Service (IRS) as 39 years for commercial buildings (Geltner et al. 2006, 322). The service
life of a building is the period of time during which the building meets space demand. However, research
has found that buildings are often demolished before their useful lives are exhausted (Kestner and Webster
2010, 10-12). Regarding a sustainable approach, it is desirable to extend that period as long as possible.
Even commercial buildings have a median life span of around 70 years in the US; buildings can have
extremely longer lifetimes due their structures.

Figure 09. Commercial Building Median Lifetimes
(US Department of Energy 2013, table 3.2.7)

There are historical considerations that can give a patrimonial (cultural or historical) value to buildings.
Under that categorization, there can be strong protections and processes that can maintain them for
centuries. The historical value of buildings is estimated when the building has reached 50 years (National
Park Service 2013). Due to the intrinsic value that they acquire, they are object of strong efforts for
maintenance and conservation, prolonging their estimated useful life. An example among those historical
14

preservation approach of that is Ville Savoye (Fig. 11) which restoration made possible to maintain its value
as one of iconic pieces of modern architecture.

Figure 10. Ville Savoye current and condition previous to restoration
(Mostafavi and Leatherbarrow 1993, 6-7)
Other point of view is to understand a building as a system of systems. In Refurbishment Manual, Giebeler
et al. describe buildings as summary of parts with different life spans (Giebeler et al. 2005, 23). Taking this
life-expectancies table, one can see that a building might require its first retrofit in its mechanical systems
after 12 years. It is also interesting to note that facade failures are estimated to appear after 20 years,
which means that buildings from the 1990s are now possible candidates in terms of facade retrofits.
Consequently, buildings from the 1970s that are the interest of this study are in direct need of assistance.

Figure 11. Lifetime of building systems
(based on Giebeler et al. 2005, table B1.2)
30
40
20
25
20
20
12
60
60
40
40
35
60
35
0 10 20 30 40 50 60 70
render, facades
pitched roofs
flat roofs
windows
insulating glass units
building envelope as a whole
heating
lifetime in years max lifetime in years min
15

As buildings are assets with different lifecycles, under a new use they could be considered born again.
When the new life of a building maintains its original function, terms such as renovation are suitable. If a
new life comes with a different function, it is generally called conversion. Loft conversions from offices or
industrial buildings are a typical example of this, worldwide. When a new function is created for historical
buildings, it is called recycling. The retrofit concept explored in this thesis concentrates on general building
performance, independent of the activity or programming in the building. Good cases exist around the
world, regardless of building use that makes them all good candidates for rebirth and creates possibilities to
improve their efficiency. This concept of several lives is one of the sustainable approaches that must be
taken for architectural design, which takes on the task to build on the past, and challenges the old buildings
to be even better than new ones.
Retrofit related terms and Building Energy Retrofit Definitions
The term retrofit has not been well defined. The dictionary definition of retrofitting is “to modify
something or install new parts, which were not available when the thing was fabricated” (Encarta World
English Dictionary 2009). Another definition is to “add (a component or accessory) to something that did
not have it when manufactured” and “provide (something) with a component or accessory not fitted to it
during manufacture” (Oxford University Press 2010). In buildings, it refers to updates in existing buildings
that can be made either to fix or repair deficiencies in the building performance, or to comply with current
standards. A building can experience several types of retrofit depending on the system being fixed, such as
structural, thermal, fire resistance, aesthetical and so on. Giebeler et al state “there is no universally
applicable term that covers all building measures on existing buildings and is also understood as
such”(Giebeler et al. 2005, 10). He explains a series of terms that refer to different scales and reason, with
the intention to clear the vagueness. In terms of scale, they can go from minor repairs to comprehensive
retrofits (where several systems form part of the intervention in the whole building); and in terms reasons
they can be technical, functional, aesthetic, and so on.
16

Figure 12. Different kinds of retrofits in buildings.

First, there are some terms that because of their nature are independent from the energy aspect of the
facade of a building, such as reconstruction and restoration. In reconstruction “the rebuilding of a structure
that no longer exists” therefore, no parts of the original building remain and it constitutes a new building.
Likewise, restoration as the required work to “finishing an incomplete structure,” which closely refers to
Viollet-le-Duc’s theory, on which restoration works reproduce original materials and features found in
documents (Giebeler et al. 2005, 11-12). These two terms lay on interventions to which, main goal is the
reconstitution of building itself more than building performance.

In fact, renovation, repair and refurbishment are the terms defined by the authors which are more suitable
for this study. Renovation/maintenance “does not add anything new to the building stock nor does it
replace old with new” (Giebeler et al. 2005, 12), the building maintains its function and value through
competent ‘upkeep’ (12), which only modifying parts can be understood as a retrofit in a minor scale.
Repairs/maintenance is “limited to the replacement or repair of defective building components” (13), which
can be related to the term retrofit since it contemplates a failure in one or several buildings’ systems.
Finally, refurbishment is one of the more suitable synonyms to describe building retrofit, which “include
intact but, for example, outdated components or surfaces” (13-14). Refurbishment contrasts with
conversion because “refurbishment does not involve any major changes to the load bearing structure or
interior layout” (14), which could be possible in whole buildings’ conversion.
retrofit
blast
energy
structural aesthetic
fire
resistance
17

Figure 13. Building facade retrofit related terms diagram
(based on Giebeler et al.[2005] definitions)

In terms of refurbishment, the authors distinguish three levels of intervention: partial, normal and total. A
partial refurbishment “involves only one component or one part of the building, e.g. the façade, the ground
floor or the east wing” (19) and they refer to work executed while the building is occupied. A normal
refurbishment can “encompass an entire building or least a part of the building that already exists as a
clearly separate, autonomous element” (13) and some of interventions under this category are fire
protection, acoustic or thermal performance improvements. Finally, in a total refurbishment “the
demolition returns the building more or less to its load-bearing carcass” (14). Building skin replacements or
re-skinning, which are also terms used in practice, could be well suited under this definition. In a total
refurbishment the building become very close to a new one in terms of its facilities and safety, complies
with current legislation and standards.

Conversions “always affect the structure of a building” (14), which will be related to energy retrofits in those
cases of extensive retrofits that require structural changes such as the incorporation of additional elements
to the facade adding an additional load to the building. On the other side, Modernization is defined as a
procedure that “serves to improve the gettable floor space by increasing the level of comfort or decreasing
the running costs” (14). It can contemplate modifications in the morphology of the building, which can be
understood as a change in the configuration and materials or re-skinning (or some of the partial
refurbishment actions as replacement windows); which could have an insulation improvement.
no
•reconstruction
•restoration
yes
•renovation/maintenance
•repair/maintenance
•refurbishment
•modernization
18

As seen, there are still varied terms referring to interventions in existing buildings. Because the focus of this
thesis is energy, the understanding of retrofit is any improvement made to an existing building system in its
operation or infrastructure to reduce its energy consumption. Referring to ‘façade-retrofit’ makes the
terms refer to one of those systems on the building that is fundamental on the improvement of the whole
building energy performance.
Building Energy Retrofit Process
The process of embracing a retrofit intervention could be similar to any project of the new design of a
building. However, the fundamental difference between the processes of retrofitting an existing building
versus a new design depends on current conditions. While the new design is planned under expected
conditions, the retrofit plan must account for real conditions such as existing materiality, failures and
occupants. This process of retrofit depends on three basic stages: analysis, evaluation and planning. The
first stage or analysis, an evaluation of the existing construction is needed; which could present many
difficulties. This requires a comprehensive audit, which may necessitate physical measurements and
laboratory analysis. Depending if a new function will be incorporated in the building, the evaluation step
might consider new conditions to be incorporated to the building. Finally, the planning stage must
consider all aspects to make the project realizable. It must include a cost analysis to determine if the
retrofit work is suitable and financially possible.

Figure 14. Planning process of retrofit
Adapted from (Giebeler et al. 2005, 22-31)
archives and building
methods
on-site measurements
visual inspection
laboratory tests
Analysis
usage-new usage
conversion potential
pattern of damage
is it worth retrofiting this building?
Evaluation
project development
(drawings and construction
documents)
demolitiion work
cost estimations

Planning
19

It is very common to see building retrofits based on replacing old mechanical systems with new, more
efficient systems that utilize renewable energy resources. However, this approach does not solve the cause
of the problem and the energy load in the building is not decreased. For example, installing solar panels or
new light bulbs in an inefficient building that is poorly insulated will still waste energy. However, there are
some examples of comprehensive retrofits that in practice are taking a holistic approach. The Empire State
Building’s retrofit project has pursued efficiency by taking the correct retrofit action in the correct order (Fig
14); that is, the load is reduced before upgrading any of the active systems (Empire State Building 2013).

Figure 15. A retrofit approach diagram
based on the main energy retrofits measures used in Empire State retrofit project (except
for energy generation)

The US Energy Information Administration (EIA) believes that efficiency is the first step to achieving a zero
carbon building. Only when a building has achieved maximum energy efficiency, is supplying it with green
power (through either utility green pricing products, or renewable energy certificates) one of the best
options for reducing indirect greenhouse gas emissions and consequently the overall carbon footprint
(“Energy Star Performance Ratings Methodology for Incorporating Source Energy Use” 2011).
Retrofit Trends
Refurbishment, retrofit or renovation practices have been practiced for a long time, since they relate to
existing buildings’ needs and failures. However, in terms of energy use, the retrofit movement can be
reduce
energy load
on site
energy
generation
efficient
new energy
systems
monitoring
and control
systems
20

thought of as one of the new concepts within the sustainable and green building design communities. Most
of the developed economies
1
have started to realize the need to focus on retrofitting existing building stock
to reduce greenhouse gas emissions and improve livable places.

During the last decade, regions and countries have considered the retrofit of the existing building stock.
Also, several global alliances of institutions have incorporated the retrofit of existing buildings as part of
their agendas. For example, the Organization for Economic Co-operation and Development (OECD) and the
International Energy Agency (IEA) joined a workshop in Tokyo in 2004 with sustainability in existing
buildings as the central topic (Thomas 2004). The International Energy Agency (IEA) has developed some
important actions for retrofitting residential and non-residential buildings. One is the exploration of high-
rise refurbishment in the European Union. Other action is a plan called Holistic Assessment Took-Kit on
Energy Efficient Retrofit Measures for Government Buildings (EnERGO or Annex 46) for governmental non-
residential buildings. Participating countries in EnERGO are: Canada, Denmark, Finland, France, Germany,
Italy, Russia and United States (IEA 2012).
European and UK retrofit trend signals
Europe has embraced existing buildings as an important piece in the construction activity, especially
focused on the residential sector. As part of a trend begun in the 1970s, an important part of the
investment for construction in the 1980s was dedicated to existing buildings. For example, 40% of Central
Europe’s construction activity was dedicated to conversions and upgrades in 2003 (Schittich 2003, 9).
Experts estimate that 20% of the total energy demanded in Europe could be reduced by focusing in actions
to reduce heating and cooling buildings (Jones 2010).

One of the important research projects carried out by the IEA focused on energy-efficient upgrades of
multi-story residences in the European Union. The research, funded by the European Alliance of Companies
for Energy Efficiency in Buildings (EuroACE), investigates the benefits that investment in energy efficiency in

1
For developed economies are understand countries with high level of economic growth that have achieved a developed infrastructure.
21

high-rise residential buildings. Residential buildings are included from the 25 member states of the
European Union, Bulgaria, Romania and Turkey. The study, recognized one of the first formal approaches
to the field for tall buildings, declares potential savings of up to 80% in energy used for heating (Waide
2006, v).

In the area of social housing, an innovative retrofit plan called the Social Housing Action to Reduce Energy
consumption (SHARE) was implemented. The project is part of a non-profit organization that clustered nine
countries and a registered educational charity and contemplates educational programs, forums, and loans
to building-owners for long-term to concrete retrofit projects. Besides allowing building owners reduce
costs on energy, it also incentives the use of renewable sources of energy through generation technologies
implemented on buildings. Other countries such as Germany and Austria have implemented residential
retrofits under the Passivhaus concept, which has been adopted as a brand and a renovation standard
(Jones 2010). Passivhaus – named “Passive house” in the US - bases building design and operation
prioritizing the use of passive heating and cooling of residential buildings.

Although there is no European retrofit certification system yet, the European Union plans to implement the
Energy Performance of Building Directive (EPBD) as one important certification method. The goal of this
program is to reduce at least 75-80% of energy consumption of buildings compared with average building
consumption. Launched in 2002 for commercial and residential buildings, this program was supposed to be
implemented in 2006, when all the countries participating were required to include energy-building
certification in their legislation. However, this date was pushed back to January 2009 “due to a lack of
qualified independent experts” (EurActiv 2012). Some of the implementations included in the plan are
efficiency measures and energy performance certificates- visible in the building- as part of the
documentation at the moment of the building sale. On the other hand, the U.K. has implemented
evaluation schemes for Domestic Refurbishments under its BREEAM (BRE Environmental Assessment
Method) by Building Research Establishment (BRE)(BREEAM 2012).
22

Asia-Pacific retrofit trend signals
Asian countries have also experienced significant growth in economy and population and consequently in
construction sector. As a result of economic growth, China’s energy consumption has been rapidly growing,
creating a major challenge for the building sector. It was estimated that the 470 billion square feet of
existing buildings are responsible for 27.46% of the total energy consumption in 2003 (Ma and Zhao 2008).
The government has started to realize the need for urgent action. The government has to pay
unprecedented attention to energy efficiency and emissions reductions, with the goal to reduce energy
intensity by 20% (Zhao, Zhu, and Wu 2009).

Various signs shown the retrofit attitude has started in China. One of the first steps was China’s Existing
Building Retrofit Conference, celebrated in Beijing in June 2009, where the Chinese government
acknowledged the real need to implement solutions for their building stock. Other of the important plans
set to retrofit 150 million square meters of existing building in cold climatic regions, by the end of 2010 (Mo
2010). Several projects have been proposed in China utilizing combined heat and power (CHP) and district
heating and cooling (DHC) approaches (Asia Pacific Patnership 2008). It includes cooperation with the USA
for training workshops, pilot programs, surveys, and relevant data collection. It also includes a funding
agreement between India and Australia on building tune-ups. As a part of the “eleventh five year”
program-the economic initiative of the Chinese government-the goal is to retrofit 0.15 billion m
2
of existing
residential buildings in northern areas of China. Energy consumption in that zone has been estimated to be
100%-200% times more than developed countries in the same latitude (Zhao, Zhu, and Wu 2009). Finally,
China as one of the big economies has experimented an exponential building growth, which has ended with
a realization that corresponding retrofit plans are not need only today, but in a close future.

In 2007, Korea presented its Seoul’s Eco-Friendly Declaration, for addressing energy reduction as one of the
main goals. Within this plan, the mayor of Seoul established the eco-friendly city plan in partnership with
the Clinton Climate Initiative and USGBC in 2009. Among the action, they established the Building Retrofit
Program, with the goal of reworking 87 buildings (45 public and 42 private) buildings in the country (Global
Energy Network Institute 2012).

23

Retrofit Trends in the United States
As in other developed countries, the United States building industry has started to realize the importance of
putting attention on energy retrofits. Important and growing signs have been proposed or implemented
through some of the bigger companies and institutions in the United States. Some private companies have
implemented new efficiency operations in their facilities; more than 900 mayors signed the Climate Change
Initiative; more than 630 colleges integrating the American College and University Presidents Climate
Commitment; President Obama is launching a special budget for energy-efficiency interventions in public
buildings; or there is the incremental growth of LEED as a certification (Yudelson 2009, xi-xvii).

Authors Jerry Yudelson in his book Greening Existing Buildings has indicates that general goals in the U.S. to
apply sustainable practices in construction are recent, and those actions directed to green and sustainable
buildings retrofits have evolved surprisingly in the last few decades (Yudelson 2009, 2-4). Even though
there were signs of energy-conscious behavior in the US from the 1970s, they were overshadowed by the
construction of new buildings, new vehicles, and a considerable increase in the GDP (Architecture 2030
2013a). Some authors recognized that it was not until the 1990s that one of first market transformations
towards energy-efficient buildings came again with the Energy Star program. Although this system was
widely accepted by the commercial building sector, it was not fully accepted by researchers, because they
argue that Energy Star evaluates “relative performance” and does not address the real contribution of a
building in terms of “absolute energy use” (Yudelson 2009, 4). Energy Star establishes efficiency as a
standard based on the 25% most efficient buildings in comparison with similar ones. The standard
measures energy consumption for a period of at least one year.

EPA Energy Performance Rating (1-100) 50
Site energy Use Intensity (kBtu/sf/yr) 119 kBtu/sf/yr
Source Energy Use Intensity (kBtu/sf/yr) 385 kBtu/sf/yr
Total Annual Site Energy Use (kBtu/sf/yr) 5,965,570 kBtu/sf/yr
Total Annual Source Energy Use (kBtu/sf/yr) 19,259,328 kBtu/sf/yr
Total Annual Energy Costs $112,564
CO 2 -eq (metric tons/yr) 1,404 metric tons/yr
Figure 16. Energy and CO
2.
average values for US commercial buildings
(EPA 2012)
24

More than a decade after Energy Star debuted as a means of measuring energy use in existing buildings, a
new program, Leadership in Energy and Environmental Design for Existing Buildings, Operation and
Maintenance (LEED-EBOM), has come into use. The program was launched in 2007 as one of the categories
of the LEED rating program, and has grown quickly, especially due the possibilities it presents for improving
market position and green branding in the private commercial sector (Yudelson 2009, 5)

LEED 2009 for Existing Buildings: Operations& Maintenance. SCALE
100 base points; 6 possible Innovation in Operations and 4 Regional Priority points.
Certified 40-49 points
Silver 50-59 points
Gold 60-79 points
Platinum 80 points and above
Figure 17. LEED-EBOM Scale.

