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A proposal for building envelope retrofit on the Bonaventure Hotel: a case study examining energy and carbon

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A Proposal for Building Envelope Retrofit on the Bonaventure Hotel:

A Case Study Examining Energy and Carbon

by

Alexxa Solomon

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

MAY 2020

Copyright 2020 Alexxa Solomon

ii

ACKNOWLEDGEMENTS

First, I would like to thank my committee members from the USC School of Architecture, Prof.
Douglas Noble (dnoble@usc.edu) for encouraging me to complete and challenge myself throughout this
thesis research. This thesis would not be possible if it wasn’t for your guidance. Thank you Prof. Marc
Schiler (marcs@usc.edu) and Prof. Joon-Ho Choi (joonhoch@usc.edu) for your suggestions, generous
patience, and wisdom.
I would also like to thank the University of Southern California for giving me this opportunity to
study this research. Special thanks to my mother, grandparents, family members, and friends for their
continued support during the process of researching and writing this thesis.
iii

TABLE OF CONTENTS

ACKNOWLEDGEMENTS .......................................................................................................................... ii

LIST OF TABLES ....................................................................................................................................... vi

LIST OF FIGURES .................................................................................................................................... vii

ABSTRACT .................................................................................................................................................. x

1. INTRODUCTION .................................................................................................................................... 1
1.1 Westin Bonaventure Hotel .................................................................................................................. 1
1.2 Unique buildings................................................................................................................................. 3
1.3 Bonaventure façade retrofit ................................................................................................................ 4
1.3.1 Façade retrofit strategies ............................................................................................................. 5
1.4 CO 2 emissions ..................................................................................................................................... 7
1.4.1 Embodied energy ......................................................................................................................... 7
1.4.2 New building materials ............................................................................................................... 7
1.5 Retrofit existing building façades ....................................................................................................... 8
1.5.1 CO 2 and energy demands ............................................................................................................ 8
1.5.2 Building façade ........................................................................................................................... 8
1.6 Façade strategies ................................................................................................................................. 8
1.6.1 Insulation ..................................................................................................................................... 9
1.6.2 Embodied and operational energy ............................................................................................... 9
1.6.3 Window glazing .......................................................................................................................... 9
1.6.4 Air tightness .............................................................................................................................. 10
1.6.5 Solar shading ............................................................................................................................. 11
1.6.6 CO 2 and façade strategies .......................................................................................................... 11
1.7 Summary ........................................................................................................................................... 12

2. BACKGROUND AND LITERATURE REVIEW ................................................................................. 13
2.1 Westin Bonaventure Hotel ................................................................................................................ 13
2.2 Unique buildings............................................................................................................................... 13
2.3 Bonaventure façade retrofit .............................................................................................................. 14
2.4 CO 2 emissions ................................................................................................................................... 15
2.4.1 Embodied energy ....................................................................................................................... 15
2.4.2 Reused and recycled materials .................................................................................................. 16
2.4.3 New building materials ............................................................................................................. 17
2.4.4 Building material inventory....................................................................................................... 18
2.4.5 Building material selection ........................................................................................................ 20
2.4.6 Benefits of timber ...................................................................................................................... 21
2.5 Retrofit existing building façades ..................................................................................................... 22
2.5.1 CO 2 and energy demands .......................................................................................................... 22
2.5.2 Building façade ......................................................................................................................... 22
2.5.3 Air leakage ................................................................................................................................ 23
2.6 Façade strategies ............................................................................................................................... 24
2.6.1 Insulation ................................................................................................................................... 24
2.6.2 Embodied and operational energy ............................................................................................. 25
2.6.3 Window glazing ........................................................................................................................ 26
2.6.4 Air tightness .............................................................................................................................. 27
iv

2.6.5 Solar shading ............................................................................................................................. 28
2.6.6 CO 2 and façade strategies .......................................................................................................... 28
2.7 Summary ........................................................................................................................................... 29

3. METHODOLOGY ................................................................................................................................. 30
3.1 Methodology diagram ....................................................................................................................... 32
3.2 Case study ......................................................................................................................................... 33
3.2.1 HOBO data ................................................................................................................................ 33
3.2.2 Building geometry ..................................................................................................................... 36
3.2.3 Revit .......................................................................................................................................... 39
3.2.4 Model the south room ............................................................................................................... 40
3.3 Data collection .................................................................................................................................. 46
3.3.1 Existing façade building materials ............................................................................................ 47
3.3.2 Athena ....................................................................................................................................... 47
3.3.3 Modeling and analysis tools ...................................................................................................... 49
3.3.4 ZWICKY chart .......................................................................................................................... 50
3.3.5 Energy Use Intensity (EUI) ....................................................................................................... 51
3.4 Façade alternatives ........................................................................................................................... 52
3.4.1 Application ................................................................................................................................ 52
3.4.2 gbXML export ........................................................................................................................... 54
3.4.3 IES-VE ...................................................................................................................................... 58
3.4.4 Climate zone selection .............................................................................................................. 58
3.4.5 Glazing values ........................................................................................................................... 59
3.4.6 Adjacent buildings ..................................................................................................................... 65
3.4.7 SunCast ..................................................................................................................................... 70
3.4.8 Export total energy data ............................................................................................................ 71
3.4.9 Base case calculation ................................................................................................................. 72
3.4.10 Retrofit calculation .................................................................................................................. 73
3.4.11 Export CO 2 data ...................................................................................................................... 73
3.4.12 Orientation simulations ........................................................................................................... 74
3.4.13 Energy consumption and carbon comparison.......................................................................... 75
3.5 10
th
floor Revit model ....................................................................................................................... 75
3.6 Summary ........................................................................................................................................... 77

4. RESULTS ............................................................................................................................................... 78
4.1 South façade ..................................................................................................................................... 80
4.1.1 Retrofit application .................................................................................................................... 80
4.1.2 Additional retrofit strategies ...................................................................................................... 82
4.1.3 South façade – summary ........................................................................................................... 92
4.2 Southeast façade ............................................................................................................................... 93
4.2.1 Southeast façade – summary ..................................................................................................... 96
4.3 East façade ........................................................................................................................................ 97
4.3.1 East façade – summary .............................................................................................................. 99
4.4 Northeast façade ............................................................................................................................. 100
4.4.1 Northeast façade – summary ................................................................................................... 102
4.5 North façade ................................................................................................................................... 102
4.5.1 North façade – summary ......................................................................................................... 104
4.6 Northwest façade ............................................................................................................................ 105
4.6.1 Northwest façade – summary .................................................................................................. 107
4.7 West façade..................................................................................................................................... 108
4.7.1 West façade – summary .......................................................................................................... 109
v