The US Department of Energy (DOE) contains the Building Technologies Program, which is a special
approach to existing buildings retrofits. Recognizing the high potential for energy savings in buildings, they
incentivize research and development in new technologies for improving energy performance. The new
technologies are understood as advanced technologies in every aspect of building systems and components
for both new and existing buildings. A special part of this program is dedicated to building-envelope
research and development. It focuses on two primary areas: walls, roofs, and foundations (as envelope
materials and envelope systems R&D), as well as windows and doors(U.S. Department of Energy 2010).

One of the extreme approaches within the act was the Zero Net Energy Initiative for Commercial Buildings
under the umbrella of the Energy Independence and Security Act (EISA). Launched in 2007 by the Office of
Commercial High Performance Green Buildings and the Office of Federal High Performance Green Buildings,
it pursues high performance in new and existing commercial buildings with strong goals for energy
reduction. The initiative created by Zero Energy Commercial Buildings Consortium-a public/private group
working with the DOE- develops and delivers technology, policies, and practices to fall dramatically the
energy used in existing commercial buildings and achieve a market transition to zero net energy buildings
by 2050. It focuses on making commercial buildings (all buildings with the exception of low-residential)
“high-performance, net-zero energy, cost-effective, and compatible with a highly reliable, low-carbon
electricity grid”(Commercial Buildings Initiative 2010).
25

New commercial buildings 2030 All US new commercial buildings
Net zero energy use 2040 50% US commercial building stock
Net zero energy use 2050 All US commercial building stock
Figure 18. Goals of Net Zero Energy Initiative for Commercial Buildings

In 2002, Architecture 2030 – one of the most influential independent organizations addressing solutions to
the global energy crisis from the buildings perspective- was founded under the leadership of architect and
researcher Ed Mazria. They proposed a drastic plan to eliminate fossil-fuel-based energy use in all the U.S.
buildings by 2030. In terms of existing buildings and retrofits, they firmly declared that there is no way to
achieve the 2030 Challenge without retrofitting the existing old and inefficient buildings. With the mission
to “rapidly transform the U.S. and global Building Sector from the major contributor of greenhouse gas
emissions to a central part of the solution to the climate change, energy consumption, and economic crises”
(Architecture 2030 2013b).

Figure 19. The 2030 Challenge.

Another important step was taken by the U.S. Environmental Protection Agency, which decided that all new
federal buildings and major renovations would have to meet the energy performance standards of the
Architecture 2030 Challenge beginning in 2010. Six states adopted the commitment-California, Minnesota,
26

New Mexico, Oregon, and Washington-and The National Association of Governors has supported all the
actions for new and renovated existing buildings (Burnhamm 2009). Besides this official announcement,
several independent groups of citizens have started to take action as well. The Seattle 2030 District- an
interdisciplinary public-private collaborative effort- joins professionals, and property owners to commit to
meeting 2030 Challenge. The goal for existing buildings is to reduce a minimum of 10% below the national
average by 2015 to achieve 50% reduction by 2030 (Seattle 2030 district 2013)

The Energy Efficiency Building Retrofit Program (EEBRP) as part of the Clinton Climate Initiative (CCI) was
launched in 2007. Since then, more than 250 retrofit projects have been studied and implemented. The
mission of the CCI is to facilitate the completion of retrofit actions worldwide through cooperation or
coordination of private and public players and overcome the market barriers. Its mission is to “bring
together many of the world`s largest cities, energy service firms and financial institutions in a landmark
effort to reduce energy consumption in existing buildings”(Clinton Climate Foundation 2010). The
achievement of this program has helped to push different projects in more than 20 countries, marking an
important first step from a logistic point of view. The projects include municipal buildings, educational
buildings, public housing and commercial buildings (the Empire State Building project) representing over
500 million sq. ft.

University campuses have also embraced existing building retrofits along with the American College &
University Presidents’ Climate Commitment (ACUPCC). Established in 2009, it committed participating
campuses to reduce their energy consumption through large-scale energy saving retrofit interventions
(Clinton Climatic Initiative 2009).

Some US states and cities have been working on plans and regulations to address energy conservation on a
domestic scale. Examples like California have been recognized as one of the states in which incentives for
renewable sources are being provided to homeowners. Implementations such as roof-mounted
photovoltaic systems are accessible to homeowners through state subsidies. Similarly, some U.S. cities such
as Chicago, Los Angeles, Houston, New York, and Philadelphia have joined the environmental global
commitment C-40, an initiative for partnership cities as part of the Clinton Climate Initiative (C40 Cities
2012).
27

The Los Angeles Retrofit Ordinance was created in 2009 as part of the National Association of Governors
Initiative. Organized by SCOPE-a group oriented to create new jobs by cleaning up the environment- the
goal is to retrofit municipal buildings to a LEED-EBOM Silver level, becoming the first city to create such a
plan with the initial goal to retrofit 100 city-owned buildings every year. The creation of green jobs is part
of the goals of the associated Los Angeles Apollo Alliance (Energy.gov 2013).

In cities as such Chicago, Clinton’s initiative plan has positioned retrofitting as a priority with the goal to
refurbish 400,000 residential units and 9,200 commercial, industrial, and institutional buildings by 2020
(Clinton Climate Foundation). The city aims pushing typical and normal buildings to adopt modern
materials, systems, and technologies. In addition to the above-mentioned actions, Chicago counts with the
first LEED Platinum building rehabilitation in the U.S., The Chicago Center for Green Technology, as well as a
24.5-acre green roof transformation in existing parking lots and urban brown fields. In addition to that,
Chicago’s Mayor has developed the City Hall Green Roof as one of the pioneer municipal buildings to follow
this plan (Richardson 2010).

San Francisco has implemented its own City and County Green Ordinance, administrated by the San
Francisco Department of Environment. As part of its initiatives, the 24x7 Energy Challenge was created, a
contest through which commercial buildings are incentivized to track and improve their efficiency
(sfenvironment.org 2010).

New York implemented the City Greater Building Plan, as part of the New York’s long-term plan to reduce
energy consumption and greenhouse gas emissions of municipal buildings and operations in 2009, with the
goal to increase the energy efficiency of dozens of city buildings. One of the sections includes a legal body
(Article 308) named Energy Audits and retro-commissioning of base building systems, which applies to city-
owned buildings. It requires existing buildings over 50,000 square feet to undergo an energy audit and
undertake retro-commissioning once every ten years. To lead by example, City buildings will also perform
any building retrofits (capital improvements) that pay for themselves within 7 years (NYC Government
2012). With this plan, the states declared itself being “the first American City to Begin a Comprehensive
and Mandatory Effort to Reduce Emissions from Large Existing Building” (NYC Government 2009).
28

In April 2010, it was announced the selection of 25 communities that would receive up to $452 million as
part of the Recovery Act funding to “ramp-up” energy efficiency building retrofits. This is a pilot program to
provide an incentive to communities, governments, the private sector, and non-profit organizations for
retrofits of neighborhoods and towns. With another benefit being job creation, retrofits also enhance the
local and national economy (U.S. Department of Energy 2010).

Figure 20. the Retrofit Ramp-up initiative in the US.
(U.S. Department of Energy 2010)
0
5
10
15
20
25
30
35
40
45
Austin, Texas
Boulder…
Camden, New…
Chicago…
Greater…
Greensboro,…
Indianapolis,…
Kansas City,…
Los Angeles…
Lowell,…
State of Maine
State of…
State of…
State of…
Omaha,…
State of New…
New York…
Philadelphia,…
Phoenix, Arizona
Portland,…
San Antonio,…
Seattle,…
Southeast…
Toledo-Lucas…
Wisconsin…
ramp-up energy efficiency retrofits
US million
29

In summary, during the last decades, several institutions and organizations have launched programs looking
to retrofit actions as a goal in the US. The first important initiatives were the incorporation of the Energy
Star rating and the U.S Green Building Council in the early 1990s. More recently, some of the programs
have been more specific with regards to existing buildings. Some of the most important programs are: LEED
for Existing Buildings and Building Operations (LEED-EBOM in 2007), Architecture 2030 (2002), the Energy
Efficiency Building Retrofit Program (EEBRP) by the Clinton Climate Initiative (2007), the Zero Net Energy
Initiative for commercial buildings (2007), the Los Angeles Retrofit Ordinance for City buildings (2009), and
the American College and University President’s Climate Commitment for academic buildings (2009). They
are only some of the examples of a growing number of initiatives and implementations that are growing in
implementation in the US.

Figure 21. Main events related to building retrofit development.
30

Building energy retrofit opportunities and challenges
As mentioned previously, retrofit measures will be defined by their feasibility: when the benefits are more
than the constraints. However, it will depend on particular conditions. Even though the first approach of
energy retrofits is to reduce energy waste, another major benefit is human productivity and health
improvements. In the future, these tremendous benefits could help justify comprehensive green retrofits
with long-term paybacks, which are currently deemed cost prohibitive. Greater energy savings could be
possible through innovative design, comprehensive retrofit conception, and also changes in behavior.

Opportunities in retrofitting existing buildings
Because the vast majority of buildings that will be in use in 2050 are ones that are already in use, it is the
first and most important opportunity, therefore, where all efforts should be focused. Architecture 2030
has qualified this moment for the building sector as “a historic opportunity”, whether upgrading its use or
converting it for a new use, retrofitting an existing building would reduce the need for new construction,
which consumes extra land, energy, materials, and financial resources (Architecture 2030 2013a). An
important part of that energy consumption is represented by the embodied energy contained in the
materials. Embodied energy is “the energy used for raw material extraction, transportation, manufacturing,
assembly, installation, and disposal during the life of a product, including the potential energy stored within
the product” (California Building Standards Commission 2009). Retrofitting an existing building allows the
energy contained in its materials to be preserved, those which might otherwise might be sent to landfills.
Even in an extensive façade retrofit, the embodied energy contained in a building’s structure, typically
concrete or steel, is saved.
31

Figure 22. Embodied CO
2
contained in materials.
Steel and concrete, the materials with the most embodied energy are the
materials which a facade retrofit maintains, since the retrofits do not
reconfigure the structure of the buildings (Baker 2009, 3)

There were almost 5 million existing commercial buildings in the US in 2000 (US Department of Energy
2013a). The forecast is that new construction and renovations will have the same amount of the
construction sector for 2035, which mean an estimated 75% of the building stock will be renovated by that
year. This is a tremendous opportunity to reverse the pattern of energy consumption facing reduction
targets (Architecture 2030 2013a).
32

Figure 23. Estimated building stock by 2035
(Architecture 2030 2013a).

According to the Commercial Building Energy Consumption Survey, provided by the U.S. Department of
Energy, approximately 70% of the total commercial buildings in the US were built during the second half of
the 20
th
century (US Department of Energy 2013a). In this time period it is possible to find the better
candidates: buildings built with as little money as possible, with no insulation, with lack of high quality
construction, or with degraded material. All those buildings possess minimally functional skins to protect
indoor spaces.
33

Figure 24. Total number of building by vintage in the US
Based on Commercial Buildings Energy Consumption Survey (CBECS), Table
A1. Summary Table for All Buildings (Including Malls) 2003. (EIA 2008)

Of the total of commercial buildings in the US, office buildings represent 17% of the total number and 19%
of the total primary energy consumed by the commercial sector (US Department of Energy 2013b) . In
times of economic crisis, renovation in commercial spaces can be more affordable than new construction.
In the current crisis suffered by the US, some real estate companies have started to roll out an energy-
monitoring network for their portfolio, demonstrating significant wasted energy. They have started also to
embrace sustainability techniques, which has attracted more property owners to follow this trend, because
there appears to be little question today that having a green building can be “particularly advantageous
when there is tight competition for space.” (Buonicore 2010)
0
200
400
600
800
1000
Number of U.S. Commercial Buildings
Number of Buildings (thousand)
34

Figure 25. Commercial sector characteristics
Office category shown as the main group in commercial stock (US Department of Energy 2013c).

Certification processes have become especially attractive for building owners to show their participation in
sustainable actions. In this regard, a LEED rating medal is desirable from a business point of view. As of
August 2010, the LEED official site registered 5,035 buildings certified in the US under any of the categories
of LEED and 610 under LEED-EB O&M (U.S. Green Building Council 2012). But more importantly, this data
gives us the idea of the huge remaining market, just in the US, for energy retrofits.
Energy efficiency interventions and their global impact
Actions to increase building energy efficiency are among the most cost-effective of all climate solutions
(Living cities and Institute for Sustainable Communities 2009). The most common ways of executing partial
retrofits include lighting and air conditioner replacement. New codes have made it mandatory to replace
outdated electrical installations. Removing or converting the outdated mechanical systems is currently
easier with new, more efficient CFC-free versions. However, through facade retrofits we can reduce the
overall energy load, and consequently the need for electricity generated from coal-fired plants. To achieve
zero net energy, it is necessary to do both.
35

Economical
Buildings that use energy inefficiently demand big amounts of money for maintenance, and when energy
prices rise, a great opportunity is to save money through “effective action to increase building efficiency
(Living Cities and Institute for Sustainable Communities 2009). Energy efficiency means big savings in the
form of a lower energy bill for the owner or tenant. Retro-commissioning that can save some 10% to 20%
in energy has an average payback of slightly over one year (Pike Research 2010). Of particular importance
is for building owners to obtain an attractive return on the investment, and energy retrofits and green
certifications are showing high rates of return on investment for owners that are carrying out such retrofits
(Yudelson 2009, 22). Property valuation is one of the first achievements, which depends on high rates of
occupancy. This is one of the reasons that building owners have started to think critically when they decide
to go further than minor repairs in a devaluated asset.

Figure 26. Energy savings and payback
(Pike Research 2010)
Productivity
The largest and most evident economical return is in workforce improvement. A study shows the result of a
survey performed on organizations that implemented LEED-certified green retrofits. They obtained that
87% of these organizations had improvement in workforce and productivity; 75% had improvement in
employee health; and 73% reported that they had achieved cost reductions as a result of green investments
(Deloitte Development LLC and Charles Lockwood 2008).

36

Referred to as “soft” benefits by some authors, they include “improvements in health, comfort, and
productivity of building occupants; enhanced marketing and public relations; risk mitigation, improved
recruitment and retention, and greater employee morale”(Yudelson 2009, xv). Research in the area of
biophilia- the science studying human relation with nature- highlight that major economic benefit come
from improving indoor environment and performance in buildings. More research in this area is needed to
broaden the understanding among building owners about this extended sense of the business of retrofit.
Green branding
The adoption of any environmental protocol means for building owners recognition among similar
buildings. This phenomenon is pushed by tenants’ demands, who want to locate their people in a green
space not only for improving productivity, but also as a marketing strategy. To be green promotes the
organization as one which takes part in a trend of sustainable energy use, conservation and operation, and
high quality indoor space for workers. For some authors, tenants’ demands for better spaces have been
one of the drivers of Energy Star’s and LEED’s explosive growth, so they represent opportunities for building
owners. These rating systems provide third-party certification that supports the building’s achievements
and makes businesses competitive. In this aspect, some other publications have analyzed and compared
properties that have embraced these two rating systems and how these properties cut the energy use and
enhanced their finances (Aston 2008) .
New Green Jobs
The new opportunity to create jobs related to green interventions has been studied for several institutions
and they predict that job in energy efficiency industries will more than quadruple before 2030 (Living cities
and Institute for Sustainable Communities 2009). Initiatives such as the Retrofit Ordinance launched by Los
Angeles in 2009 was conceived as a result of projects to overcome unemployment (Energy.gov 2013).

37

Challenges and constraints
Evidence to support energy retrofits are neither abundant nor cheap. To be feasible, a retrofit study should
demonstrate that the required investment will return in an expected period of time. It has become
especially difficult in tough economic times, such as the one being experienced since 2008. Also, it will
depend of particular conditions of the building and its diagnosis. In addition, if the retrofit considers only
energy, the payback seems to be insufficient for a return of the investment, mainly due to energy prices are
still not high enough to trigger a massive concern by building-owners.
Preconditions
Challenges for achieving important energy savings in retrofitting existing buildings can be bigger than in
new buildings, since there are defined preconditions. For example, existing morphology, materiality, a
defined orientation in the place, and with operational conditions already defined by the building size and
building function.
Financial benefits
Financial benefit is one of the driving factors in the decision of taking or not a retrofit. When few incentives
and subsidies exist, significant barriers exist in financing and market fragmentation in most of the cases for
privately-owned buildings. Although energy costs represent a third of all operating costs for commercial
buildings, the concern is relative to how much of these costs affects either owner or tenant budget. Many
building owners that have triple net tenants do not see further benefits of undertaking that risk (Yudelson
2009, 28-29)

38

CHAPTER 3: RESEARCH SCOPE, OBJECTIVES, METHODS AND PROCEDURES
This thesis focuses on post-World War II commercial buildings in the United States and how interventions in
the building façade could result in reductions in energy use. A mixed methodology has been established as
a suitable process to examine the required background information and technical data analysis based on
energy simulations.

39

Scope
The focus of this study focuses on what energy reductions are possible to achieve through interventions on
the building façade. The analysis centered on post-war commercial buildings. Specifically, retrofitting
privately owned office buildings is a segment that is underdeveloped at the present, but it has started to
grow faster. Some studies have forecasted this market will experience strong growth through 2014 and
beyond (Pike Research 2010, 1). Also, office buildings and especially those destined to leasing experience
an increasing interest for green branding as part of their business strategy.

Figure 27. Diagram with the main scope of the thesis
BUILDING
RETROFIT
RETROFIT
STRUCTURE
ENERGY
LOCATION
ORIENTATION
SITE RELATION
JUXTAPOSITION
FORM
SIZE
SHAPE
STRUCTURE
(ENVELOPE)
METABOLISM
ENERGY
CONVERSION
CONTROL
AESTHETICS
FIRE
RESISTANCE
BUILDING
RESIDENTIAL
NON
RESIDENTIAL
AGE
PRE 1950s
POST 1950s
40

Objective
The objective of this study is to find to what extent facade retrofit represents a cost-effective alternative for
improving the energy performance of a building. Taking a typical office building, it is possible to approach
improvements for this type of buildings based on Los Angeles climatic conditions. Part of this goal is to
explore the energy reductions of several changes in the facade system and materiality.
Methodology
This thesis has adopted a mixed methodology. A qualitative approach was used for the background
research and the particular building case study. Literature about energy retrofits is still scarce, even though
facade retrofit has several examples in practice. In this context, authors recommend a qualitative approach
when there is little research about a topic that needs to be understood as a first step (Creswell 2008, 18).
Due to the fact that a qualitative study is exploratory by nature, it is useful to understand the more relevant
aspects or variables involved in facade retrofit actions. By taking this exploratory approach, literature
review, and an inventory of cases, a general background was developed. Lastly, based on the exploration of
real cases of building retrofits, a classification has been introduced to define a retrofit typology with five
categories in facades.

Figure 28. Methodology of the thesis

Façade Retrofit
inventory
Typology
Single skin
Sunshades
Over-cladding Matrix
Re-cladding
Double skin
CASE STUDY
SIMULATION IN ENERGY
SOFTWARES
Literature review
41

The mix of methods considers a cross analysis of both qualitative and quantitative approaches, which in this
thesis is represented by literature review, a survey, interviews, and computer modeling. The survey of
existing cases of retrofitted buildings is part of the qualitative approach. It provides an idea of the “state of
the art” of facade retrofit. After that, the particular case study will be the object of simulations and
quantitative analysis where those concepts derived from the background bases will be applied. Once the
different scenarios are simulated, there it will be two comparative analyses. The first is the comparison of
the energy reduction of single retrofits of the different categories. A second analysis will combine the best
retrofit by category.

Software
The U.S. Department of Energy contains more than 300 building software tools for energy efficiency related
issues (U.S. Department of Energy 2010). From the recognized packages, EQuest and Design Builder have
been chosen because they perform whole analysis in buildings. Professionals and academics in the field of
energy evaluation commonly use both simulation packages. EQuest is referred to as “one of the most
widely used building energy simulation programs in the United States” with full program downloads
averaging close to 10,000 annually (US Dep. of Energy 2011). Designed in base to the DOE-2.2 simulation
engine, it provides a whole building’s performance analysis. The concept of whole building conceives the
building as a “system of systems;” a group of interrelated systems as a part of an integrative process of
envelope, lighting, hot water, HVAC equipment, windows, and so on. Under parametric analysis, called
Energy Efficient Measures or Parametric Analysis (EEM Analysis) the software provides the platform to
evaluate design options. Design Builder uses Energy Plus as engine, which is a sophisticated and broadly
used platform for trustable energy simulation analysis.
Procedure in the case study
For achieving the analysis in the case study, the following steps have been included:
1. Collect the real data for developing an energy simulation of the building.
42

In this stage, understandings of the different factors that determine the energy were compiled. These
factors range from description of the envelope in its materiality and configuration to space occupancy,
operation schedules, and HVAC systems. After gathering the existing conditions, the computational model
is constructed.
2. User Profile.
The energy consumed in the building is determined by the use given for its function. The factors in this case
relate to office activities, schedules of work, and operational habits. Understanding if the building has a
seasonal operational schedule is crucial. It is also important to know the level of occupancy of the different
offices or floors throughout the building.
3. Envelope thermal profile
At the core of this thesis is facade performance. It is a fundamental part of this study to establish the
relationship between the properties of the envelope and the energy which is wasted due to its
performance. The R-value refers to the capacity of the facade system of thermal transfer through these
components.
4. Internal Heat gain.
Internal heat is produced by different activities in the buildings wherever there are lighting fixtures,
computers, and other equipment. This study considers a general diagram with the building devices that are
part of the energy consumed as part of the energy consumption profile.
5. HVAC System and Control Mechanism in the building
It is not possible to know from energy bills alone how much energy is consumed by the end uses. However,
based on the fact that the building does not consider natural ventilation (i.e. operable windows) the task of
maintaining indoor comfort levels relies totally on HVAC systems.
6. Building Energy Consumption Profile
This stage utilizes the collected electricity and gas bills provided by the owner for a given period to generate
the current energy consumption profile. After knowing this information, a comparison with standards or
benchmarks could be done.
7. Building Energy Simulation Models.
43

Two energy simulation packages were employed to simulate the current energy consumption of the
buildings: eQuest and Design Builder. Careful checking of the inputs was a fundamental step in the
calibration of the model with the real data, which results in a baseline, which later is the object of
application to the different retrofit schemes.
8. Retrofit schemes
Based on the typology developed, five different schemes were chosen and simulated for comparison
against the baseline. Energy reductions could be visualized from those different schemes.

Table 1. Retrofit schemes for case study

type description Intervention in the facade
SINGLE SKIN The original facade is maintained, but some
components or all of them are upgraded or
replaced.
- Window replacement
- Different low-e films
incorporation to glass
- Seals and infiltration controls.
SUNSHADES The facade is maintained, but external
elements are incorporated with the goal to
control solar heat gain in the building.
- Overhangs
- Fins
- combination
OVER-CLADDING Layers are added to the existing facade
configuration
- Internal and external
insulation
- Addition of new cladding
materials to the façade.
RE-CLADDING The original facade is turned down and a
totally new skin is built.
- Full glazed skin
- Glazing replacing opaque
spandrels
DOUBLE SKIN An additional glazed skin is added to the
original façade. It can be closed or allowed
to receive ventilation.
- Multistory double skin
- Full height Double skin
44

CHAPTER 4: TYPOLOGIES OF FACADE RETROFIT
A growing stock of retrofit interventions has started to add up around the world. All of them represent
unique characteristics and respond to specific budgets, context, and function. The goal of this chapter is to
classify those interventions into five categories of façade retrofit, in order to better understand how those
cases deal with energy improvements. As most of the cases present several system updates in conjunction
to facade retrofits, they have been also mentioned.

45

Existing buildings are varied. Focusing even just on the post-war period, it is possible to find several
material use tendencies, techniques, and stylistic trends. In the OECD/IEA Workshop developed in Japan in
2004 there was consensus that there was a need to determine different typologies of retrofits based on the
original building features for adopting later measures according to these types (Thomas 2004). For this
thesis, a typology is elaborated on the basis of retrofit intervention in the building facade based on the
types observed in the survey. Further study would be useful to examine typologies of existing buildings and
their most effective retrofits.

In this process, the first step was to collect cases on which the facade has been part of the retrofit project
and execution. They were listed and detailed in an Excel spreadsheet with the purpose of creating a
database for the posterior classification. This survey has no parameters, other than elucidating the basic
typologies of intervention used in those cases.

46

Figure 29. Section of the ddatabase of facade retrofit cases
(Excel screen shot).
47

After knowing the main kind of interventions performed in existing buildings from the inventory, five
categories have been defined:

Table 2. Typology of façade retrofit

type description Intervention in the facade
SINGLE SKIN The original facade is maintained, but some
components or all of them are upgraded or
replaced. The look of the building does not
change.
- Window replacement
- Low-e films incorporation to
windows’ glass
- Seals and infiltration controls.
SUNSHADES The facade is maintained, but external
elements are incorporated with the goal to
control solar heat gain in the building. Look
changes.
- Overhangs
- Fins
- Screens
OVER-CLADDING Layers are added to the existing facade
configuration. Look changes.
- Internal and external
insulation
- Addition of new cladding
materials to the façade.

RE-CLADDING The original facade is turned down and a
total new skin is built. Look changes
completely.
- Full glazed skin
- Glaze in opaque spandrels
DOUBLE SKIN An additional glazed skin is added to the
original façade. It can be closed or allowed
to receive ventilation. Look changes
completely.
- Box window facade
- Double skin

48

1. Single Skin
This category conserves the general fabric of the façade, but adds or replaces some of the parts improving
energy performance of the system. Some of the actions in this category are low-e film applied to glass,
insulation applied to some parts of the envelope, mullions or windows replacement, and air sealing
packages. Two examples of this approach include the Empire State Building and the Sears Tower.

Building Name Empire State
location New York
country USA
building type multitenant office building
Team/Owner/Players
Jones Lang LaSalle, Rocky Mountain Institute, the Clinton Climate Initiative and Johnson
Controls
year of original building 1931
number floors and area 2.1 million sq. ft. 102 stories
façade-envelope-roof
Remanufacture more than 6514 windows. Removing the building`s 6514 window`s
sashes and glass, cleaning the glass and adding a low emissivity (low-E) film and gas
mixture between the reused panes. Radiative barrier in walls.
HVAC / ventilation strategies replace more than 300 existing AHUs with new AVA and control systems for tenants
lighting daylighting strategies using a plug-load occupancy sensors
water retrofit chiller plant
cost US million 100 $500
expected savings 38% and U$4.4 million year
payback 3 year payback
occupied building yes
project area 2.1 million Sq.ft.
renovation project's end 12 del 2013
annual energy use 88 k Btu /sq. ft.
pick electric demand 9.5 MW (3.8 W/sq. ft. inc. HVAC)
annual CO2 emissions 25,000 metric tons (22 lbs./sq. ft.)
annual utility costs $11 million ($4/sq. ft.)
Figure 30. Empire State building retrofit information
(Empire State Building 2013)

49

Building Name Sears Tower
location Chicago
country USA
building type commercial
Team/Owner/Players SOM - Adrian Smith + Gordom Gill Architecture
year of original building 1973
number floors and area 4.5 million sq. ft. 110 stories
façade-envelope-roof replacement of all 16,000 single pane windows with more efficient, modern windows
HVAC / ventilation strategies mechanical systems upgrades
lighting Advanced lighting control systems,
water More water efficient water fixtures will also be installed.
green roof
Green roofs will be added to reduce storm water runoff and improve insulation, as well as
add some beautiful roof-top viewing areas to see the amazing city skyline
self-generation of energy
Energy will be generated on site with the use of renewable energy technologies like wind
turbines, photovoltaic and solar hot water heating
cost US million $350
expected savings reduction by 68.000.000 kWh per year 80%annual current consumption
project area 4.5 million sq. ft.
Figure 31. Willis tower retrofit information
(Meinhold 2009)
2. Sunshades
Many buildings present the same features in all their orientations. This is one of the big failures in
architectural design that relied on indoor mechanical conditioning. For those facades exposed to high heat
gain, a good retrofit technique is to incorporate elements of shade to protect the building from direct solar
heat gain. Some examples of intervention with protective elements include overhangs, louvers, fins, blinds,
or perforated screens to enhance the performance of those exposed facades. Examples like screens applied
to CIC Camden in UK or the Aidlin office in the US, or the sunshades of the German Air Traffic Control Office
in Germany are great examples as it is the proposal of a living screen for the GSA building in Portland are
described below.
50

Building Name CIC Camden
location London, UK
country UK
building type College building
Team/Owner/Players ARUP
type of construction Concrete frame
year of original building 1960s
number floors and area 4
façade-envelope-roof
A new three story high suspended glass natural ventilation screen on the building`s north
elevation, for buffing street noise while allowing natural ventilation. A timber brise-soleil
was installed to the south-facing courtyard facade, reducing solar gains and creating a
gathering area shielded from the sun.
HVAC / ventilation strategies
Holes cut through the existing post and beam structure created new, open ventilation
shafts in the deepest part of the existing floor plates. A new circulation strategy focused
on separating the building around a central courtyard rather than a single, doughnut-
shaped building.
Figure 32. CIC Camden building retrofit information
(ARUP 2009, 23)

Building Name German Air Traffic Control Office
location Langen, Germany
country GERMANY
building type office building
Team/Owner/Players ARUP
year of original building 1980s
number floors and area 6
façade-envelope-roof
installation of a highly efficient glazing system combined with an exterior sun protection
system for the new facade and an incorporated passive night cooling system
HVAC /vent. strategies passive night cooling system
failures
the office suffered from overheating due to a combination of a poor facade and heat
produced by the numerous computers and server rooms (the building is used as a
calculation and simulation center)
Figure 33. German air traffic control office
(ARUP 2009, 53).
51

Building Name Aidlin Darling Architects
location San Francisco
country USA
building type 3 story office
Team/Owner/Players Aidlin Darling Architects, Simon & Assoc., CB Engineers
façade-envelope-roof
New corrugated skin to replace the original, historically significant steel cladding. The
skin is perforated with small holes designed to allow light and air to pass through new
windows hidden behind it. This perforated barrier controls solar heat gain while
enabling cross-ventilation of the interior.
renovation project's end 2009
Figure 34. Aidlin Darling Architects building
(Zerofootprint 2010)

Special cases include green or vegetated skins. One of them is a green roof application to existing
buildings, of which there are several well-known cases. However, a new concept is in the vertical
envelope: green curtains built as trellises over the existing facade. They provide relief from solar
heat excess in a glass surface, and they also improve the overall look by creatively integrating the
built with the natural environment. Some of the benefits of having vegetated surfaces are
avoiding excess heat gain in those facades exposed to direct sun; enhancing conversion of CO2
into oxygen by plants; and reducing the temperature of the air through evaporation of water from
the plants. Green walls that apply some of the green roof technologies in a vertical format for
energy reasons are an up-and-coming feature (Pierce 2010). However, the constraints could be
bigger since different operational and maintenance considerations must be taken into account.

52

Building Name GSA (General Service Administration) project
location Portland, Oregon
country USA
building type governmental
Team/Owner/Players Original building: SOM Renovation: SERA Architects
type of construction 18-storey international style. Concrete and steel
year of original building 1975
number floors and area 370,000 sq. ft.
façade-envelope-roof
Green wall. 250-foot-tall trellises designed to shade the west side. The most extensive
vertical gardens besides complete building re-cladding.
HVAC / ventilation strategies HAAC replacement. A new radiant heating and cooling system.
lighting Electrical retrofit. An energy-efficient interior lighting.
water Reduction of water usage with low flow fixtures and recycled roof . ADA restrooms,
structural seismic renovation
green roof
landscape-storm water runoff a rainwater harvesting system
self-generation of energy PV panels
others implementations security systems, finished, lower level exit
cost $350 million
expected savings $280,000
occupied building yes
project area 500,000 sq. ft. of space
renovation project's end
This project was replaced by a trellis due to the additional cost of implementing an HVAC
system for the period of growing plants in the facade
Figure 35. GSA Building retrofit information
(World Interior Design Network 2010)

53

3. Over-cladding
Over cladding adds a new layer to the original building facade. Those new layers can take the form of
additional elements, such as balconies or additional layers of insulation. In most cases, those new
elements or layers change the image of the existing building. Balcony inclusions modify the morphology of
the facade, which improve thermal performance by creating buffers through extensions of the indoor space
to these intermediate spaces. Examples are found in the massive projects is the Mayor’s residential towers
renewal in Canada; the New York County Family Court in the US, or the Cooperative Insurance Society
tower in UK.

Building Name Mayor's Tower Renewal
location Toronto, Canada
country CANADA
building type residential
Team/Owner/Players
E.R.A.Architects + Faculty of Architecture, Landscape and Design at the University of
Toronto
type of construction concrete high rise
year of original building post war, primarily 1960s and 1970s
number floors and area Over 20
façade-envelope-roof over cladding of walls and balconies, new windows
HVAC / ventilation strategies replacement of HVAC systems
lighting lighting system retrofit
water replacement of plumbing fixtures with water conserving technology
landscape-storm water runoff urban agriculture
others implementations new insulated roofing
cost $4 to $5 million for a typical 20-storey tower apartment building
expected savings 50% energy consumption reduction
payback
payback period range between 10 and 12 years and yield impressive rates of return
between 13% -17%
occupied building yes
Figure 36. Mayor’s Towers retrofit information
(City of Toronto 1998)
54

Building Name New York County Family court
location New York
country USA
building type public
Team/Owner/Players Mitchell/Giurgola
year of original building 1969
number floors and area 500,000 sf
façade-envelope-roof
Failure of stone cladding. The installation of one-inch-thick insulated glass would in itself
significantly improve the thermal envelope. The exterior wall is a 14 inches concrete shear
wall. This condition highlighted the need to treat the façade as a thin veneer over an
otherwise massive object. The new cladding is a curtain wall. A unitized curtain wall
system is composed of repetitive, shop-manufactured units that can support stone, glass,
and metal panels equally. The units are one floor high by one bay wide and are
constructed of aluminum framing. Cladding materials hang on this rigid frame. The work
in the field becomes a simple and repetitive connection between steel tabs on the curtain
wall and steel clip angles on the concrete wall. Granite is the primary cladding material.
The window strip recessed from the plane of the wall establishes relief on the facade.
occupied building yes
project area 120,000 sq. ft.
Figure 37. New York County Family court
(Mitchell, Giurgola Architects 2005)

Some cases exist in which renewable technologies have been applied as a retrofit technique. In
these cases, part of the energy required is produced onsite, as is the case with the CIS Chief Office
in Manchester, where the decision to clad the building with PV panels reversed the failure of the
mosaic cladding and the energy generation to cover building activities.

55

Building Name CIS Chief Office, Co-operative Insurance Society
location Manchester, UK
country UK
building type office
Team/Owner/Players ARUP
type of construction 25-storey with glazed aluminum curtain walls and a service tower clad with mosaics.
year of original building 1962
number floors and area Over 20 floors
façade-envelope-roof the existing mosaic finish was conserved beneath the new photovoltaic panels
self-generation of energy 7000 photovoltaic panels
failures Mosaic failure on a listed building an innovative approach was required.
Figure 38. CIS Chief office in Manchester
(ARUP 2009, 8)

56

4. Recladding
When the enclosure system does not meet even the minimal standards, such skins, in general, do not merit
retrofit measures. In such cases, an entire facade replacement is needed, creating the opportunity to
significantly boost efficiency and renovate the image of the building.