4.8 Southwest façade ............................................................................................................................ 110
4.8.1 Southwest façade – summary .................................................................................................. 111
4.9 S, SE, E, NE, N, NW, W, and SW summary .................................................................................. 111
4.10 10
th
floor – façade retrofit design .................................................................................................. 114
4.10.1 Operational CO 2 calculation .................................................................................................. 123
4.11 Summary ....................................................................................................................................... 125

5. DISCUSSION ....................................................................................................................................... 127
5.1 Evaluation of the workflows ........................................................................................................... 128
5.1.1 ZWICKY chart ........................................................................................................................ 129
5.1.2 Revit room modeling ............................................................................................................... 129
5.1.3 IES-VE room simulations ....................................................................................................... 130
5.2 Comparison of results ..................................................................................................................... 130
5.2.1 South façade ............................................................................................................................ 131
5.2.2 Southeast façade ...................................................................................................................... 131
5.2.3 East façade............................................................................................................................... 132
5.2.4 Northeast façade ...................................................................................................................... 132
5.2.5 North façade ............................................................................................................................ 132
5.2.6 Northwest façade ..................................................................................................................... 133
5.2.7 West façade ............................................................................................................................. 133
5.2.8 Southwest façade ..................................................................................................................... 133
5.2.9 S, SE, E, NE, N, NW, W, and SW .......................................................................................... 134
5.2.10 10
th
floor – façade retrofit design .......................................................................................... 136
5.2.11 Operational CO 2 .................................................................................................................... 138
5.3 Summary ......................................................................................................................................... 138

6. CONCLUSION AND FUTURE WORK ............................................................................................. 140
6.1 Conclusion ...................................................................................................................................... 140
6.2 Evaluation of methodology ............................................................................................................ 141
6.2.1 Improvements to current workflow ......................................................................................... 142
6.2.2 Façade variation strategy ......................................................................................................... 143
6.2.3 Future work ............................................................................................................................. 144
6.3 Summary ......................................................................................................................................... 145

REFERENCES ......................................................................................................................................... 148

vi

LIST OF TABLES

2. BACKGROUND AND LITERATURE REVIEW ................................................................................. 12

Table 2.1 Building weights ......................................................................................................................... 18
Table 2.2 Building embodied energy .......................................................................................................... 18
Table 2.3 Embodied energy and carbon emissions ..................................................................................... 19
Table 2.4 Energy breakdown (W h/m2) ...................................................................................................... 25
Table 2.5 Reduced energy (%) .................................................................................................................... 27

3. METHODOLOGY ................................................................................................................................. 30

Table 3.1 Existing façade materials ............................................................................................................ 47
Table 3.2 Modeling software ...................................................................................................................... 49

4. RESULTS ............................................................................................................................................... 78

Table 4.1 Energy savings per façade system (%) – south façade ............................................................... 82
Table 4.2 Energy savings per façade system (%) – south façade ............................................................... 87
Table 4.3 Energy savings per façade system (%) – south façade ............................................................... 88
Table 4.4 Energy savings per façade system (%) – south façade ............................................................... 91
Table 4.5 Energy savings per façade system (%) – southeast façade ......................................................... 94
Table 4.6 Energy savings per façade system (%) – east façade .................................................................. 98
Table 4.7 Energy savings per façade system (%) – northeast façade ....................................................... 101
Table 4.8 Energy savings per façade system (%) – north façade .............................................................. 103
Table 4.9 Energy savings per façade system (%) – northwest façade ...................................................... 106
Table 4.10 Energy savings per façade system (%) – west façade ............................................................. 108
Table 4.11 Energy savings per façade system (%) – southwest façade .................................................... 110
Table 4.12 Energy savings per façade system (%) – S, SE, E, NE, N, NW, W, and SW orientations ..... 112
Table 4.13 Energy savings per façade system (%) – 10
th
floor façade model .......................................... 117
Table 4.14 Operational CO 2 per façade system (%) – 10
th
floor façade model ........................................ 125

vii

LIST OF FIGURES

1. INTRODUCTION .................................................................................................................................... 1

Figure 1.1 Westin Bonaventure Hotel: façade glare ..................................................................................... 3
Figure 1.2 Westin Bonaventure Hotel: façade deterioration ......................................................................... 3

2. BACKGROUND AND LITERATURE REVIEW ................................................................................. 12

Figure 2.1 Renaissance Center and Westin Peachtree Plaza Hotel ............................................................. 14
Figure 2.2 Building facade heat transfer ..................................................................................................... 23
Figure 2.3 Embodied and operational energy ............................................................................................. 26
Figure 2.4 Air infiltration ............................................................................................................................ 28

3. METHODOLOGY ................................................................................................................................. 30