Building Name 35 Newhall Street
location Birmingham, UK
country UK
building type office building
Team/Owner/Players ARUP
year of original building 1980s
number floors and area 5 stories
façade-envelope-roof
A replacement of the existing brickwork cladding with a curtain walling system. This new
exterior curtain-walling gave the building a more open feel, minimizing the negative impact
of the restricted existing structural grid and making open-plan office possible.
HVAC / ventilation strategies new mechanical ventilation (inexistent in the building) in raised access floors
water new centralized lift shafts and toilets
structural
A new fifth floor and rooftop plant room were added to take advantage of additional
structural capacity.
others implementations
Net leasable floor area was increased by approximately 34% by in-filling the existing,
ineffective light well and extending the existing floor plates outward.
cost 7M euros refurbishment
failures
The building had not aged well. Small exterior windows on the building exterior coupled
with an ineffective central light well gave the space an unappealing, low-quality feel. In
addition, the office space had no mechanical ventilation, and lettings suffered as a result.
As the building was only 20 years old and structurally in good condition, it was decided
that the building should be refurbished with as much of the building frame retained.
Figure 39. 35 Newhall Street building retrofit information
(ARUP 2009, 57)

57

Building Name Sparkasse Vorderpfalz
location Ludwigshafen
country Germany
building type bank
Team/Owner/Players
Egon Weiß (1974), Thiemo Ebbert, imagine-envelope (2009) Arch.; Rudolf P. Evers,
General Planner; Balck and Partner, Facility Engineering
façade-envelope-roof
the project to refurbish the building`s facade and services had to be carried out without
affecting the bank`s operations or damaging recent interior renovations. The original
ventilated cladding was removed and then a secondary glazing was added to the
tower.
structural Improvements of the load-bearing structures
expected savings 64%energy performance has been improved
occupied building Yes
renovation project's end July 2009
Figure 40. Sparkasse Vorderpfalz building information
(Zerofootprint 2010)

Building Name The Lighthouse International Headquarters
location New York
country USA
building type Office
Team/Owner/Players Mitchell / Giurgola Architects
year of original building 1964
number floors and area 14 84,500 sq. ft.
façade-envelope-roof
The precast concrete façade, with energy inefficient single pane windows, was replaced
with insulated glass ribbon windows to maximize daylighting in the offices and
classrooms. The failing windowless east façade party wall was removed and replaced
with a wall with punched openings to provide needed daylight into the middle zones of the
long narrow through-block floor plate
HVAC / ventilation strategies
The existing single source building-wide air conditioning system was replaced with fan
rooms on each floor
structural yes
occupied building no
project area 84,500 sq. ft.
renovation project's end 1994
Figure 41. The Lighthouse International Headquarters retrofit information
(Mitchell, Giurgola Architects 2005)
58

Building Name Cathay Bank
location Los Angeles
country USA
building type Bank
Team/Owner/Players Gensler
year of original building 1970s
number floors and area 7
façade-envelope-roof
Using the existing structure, the design team increased the visual prominence of the
building. They hung a high-performance glass curtain wall from the concrete structure.
High performance glass
water yes
others implementations
photovoltaic canopies that will shade the parking lot and generate 33% of the building's
electricity
Figure 42. Cathay Bank retrofit information
(Gensler 2013)

59

5. Double Skins
Double skins are additional glazed skins added to the facade using a gap between the layers. The gap can
range anywhere from 0.3 to 1.5 meters (Baker 2009, 63). The retrofit project can maintain the original
facade in cases where it is not cost-effective to invest in it. However, it is possible to integrate shading
devices to control solar heat gain, and also to incorporate techniques for natural ventilation.

Building Name 100 Park Avenue
location New York
country USA
building type office
Team/Owner/Players Original: Kahn & Jacobs. Construction: Tishman
type of construction curtain wall
year of original building 1950
number floors and area 36 / 955,000
façade-envelope-roof
New glass curtain wall façade. The building envelope consists of an all new highly energy
efficient façade with a sleek, reflective curtain wall design. The new façade will contribute
to energy efficiency by keeping conditioned air contained within the building and keeping
outside air from permeating the building envelope. over the existing facade
HVAC / ventilation strategies new cooling tower, steam chillers
lighting increment of electrical capacity
water low flow water fixtures for 50% of water consumption reduction
structural yes
landscape-storm water runoff green roof
self-generation of energy no
cost 70 million
expected savings 29% less energy
payback yes
renovation project's end 2007
Figure 43. 100 Park Avenue building retrofit project
(SL Green Realty Corp. 2013)
60

Some conclusions are drawn from 40 cases of the database are shown below. By taking a sample of 40
buildings, it is noticeable that more than 50% cases correspond to office buildings. A third of them fit under
the “single skin” category, and those simple skins are typically the interventions made in buildings built
before 1950.

Table 3. Number of cases by typology and year

Double skin Overcladding Recladding Single skin Sunshades total
Series1 5 6 11 14 4 40
0
10
20
30
40
50
Number of buildings
Retrofits by type
academi
c
guverna
mental
hospital office ofice
residenti
al
retail station office
Grand
Total
Series1 3 1 1 25 1 4 3 1 1 40
0
10
20
30
40
50
Number of buildings
Retrofits by use
Count of ID Column Labels
Row Labels 1871 1899 1906 1916 1929 1930 1931 1940 1950 1952 1958 1960 1962 1963 1964 1967 1969 1970 1972 1973 1974 1975 1980 1998 1960* n.d. (blank) Grand Total
Double skin 2 1 1 1 5
Overcladding 1 1 1 1 1 1 6
Recladding 1 1 1 1 1 1 1 2 2 11
Single skin 1 1 1 1 1 1 1 1 2 2 1 1 14
Sunshades 1 1 1 1 4
(blank)
Grand Total 1 1 1 1 1 2 1 1 4 1 1 4 1 1 1 1 2 2 1 1 2 1 4 1 2 1 40
61

CHAPTER 5: CASE STUDY
An important goal in studies like retrofitting existing buildings is to explore the potential applicability of the
results to similar cases. A large number of existing buildings have underperforming facades, and they are
targets for considering improvements in their façades. The building used as the case study for this
investigation is a typical office building, very common in the Los Angeles area and possible to find in any city
around the world. In this chapter the main features, operation and systems of the building will be
described emphasizing its energy consumption profile.

62

General description
The building is a twelve-story office tower located near the Pacific coast in the Los Angeles area. Built in
1972, the tower represents a facade with vertical bands of tinted glass engaged in painted steel columns.
The building has open views in every direction and free exposure to the sun and wind in all its facades, since
there are no other tall buildings surrounding it.

Figure 44. Different views of the case study building

Year of construction : 1972
Number of floors : 12
Building’s height : 176 ft.
Certification : In 2009 the building registered EnergyStar. No LEED level
Area : 199,199 sq. ft.
Floor Area : 15,000 SF (typical approx.)
Ceiling Heights : Slab to slab heights on office floors average: 11’7”
Standard floor to ceiling height is 8’1’’
Mullion Spacing : 4 feet
Interior Columns : Spacing generally every 30 feet
Façade : The longest facades are SW and NE with a tilt of 39°with regard to the North.

63

Figure 45. Building orientation and typical floor

Figure 46. Facade elevation.
Occupancy schedule profile
By contract with its tenants, the building is operative from Monday to Friday from 8:00am to 6:00pm and
Saturdays from 10:00 to 1:00pm. The operational hours (when the HVAC system starts and stops working)
are 2 hours early from Monday to Friday (6:00am), and one hour early on Saturdays (9:00am).

Multi-tenant offices occupy the building; however, a centralized management system controls all the
facilities. A medical office occupies one of the floors. The building’s Energy Star report indicates that the
64

medical office operates 70 hours a week and has a total of 62 workers. The report estimates that the
percentage of hours used for cooling is 100% and 50% for heating in the medical office. The rest of the
building has been described with the same 70 operational hours and with 469 workers. The estimated
percentage of hours for cooling is more than 50% and less than 50% for heating. There is an estimate of
562 PCs in the building. The Energy Star report also notes that two floors were vacant in 2009, when the
report was written.
Envelope profile
The envelope of the building is a very good example of curtain-walled office buildings commonly seen in the
Los Angeles area. It displays vertical glazed bands separated by concrete columns. With larger exposure to
SW and NE directions, all facades have clear exposure in all directions, without obstructions from
neighboring buildings. It features ¼” single glass in spandrel, and vision sections mounted in black
neoprene to a non-thermal broken aluminum frame. All opaque parts of the facade have 1” insulation, but
there is no information about the specific type of material.

65

Figure 47 Detail of original facade components.
Window proportion

Although the building appears to have a long vertical–glass area, the real openings average less than 30% of
the façade. The floor to ceiling height is 8 feet, and only 4 feet is dedicated to windows. Windows feature
single pane clear glass with a reflective film added during the 1990s. Window spandrels are made of
spandrelite, a popular and common material in the 1960s and 1970s. Introduced to the market by the
Pittsburgh Plate Glass Company, it was defined as “the first ceramic-coated glass”

with several options in
color and size (“Spandrel Glass - Preservapedia” 2010).

At some point in the past, windows in the building were covered with tinted film typically used for cars until
the current management added a reflective film inside the windows. The film- 3M RE20- is part of the
Traditional Series film series by 3M Company and is described as one of the Sun Control Window Films--one
of their high-performing neutral and reflective films. The film is recommended for single, clear window
glass.

As a stick curtain wall system, it comprises a frame of mullions and transoms with an infill of glass and
insulated panels. A schematic module has been diagramed in both facade lengths to estimate more
66

precisely the average window area. Figure 47 shows the proportion of windows in both facades: 29% in
the larger facades (SW and NE) and 23% in the shorter one (NW and SE). The building has approximately
132,000 square feet of façade.

Figure 48. Facades modularity and WWR.
Thermal Resistance (R) and Thermal Transmittance (U-value) of the Facade

One of the important steps in determining energy lost is to estimate heat transfer through the envelope.
Energy transfer in the facade occurs mainly by convection/radiation and air leakage through both sides of
the envelope. In the case of windows, energy transfer through windows happens basically by temperature
differences between warm and cold areas, air leakage, and solar radiation (Center for Windows and
Cladding Technology 2011).

67

As a first exploration, the thermal resistance of the facade is calculated using thermal resistance of the
different components in the system. After that, the heat gain and loss by conduction through the facade is
calculated. Factors related to energy transfer through windows are thermal resistance of the facade system
(the overall U-value), which exists in proportion to the thermal transference values for its different
components. Thermal resistance (R-value) is defined in Title 24 as “the measure of the thermal resistance
of insulation or any material or building component expressed in ft
2
-hr-°F/Btu” (California Building
Standards Commission 2009). The values from the layers that compose the package of façade, gives an
overall estimated U-value. For this calculation, the mullion, spandrel, and glass proportions of the facade
were considered.

mullion Air film (interior) Assuming surface emittance
of=0.20
1.35
Mullion face 1 0
Air gap of mullion. Both surfaces emittance of
0.15 (
2
)for steel and assuming
90°F (mean T°)and 10°F (T° diff)
2.08
Mullion face 2 0
Air film (exterior) Assuming surface emittance
of=0.20
1.35
R-value total= 4.78 x 10% of facade = 0.48

spandrel Air film (interior) e=0.2 0.74
5/8”Gypsum
board
0.62 x 0.45 0.27
1” insulation glass
fiber
1 x 3.7
(94
) 3.7
Air film (exterior) moving air summer 0.25
R-value= 4.96 x 60%= 2.98

Total R-value opaque area= 3.46 U-value= 0.28

2
Based on Table 4.2. Thermal Properties of Typical Building and Insulating Materials by Stein, Benjamin and Reynolds, John;
Mechanical and Electrical Equipment for Buildings, 9
th
Ed.; John Wiley & Sons, New York, 1999.
68

Total R-value windows= 0.85 (inverse of U=1.17 Single Ref-D Tinted glass in Aluminum without
thermal break from DOE.2 library on eQuest)
R value - 10% mullion= 0.48
R value - 60% opaque= 2.98
R value - 30% window= 0.25
Total R-value façade= 3.7 Overall U-value façade= 0.27

Heat transfer through the façade

After knowing the thermal resistance of the wall, the load through the façade is calculated. Both summer
and winter conditions are analyzed, despite cooling being the predominant load in the building. Two
calculations have been done: instantaneous heat transfer (for peak high and low temperatures) and
cumulative heat transfer. For the former, Marina Del Rey’s weather data was used for the year. The
cumulative heat transfer needs cooling degree days and heating degree days that have been obtained from
online tools. The Los Angeles’ Airport data was used in this calculation because it is not possible to
customize a weather file.

69

Figure 49. Maximum and minimum dry bulb temperature for Marina del Rey
(real 2009 weather data in Climate Consultant)

Table 4. Instantaneous heat transfer
ƪc = UA ΔT (instantaneous)
U-value
(Btu /h/sf)
facade
(sf) cooling/heating (°F)
Total load
(Btu/hour)
tons total
0.27 79,360 (89.24°-72°) 18.24 369,405
30.78 Heat gain
0.27 79,360 (43.34°-70°) 27.6 -571,249
47.6 Heat lost

Heat transfer through the facade is calculated for the two maximum and minimum registered temperatures
for 2009 in Marina Del Rey (fig.49). Heat gain through the facade in summer is 369 Kbtu/hour for an outside
temperature of 89.24°F. Only this heat gain could account for the 30 ton- cooling capacity in the building.
On the other hand, heat lost through the facade is 592 Kbtu/hour for an outside temperature of 43°F.
70

Table 5. Cumulative heat transfer
ƪc = UA 24DD (cumulative)
U-value
(Btu/h/sf)
facade
(sf) hrs CDD/HDD ° day* Total load Btu

0.27 79,360 24 212 109,021,593
Cooling degree day
0.27 79,360 24 2,879 1,480,533,811
Heating degree day
*using degree days based in Los Angeles’ Airport station.

In terms of an estimated value of the annual heat transfer in the façade, this calculation has used the
number of degree days based on Los Angeles’s weather data allowed by an online tool. The building has
a total annual heat loss of 109 million Btu. However, the heat gain through the facade in the building is
1,480 million Btu.

As parameter of comparison, a conventional building uses 1 ton of cooling for 400sf of floor space
(Energy design resources 2013), which in this building should results in 500 tons. The building has a
cooling capacity of 406 tons. It has also been estimated that an energy efficient commercial building uses
one ton of cooling per 800 to 1000 sf. of floor space, which in this building would mean instead 200 tons of
cooling capacity.

Description: Fahrenheit-based cooling degree days for a base temperature of 72°F
Source: www.degreedays.net (using temperature data from
www.wunderground.com)
Accuracy: No problems detected
Station: Airport: Los Angeles, CA, US (118.41W,33.94N)
Station ID: KLAX

Month starting CDD
1/1/2009 26
2/1/2009 8
3/1/2009 2
4/1/2009 22
5/1/2009 3
6/1/2009 0
7/1/2009 19
8/1/2009 41
71

9/1/2009 48
10/1/2009 27
11/1/2009 13
12/1/2009 3
212

Description: Fahrenheit-based heating degree days for a base temperature of
70F
Source: www.degreedays.net (using temperature data from
www.wunderground.com)
Accuracy: No problems detected
Station: Airport: Los Angeles, CA, US (118.41W,33.94N)
Station ID: KLAX

Month starting HDD
1/1/2009 336
2/1/2009 392
3/1/2009 379
4/1/2009 316
5/1/2009 189
6/1/2009 149
7/1/2009 85
8/1/2009 91
9/1/2009 65
10/1/2009 188
11/1/2009 266
12/1/2009 423
2879
Figure 50. Cooling and heating degree days
(Los Angeles’ Airport weather station considering a band of 70° and 72°F. (On-line tools used
was www.degreedays.net))

A better thermally resistant facade could proportionally reduce the amount of heat transfer. For example,
assuming an R- 10 façade, the instantaneous heat gain in this building should be 144,752 Btu/h for the
maximum temperature, and the heat lost should be 219,033 Btu/h. As well as the instantaneous heat
transfer, the cumulative heat moving through the facade could be reduced by 37%. However, façades with
an R-10 are challenging to achieve, even more in highly glazed curtain-walled buildings.

72

HVAC SYSTEM OF THE BUILDING
The cooling system is managed by a central plant located on the roof. The system is a direct-expansion (DX)
system, which consists of: three chillers (Carrier DX for a total of 406 tons of cooling), one cooling tower,
and two air handling units (AHU). Both cooling and heating distribution for the office spaces and common
areas is provided by the AHUs, which use modulating outdoor air dampers for economizer operation.
Variable air volume (VAV) and Direct Digital Control (DDC) boxes provide cooling for the interior core.
Quadrant controls provide heating and cooling for the building perimeter. DDC and pneumatic thermostats
maintain the space temperature.

Figure 51. Views of the building’s systems
(photo by A.Martinez)

73

Figure 52. Refrigeration, Hot water, and Fan Elements Diagram.
EVAPORATIVE CONDENSER
Baltimore Aircoil MODEL VLC-150
Cap.180 TON@67°F W.B. 104.5°F CT
1-15 HP FAN MTR- 1-1HP PUMP MTR. 480-3Ø-
60, OPER.WT CONDENSOR+BASE 12500 LB
COMPRESSORS R-22 Reciprocal
CARRIER MODEL #5H-80, CAP.
90TON @42.7°F S.T. 104.5°
COND.T
100 HP MTR. 480V-3Ø-60
OPER.WT.2950 LB.
DIRECT EXPANSION COILS
FRIGID DX-COILS, 6 ROW-8 F/in
2 ROW-4 ROW SPLIT 4-168’’x30
HI 76.8°DB 64.4°WB ENT. 53.0°DB
52.0°WB LVG. FACE AREA 140 FT2
83500 CFM
OPER.WT 5000 LB Approx.
HOT WATER BOILERS (2)
THERMO-PAK MODEL
#GW 1800
1800 MBH INPUT,1440
MBH OUTPUT,
OPER. WT 3200 LB. EACH
approx..
HW PUMP
WEINMAN MODEL #3TV-2 (in
line) 6.75’’ IMPELLER 1750RPM
144 GPM 33’-0’’ HEAD
2 HP 480 V- 3Ø-60, 5’’ SUCTION
3’’DISCH.
HEATING COILS
FRIGID HW COILS 2 ROW 8F/in
2-168’’x30’’ HI, 76.8°DB ENT.
103.5°DB LVG., FACE AREA 70 Ft2
73000 CFM, OPER WT 1000 LB
approx. MOUNT ON COOLING
COIL
SUPPLY FAN
PEERLESS AIRFOIL SIZE 660
DWDI-C.W.-T.H.D.- ARR#3
104000 CFM- 2’’ S.P. 465 RPM
60 HP. MTR 480 V-3Ø-60
EVAPORATIVE CONDENSER
Baltimore Aircoil MODEL VLC-175
Cap.222 TON@67°F W.B. 106°FCT
I-15 HP FAN MTR - 1-1HP PUMP MTR. 480-3Ø-
60, OPER.WT CONDENSOR+BASE 13500 LB
VAV boxes
Economizer
74

Building’s energy consumption profile
The compilation of energy consumption of both electricity and gas for the 2010-year period informs the
consumption profile of the building. The building uses primarily electricity in all its operation.