Figure 3.1 Method diagram ......................................................................................................................... 32
Figure 3.2 HOBO at window sill ................................................................................................................ 34
Figure 3.3 HOBO 5ft from sill and center .................................................................................................. 34
Figure 3.4 HOBO in HVAC unit ................................................................................................................ 34
Figure 3.5 HOBO at back of room .............................................................................................................. 34
Figure 3.6 HOBO at window sill ................................................................................................................ 35
Figure 3.7 HOBO 5ft from window sill ...................................................................................................... 35
Figure 3.8 HOBO at center ......................................................................................................................... 35
Figure 3.9 HOBO back of room.................................................................................................................. 36
Figure 3.10 Westin: Plans ........................................................................................................................... 37
Figure 3.11 Westin: Plans ........................................................................................................................... 37
Figure 3.12 Westin: Plan ............................................................................................................................. 38
Figure 3.13 Westin: Evacuation plan .......................................................................................................... 38
Figure 3.14 Westin: Hotel room plan.......................................................................................................... 38
Figure 3.15 Westin: Hotel room layout plan ............................................................................................... 39
Figure 3.16 Insert hotel room plan .............................................................................................................. 41
Figure 3.17 Scale hotel room plan .............................................................................................................. 41
Figure 3.18 Insert hotel room layout plan ................................................................................................... 42
Figure 3.19 Scale plan to 27’ ...................................................................................................................... 43
Figure 3.20 Construct wall .......................................................................................................................... 43
Figure 3.21 Construct interior partition walls ............................................................................................. 44
Figure 3.22 Add curtain wall ...................................................................................................................... 45
Figure 3.23 Add floor ................................................................................................................................. 45
Figure 3.24 Add floor and ceiling ............................................................................................................... 46
Figure 3.25 ZWICKY chart ........................................................................................................................ 51
Figure 3.26 Revit façade retrofit strategies ................................................................................................. 54
Figure 3.27 Revit space placement ............................................................................................................. 55
Figure 3.28 Revit gbXML export ............................................................................................................... 55
Figure 3.29 Revit gbXML export ............................................................................................................... 56
Figure 3.30 Revit gbXML export ............................................................................................................... 57
Figure 3.31 Revit: gbXML export .............................................................................................................. 58
Figure 3.32 IES-VE climate location .......................................................................................................... 59
Figure 3.33 IES-VE single-glazed values ................................................................................................... 59
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Figure 3.34 IES-VE double-glazed air values............................................................................................. 60
Figure 3.35 IES-VE double-glazed argon values ........................................................................................ 60
Figure 3.36 IES-VE double-glazed krypton values .................................................................................... 61
Figure 3.37 IES-VE triple-glazed air values ............................................................................................... 61
Figure 3.38 IES-VE triple-glazed argon values .......................................................................................... 62
Figure 3.39 IES-VE triple-glazed krypton values ....................................................................................... 62
Figure 3.40 Façade retrofit iterations .......................................................................................................... 63
Figure 3.41 Façade retrofit iterations .......................................................................................................... 64
Figure 3.42 Construction lines .................................................................................................................... 65
Figure 3.43 Construction lines: plan view .................................................................................................. 66
Figure 3.44 Draw extruded shape ............................................................................................................... 66
Figure 3.45 Shape trace ............................................................................................................................... 67
Figure 3.46 Model to adjacent building ...................................................................................................... 68
Figure 3.47 Model to adjacent building ...................................................................................................... 69
Figure 3.48 Model to adjacent building ...................................................................................................... 69
Figure 3.49 IES-VE sun cast ....................................................................................................................... 71
Figure 3.50 IES-VE sun cast ....................................................................................................................... 71
Figure 3.51 IES-VE energy usage............................................................................................................... 72
Figure 3.52 IES-VE total carbon................................................................................................................. 74
Figure 3.53 IES-VE orientations ................................................................................................................. 75
Figure 3.54 10
th
floor Revit model .............................................................................................................. 76
Figure 3.55 10
th
floor Revit model: plan ..................................................................................................... 76

4. RESULTS ............................................................................................................................................... 78

Figure 4.1 Façade retrofit iterations ............................................................................................................ 80
Figure 4.2 South façade .............................................................................................................................. 81
Figure 4.3 South façade – versions 1 to 15 ................................................................................................. 90
Figure 4.4 South façade – versions 15 to 22 ............................................................................................... 92
Figure 4.5 Southeast façade ........................................................................................................................ 93
Figure 4.6 Southeast façade ........................................................................................................................ 94
Figure 4.7 Southeast façade – versions 1 to 11 ........................................................................................... 96
Figure 4.8 Southeast façade – versions 5 to 11 ........................................................................................... 96
Figure 4.9 East façade ................................................................................................................................. 97
Figure 4.10 East façade ............................................................................................................................... 98
Figure 4.11 East facade – versions 1 to 8 ................................................................................................... 99
Figure 4.12 Northeast façade .................................................................................................................... 100
Figure 4.13 Northeast facade – versions 1 to 8 ......................................................................................... 102
Figure 4.14 North façade .......................................................................................................................... 103
Figure 4.15 North facade – versions 1 to 5 ............................................................................................... 104
Figure 4.16 Northwest façade ................................................................................................................... 105
Figure 4.17 Northwest facade – versions 1 to 7 ........................................................................................ 107
Figure 4.18 West facade – versions 1 to 8 ................................................................................................ 109
Figure 4.19 Southwest facade – versions 1 to 7 ........................................................................................ 111
Figure 4.20 Façade retrofit energy savings ............................................................................................... 113
Figure 4.21 Revit 10
th
story design gbXML export .................................................................................. 116
Figure 4.22 IES-VE 10
th
story design gbXML import .............................................................................. 116
Figure 4.23 Story designs ......................................................................................................................... 119
Figure 4.24 Story designs ......................................................................................................................... 120
Figure 4.25 Design v2 ............................................................................................................................... 120
Figure 4.26 Design v3 ............................................................................................................................... 121
ix

Figure 4.27 Design v4 ............................................................................................................................... 121
Figure 4.28 Design v8 ............................................................................................................................... 122
Figure 4.29 Design v9 ............................................................................................................................... 122
Figure 4.30 Design v20 ............................................................................................................................. 123

5. DISCUSSION ....................................................................................................................................... 126

Figure 5.1 10
th
floor façade retrofit results ............................................................................................... 135
Figure 5.2 10
th
floor façade retrofit results ............................................................................................... 137

6. CONCLUSION AND FUTURE WORK ............................................................................................. 139

Figure 6.1 IES-VE batch simulation ......................................................................................................... 142
Figure 6.2 Façade variation strategy ......................................................................................................... 143

x

ABSTRACT

As buildings age, they can be perceived outdated compared to their more modern counterparts with
regards to sustainability and energy. The state of art in building envelopes continues to advance and new
technologies are developed. A building that is merely 50 years old might have energy and daylighting
profiles that compare unfavorably to modern buildings. Demolishing and replacing buildings can improve
their energy consumption, but the financial costs can be excessive. Sometimes the costs and implications
of demolition outweigh the advantages of the energy improvements. Embodied energy costs of new
materials, transportation, construction, and disposal are additional costs that should be considered when
designing architecture. Often it can make economic sense to rehabilitate or upgrade the envelope of a
structurally and spatially sound building. A unique building in downtown Los Angeles has been selected
as a testbed for various hypothetical façade replacement strategies implementing energy and carbon control.
This iconic building that is well-known to residents of the region will be re-examined for façade retrofit
instead of demolition. The study will propose and analyze a small set of design alternatives for the Westin
Bonaventure Hotel in Los Angeles.

HYPOTHESIS

Façade retrofit on the Bonaventure Hotel can reduce 40% of energy consumption and 20% of CO 2
emissions.

RESEARCH OBJECTIVES

- Provide a set of possible resolutions for building façade retrofit,
- Examine the current energy performance conditions of the Westin Bonaventure Hotel,
- Implement 2000 era façade strategies,
- Reduce energy consumption and carbon footprint.
1

1. INTRODUCTION

The building sector accounts for 30-40% of the total energy consumption in the United States.
Heating, cooling, and lighting are the main contributors of energy consumption. If existing façades are
retrofitted, energy consumption and carbon footprint are expected to decrease. Retrofitting outdated façades
are also beneficial to the appearance of the building. A case study building built in 1976, the Los Angeles
Westin Bonaventure Hotel, will illustrate this analysis of retrofitting an existing façade. The purpose of this
thesis is to analyze a unique 1970s building, retrofit the existing façade, reduce CO 2 emissions, decrease
the current energy consumption, and enhance environmental sustainability.