Electricity grid purchase 2,555,952 kWh/year 8,720,509 kBtu/year 43.74 kBtu /sf/yr
Gas 6,408 terms 640,800 kBtu/year 3.22 kBtu /sf/yr
Total 9,354,312 kBtu/year 46.95 kBtu /sf/yr

Figure 53. Real energy consumption for the building in 2009.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
ELECTRICITY (kBtu) 680,779 741,523 661,699 697,720 700,415 731,840 833,030 809,801 853,884 745,826 692,278 571,715
GAS (Kbtu) 121,800 91,100 91,100 26,000 13,000 10,800 16,800 17,000 13,200 13,700 34,300 192,000
0
100,000
200,000
300,000
400,000
500,000
600,000
700,000
800,000
900,000
kBtu
Building's Energy Consumption (2009)
75

Summary of energy consumption in the building
The goal of this part of the analysis is to explore the energy usage of this particular building based on its
energy bills. According to logic, if its energy bills are high, the building is probably wasting more energy
than that which is needed to maintain comfort levels. However, benchmark information is very broad for an
accurate evaluation. Available benchmarks such as the Commercial Building Energy Consumption Survey
(CBECS) and the California Energy Use Survey (CEUS) have been detailed in Table 6. In addition, since the
building obtained Energy Star rate, the Energy Star’s Statement of Energy Performance was obtained for
the building from 2009(“Statement of Energy Performance” 2011). According to that report, the building
had an Energy Intensity Use (EIU) of 48 kBtu/sf/yr (site energy) and 151kBtu/ft
2
/yr (source energy). Also,
the obtained data for 2010 resulted in EIU of 43.5kBtu/sf/yr for electricity and 3.2kBtu/sf/yr for gas
consumption. Consequently, the building’s EIU categorizes it as a relatively low energy consumer compared
to national averages EIU of 93KBtu/sf/yr (office buildings), or 97 KBtu/sf/yr (same vintage buildings) (U.S.
Energy Information Administration 2013). Compared to California averages, the building still perform
relatively low compared to average of 72.7 KBtu/sf/yr for large offices (California Energy Commission and
Itron Inc. 2006).
Table 6. Energy Intensity Use comparison to benchmarks
Item Electricity
kBtu/sf (kWh/sf)
Gas
kBtu/sf
Total
kBtu/sf
CBECS office buildings 59 (17.3 )
3
32.8
4
92.9
5

CBECS by year constructed 57 (16.7)
1
45.7
2
97
3

CBECS by region (West/Pacific) 48 (14)
1
30.1
2
71.6
3

CEUS (all offices) 54.8 (16.08)
6
17.90
4
72.7
1
CBECS Table E6A Electricity Consumption (kWh) Intensities by End Use for All Buildings, 2003;
2
CBECS Table E7A. Natural Gas
Consumption (Btu) and Energy Intensities by End Use for All Buildings, 2003;
3
CBECS Table E2A. Major Fuel Consumption (Btu)
Intensities by End Use for All Buildings, 2003;
4
CEUS Table 8-1: Overview of Energy Usage in the Statewide Service Area (U.S.
Energy Information Administration 2013)(California Energy Commission and Itron Inc. 2006, 150)

3
CBECS Table E6A Electricity Consumption (kWh) Intensities by End Use for All Buildings, 2003
4
CBECS Table E7A. Natural Gas Consumption (Btu) and Energy Intensities by End Use for All Buildings, 2003
5
CBECS Table E2A. Major Fuel Consumption (Btu) Intensities by End Use for All Buildings, 2003
6
CEUS Table 8-1: Overview of Energy Usage in the Statewide Service Area
76

Over time, there have been changes in the context that the building was designed in. Some changes relate
to external conditions and others to internal factors. One example is the temperature change known as the
urban heat island effect. Future studies could compare 1972 with 2009 weather data and look for a
relationship of the facade to those specific outdoor conditions. Only after that information is available
would it be possible to judge if variations in temperature over 40 years become an important factor in the
energy analysis. On the other hand, changes in office equipment over the last 40 years results in an
increase of internal heat gain. The building studied was designed in the 1970s where few or no computers
were probably present in the building. Therefore, the building was not equipped to handle the heat output
by the more than 500 pc and other modern equipment exiting today within it.

The building maintains the original mechanical system conception, which considers a “curtain heating” not
typically used in the Californian climate as it is in other colder zones in the U.S. Comfort levels are difficult
to achieve because it is controlled by large thermal zones. Specifically, occupants of the central zones
complain of excessive cold. Due to the perimeter heating system, that need is difficult to cover in the
central zones of the building. It could also be a question of system balance. In order to keep the perimeter
cool, it is necessary to run the system at too high a rate for the interior. Exterior zones have radiant gain
and internal loads. Interior zones have only internal loads.

77

CHAPTER 6: SIMULATION AND TESTING
In this chapter, the features and behavior of the building will be simulated using two energy software
packages: eQuest and Design Builder. An important part of this process is to calibrate these digital models,
which is the process by which to obtain a trustworthy model, with values closest to the actual building’s
consumption. As part of this calibration, actual data for the location of the building in both energy bills and
weather data are available. Weather data is a key piece in this process, which allows for closely matching
externalities in the analysis. After calibrating the model, different scenarios are studied; these scenarios
derive from the typology developed in Chapter 3. Therefore, different impacts in the energy consumption
are shown through the five main categories of intervention defined for the facade: single skin, sunshades,
over-cladding, re-cladding and double skin, as well as their sub-schemes.
78

eQuest simulation
DesignBuilder
simulation
Sunshades
Single Skin
Over-cladding
Re-cladding
Double Skin
Computer Energy
Simulation

Figure 54. Diagram of simulations taking retrofit typology.
eQuest simulation model
EQuest is one of the software programs widely used by energy analysts. It is defined as a “sophisticated,
yet easy to use, freeware building energy use analysis tool that provides professional-level results with an
affordable level of effort” (Hirsch & Associates 2010). Since the DOE-2, the engine used by eQuest, is a non-
graphic platform, eQuest offers the possibility to input the geometric model through a graphic manner,
initially using schematic or design development building creation wizards and then a more detailed analysis
platform. eQuest 3.64 has been used for the analysis.

79

Calibration
Calibrating the digital energy model is an important step, allowing a closer match to the base case for the
evaluation of the existing building performance. In an ideal scenario, testing and measurement of the
building systems are part of the diagnostic stage that feed the model and eliminate uncertainties. In the
best case, the calibrated model could end in ranges less than 10% of difference with respect to the actual
performance of the building.

Figure 55. Description of the calibration process in eQuest.

Some small measurements have been done for this study. However, besides assumptions, it is common to
merely survey the building and to refer to drawings as methods of documentation. Another potential
source of information is codes that were in force during the construction year. The California Building
Standards Code (Title 24) is the regulation frame for minimum building performance in California. In this
case, Title 24 was not existent at the time of the building construction.
Baseline
For modeling the basics, eQuest allows simple design approaches based on two Wizards: a Schematic
Wizard (especially for early stage of design), and a Design Development Wizard (appropriate for more
complicated designs). Since the case is an existing building, all of the information obtained in the survey
served as inputs. Both Wizards are suitable. The Schematic Wizard is useful if the building is defined as a
simple box. Due to the fact that the first floor of the building has a footprint slightly smaller than the rest of
weather
data
building's features
survey of
systems
(setpoints, HVAC
efficiencies)
measurement of
systems
assumptions
80

the building, the Design Development Wizard was chosen. Then, two different shells were created to
recognize the different geometrical profile of the first floor in regard to the body of the building. The
multiplier option contained in eQuest was used in the main body of the building, which decreases the time
needed to run the simulation.

Figure 56. eQuest basic geometry

Figure 57. Wall showed by type and construction in eQuest.

Footprint and Zone pattern definition: One of the default building footprint options is a rectangle and a
“Perimeter/Core” pattern for zone definition.

Zone Group Definitions: Due to the definition of two shells, we count with 2 groups of zones: EL1(1
st
floor)
and EL2 (2
nd
to 12
th
floor).

81

Figure 58. EQuest zone Groups for shell 1 and 2.

HVAC Systems Definition: The building has a DX Coil-based system with air distribution through the VAV
System within the building (150 VAVs approximately in the building). There are two air-handling units
located in the roof. The building possesses a perimeter heating system. This condition mandates the use
of the perimeter zone with an independent system. As a first attempt, every system was defined with a
unique function (core-only cooling and perimeter-only heating), but it resulted in very low results in the
consumption levels. As a consequence, systems designed for only cooling or only heating make it difficult
to achieve the consumption levels, especially for electricity consumption derived by cooling the building, as
the results deviate far from the real consumption. Finally, a more correct configuration is modeled: a
cooling system (excluding heating) has been attibuted to the core of the building, and the integration of
both cooling and heating has been attributed to the perimeter. This configuration creates a more suitable
situation, since the perimeter heating system is restricted, allowing the cooling to be present in both zones,
which is close to reality.

82

Figure 59. HVAC Systems Definition perimeter zones

Exterior Lighting Load: No real data was obtained for exterior lighting, whose load has been estimated as
0.007 W/sf for modeling purposes.
83

Weather data
To refine the calibration of the model, real weather data has been gathered. For simulation purposes, there
are several types of weather files, most in statistical patterns and not specifically corresponding to a
particular year. For the United States, some of the weather data available are: CZ2 for the 16 Californian
Climate Zones by California Energy Commission; Typical Meteorological Year (TMY) hourly data for 238
locations in the U.S. from US NOAAs NCDC TMY datasets (with several versions TMY, TMY2 and TMY3); TRY
(Test Reference Year, which is good if the year matches) for 60 locations; WYEC (Weather Year for Energy
Calculations) (DOE2 1998).

One of the TMY based weather-data are EnergyPlus (.epw) file. EPW Information is a comma-separated
value (CSV), which is a common format file used to store tabular data. Using numbers and text, .csv format
contains lines (represents rows of a table) and commas (to separate the fields in the tables row) to store the
data in text, which could be read in a text editor as Word or Notepad. The data contained in TMY is hourly
weather data from meteorological elements and solar radiation taken from a period that spanned over a
year. TMY 2 is the second version and stores weather data between 1961 and 1990 for 237 locations in the
U.S.

By default, eQuest takes its DOE-2 BIN files linking to the DOE-2 website, which frames the analysis in more
generic weather conditions than the specifics for the year of analysis. In terms of weather, the goal of the
thesis is to fit the results of the simulations according to actual weather data for the year 2009. A
fundamental part of the effort has been to obtain weather data for the weather station specific to the
location of the building (there was a weather station close to the site in Marina Del Rey). With this
information, the margin of error is minimized in the calibration, because the simulation works in a real year
instead of a statistical year. Real EPW data was available for this study for the year 2009
7
. Using the
application eQ WthProc, it was possible to convert this .epw file into eQuest and DOE-2 (.bin) files.

7
Source: Weather Analytics facilitated the weather data in epw format for this study.
84

However, this process was not an easy task. Converting the .epw file gives an error (Fig.42), which
prompted several reviews to the format of the file. The first step in this process was to open the .epw file in
a text-based Reader software (Notepad) to be able to see the data.

Figure 60. Error obtained in EPW to DOE format conversion process.

Figure 61. Comparison between an .epw files
(format to be read for the eQ WthProc and one opened as .csv)

As part of the exploration in this failure, a correct .epw file for another location was taken as a point of
comparison. Clearly, the .epw for Marina Del Rey shows a different format in a text-reader. The data was
transferred to an Excel file and saved as a .csv format. Then it was saved as an .epw extension. Several
85

checks included: checking for the correct number of days and hours in the file, seeing that the font is clear
(Courier New as preferred), checking the order of the columns of data, and so forth. However, the critical
point in resolving the problem was changing the heading information of the file by the one from the
heading data from Los Angeles’ .epw weather file. This option was previously explored without success
using the Santiago-Chile .epw file, perhaps due to the hemisphere difference.

A complement to this exploration has been to compare the differences of taking those suitable weather
data offered for eQuest analysis, assuming the real weather data was not available. For the building in
study, three locations could be used as base weather files in eQuest: California Climate Zone 09, Los
Angeles, and Santa Monica. First, the .epw files have been obtained from the EnergyPlus website and run in
Climate Consultant, obtaining the following information:

86

Table 7. Weather data summary and temperature range for CZ9
(Climate Consultant)

Table 8. Weather data summary and temperature range for Los Angeles
(Climate Consultant)
87

Table 9 Weather data summary and temp.range for Marina del Rey 2009
(Climate Consultant)

88

89

Figure 62. Temperature comparison (dew point) for three possible locations in eQuest.

Actual weather data for Marina Del Rey presents some expected differences, since different options in
eQuest make reference to a different weather database, even in more general parameters, as the case of
taking CZ09. One of the first major differences is the variation in maximum temperatures, which is lower in
the studied location. For example, the Marina Del Rey data shows 6°F (June) and 5 °F (July), lower with
respect to California Zone09 .epw weather data. Also, there is a peak in January in Marina Del Rey, which
follows, to some extent, the behavior of the Los Angeles curve, but contrary to the CZ09 for that part of the
year.

In terms of the relationship between the weather and the building’s electric consumption, the maximum
consumption took place in the period of July-September. For those three months, the mean temperature
(dry bulb) surpassed the 70°F in Marina Del Rey. Interestingly, energy bills for July and September are
almost equal, but the temperatures in the two months differ.
90

WEATHER COMPARISON

Figure 63. Differences in energy prediction from different weather options in
eQuest.

91

Finally, using some of the options for weather files in eQuest makes a difference in energy consumption up
to 3.7% of the total energy consumption calculated for the building under study. These differences can
account for up to 2.7% less in electricity consumption and up to 22% less in gas consumption for the same
building.
Calibration
The calibration process compares actual data with the model outputs. It takes power and gas bills
consumption as the real base and compares it with the energy consumption given by the computer model.
There are clue systems and values to check to achieve a model closer to reality:

-Activity Areas. EQuest presents a default estimated usage area. However, the default for offices
does not consider the computer room (Mainframe/sever). It has been implemented
instead as a conference room, with an estimated of 2% of the area of the building.
-Glass. 1/4” Single tinted reflective glass.
-Plug load. Miscellaneous loads are defined as default in 0.75 W/SqFt in eQuest. This was
considered low for most of the current loads in the building. A value of 1.2 W/SqFt has
been replaced instead for office spaces.
-Boiler efficiency. Assuming the existing are the original boilers from building construction, base
standards are considered at 80%. In this case, the efficiency of both boilers has been
adjusted to 70% due to their vintage.
-Thermostats. The building works with a band of indoor temperature with a set point of 71.8°
measured by return air for cooling and 70° for heating.

Statistical methods are then used in the identification of error margins, such as the coefficient of variation
of the root mean square error (CVRMSE) and the Normalized Mean Bias Error (NMBE) (Hubler, Tupper, and
Greensfelder 2010). These error values are compared with standards such as ASHRAE 14, International
Performance Measurement and Verification Protocol (IPMVP), and Federal Energy Management Program
(FEMP) (US Dep.of Energy 2008). In this study, monthly values have been compared to ASHRAE 14 (Fig 63).
The eQuest model in this case is within the range of calibration for electricity, but out for gas prediction.
92

Figure 64. Comparison between actual data and eQuest model for electricity and gas.

ELECTRICITY CMRMSE NMBE
Electricity 10.13 1.85
Gas 69.30 21.61

93

Figure 65. Baseline end-uses (percentage and KBtu/yr)
Typology applied to Schemes
In this part, several interventions in the facade are simulated and the variations are reflected in the end-
uses and the total energy used in the building. As a first step, the end uses of energy related to the facade
are identified. Thus, the maximum amount of energy possible to be reduced is identified. Ambient lighting,
space cooling, and space heating are essentially the end-uses that are influenced, accounting for more than
60% of the energy use of the building. Although energy by miscellaneous and exterior lights is not part of
the focus of reduction efforts, it will nonetheless be indicated in the data along this section.

space cooling 2,830,641
misc.and others 3,085,027
lighting 2,650,252
space heating 436,180
DHW 67,650
94

Figure 66. End uses related and not related to facade interventions.
The alternatives for measuring the existing facade have been explored using the Energy Efficiency Measures
(EEM) Wizard in eQuest. This possibility within the software, which uses parametric analysis, facilitates
comparison among different scenarios and further cumulative effects of several retrofits in the study.