1.1 Westin Bonaventure Hotel
The Westin Bonaventure Hotel is a landmark building designed by John C. Portman in Los
Angeles, California. John C. Portman is an American architect and real estate developer who is widely
known for designing multi-story atriums. Portman is from Atlanta, Georgia and was one of the first
architect-developers in the United States. In the 1960s, architects who were also developers were perceived
to have an unethical joint career (Faoro and Merrill 1990). Although Portman was a developer, he was
known as an architect first and used his skill to design notable atriums. Portman has designed similar atrium
hotels throughout the United States and has explored the atrium concept with various geometric forms.
Buildings similar to the Westin Bonaventure Hotel are the Renaissance Center in Detroit, Michigan, Hyatt
Regency Embarcadero Plaza in San Francisco, and Westin Peachtree Plaza Hotel in Atlanta, Georgia.
Though the Renaissance Center and Westin Peachtree Plaza Hotel are also significant buildings, the Westin
Bonaventure Hotel will be used as a case study to provide retrofit resolutions for other unique structures.
The Bonaventure is a 367-foot, thirty-three story building with four mirrored cylinders surrounding
a central tower. These hotel cylinders and tower are placed on a high concrete base with a revolving cocktail
lounge on the top floor. The Bonaventure Hotel was designed to have a revolving lounge on a circular
platform with a 360º view of Los Angeles. A glass façade was also applied to maximize the views of L.A.
2

and used bronze mirrored glass for minimal transparency to not expose the interior. In the 1970s, mirrored
glass was a common building material for the reduction of heat transfer. Now, the mirrored glass is outdated
and newer technologies are expected to improve the current energy performance.
Additional materials used on the Bonaventure are steel mullions and sand colored concrete. The
concrete was used for the foundation of the hotel, floor slabs, parking garage, interior walls, and structural
core. Steel was primarily used for the mullions of the curtain wall system and elevators. The elevators
mainly consist of glass and steel with a capsule like form. These four elevators all surround the central core
of the building and are seen from the exterior after the sixth floor. Inside each of the elevators, visitors have
views of the Los Angeles landscape as well as the façade of the hotel. Since the façade of the Westin
Bonaventure can be closely seen within the elevators, façade retrofitting is significant to the appearance of
the building. As a guest of the Bonaventure, seeing rusted steel or discolored glass film is not appealing
when staying at the hotel.
This Westin Bonaventure Hotel is postmodern style architecture, recognized in the book
Postmodernism, or, the Cultural Logic of Late Capitalism (Jameson 1992) and Postmodern Geographies:
The Reassertion of Space in Critical Social Theory (Eflin and Soja 1990). The Bonaventure was
additionally acknowledged in over fifteen Hollywood blockbuster movies (Westin Bonaventure Hotel and
Suites 2019). John C. Portman’s innovative hotel evokes a unique building concept that might benefit from
an updated façade system.

3

Figure 1.1 Westin Bonaventure Hotel: façade glare (Author 2019)

Figure 1.2 Westin Bonaventure Hotel: façade deterioration (Author 2019)

1.2 Unique buildings
Since some older buildings are often known to perform inefficiently, there is an opportunity to
decrease operational energy and embodied energy by replacing the building envelope. There are many
significant buildings throughout the world that can reduce energy consumption worldwide. In researching
4

the Westin Bonaventure Hotel as a case study, this circular shaped building can propose similar strategies
to the Renaissance Center and Westin Peachtree Plaza Hotel. There is an opportunity to apply unique façade
strategies to buildings like the Bonaventure that are not commonly built in the U.S.

1.3 Bonaventure façade retrofit
Unfortunately, the Westin Bonaventure Hotel and similar buildings built in the 1970s show strong
indications of wear and are visually outdated. Rather than demolish an existing building, and construct a
new building – can the Westin Bonaventure be re-used? Building demolition is common in the building
industry and significant CO 2 emissions are emitted during demolition. Although existing buildings are not
often re-examined and retrofitted for efficient energy performance, this study will show a reduction in
carbon footprint and energy consumption. By replacing the existing façade, energy efficiency can improve.
Currently, the bronze façade on the Bonaventure Hotel is mainly known for the reduction of heat
transfer. Fredric Jameson argues that the mirrored glass applied on the Bonaventure is a design aesthetic
(Jameson 1992). Jameson believes that the distorted images is a symbol of induced physiological effects
and the visual effects of the mirrored glass is part of the design (Jameson 1992). Yet according to Portman’s
works, other critics suggest that the distorted images on the mirrored glass are a result of the glazing
technology and the glass was used for an economic benefit. Fieldhouse and Ocran mention that Portman’s
previous statements focuses on the economic savings of the 1970s (Fieldhouse and Ocran 1998). Portman
understood that architecture development is a profit-oriented system, and construction costs needed to be
cut (Fieldhouse and Ocran 1998). This implying, that the bronze mirrored glass on the hotel is used for the
reduction of heat and not for a unique aesthetic appearance.
John Portman, with an architect and developer background, believed in incorporating large atrium
spaces that may be considered “wasted spaces” into hotel design. However, in order to include this atrium
design, cutting construction costs was further implied in his completed works. Barnett mentions that
applying mirrored glass on the Bonaventure was the most economical use of technology that Portman could
have used (Barnett 1976) (Fieldhouse and Ocran 1998). Implementing atrium spaces in hotel design was
5

later mentioned as an additional cost to improve the hotel’s interior. The construction costs of the exterior
needed to be cut for the interior of the hotel to have “wasted spaces.” In Portman’s later works, he elaborated
mostly about the interior of the building than the exterior. Portman had a passion for interior atrium spaces
and the exterior façade does not appear to be aesthetically necessary to preserve. The façade of the building
will be examined as economically driven, and further additions and replacements can improve the idea of
a 2020 façade.
Countries around the world are also proposing a goal similar to the U.S. 2030 challenge – to
decrease carbon emissions and energy consumption. Through retrofitting existing building façades, an
increase in energy savings can usually be achieved. The Westin Bonaventure Hotel will be analyzed to
study the benefits of façade retrofit.
Since the objective is to reduce energy consumption and carbon footprint – a resolution is to retrofit
an existing building’s insulation, lighting, and glazing. Instead of demolishing the building, there is an
opportunity to avoid the embodied energy used to build a new building and the CO 2 emitted during the
construction process.

1.3.1 Façade retrofit strategies
As heating, cooling, and lighting are key contributors to the energy consumption in a building –
façade strategies are implemented to decrease heat transfer. Façade retrofits can also improve the
appearance of the existing building with the use of current façade technologies. This thesis analyzes
efficient façade strategies for an existing glass façade. The main objective is to apply an updated façade
technology of the 2000 era onto a unique 1970s building. The façade strategies will combine the appearance
of the current building envelope with a new efficient technology.

The research objectives include:
- Provide resolutions for building façade retrofit,
- Examine the current energy performance conditions of the Westin Bonaventure Hotel,
- Implement 2000 era façade strategies,
6

- Reduce energy consumption and carbon footprint.

Buildings prior to the 1990s, were constructed with inefficient façades in comparison to today’s
technology. While many existing buildings are occupiable, energy efficiency is lacking. By using 2020
façade technology on existing buildings, the façade systems can implement an environmental change to
buildings energy consumption. Energy efficient façade technologies can be adapted to the present buildings
that are lacking energy efficiency.
Weathering and deterioration of the building façade systems are likewise significant in adapting
retrofit technologies to a 1970s building. As appearance is important to the building and the public, not only
restoring the existing façade is necessary. The Bonaventure has the opportunity to become a new 2020
building. With the application of an updated façade, the Westin will be combined with a modern hybrid
façade system. Yet, the appearance of the Westin Bonaventure will not be restored to its original nor
demolished to be solely new. The façade retrofit is a hybrid of both old and new.
Failures of the current façade systems are considered, including the corrosion due to weathering
and age-related deterioration. Addressing the problems of the Westin now can allow for the existing
building to be saved from further damage. In order to meet future energy performance goals of the 2030
challenge, existing buildings need to be re-examined.
Traditionally, air leakage is present in older buildings like the Bonaventure Hotel. Since the
Bonaventure’s façade is mainly outdated with the mirror film deteriorating and rusted mullions, the air
leakage is expected to cause energy inefficacy compared to the new façade technologies. Although
retrofitting mechanical systems are common in reducing operation and demolition CO 2, façade retrofits can
also increase energy savings in the long term. If new 2020 HVAC systems are installed in the hotel without
taking into account that there is an aged curtain wall system – the building will not perform to its potential.
Air intended to heat and cool a room will seep through the curtain wall system and not serve the interior
comfort of the hotel room. By first replacing the façade system as the main contributor in decreasing HVAC
costs, later improvements can be made for increased energy performance and cost savings. Since future
7

energy performance and CO 2 emissions goals will impact the hotel’s design process, implementing the
reduction CO 2 should be considered during the initial steps of retrofitting the façade.

1.4 CO 2 emissions
Though building CO 2 emissions does not consist solely on the demolition of buildings, CO 2 and
other factors should be considered for the reduction of emissions. The life cycle assessment (LCA)
evaluates building CO 2 emissions in three categories; embodied energy, operations related CO 2, and
demolition. The following categories: embodied energy, operations, and demolition are analyzed in this
research.

1.4.1 Embodied energy
CO 2 is a chemical compound that is a result of burned fossil fuels. In the building industry,
embodied energy includes transportation during construction, extraction of the raw materials, and
maintenance of the materials when completed. Operation and demolition energy are additional LCA factors
that burn fossil fuels and emits CO 2. Operation energy is produced by HVAC systems and lighting.
Demolition energy consists of onsite material waste and material transportation to the dump site. CO 2, in
addition, is analyzed as it contributes to energy consumption.

1.4.2 New building materials
The façade materials are also considered and changed or augmented using these retrofitting
strategies. Since façade materials impact embodied energy, the intention is to examine materials that
contribute to energy consumption. Although the main objective is to focus on retrofitting an existing façade,
using materials that are less energy intensive are as significant in this thesis.
8

1.5 Retrofit existing building façades
1.5.1 CO 2 and energy demands
To decrease carbon footprint and energy consumption, in the building sector, existing buildings
should be re-examined. Retrofitting existing buildings can reduce energy consumption through adding new
façade systems. Façades systems with efficient technology can reduce the operational energy needed to air-
condition the building. When the building uses less electricity for HVAC systems then less CO 2 is emitted.
In addition, retrofitting existing buildings can produce less carbon waste than constructing new buildings.

1.5.2 Building façade
One of the primary sources of heat transfer is building façade systems. Updating façade systems
are important to the mitigation of heat entering and exiting the building. The recommended retrofit
strategies include; improving the existing building’s insulation, adding solar shading, and adjusting the
current glazing systems. Solar protection, and safety are likewise significant. Increasing thermal insulation,
improving window glazing, and adding solar shading to an existing building, overall reduces energy up to
31% (El-Darwish and Gomaa 2017).

1.6 Façade strategies
Since existing building façades can allow up to approximately ¼ of energy savings, façade systems
are further analyzed. The retrofit façade strategies are; insulation, glazing, solar shading, and lower CO 2
emissions through materiality. In addressing these façade options, a reduction in energy consumption is
expected for the Bonaventure Hotel. Increasing the current insulation of the building, examining different
layers of glazing, and placing solar shading, is expected to decrease energy consumption. Glazing layers to
consider are; single, double, and triple. The glazing layers can also improve the insulation of a building
façade system.

9

1.6.1 Insulation
Insulation is a façade strategy that will benefit the building envelope moderately. Building
envelopes during the Post-World War were not constructed with efficient insulation (Martinez et al. 2015).
In the application process of the retrofit strategies, insulation increased and energy consumption was
compared. After applying 0.05m of insulation to a case study building in Egypt, energy consumption
calculated decreased by 386.95 W h/m2 (El-Darwish and Gomaa 2017). Façade retrofits have shown that
energy consumption can be reduced by implementing updated façade strategies (El-Darwish and Gomaa
2017).

1.6.2 Embodied and operational energy

Although building operational energy can significantly decrease with newer HVAC systems, the
embodied energy in the new materials represent an increase if the building is demolished. CO 2 emitted from
building operations is combined with the deconstruction of materials. If decreasing operational energy is
solely considered with energy efficient mechanical equipment, an opportunity to reduce additional energy
consumption cannot be achieved.