Figure 67. Simulation diagram in eQuest.
related to façade (kBtu/yr) 6,089,304 66%
no related (kBtu/yr) 3,151,653 34%
total 9,240,957
eQuest
base case
baseline with
daylighting
controls
single skin
sunshading
overcladding
recladding
double-skinning
95

Before simulating the five main categories of intervention in the model, a new baseline incorporating the
function of daylighting controls has been incorporated. This modification to the real building condition
allows identifying the impact in ambient lighting as product of daylighting variations along the different
schemes. In order for this effect to take place, a couple of tests are run to find out which type of daylighting
control is the most effective over the baseline model. Side-lit options are evaluated using a simplified
methodology, where the most effective is using a photo sensor controlling 100% of the lighting through a
switch method of Full-2/3-1/3-off. It results in 4.39% of savings compared to the actual baseline.

However, eQuest positions a daylighting sensor at the middle of the zone by default. That default
configuration causes options that are considering one sensor to leave some part of the zone under
desirable lighting conditions. When two daylighting sensors are chosen, the second sensor is positioned on
the back of the zone. Even though option d) is the one that saves most energy, it could, at the same time
be possible to have low daylighting levels in some parts of the floor. A disadvantage found during this
exploration is that it is not possible to visualize the position of the sensors when defining the amount of
sensors in the Energy Efficiency Measure Wizard. Future studies of lighting retrofit could be focused in
daylighting sensors in eQuest.

Table 10. Daylighting control options in eQuest
Daylighting
option
Daylighting
methodology
# of Photo sensors Lights controlled Design light
level
Control Method
a Side Lit Simplified 1 100% 50 fc On/Off
b Side Lit Simplified 2 50% each 50fc On/Off
c Side Lit Simplified 1 100% 50fc Fluorescent: Hi/Lo Ballast (full-60%
power)
d Side Lit Simplified 1 100% 50fc Switched: Full-2/3-1/3-Off

96

Figure 68. Comparison for different daylighting control within eQuest.

97

Type 1: Single Skin
In this typology, different types of glazing and frames have been studied. Energy lost through inefficient
windows account for a large amount of energy used in heating and cooling. Therefore, different types of
glazing, such as single, double, triple and quadruple, and with different characteristics such as reflective
glass, low-e have been studied under this category. The National Fenestration Rating Council (NFRC) - a
nonprofit, public/private organization which establishes an energy rating system based on the whole
product performance- focuses in these factors: U-value, SHGC and Visible Transmittance (VT). As
general idea, their recommendations for the Southern zone are as follows (NFRC 2011):

- U-Factor: a low U-factor reduces heat transfer by conduction. It is useful during cold days when
heating is needed, as well as during hot days when is desirable to keep out the heat from the
outside air temperature. However, it is less important than SHGC in warm climates, because it
does nothing to reduce direct gain from sunlight. Recommendable U-values are lower than 0.75
and, if possible, lower than 0.60.
- SHGC: a low SHGC is the most important window property in warm climates; a factor of 0.40 or
less is recommended.
- VT: High values are desirable for better daylighting levels.
In addition to NFRC recommendations, a small test has been run in REFEN, simulation software for
residential applications (Appendix 1). A box is modeled using single glass, and it is contrasted with one
using a triple glass which responds to both low U-factor and SHGC. The single glass (U-value of 1.16 and
SHGC of 0.76) has been compared to a triple glass (U-value of 0.18 and SHGC of 0.4). The evaluated triple
glass, which possesses the NFRC recommendations, results in nearly 50% of savings of the total energy used
for the baseline.

The additional factor is the frame. Some reports state that 15% of the estimated of energy loss in the
window is through the window frame (Aclara Technologies LLC 2013). The building in this study has all the
frames in aluminum without thermal breaks. With advanced technology and new materials, better frames
are fabricated with insulating materials to prevent thermal bridges. In addition to that, spacers (connectors
separating multiple glass layers in a window) can create great conductivity in the frame connection
depending on the material, especially if it is metal. In the simulations, different frames are used in
98

combination with the best glass option to visualize the impact in the window system. EQuest works with
the DOE2 library of glass.

Single pane glass
As part of the exercise, a simulation considering single pane glass has been run both with daylighting
controls and without them. The reason is to determine how much energy the building could use if it
maintains the same single glass under different films. The alternatives use three type of glass: single clear
(assuming that the current film is peeled), a single high reflective, and a low-e glass.

glass
U-
value
in
frame SHGC Tvis frame
0 Base Design, Single Ref-D Tint (1418) 1.17 0.46 0.25 w/o break fixed
base daylighting controls 1.17 0.46 0.25 w/o break fixed
S1 dl-single clear (1000) 1.21 0.86 0.9 Al w/o break fixed
S2 dl-single low-e (1602) 0.81 0.72 0.81 Al w/o break fixed
s3 dl- single reflective (1400) 0.93 0.19 0.08 Al w/o break fixed
S4 dl-singlereflective + w/Al brake frame 0.88 0.72 0.81 Al w/brake frame
S5 dl-single reflective + w/fiberglass frame 0.78 0.72 0.81 vinyl frame
S1 nd dl-single clear (1000) 1.21 0.86 0.9 Al w/o break fixed
S2 nd dl-single low-e (1602) 0.81 0.72 0.81 Al w/o break fixed
S3 nd dl- single reflective (1400) 0.93 0.19 0.08 Al w/o break fixed
S4 nd dl-single reflective + w/Al brake frame 0.81 0.72 0.81 Al w/brake frame
S5 nd dl-single reflective + w/fiberglass frame 0.81 0.72 0.81 vinyl frame
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Figure 69. Results for different alternatives of single glass

Double-pane glass
Another alternative to consider in this category is the addition of a second pane of glass to the existing
window. Although this alternative is very difficult to build on-site, it allows the existing windows to be kept
by constituting a layer of still air between both the existing and a new pane of glass. This procedure is being
done as part of the Empire State’s retrofit plan, which affixes all existing windows with a second pane of
glass, by way of infill gas (Empire State Building 2013). Other substances, such as argon, or less commonly
krypton, can be used in spaces from ¼” to 3/8”, but they are more commonly used in triple-pane windows.
Windows with krypton are usually more expensive due to the expensive gas and up-scale designs (Aclara
Technologies LLC 2013).
100

Whether adapting the existing windows or replacing them, several double glass versions have been
simulated in this section, because they are based on layers of clear 6mm glass (which is the existing glass).
The rest of the schemes consider glass and frame replacement. As part of the exploration, three different
frames have been combined with every glass option, resulting in the following nine schemes:

glass
U-
value
in
frame SHGC Tvis frame
0 Base Design, Single Ref-D Tint (1418) 1.17 0.46 0.25 w/o break fixed
base daylighting controls 1.17 0.46 0.25 w/o break fixed
D1 Double clear (2000) 0.76 0.76 0.81 Al-w/o break fixed
D2 Double tinted grey (2214) 0.46 0.61 0.55 Al-w/o break fixed
D3 Double reflective 0.25 air gap (2400) 0.65 0.14 0.07 Al-w/o break fixed
D4 Double reflective 0.25 Argon gap (2402) 0.49 0.12 0.07 Al-w/o break fixed
D5 Double low-e 0.25 Argon gap (2668) 0.37 0.28 0.41 Al-w/o break fixed
D6 2668 0.31 0.28 0.41 Al with break fixed
D7 2668 0.27 0.28 0.41 Reinf vinyl fixed
D8 2668 0.25 0.28 0.41 Fiberglass, ins separat
101

Figure 70. Results for different alternatives of double glass

102

Triple glass
Three types of triple glass have been simulated. After defining which is thee best triple glass option under
the current frame condition, that glass is taken for additional frame simulations.

glass
U-
value
in
frame SHGC Tvis frame
0 Base Design, Single Ref-D Tint (1418) 1.17 0.46 0.25 Al w/o break fixed
base daylighting controls 1.17 0.46 0.25 Al w/o break fixed
T1 Triple Low-e (e=5=.1 Argon gap 0.5) (3603) 0.39 0.58 0.7 Al-w/o break fixed
T2 Triple Low-e (e=52=e5=.1 Argon gap 0.5) (3623) 0.29 0.47 0.66 Al-w/o break fixed
T3 Triple Low-e (33 Air gap 0.5) (3692) 0.43 0.15 0.17 Al-w/o break fixed
T4 Triple Low-e (33 Air gap 0.5) (3692) 0.36 0.15 0.17 Al with break fixed
T5 Triple Low-e (33 Air gap 0.5) (3692) 0.29 0.15 0.17 Reinf vinyl fixed
T6 Triple Low-e (33 Air gap 0.5) (3692) 0.27 0.15 0.17 Ins fiverglass fixed
103

Figure 71. Results for different alternatives of triple glass

104

Quadruple glass
Only one option for quadruple glass is available in eQuest. This glass has been combined with four different
types of frames to see effects of the four different combinations. The values in this case (as all the glazing
options before) consider daylighting sensors as part of the simulation, which reflects the changes in
daylighting occurring for the application of this particular glass in the facade as well. However, a wider
implementation of quadruple glass is mainly limited by high costs, which can reach estimated paybacks up
to 10 years (Yeomans 2013)

glass
U-
value
in
frame SHGC Tvis frame
0 Base Design, Single Ref-D Tint (1418) 1.17 0.46 0.25 w/o break fixed
base daylighting controls 1.17 0.46 0.25 w/o break fixed
Q1 Quadruple, Two Low-E Glass, Two Low-E Film, Clear. Krypton 0.28 0.45 0.62 Al-w/o break fixed
Q2 Quadruple, Two Low-E Glass, Two Low-E Film, Clear. Krypton 0.22 0.45 0.62 Al-w break fixed
Q3 Quadruple, Two Low-E Glass, Two Low-E Film, Clear. Krypton 0.18 0.45 0.62 Reinf vinyl
Q4 Quadruple, Two Low-E Glass, Two Low-E Film, Clear. Krypton 0.17 0.45 0.62 Ins fiberglass
105

Figure 72. Results for different alternatives of quadruple glass

106

The savings, expressed in percentage, for all types of glazing options are compiled in the graph below.
Whether the results measure site or source energy, the best type is the Triple low-e (air gap 0.5’’) glass.
When it is used with insulated fiberglass, the vinyl frame reduces 14.56% of the site energy and 13.17% of
the source energy used by the building.

Figure 73. Summary of all options for glazing replacements
107

Type 2: Sunshades
The first step in this typology was to define a proposal for the sunshade dimensions. Using Solar Tool, an
Autodesk application contained in Ecotect, variation in the size of the overhangs and fins were tested. The
goal was to estimate the dimensions for suitable sunshade elements for obtaining over 80% of shading in
the windows facing South, East, and West. Alternatives Ssh1 and Ssh2 evaluate overhangs and fins
independently. Alternatives Ssh3, Ssh4 and Ssh5 are a combination of both on different sizes. Such
solutions might reduce the need for low SHGC windows.

Figure 74. Solar Tool’s calculation of overhangs and fins.
Table 11. Detail of different alternatives of shading

North
facade
South
facade
East
Facade
West
facade
Ssh1 -

Ssh2 -

108

Ssh3 -

Ssh4 -

Ssh5 -

109

Figure 75. Results for different alternatives of sunshade devices

110

Type 3: Over- cladding
Two kinds of groups of insulation categories have been simulated: exterior and interior. A total of six
independent insulations were simulated first, and then three combinations of them considering matching
the same insulation material for interior and exterior.

scheme description
0 Base Design, Single Ref-D Tint (1418)
base daylighting controls
Ov1 Int Insulation, 1" polystyrene (R-4)
Ov2 Int Insulation, 1" polyurethane (R-6)
Ov3 Int Insulation, 1" polyisocyanurate (R-7)
Ov4 Ent Insulation, 2" polystyrene (R-8)
Ov5 Ent Insulation, 2" polyurethane (R-12)
Ov6 Ent Insulation, 2" polyisocyanurate (R-14)
Ov7 Ov 1 + Ov 4
Ov8 Ov 2 + Ov 5
Ov9 Ov 2 + Ov 6
111

Figure 76. Results for different alternatives of over cladding

112

Type 4: Re-cladding
Two configurations are evaluated: Vertical windows or “no-spandrel” and more fully-glazed façade. On a
“no-spandrel” scheme, the vision glass is extended to the spandrel portion and maintains the image of the
facade as embedded windows within the columns. The second scheme gets closer to the idea of “re-
skinning”, where windows have been defined in 90% of the facade surface. Also, both configurations have
been simulated using triple low-e glass, the glass that produced the highest energy savings under the single
skin category.

scheme description
0 Base Design, Single Ref-D Tint (1418)
base daylighting controls
Re1 less spandrel (60% windows)
Re2 90% glass
Re3 less spandrel (60% windows) + triple low-e
Re4 90% glass + triple low-e
113

Type 5: Double skin
It is not possible to run certain schematic simulations of a double skin in eQuest. In this case, the second
software (Design Builder) is used ahead in the thesis to give the performance in this category.

114

Single schemes compilation
All schemes resulting from Single, Sunshade, Over-cladding and Re-cladding are compiled in the graphs
below. They indicate percentages of saving for both site and source energy.

Without daylighting controls, some of the schemes such as D1 (double clear glass), D2 (double tinted glass)
and Re2 (recladding as 90% of single tinted clear glass) result in increments of energy consumption, and
some of the schemes, such as Ssh2 (fins in facades), Re1 (vertical windows) and Re2 (re-skinning with 90%
glass), provide savings less than 1%. The scheme D4 (double reflective Argon gap) represent the biggest
savings with 5.55%.

Incorporating daylighting controls as part of the facade retrofits results in saving 7.29% (site) and 7.75%
(source) energy. The result from adding daylighting is better than any of the results of the schemes tested.
Interventions of over-cladding (insulation) are not affected by daylighting controls, and thus they maintain
the same values in both analyses.

Application of daylighting controls does not respond to a simple mathematical sum of the savings. It
depends on the specific visible transmission of the glass. For example, the better double glass is D4 (5.55%)
without daylighting control conditions are is not the best option with daylighting control (8.59%). The
highest savings under a daylighting control condition is using double low-e glass D8 for the same proportion
of windows (13.43%).

Of all single schemes, the replacement of windows for a triple low emissivity glass with gap of 0.5” with air
(eQuest code 3692) is the best option for total energy savings. The properties of this glass are very low: U-
value of 0.27 Btu/hr-sq ft °F, SHGC of 0.15 and a visible transmission of 0.17, which is achieved in an
insulated fiberglass frame for fixed windows.
115

Figure 77. Percentage of savings of all single retrofits options
116

Cascading Analysis
Although the previous section shows that a triple glass replacement should provide best results in the
building, an analysis combining different retrofits types is worth exploring. Called cascade analysis, this
process allows results to be accumulative; where each scheme uses a previous scheme as base of
calculation. In this part of the thesis, the resulting more efficient single schemes are combined, which have
been done depending on their complementation. A first run (Analysis 1) combines single skin, sunshades
and over-cladding best results. However, a second analysis (Analysis 2) was needed in the process, due to
incompatibility between the kind of glass and sunshades.

Analysis 1: Three best schemes are combined: T6 (triple low-e glass), Ssh5 (overhangs and fins), and Ov9
(interior and exterior insulation). They follow different orders, which impact the accumulative savings and
the final energy result. These schemes consider daylighting controls as the base case.

Table 12. Best single schemes for cascading analysis 1.

SAVINGS AS INDEPENDENT RETROFITS Site Source
T6
Triple Low-e (33 Air gap 0.5) (3692) 14.56 % 13.17 %
Ssh1 Sunshade 5 (overhangs and fins E=3.5’, S=4.5’ and W=4.5)
12.81 % 12.29 %
Ov9 Int Insulation, 2" polyisocyanurate (R-7)+ Ext 2” polyisocyanurate (R-14)
3.15 % 1.75 %

This cascading analysis considers the following configurations:
- Order 1: T6 –Ssh1-Ov9
- Order 2: T6 –Ov9- Ssh1
- Order 3: Ssh1 –T6-Ov9
- Order 4: Ssh1 -Ov9–T6
- Order 5: Ov9–T6- Ssh1
- Order 6: Ov9 - Ssh1–T6
117

Figure 78. Results of total savings for cascading analysis 1

The final savings of this analysis reaches 15.99%. Although the six versions of cascade analysis provide the
same final savings, the difference is when more savings are obtained sooner in the consecutive schemes.
As seen previously, applying daylighting control gives a base energy saving of 4.39%, which constitutes the
baseline for the following schemes. The order that each modification takes more or less determines the
impact individually. This cascading analysis shows an incompatibility between the triple glass and
sunshades that allow savings to be 16.55%. Whenever sunshade is applied after triple glass, it produces an
increase in the total energy consumption. The following cascading analysis (Analysis 2) shows the same
schemes using double low-e glass (the second best glass).
118

Analysis 2: According to the incompatibility shown between triple glass and sunshades implementations,
the present analysis will find the results replacing the triple low-e glass for a double low-e glass. The
following schemes are combined: D8 (double low-e glass), Ssh5 (Overhangs+ fins), Ov9 (interior and
exterior insulation) are combined.

Table 13. Single schemes for cascading analysis 2

SAVINGS AS INDEPENDENT RETROFITS Site Source
D8
Double Low-e (0.25 Argon gap (2668)) 13.02 % 12.13 %
Ssh1 Sunshade 5 (overhangs and fins E=3.5’, S=4.5’ and W=4.5)
12.81 % 12.29 %
Ov9 Int Insulation, 2" polyisocyanurate (R-7)+ Ext 2” polyisocyanurate (R-14)
3.15 % 1.75 %

This cascading analysis considers the following configurations:
- Order 1: D8 –Ssh1-Ov9
- Order 2: D8 –Ov9- Ssh1
- Order 3: Ssh1 –D8-Ov9
- Order 4: Ssh1 -Ov9–D8
- Order 5: Ov9–D8- Ssh1
- Order 6: Ov9 - Ssh1–D8
119

Figure 79. Results of total savings for cascading analysis 2

This cascading analysis shows a maximum savings of 19.03%. It also shows compatibility between the
double low-e glass and the sunshading scheme in their cumulative effect. All orders show increasing
increments of energy savings, with more or less impact of each of the schemes.