1.6.3 Window glazing
Though glazing systems are commonly used, single-glazed windows are unfortunately lacking
energy efficiency due to the higher U-values and minimal insulation. Single-glazed systems are re-
evaluated for the purpose of improving energy efficiency. As common as high-performance glazing systems
are in more recent architecture, 1900s buildings can benefit from the updated system. Currently, the 1970s
glazing material is lacking energy efficiency and can gain knowledge from the 2000s era glazing
technology. The glazing technology as of now, can perform with embedded ventilation and insulation that
was not applied during the construction of the 1970s. By updating the glazing system of the Westin
Bonaventure and similar case study buildings, an increase of energy performance is expected. Window
glazing can also decrease the use of HVAC systems and lighting.
10

Two glazing manufacturers used for reference are Milgard and YKK. Milgard has 2000 era double-
glazed products with a 0.46 U-factor, visual transmissivity (VT) of 0.56, and less than 0.3 air leakage
(NFRC Detailed Product Ratings 2019). YKK also has double-glazed products with U-factors of 0.47 and
VT of 0.59 (NFRC Detailed Product Ratings 2019). As of now, double-glazed products are known to have
U-values that are significantly less than the average single-glazed product. The average single-glazed U-
factor is approximately 1.0 with a VT of 0.84 (ASHRAE Standard: Standard Method of Test for the
Evaluation of Building Energy Analysis Computer Programs 2010). Lower U-values are expected to
perform more efficiently than higher U-values. Some triple-glazed products have approximately 0.44 U-
factors and a VT of 0.50. Triple-glazed low-e products are also more energy efficient with a 0.19 U-factor
and a 0.42 VT.
In addition, applying specific gas-fillers in a glazing unit can allow the glazing product to perform
more efficiently. Insulated glass can include air, argon, krypton, or xenon. Air is the most common filler
for insulated glass since it is less expensive. Yet, argon, krypton, and xenon are more efficient in energy
performance compared to air (Argon, Krypton, and Xenon-What's the Best Gas-Insulated Window? 2019).
With comparison to krypton and argon – xenon appears to be the most efficient due to the lower U-factor,
yet argon is commonly used since it is more affordable (Argon, Krypton, and Xenon-What's the Best Gas-
Insulated Window? 2019). Low-e can also be combined with the gas-filler and allow an additional decrease
in heat gain.

1.6.4 Air tightness
Air tightness is a construction method that can be applied to a building’s façade to reduce air
infiltration and exfiltration. Since a building’s temperature can become impacted by heat and also air, air
infiltration is necessary to mitigate the temperature of the room or building. With the use of air tightness in
a building retrofit system, air exchange is limited, and the exterior air is less likely to enter the building.
Interior air will also be less likely to exit the building, allowing the maintenance of the indoor air quality
(IAQ). With the use of air tightness in façade envelope systems, the reduction of air leakage can improve
11

the IAQ for the building occupants. Buildings that receive too much air leakage can also enforce areas of
the building to become moldy and cause health complications for the occupants (ASHRAE Position
Document on Limiting Indoor Mold and Dampness in Buildings 2018). Building occupants are significant
reasons to reduce air leakage, aside from energy performance. Occupants staying at the Bonaventure Hotel
and likewise buildings should have the accommodation of better temperature accuracy. Condensation can
also occur in the façade systems and enforce additional mold. As significant as infiltration is to the indoor
environment, exfiltration is equally important. The indoor air can also exit the building, causing the loss of
heated or air-conditioned air.

1.6.5 Solar shading
Solar control is likewise important in reducing energy consumption of operational CO 2 (HVAC
systems and lighting). Louvers and overhangs are optimal shading devices that can be applied to window
glazing and improve insulation. These solar shading devices are valuable façade systems for windows and
curtain walls to mitigate solar radiation. Solar shading is also beneficial in combining a variety of material
choices. Louvers made of wood and steel are commonly used on buildings. Yet, embodied energy for wood
is approximately 8 MJ/kg and steel is 30 MJ/kg. Before selecting louvers or additional façade systems as
an application, embodied energy per material is beneficial to note.

1.6.6 CO 2 and façade strategies

In this thesis, CO 2 emissions are considered when applying façade strategies to the Bonaventure
Hotel. Since new construction can emit more CO 2, these retrofit strategies will suggest minimal construction
changes. When constructing a new envelope, material extraction and type of material should be equally
measured when implementing façade retrofit changes. Building materials are analyzed simultaneously
when applying retrofit changes to the existing building.

12

1.7 Summary
Embodied CO 2, operations related CO 2, and demolition were all significant factors in analyzing the
CO 2 emittance of the Westin Bonaventure in this research. The objective of this thesis is to determine how
to decrease CO 2 and energy consumption by retrofitting an existing façade and applying it to unique
buildings. Façade material variables are changed and energy performance is adjusted using the retrofitted
strategies of insulation, window glazing, solar shading, and material selection.

13

2. BACKGROUND AND LITERATURE REVIEW

2.1 Westin Bonaventure Hotel
Th Westin Bonaventure Hotel has 1,354-rooms with commercial businesses on the second through
sixth floor. There is a banquet room, California ballroom, restaurants, and shopping areas surrounding the
atrium. On the lobby level there is a circular bar with a reflecting pool surrounding. Circular stairs are seen
around concrete columns on the third and fifth floor connected to bridging walkways. There are external
glass elevators surrounding the central core for circulation into the four neighboring cylinders. These
elevators enter the top of the atrium space and then become internal elevators in the lower floors. The lobby
floor is complex, with the first six floors forming the atrium space. In the lobby the atrium can be seen, but
thereafter the exterior views of the hotel rooms become visible. Each standard hotel room is approximately
200 square feet and suites are up to 2,520 square feet with floor-to-ceiling windows. The Bonaventure
façade is combined with mirrored glass, steel, and attached to a concrete foundation. In 2011, the rooms at
Westin Bonaventure Hotel were initially renovated and again renovated in September 2019. Plans to
renovate the exterior were not disclosed, and this invites the idea of analysis to examine the potential energy
savings through façade retrofit.

2.2 Unique buildings
Approximately 15% of buildings in the U.S. were built before 1950, 50% between 1950 to 1979,
and 12.5% are 1980 to current (Martinez et al. 2015). Half of the buildings in the U.S. could require re-
examination of their building performance. Out of the 50% of buildings built during 1950 to 1979, 17%
were stated as restored or preserved (Martinez et al. 2015). Thus, 48% of existing buildings in the U.S.
could profit from an updated building performance system rather than demolishment. Demolishing
buildings can impact not only the demolition CO 2, but the use of additional embodied energy to transport
and extract new materials. Buildings that are unique or common, suggest an energy performance analysis
for the future of energy efficiency. In order to achieve the 2030 challenge, new and existing buildings
14

require efficient energy performance. With comparison to the Westin Bonaventure, the Renaissance Center
and Westin Peachtree Plaza Hotel can likewise benefit from this study. Although the buildings are in
different states, the circular floor shapes are similar to the Bonaventure Hotel in Los Angeles. Both, the
Renaissance Center and Westin Peachtree Plaza have outdated glass and can gather new data from a similar
façade retrofit analysis.

Figure 2.1 Renaissance Center and Westin Peachtree Plaza Hotel
(Detroit GM Renaissance Center 2014) (Cramer 2019)

2.3 Bonaventure façade retrofit
Currently, limited information is available for unique building façade retrofits. Previous studies
have examined building envelope refurbishment for common building types. Yet, the buildings studied do
not examine 1970s mirrored glass and do not follow a circular building form. In researching the
Bonaventure Hotel, the mirrored glass is examined further. The mirrored glass applied is found to be a solar
bronze tinted reflective glass with a very thin layer of metal or metallic oxide. The metal or metallic oxide
coatings are a surface application and not a bronze color agent. This technique was common in the 1970s
and is now an older technology. Although producing reflective glass was energy efficient during the 1900s,
technology now has greatly improved. The goal is to improve the façade of the Bonaventure Hotel with a
15

higher-performing façade system, keeping the hotel accessible to the community, and providing an indoor
quality environment with sustainable characteristics. An updated façade system also increases energy
savings due to the reflecting and absorption of sun rays.
Façade retrofits are overall useful in reducing HVAC usage and decreasing operation CO 2. With
the help of LA’s Green New Deal: Sustainability Plan 2019 and 100% Net Zero by 2050 taking into effect,
the Westin Bonaventure and other similar buildings can benefit from this implementation of a façade retrofit.
There is an environmental emergency and moral imperative to reduce carbon emissions in Los Angeles
soon (L.A.’s Green New Deal: Sustainability Plan 2019 2020). The Bonaventure is one of many existing
buildings in Los Angeles that can meet the Net Zero goals, if façade retrofits are applied.
Demolition is an option for better energy performance in new buildings, yet demolition CO 2 and
embodied energy CO 2 should also be considered. Carbon emissions from demolition, extracting new
materials, transporting materials, and building a new building won’t assist with the Net Zero goals. In order
to retrofit unique buildings similar to the Bonaventure Hotel, a simulated model was necessary to compare.

2.4 CO 2 emissions
2.4.1 Embodied energy
A study conducted by Gaspar and Santos indicated that the total embodied energy (EE) by new
construction was three times the EE of the existing building (Gaspar and Santos 2015). The embodied
energy was then analyzed, and the new construction’s EE increased due to the modern materials used. Since
the new building was built with newer materials, the embodied energy was newly expended compared to
the existing. The embodied energy included the transportation of materials during construction and the
extraction of materials. Materials used for both studies, scenario N (new building) and scenario R
(retrofitted building) – showed that less materials were extracted for the retrofitted building than for the
new building, with less weight of the material wasted. Thus, there was more energy expended and
embedded in the new materials than what was expended modifying the old.
16

The following materials used are examined by weight, defining the embodied energy during demolition
and construction. Percentages include the amount the building weight consists of (Gaspar and Santos 2015):
● Concrete - 46%
● Wood - 3.5%
● Steel and Metals - 2%
● Glass - 0.2%
If the building per this case study is demolished, all the structural concrete and additional materials that
could have been saved would be wasted. Carbon is emitted during deconstruction of the existing building
and construction of the new building. Though less energy intensive materials exist, their production is
nonetheless additionally emitting carbon. Carbon emissions include transportation of materials – as
previously stated. Even if the materials chosen are less energy intensive, they are still emitting CO 2 through
the transportation of materials.

2.4.2 Reused and recycled materials
When extracting new materials, the amount of materials extracted are likewise significant. In order
to significantly decrease material extraction, recycled materials should also be explored. With the
application of recycled materials, there is an additional opportunity to reduce negative environmental
impacts and increase economic savings (Camañes et al. 2014). Reusing materials similar to wood, brick,
and steel can be a sustainable effort in reducing CO 2 emissions. However, for the purpose of retrofitting the
façade of the Bonaventure – steel will mainly be considered. Through this study of recycled materials,
recycling can be proposed in the design process to achieve a greater reduction in CO 2 emissions.
In addition, by applying reused materials and preserving the building footprint of the Bonaventure
then the historical context can also be preserved. The history of the Bonaventure Hotel and its circular shape
is part of the Los Angeles landscape. If demolition was an option, then the historical presence of this hotel
would be lost. The appearance instead could be re-designed to acknowledge a newer version of the
Bonaventure with reused or recycled material. This façade retrofit design is an exploration of the
17

Bonaventure Hotel’s retrofit potential. Using recycled or reused materials in the design process can show
that if it is possible for a circular shaped building footprint, it can also be applied to a box shaped building.
Reused materials are materials that are from the same product and reused for the same propose. Recycled
materials are salvaged materials that are used to create a different product. In either instances, these recycled
or reused products are reducing the need to extract new materials from the Earth’s ecosystem. In Latin
America and subtropical areas in Asia, a high rate of resources are becoming depleted due to deforestation
of logging (Lugt 2019). Logging is the act of chopping trees, cutting and preparing new timber. During this
process, if the extraction is excessive there can be a degradation of water sources, habitat loss, release of
toxic chemicals, and threats to endangered species (Lugt 2019). Carefully managed extraction is necessary
to not harm the environment.

2.4.3 New building materials
Based on the previous analysis of material extraction and CO 2 emissions, modern materials are
examined in comparison. Materials that are unexpectedly energy consuming are (Gaspar and Santos 2015):
● Aluminum
● Zinc
● Polymers
● Insulation layers
Generally, when constructing a new commercial building or modern home after demolishing an existing
building then the CO 2 emissions increase. If material selection was examined, CO 2 emissions could reduce
globally. Aluminum is a common building material that is used in modern construction, including modern
glass homes. Modern materials are analyzed further to compare the carbon footprint to an existing building.
Aluminum has an embodied energy of approximately 200 MJ/kg, compared to 22 – 30 MJ/kg for recycled
aluminum (Ashby 2013). Aluminum also has a CO 2 footprint of 11 – 13 kg/kg during primary production
and 2.1 kg/kg for recycled aluminum during the recycling process (Ashby 2013). Although aluminum is an
energy intensive material, recycled aluminum is less energy intensive and emits less carbon. Recycled
18

aluminum is recommended instead of newly produced aluminum as it decreases the overall embodied
energy.
Gasper and Santos mentioned that the case study building, scenario N required twice the embodied
energy than scenario E (existing building) (Gaspar and Santos 2015). Approximately, 39% more material
was required to build the new building. The new building resulted in a lighter building weight with the use
of modern materials and the embodied energy increased by 37% (shown in Table 2.1 and 2.2). Although
the building weight of modern materials was lightweight, the retrofitted building process in reducing the
extraction of raw materials and material transportation is more energy efficient.