120

Comparison Analysis 1 and Analysis 2.

It was initially estimated that taking the best independent schemes for the cascading analysis should
provide major savings. However, using triple glass in combination with sunshades increases energy
consumption. This situation does not take place by replacing the triple low-e glass with double low-e glass.
In this section, a comparative cascading analysis is done with the following sequence: glass- sunshading-
overcladding. The central idea is to determine which factor causes double glass to perfom better than triple
glass in this sequence. Both glass types have U-values (double 0.27, triple 0.25) and SHGC (double 0.28,
triple 0.17) less than 0.4 as reccommended by NFRC. With both lowest values, the triple glass performs
better for heating energy consumption, but not for electricity (the prevalent one). Taking a breakdown of
the electricity consumption, it is seen that sunshading decreases cooling for both cases and leaves them in
the same position in this end use. In addition, sunshading devices increases lighting in both cases, but it
impacts the triple glass almost twice as much. The used double glass has a higher visibility transmission
(0.41) compared with the triple glass option (0.17). In the building, lighting consumption accounts for a
third of the electric use.

121

Figure 80. Comparison of total energy and end-uses for double and triple
glass.

122

Design Builder simulation model
In this thesis, Design Builder has been chosen to supply the fifth scheme of the typology, the “double skin
retrofit”. Design Builder is one of the commonly used energy-simulation platforms in practice. Defined as
“state of the art software tool for checking building energy, carbon, lighting and comfort
performance”(DesignBuilder Software Ltd 2013), it represents a powerful modeling tool, simulating building
thermal responses from a flexible and customizable platform. Design Builder uses Energy Plus 6.0 as
engine, and version 2.4.2.016 has been used in this simulation.

Figure 81. Design Builder model of the building

123

Baseline and calibration.
In terms of weather, DesignBuilder uses TMY3 weather data. For the Los Angeles area, it contains three
weather data files: California Climate Zone 9 (Source CTZRV2), Long Beach_Dauigherty (TMY3, WMO
station 722970), and Los Angeles INTL AP_TM (source TMY3, WMO station 722950). However, actual data
is modeled using the real .epw weather file used along the previous process. In this case, the .epw needs to
be converted to a .stat file, which contains information of summer and winter degrees. It is generated
within DesignBuilder weather configuration. For this simulation, the .stat file of Los Angeles was adapted.

Figure 82. Definition of building as a block and zones for core and perimeter

All the geometry, zoning, and scheduling follow the same parameters as the eQuest computer model did.
However, Design Builder does not accept the U-value of 1.08 used before. Instead, the maximum number
allowed 1.028 (Btu/hr-sf-F) was used.

The scheduling process in Design Builder allows two kinds of types. The compact schedule type is used,
which refers to the same values used in eQuest. According to the statistical margin of error, the model is
calibrated in terms of electricity, but out in gas prediction.

124

Figure 83. Calibration in Design Builder for electricity and gas.

ELECTRICITY CMRMSE NMBE
Electricity 8.27 -1.66
Gas 60.29 18.13

125

Double skin configuration
Design Builder works using a configuration of blocks to define the main geometry and thermal zones of the
building. However, using a new block to define the double skin in the building is not a suitable procedure.
Design Builder considers a block as independent volume, which, in this case, duplicates the interior wall (the
existing facade with a new one) in the model. An alternative procedure inside the software is explored,
generating a partition inside the current building.

.

Figure 84. Double skin configuration in Design Builder

It results in a new thermal and physical zone with independent properties. The resulting difference of
dimension (the idea is to add an exterior new façade) is later corrected, stretching the opposite facade of
126

the building. This action restitutes the original building dimension. The incorporation of a buffer area
defines a new zone in every floor. The images show both walls, the interior one maintaining the original
characteristics and the new one set up with 100% fitted glazing wall. Two configurations have been
developed for the double skin façade: a multi-story double cavity, and a full-story cavity.

Multi-story double skin
This first configuration takes cavities every three floors. It does not consider ventilation.

Figure 85. Multi-story double skin façade model in Design Builder

Full-story double skin facade
This second configuration takes the whole eleven floors height (from the 2
nd
floor). It considers ventilation,
which is represented by five vents located at the bottom and the top of the double skin façade.

Figure 86. Full-story double skin with incorporation of vents in Design
Builder.
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Results
Double skin simulation in Design Builder shows that the building experiences an increment in electricity
consumption but a decrease in gas. The incorporation of ventilation through the vents is minuscule, and it
does not reflect any variation in the result. As final result, the building increases its total energy
consumption by 0.7%, due the incorporation of this new layer of façade. The benefits of double skin facade
have been proven to be more beneficial in colder climates, as the benefits of the additional cavity reduces
the need for heating. It follows that there are almost non-existing double façades in this climate. However,
future studies could further explore this specific solution, specifically if it includes natural ventilation and
solar control devices.

Figure 87. Total energy use for double skin façade retrofit using Design
Builder
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CHAPTER 7: DATA ANALYSIS
The main goal of the simulations in Chapter 6 was to explore how different facade interventions can
optimize energy in a particular building in the Los Angeles climate. The result of those interventions can be
evaluated from several perspectives: economical, feasibility, life cycle cost, CO
2
reduction and so forth. In
the interest of this thesis, the results are measured in terms of energy reduction of the building’s total
energy use.

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Site vs. Source Energy
The evaluation of energy use in a building can be approached depending on the type of energy considered
in the analysis. Site energy is just a part of the total primary or source energy. These two approaches allow
us to understand energy beyond the building’s limit and to approach a more complete evaluation of the
overall building energy consumption and its actual implications to society. Energy values have been
expressed in terms of both site energy and source energy throughout this thesis.

In terms of site energy, the building is quite efficient compared with averages collected in national statistics.
The total actual energy consumption is 46.95 KBtu/sf. This consumption is significantly lower compared to
several similar references. Commercial building dating from the years 1967-1976 use, on average, 76.8
KBtu/sf (US Department of Energy 2013d) and Class B buildings 74.9 KBtu/sf (US Department of Energy
2013e, 3).

Table 14. Energy Consumption per sf of office floorspace by vintage
(US Department of Energy 2013d)

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Table 15. Energy expenditures per sf of office floorspace by function and
class
(US Department of Energy 2013e, 3)

In terms of source energy, the EPA has established a procedure to calculate source energy for a better
comparison in commercial buildings. Source energy is defined as “the total amount of raw fuel that is
required to operate the building” (EPA 2011). In fact, it includes all the energy used in the whole process:
from generation, storage, transmission, and delivery, to the losses along the way. In sum, the EPA
recognizes source energy as a more accurate estimate of carbon emissions and real social cost, than site
energy can approximate.

Figure 88. Table 1. EPA’s ENERGY STAR Performance Ratings,
(EPA 2011).
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Figure 89. Site and Source energy consumption of the case study building.

The percentage of electricity and gas use in the building for both site energy and source energy are shown.
In the case of the building in the study, the energy use is comprised of mostly electricity, which represents
98% of the source for the building’s operation.

Weather
It is important to highlight that measuring retrofit actions (as in new design) depends primarily on location.
Some measures, such as adding insulation, can produce a greater benefit in a cold climate, as opposed to
California’s mild climate. Other measures, such as shading devices, can be more effective in the typical Los
Angeles climate. An important consideration in this thesis has been to focus on weather and to explore
how similar weather data could result in different outcomes. As shown in Chapter 6, using a close weather
data instead of the real weather data reveals differences up to 5°F in peak periods in different weather files.
As a result of those differences, the calibration could vary in electricity consumption by up to 6% less and
gas by up to 22% less. The total energy use in the building can be altered by up to 3.79 % less compared
with the baseline based on the real weather file.
SITE
electricit
y
94%
SITE gas
6%
Baseline - Site energy
SOURCE
electricity
98%
SOURCE
gas
2%
Baseline - Source energy
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Envelope
Some studies report that normal thermally-broken commercial aluminum windows and curtain walls have
R-2 (U-values of about 0.5). In best conditions such as best low-e coated, argon-filled double-glazed (R-4
center glass) that value gets close to R-3 (Straube 2008). In the case study building, a R-value of 3.7
probably positions the building in a good position regarding the previous referents, which is possible
because the window/wall ratio is around 0.3. However, any aging factor has not been applied in any
calculation of materials and their thermal resistance values. Insulation, for example, decreases its
properties in evident shorter periods than the lifespan of the building. Therefore, a closer estimate of the
thermal resistance of the facade should consider aging, and more accurate measurements could help in
that definition. Both thermal resistance calculations and the ‘aging’ component in that process are worthy
of future studies.

Figure 90. Relation between R-value and WWR for curtain walls
(Source: Buildingscience.com)
Schemes results:
The decision to incorporate daylighting controls to the baseline was made to determine the effects in
ambient lighting consumption as a product of some of the retrofit interventions. Variations in the type of
glass, size of the windows, and/or sunshades devices affects daylighting, but insulation does not. Therefore,
that correlation of retrofits can be visualized, which would otherwise be constant throughout the analysis.
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The best alternative of daylighting control that was analyzed in chapter 5 (1 photo sensor covering 100% of
the 15’ perimeter of the building, with levels of 50fc, and switched full-2/3-1/3-off) resulted in savings, in
total energy consumption, of 4.39%.

Single clear glass
All the possibilities to use the same glass and add different kinds of films are evaluated assuming some of
the glazing options contained in the DOE2 library in eQuest. However, the results lack accuracy, since
adding a film performs differently to a glass originally fabricated with those attributes. On the other hand,
the results obtained help to formulate an initial idea of those alternatives.
- Removing the current film from the windows results in increases to both electric consumption
(5.1%) and gas (9.7%) and a consequent increment in the total energy consumption of 5.4%.
Therefore, the decision made in the building in the past was adequate.
- With no daylighting controls installed in the building, the best option for reducing the electricity
consumption is highly reflective glass, saving 4.3% in no thermally broken aluminum frame and
4.8% when in a fiberglass frame. In gas, reflective glass is also the more efficient one, giving a
maximum 29.6% of savings. Consequently, reflective glass achieves an overall energy reduction
of 5.46%, which improves in a fiberglass frame to 6.22%.
- With daylighting controls, reflective glass achieves 8.8% of electricity reduction, which reaches
9.2% when in a fiberglass frame. In gas, there is also reflective glass (14.5%), which achieves 23%
when it is in a fiberglass frame. Consequently, this specific reflective glass improves in almost
10% the total energy consumption, despite the baseline already containing a grade of reflection
due to the window film.
As an additional analysis, the savings identified in the film on windows is compared in an on-line product
simulator (fig 90). The calculator displays a basic format for possible savings derived from the application of
different types of films. The main characteristics of the buildings are used as input, and then three kinds of
films have been simulated (Standard, Medium and High performance). Only the standard type produces
results similar to the eQuest model. No more technical features of the simulated film are obtained from
this application to complete the comparison.
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Figure 91. 3M product on-line simulator
(Window Solutions 2013)

The product simulator shows savings for High, Medium and Standard performance film for the building.
Based on this, the value obtained from the eQuest calculation (8.95%) is within the range contained on the
online calculator.

Double glass
Daylighting controls have been assumed as initial implementation in the building in this type and the rest of
the options of glass. Otherwise, values in ambient illumination are not affected, which is an unreal situation.
- Savings of more than 11% in electricity come from the use of Double low-e glass with 0.25 Argon
gas (D5), which possesses both SHGC and U-value with values within those recommended by the
National Fenestration Rating Council.
- In gas reduction, it is the Double reflective (D4) that is the better performer, achieving more than
34% of savings (considering it is mounted in an aluminum without break, it could achieve more in
a better frame). This glass is that which has the lowest SHGC of all glazing in combination to a
very low Tvis, but not the lowest U-value.
- As total energy reduction, the double low-e glass (D5) achieves the most significant savings with a
11.67% in aluminum without a break frame. It can reach the 13.03% if a fiberglass frame is used.
- The less effective option in this category is the double clear glass (D1), which only results in
around 1%.
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Triple
Even though the two first glass triple low-e types (T1 and T2) are better alternatives in terms of visible
transmission, they do not perform as well as T3, a triple glass with merely 17% of visibility.
- T3 (triple low-e with air gap) option with the lowest SHGC (0.15) performs better in electricity
savings achieving 12.2% in the current frame and slightly better 12.5% in fiberglass frame (when
possesses the lowest U-value).
- The T3 is also the most efficient for gas reduction, achieving 39.5% in aluminum without a break
frame. The resulting savings reach 48% if an insulated fiberglass frame is used instead.
- In total energy reduction, the best option is consequently T3 with 13.6% of total energy reduction
when it is in aluminum without break, and over 14% if is in an insulated vinyl or fiberglass frame. As
seen in the double glass analysis, a good performance is a combination of low U-value (0.27) and low
SHGC (0.15). However, this triple low-e glass also includes the lowest visible transmission value,
which could be a disadvantage, considering the views that the building possesses.

Quadruple
- In electricity consumption, the quadruple glass saves 8%. The savings are not bigger than those
from double or triple glass. This situation slightly improves if the frame is thermally broken or
highly insulated.
- Quadruple glass improves gas consumption by a mere 6.9% when is mounted in aluminum
without thermal brake. Any of the better frames improve gas use.
- As total energy savings, a quadruple glass is not more efficient (as if we expect in terms of more
layers) than 7.92%, which is the best result.
It is observed that quadruple glass combined with better insulated frames performs worst in terms of
energy than just using a no-broken aluminum frame. Those better frame alternatives increment both
electricity (for concept of cooling) and gas consumption (for heating). Due to this situation, an additional
test was performed using a simple box where quadruple glass was combined with the same frames here
and this situation repeated (APPENDIX 3). The test agreed in thermally broken frames performing worse
than the non-thermally broken. The main element defining the differences was the type of separator and
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not the material of the frame. Analyzing how these assemblies are defined in the software, it might be
worth of further exploration.

After simulating all glazing options in eQuest, the best glass option for the building is the triple low-e glass
(triple low-e with air gap U=0.27, SHGC=0.15, Tvis=0.17). In the case of quadruple glass, even though the
quadruple glass has a U-value of 0.17 (the lowest); it is not the property addressing energy reductions.
Total energy savings using quadruple glass are lower than the savings achieved by both double and triple
glass. The triple glass has the lowest Tvis (0.17) results the biggest savings in gas. The double glass, which
has the lowest U-value, is not the best option neither for electricity or for gas. Finally, the triple does not
possess neither the lowest U-value (0.27) nor SHGC (0.15), but rather the lowest Tvis (0.15). The
combination of those low values helps to decrease more effective energy in this building in these climate
conditions. In addition, a varied transmission visibility factor in the triple glass can have adverse effects in
the building’s views, but it seems to help in the performance to make the triple low-e be the more efficient
glass between the glazing alternatives.

Sunshades
- In terms of electricity, all the alternatives decrease electricity; being the more efficient Ssh3 (a
combination of 3’ overhangs and 3’ fins in S, W, and E facades). Cooling need decreases as much
the window is covered, so the larger sunshades might be the best solution. However, the larger
the sunshades, the greater the need for artificial lighting.
- Due to electricity being the target to be reduced, and the fact that half is due to lighting and half
to cooling, only overhangs on windows are the most efficient way to reduce the total electricity
use, because it balances both conditions. That balance should be found between enough shading
for not decreasing the daylighting harvesting possibilities because of the overhangs. The options
incorporating fins result in increasing gas consumption. This may also vary with fin size,
placement and orientation.
- When it comes to gas consumption, the more covered the window is, the more energy that is
saved. The explanation is that the software weighs the consequent increase of lighting inside the
building, instead of direct solar heat gain.
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- As total energy consumption, the scheme is a combination of both overhangs and fins (Ssh3),
basically because it is a fair combination of enough shading to decrease cooling and enough to
have a decrease in gas because of the heating saved for more artificial light.
- Without daylighting controls, and with the lighting consumption as a constant, scheme Ssh5 is
the more efficient alternative, because it is the one that almost completely covers the windows
with both overhangs and fins. Contrary, using only fins (Ssh2) is the alternative for which more
sun rays are allowed through the window, and consequently more cooling is is needed. Finally,
due to the fact that savings in cooling are greater than those in heating, Ssh5 (combination of
both overhangs and fins) is the more efficient alternative, which saves 6.51%.

Over-cladding
Daylighting controls have been considered as the first intervention to have the same baseline for
comparison, even though it is not affected by over-cladding retrofits. Insulation applied to the building is
not one of the most effective schemes in a mild climate. It affects electricity reduction by less than 1%.
The effects are more notorious for gas. Finally, in terms of overall energy, all schemes, whether additional
or interior insulation, range from 6.55% to 8.43% (but considering 4.39% from daylighting control effect).
However, those maximum savings are achieved, combining 2” of interior and exterior polyisocyanurate
(Ov9).
Roof insulation and the ground floor have not been considered in the simulation, but it would be
worthwhile to explore in future work.
Re-cladding
Daylighting controls have also been considered in this scheme as the first intervention. Two kinds of
intervention have been evaluated: more glass (60% estimated window area, decreasing the spandrel by the
extension of the glass proposed windows); and re-skinning (with 90% of window ratio). The major savings
in electricity consumption rises to 11.4%, which is only possible using the best glass resulting from the single
skin retrofit section. Re-cladding the building using the current kind of glass results logically in increments
of energy; the situation is corrected when a triple glass is used in the re-skinning. This category can be
successful if the proportion of glass is adequate. As shown, increasing the window ratio will always benefit
138

energy used in lighting in the building when daylighting controls is implemented. But, at some point, that
proportion starts to increment cooling load. With 60% of windows, it is still possible to decrease cooling.
With the best scheme, it is basically possible to harvest daylighting and also reduce cooling. The
possibilities for overheating are controlled by the triple glass (a U-value and control of solar heat gain in the
necessary amount to reduce cooling). The total energy reduced achieves 13.38% of savings in this scheme.

Double skin
The alternative of evaluating a double skin facade responds to the initial idea to analyze the
convenience of a this in a climatic condition such as those like Los Angeles. In fact, double façades
are almost nonexistent solutions in this area. It constitutes the fifth category of retrofits, and the
results of the simulations for the building agree with the nonexistence of real examples in the
zones. Double skin retrofits do not generate any energy benefit to the building. The gas
consumption decreases because of the benefit of having a buffer zone, but it is insignificant
compared with the enormous electricity load. Finally, double skin facade retrofits only slightly
increases overall energy consumption in the building. This might depend on the particular
configurations considered and is worthy of further study.

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CHAPTER 8: CONCLUSIONS AND FUTURE WORK
This study is a compilation about building retrofits with special emphasis in the facade system. In this
regard, the current concern of global warming and the essential role that buildings take in that context,
make these types of studies especially relevant. Currently, tangible benefits of retrofitting the facade in
existing buildings are not broadly known. Therefore, the main focus of this thesis is to understand building
retrofit as an energy efficient tool for decreasing energy consumption in buildings, and one particular
building gives an idea of the possible savings in a specific climate. This thesis measures five categories of
retrofits, which shows the resulting energy reduction in terms of site and source energy.

140

The building has a total EUI of less than 50kBtu/sf/yr for the year in study (2009- site energy). It is not as
high as it was thought at the beginning of the study; an expectation created as the façade was first glance.
DOE has surveyed averages energy use intensities over 90 kBtu/sf/year in office buildings and also for
buildings from the 1970’s in the United States (DOE, Energy Efficiency & Renewable Energy, Databook Table
3.6.1, 2008). Although average energy use intensities for buildings in California are lower than national
averages, the building in study rated low. Therefore, it was found that the building is relatively efficient in
overall energy consumption, when compared to buildings of the same vintage. It is still too high, however,
for carbon footprint concerns. Whether the focus of the analysis considers site or source energy, it is
nevertheless shown that the options for the retrofit of the building are basically those oriented to decrease
the amount of electricity use, which represent 94% of the energy use in the building (98% of source energy).

The calibration process constitutes the first important step in retrofit energy simulations. Working with
actual weather data minimizes uncertainties in the process. As shown in the study, using traditional
weather data can result in differences of up to 22% in gas, 6% in electricity and 3.8% in the total energy use.
Statistical weather information or from a close location are the alternative of most energy simulation tools,
in this study, both softwares allowed customize the weather file.

Derived from the calibration of the model, the end uses of the building can be determined. A third of the
energy in the building is used in miscellaneous and plug loads. That part of the energy consumption is not
possible to control by any intervention in façade. The remaining two-thirds of the energy is used in cooling
and illuminating the building. Cooling represents 31% of the energy use, which makes it the biggest end-
use, as well as the place to focus energy saving procedures. Lighting represents 29% of the energy use,
which makes daylighting control and daylighting harvesting important factors included in the retrofit
analysis. Even though daylighting control it is not a direct intervention in façade, it is an important
complementary part of the facade retrofit implementation. When incorporated as first scheme, daylighting
controls represent saving of around 4% in total energy use.

The schemes simulated in chapter 6 show a 14.5% energy saving result when applied single schemes. Those
saving are possible, as mentioned before, only because the incorporation of daylighting controls as first
intervention in the facade system. If no lighting controls are incorporated, the best single scheme results
141

on 7.5% of energy saving. In these independent interventions, the most effective solution is replacing the
current windows by a triple low-e glazed window. In the cascade analysis, energy saving reaches 19% of the
total consumption of the building, but considers a combination that include double low-e glass instead a
triple glass.

All the previously indicated percentages of reduction are expressed as a function of total energy use in the
building. As mentioned, a third of the energy is not influenced by facade retrofit interventions. When just
the part of the energy possible to be affected by facade retrofit is considered, savings reaches 28.9% of that
universe.

It seems a challenging task to achieve the remaining energy reduction towards zero net energy (ZNE)
condition in this particular existing building. The building is dominated by internal loads, which are mainly
not affected by the influence of the façade. In addition, the mild Californian climate does not define an
aggressive context for the facade influence in this kind of analysis. Further exploration should consider
lighting and mechanical retrofit in estimating the amount of energy saving for the remaining part of the
energy in the building. Plug loads might also be considered.

There are other areas to focus further on than this thesis has covered. One relates to the calibration
process, a fundamental step in every retrofit project. If there is an open access to the building installations,
it will be interesting to have measured values. As a consequence, the calibration process may be better fed
and closer to representing the actual condition of the building. Future work should examine that stage in
the retrofit process and evaluate how actual data from the building differ from the default values contained
in the energy simulation software.

There is interesting scope for future work analyzing the scope of eQuest related to lighting. When working
on all the different schemes of intervention without daylighting controls, eQuest does not show variations
in daylighting. For that reason, this study considered a new baseline including daylighting control. Only
after including daylighting controls, simulations reflected the variations in lighting consumption, due to
daylighting access in the building under those different schemes. The software does not recognize variation
in lighting consumption when working under a building without daylighting controls. It was seen, for
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example, even though different types of glass were used without daylighting controls, that lighting
consumption did not vary. In addition, if daylighting sensors are one of the improvements as part of the
retrofit (as in this thesis), the present exploration did not find any graphic visualization of the position of the
sensors within the building zones. Future studies in lighting retrofit could be focused to exploring some
computer application for this area.

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APPENDIX 1. GLASS STUDY FOR CASE STUDY
A small test has been run in eQuest for distinguishing different types of single glass that could closely
represent the existing glass of the building. Original ¼” single clear glass received a sun reflective film,
which modified the performance characteristics of the building windows. A comparative table is done to
determine the glass type which might match closer to the existing one. The single reflective D-Tint glass
(1418) is used in the model. The film Neutral 20 is recommended for single glass with the following
performance when applied to a ¼”single clear glass (3M Building and Commercial Services Division):

- Visible Light Transmitted 16%
- Total Solar Energy Rejected 66%
- UV Light Rejected 99%
- Glare Reduction 82%
- Visible Light Reflected 17%
- Shading Coefficient 0.39
- Emissivity 0.84
- U value 1.06
- Solar Heat Reduction 46%

Table 16. Comparison of three types of single glass types
(eQuest with reflective film)
glass U-value SHGC Shading
Coeff SC
Visible
Trans Tvis
Solar
Trans Tsol
Visible
Reflect Rfvis
Solar Reflect
Rfsol
Film applied on ¼” single clear glass 1.06 0.44 0.39 0.16 0.17
¼” Single clear glass (1000) 1.11 0.86 1 0.9 0.84 0.08 0.08
Single Tint Grey (1205) 1.09 0.59 0.69 0.43 0.46 0.05 0.05
Single reflective D-Tint (1418) 1.08 0.46 0.53 0.25 0.3 0.18 0.14

As mentioned in the building description, the building received sun reflective film in all its windows during
the 1990s. The first exploration in this category is to identify an approximate amount of the saving that
144

intervention meant to the energy usage in the building. However, the estimate considers the supplier
company’s technical data, and no considerations to aging or degradation of the material performance has
been evaluated. According to the film’ technical characteristics and as result of comparison showed in table
12, single reflective tinted glass is used from the eQuest library for the baseline model.

Figure 92. Comparison between ¼”single clear and single reflective glass

Using reflective glass, a more adjusted model represents a closer reflection of the real building envelope. It
is interesting to discover that the incorporation of film in the building windows could mean an approximate
4.5% in savings at the time it was installed. Unfortunately, the facility department did not save or register
the energy consumption during that period.

145

APPENDIX 2. RESFEN AND CONFEM TESTS
RESFEN TEST
RESFEN is a tool for residential energy analysis for fenestration analysis (LBNL 2013a). A simple test is run to
see the differences applied to a 1500sf, one story house in Los Angeles. The comparison is made between a
Single Clear glass in aluminum frame (high U-value and SHGC) and a 3 HT Super, insulated frame (low U-
value and SHGC). The results show that a reduction in total energy consumption up to 50% is possible.

Glass type U-value SHGC Air leak
(101) Alum single clear glass 1.16 0.76 0.3
(451) Insulated triple HT Super glass 0.18 0.4 0.3

146

Figure 93. RESFEN using Single clear glass in aluminum frame

Figure 94. RESFEN using triple super insulated glass (cod.451 U-value: 0.18
and SHGC: 0.40)
147

Figure 95. RESFEN using triple super insulated glass (cod.452, U-value: 0.18
and SHGC: 0.26)

The idea is to know how much less energy is used when decreasing the SHGC. Maintaining all the same
other parameters (U-values and air leakage,) but varying the SHGC from 0.4 to 0.26 does not decrease the
total energy consumption in this case. It is mainly because heating is increased and it plays a more
important part in residential buildings.

An additional test is run using a user- defined glass. Taking as baseline the single clear values, the first run
modifies the U-value to 0.18 (the lowest U-value within RESFEN options); the second run modifies the SHGC
to 0.26 (the lowest U-value within RESFEN options).
148

Figure 96. results using user-defined performance factors of glass in RESFEN

None of these additional runs result in a lower energy consumption total in the test cell. Decreasing the U-
value gives more savings than decreasing the SHGC. However, none of those tests give better results than
the triple glass (cod 451), even though it does not have the lowest SHGC.

Finally, the triple glass with a combination of U-value of 0.18 and SHGC 0.40 is the glass type that decreases
the most energy in this test using RESFEN, which presents a just combination of both low U-value and SHGC
in a certain range. That range in the combination of U-value and SHGC for Los Angeles and other areas is an
excellent area for future studies and evaluating the related trade-off.
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COMFEN SIMULATION BOX
COMFEN is software tool developed by the Lawrence Berkeley National Lab, Windows and Daylighting
Group for calculating energy use of windows in commercial buildings. It uses Energy Plus as its analytical
engine (LBNL 2013b). The test consists of a 3m x 3m x 3m (height) box, which has been simulated in Los
Angeles. The box’s facade -with one window covering 50% of the area- is oriented in the four orientations.
COMFEN allows calculate heating and cooling energy use, with peak demands for this specific window.
Since COMFEN does not allow modification of weather data, the test has been run using the Los Angeles
contained option as location.

150

Figure 97. COMFEN results
Comparing a window using single 6mm glass and Double glazed triple silver with argon.

151

APPENDIX 3. DATA LOGGERS
Measurements of temperature and relative humidity were taken in the case study building. 17 Hobo Data
loggers were located in different positions throughout the building for a two-week period. They were
located in different parts of the envelope and core of the building. In each of these locations, a set of three
data loggers where positioned close to floor, medium ceiling level to also see if there exist some
stratification of those environmental factors.

Figure 98. Location of data loggers in the building
152

Figure 99. Temperatures from data loggers
The maximum peak of exterior temperature was 124.5° on Sunday April 16
th
at 2:00PM. The lowest peak in
exterior temperature was 89° on Monday 19
th
at 2:49PM.

153

Figure 100. Detail of temperatures for two days
50
60
70
80
90
100
110
12:00 AM
1:00 AM
2:00 AM
3:00 AM
4:00 AM
5:00 AM
6:00 AM
7:00 AM
8:00 AM
9:00 AM
10:00 AM
11:00 AM
12:00 PM
1:00 PM
2:00 PM
3:00 PM
4:00 PM
5:00 PM
6:00 PM
7:00 PM
8:00 PM
9:00 PM
10:00 PM
11:00 PM
T° Sunday April 10, 2011
H01-East F-d
H02-East F-m
H03-East F-u
H04-North F-d
H05-North F-m
H06-North F-u
H07-West F-d
H08-West F-m
H09-West F-u
H10-South F-d
H11-South F-u
H12-South F-missing
50
60
70
80
90
100
110
12:00 AM
1:00 AM
2:00 AM
3:00 AM
4:00 AM
5:00 AM
6:00 AM
7:00 AM
8:00 AM
9:00 AM
10:00 AM
11:00 AM
12:00 PM
1:00 PM
2:00 PM
3:00 PM
4:00 PM
5:00 PM
6:00 PM
7:00 PM
8:00 PM
9:00 PM
10:00 PM
11:00 PM
T° Monday April 11, 2011
H01-East F-d
H02-East F-m
H03-East F-u
H04-North F-d
H05-North F-m
H06-North F-u
H07-West F-d
H08-West F-m
H09-West F-u
H10-South F-d
H11-South F-u
H12-South F-missing
154

Figure 101. Temperature in façades of the building

Temperature registered for each facade for a weekday (Wednesday April 13
th
) and a weekend day (Sunday
April 17
th
). In the weekday, the temperature raise around 6am can be produced either by the sunrise or
because the heating system started working. The sunrise time for Wednesday 13
th
was at 06:25 AM while
155

for Sunday 17
th
it was at 06:20AM
8
. Therefore, the temperature shown for all the façades started to slightly
rise before that time, even in the west façade.

Figure 102. Temperatures in the core of the building

Temperature was registered at the core of the building for both days. With a tendency to range
between 75° and 80° without the air conditioning system, they decrease to a range of 72° and 74°
when the air conditioning system is working.

8
Time and date website. http://www.timeanddate.com/worldclock/astronomy.html?n=137&month=4&year=2011&obj=sun&afl=-
11&day=1
156

APPENDIX 4. EQUEST TEST FOR QUADRUPLE GLASS
A simple simulation has been run just to compare the same quadruple glass (two low-e glass, two low-e
films, clear krypton filled) in different frame configurations. A 10’x10’x10’ box with one window facing
south was modeled in Los Angeles (Climate Zone 06). The schemes simulated used all the options for
frames contained on eQuest.

Figure 103. View and results of different types of quadruple glass in eQuest

3,545 3,562 3,600 3,562 3,600 3,562 3,600 3,562 3,600
6010.8 6011.4 6001.7 6011.4 6001.7 6011.4 6001.7 6011.4 6001.7
wo break w break,
mtl spac
w break,
ins spac
w break,
mtl spac
w break,
ins spac
w break,
mtl spac
w break,
ins spac
w break,
mtl spac
w break,
ins spac
Alum Alum Alum Reinf vinyl Reinf vinyl Wood clad
Al
Wood clad
Al
Ins.
Fiberglass
Ins.
Fiberglass
Quadruple glass , fixed
elect.Kbtu gas Kbtu
157

The main factor determining the amount of energy used is the kind of separator contained and not the
material of the frame. All frames with metallic spacers show the same performance, as well as those with
insulated frame. First, all the tested thermal broken frames result in more electricity consumption.
Secondly, gas consumption decreases only when the frame contains insulated separators. As total
consumption, the non-thermally broken frame performs better than all the insulated ones. For example,
and just comparing the aluminum frame, the thermally broken frame has higher energy consumption (in
both electricity and gas) than the aluminum frame without break. Therefore, there corresponds a condition
defined in eQuest, which is worth exploring in future studies.

158

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Abstract (if available)

Abstract Buildings in the United States are responsible for over 40% of the energy used (US Department of Energy 2013a, Architecture 2030 2013a) in the country. During the life span of buildings less than 20% of energy consumption is for extraction of raw materials, materials sourcing and construction, and over 80% of the total energy consumption occurs during building operation (United Nations Environment Programme and World Resources Institute 2010). That energy, supplied by mechanical means, is wasted due to poor building performance in building facades, such as leaking windows, deficient insulation, or defects in construction. Retrofit strategies not only rescue embodied energy contained in buildings already built, but also save energy in their operational phase. ❧ A special focus of this thesis is the exploration of mid-20th century buildings. Since many of them were built with an emphasis on mechanical-conditioned spaces, they are excellent candidates for a new life reconsidering a passive approach. As the first part of the exploration, a general typology of facade retrofits is defined, examining existing cases worldwide. Building retrofits range from partial to total, presenting different combinations. Most of the existing cases of facade retrofits have been made as urgent response to facade failure mitigation. Since the cases vary in a wide range - from low-e film application in windows to whole building retrofit - this thesis typologizes these cases prior to testing through simulation modeling and in a case study. ❧ A specific case study focuses on alternative and passive energy solutions applied to an existing building in a mild climate. The building is a 12-story office building in Los Angeles area built in 1972 with a curtain wall facade. The goal of the thesis is to examine different scenarios for facade upgrading in the building using energy simulation modeling and drawing upon what was learned from the typological analysis of existing cases. Two energy software packages- eQuest and Design Builder- are explored in the case study building to evaluate selected facade solution alternatives. As the first part of the exploration, current building energy consumption and a survey of the components of the facade have been collected and transferred to the computer model. After calibrating the model, five different schemes are explored: (1) replacing existing windows for double, triple or quadruple glass, (2) adding interior and exterior insulation (3) adding overhangs and fins to fenestration, (4) re-skinning with more glazed area, and (5) attaching a double glazed skin to the existing original facade. ❧ These possibilities for the first step in the energy demand derived from facade interventions are explored in this thesis, which considers the results of the energy simulations and recorded energy consumption data. Each facade retrofit scenario is evaluated individually and combined with the most effective from each type. The thesis approach is based on the belief that building facade retrofits represent a unique opportunity to have a major impact on total energy use of existing buildings. Further research will expand this thesis results beyond the purely energy perspective.

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Asset Metadata

Creator Martinez Arias, Andrea Soledad (author)

Core Title Facade retrofit: enhancing energy performance in existing buildings

School School of Architecture

Degree Master of Building Science

Degree Program Building Science

Publication Date 11/27/2013

Defense Date 09/30/2013

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

Tag energy performance,energy simulation,existing buildings,OAI-PMH Harvest

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Noble, Douglas (committee chair), Berney, Rachel (committee member), Schiler, Marc (committee member)

Creator Email ama912@gmail.com,asmartin@usc.edu

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c3-352554

Unique identifier UC11287882

Identifier etd-MartinezAr-2194.pdf (filename),usctheses-c3-352554 (legacy record id)

Legacy Identifier etd-MartinezAr-2194.pdf

Dmrecord 352554

Document Type Thesis

Rights Martinez Arias, Andrea Soledad

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