Table 2.1 Building weights (Gaspar and Santos 2015)

Scenario E Scenario N Scenario R outputs
Total weight (t) 246.310 341.890 (115.811)
Weight / sqm (t/m²) 1.498 1.392 (0.704)

Table 2.2 Building embodied energy (Gaspar and Santos 2015)

Scenario E Scenario N Scenario R outputs
Embodied energy (GJ) 587.010 1,198.332 (373.611)
EE / sqm (GJ/m²) 3.570 4.881 (2.272)
EE / weight (GJ/t) 2.383 3.505 (3.226)

An existing building is beneficial in decreasing new CO 2 emissions involved in manufacturing new
materials, rather than demolishing the existing building. The results, moreover presented, retrofitting
buildings as more sustainable with less building materials wasted and lower CO 2 emitted.

2.4.4 Building material inventory
With consideration to building materials, embodied energy and carbon emissions – the following
list was used to identify the less intensive CO 2 emitting materials. Bricks, cement, concrete, glass, steel,
and timber were compared.

19

Table 2.3 Embodied energy and carbon emissions (Hammond and Jones 2008)

Material

Embodied energy: MJ/kg

Embodied carbon: kgCO2/kg

Bricks
General
Limestone

Cement
General
Portland cement, wet kiln
Portland cement, semi-wet kiln
Portland cement, dry kiln
Portland cement, semi-dry kiln
Fibre cement
Mortar (1:3 cement: sand mix)
Mortar (1:3)
Mortar (1:0.5: 4.5 cement: lime: sand mix)
Mortar (1:1:6 cement: lime: sand mix)
Mortar (1:2:9 cement: lime: sand mix)
Soil-cement

Concrete
General (1:2:4)
Precast concrete, cement: sand: aggregate
1:1:2 (high strength)
1:1.5:3 (used in floor slabs and columns)
1:2.5:5
1:3:6 (non-structural mass concrete)
1:4:8
Autoclaved aerated blocks (AACs)
Fibre-reinforced
Road and pavement
Road example
Wood-wool reinforced

Glass
General
Fibreglass (Glasswool)
Toughened

Steel
General, ‘typical’ (42.3% recycled content)
General, primary
General, secondary
Bar & rod, ‘typical’ (42.3% recycled content)
Bar & rod, primary
Bar & rod, secondary
Engineered steel, secondary
Galvanised sheet, primary
Pipe, primary
Plate, primary
Section, ‘typical’ (42.3% recycled content)
Section, primary

3
0.85

4.6 2
5.9
4.6
3.3
3.5
10.9
1.4
1.21
1.37
1.18
1.09
0.85

0.95
2
1.39
1.11
0.84
0.77
0.69
3.5
7.75
1.24
2085 MJ/m²
2.08

15
28
23.5

24.4
35.3
9.5
24.6
36.4
8.8
13.1
39
34.4
48.4
25.4
36.8

0.060
-

0.226
0.248
0.226
0.196
0.202
0.575
0.058
0.048
0.053
0.044
0.039
0.038

0.035
0.059
0.057
0.043
0.030
0.026
0.022
0.076-0.102
0.123
0.035
51 kgC/m²
-

0.232
0.417
0.346

0.482
0.749
0.117
0.466
0.730
0.114
0.185
0.768
0.736
0.869
0.485
0.757
20

Section, secondary
Sheet, primary
Wire
Stainless

Timber
General
Glue laminated timber
Hardboard
MDF
Particle board
Plywood
Sawn hardwood
Sawn softwood
Veneer particleboard (furniture)
10
31.5
36
56.7

8.5
12
16
11
9.5
15
7.8
7.4
23
0.120
0.684
0.771
1.676

0.125
-
0.234
0.161
0.139
0.221
0.128
0.123
0.338

2.4.5 Building material selection
Brick and timber were recorded as consuming less energy than glass, cement, steel, and concrete.
Although brick and timber embodies less energy and carbon overall, quantities of concrete and cement are
likewise less energy intensive. Precast concrete, cement: sand: aggregate, 1:1:2 (high strength), 1:1.5:3
(used in floor slabs and columns), 1:2.5:5, road and pavement, 1:3:6 (non-structural mass concrete), and
1:4:8 – are also listed as less than three embodied energy (< 3 MJ/kg) and less than 0.06 embodied carbon
(< 0.06 kgC/kg). Concrete mortar is also documented as less energy intensive than steel and glass. Yet,
mortar combined with bricks as a wall assemblage, is more energy intensive than precast concrete. Precast
concrete is approximately 2 MJ/kg and can be used as the sole material of wall construction. By using a
combination of materials, embodied energy can increase or decrease. Combining materials similar to steel
and glass can increase the embodied energy of a building significantly. Curtainwalls are commonly used in
new building construction and are not considering the overall CO 2 emitted through extracting building
materials. In using building materials carefully, demolition CO 2 and embodied CO 2 can considerably
decrease.
21

Steel and glass are common building materials, and timber is not occasionally used on high-rise
buildings. Yet, with an exploration of combining the timber materials with the new 2000s façade strategies
– a decrease in CO 2 emissions can be accomplished. With consideration to timber, glass, and steel – these
new building materials were further measured.
Since timber production requires less manufacturing, timber has a lower embodied energy
compared to steel and glass. For comparison, glue laminated timber is 12 MJ/kg, engineered steel is 13
MJ/kg, and general glass is 15 MJ/kg. Yet, if façade materials were instead toughened (tempered) glass,
engineered steel, stainless steel, galvanized sheet steel or primary sheet steel, the embodied energy would
increase. Toughened glass embodied energy is 23.5 MJ/kg, ‘typical’ recycled steel is 24.4 MJ/kg, stainless
steel is 56.7 MJ/kg, galvanized sheet steel is 39 MJ/kg, and primary sheet steel is 31.5 MJ/kg (Hammond
and Jones 2008). To select façade materials emitting less CO 2 – recycled steel, engineered steel, timber,
general glass, and toughened glass were further analyzed in this research.

2.4.6 Benefits of timber
Timber is analogously analyzed in this thesis since it is a building material that sequesters CO 2.
Timber is known through photosynthesis to absorb CO 2 and solar energy during the creation of wood. Wood
also releases oxygen and can store carbon depending on the wood density. If wood is used as a building
material with a high wood density, then more carbon can be stored. Approximately 1 m
3
of wood could
store over 1 ton of CO 2 (Lugt 2019) (Wegener 2011). Using sustainable wood can suggest a reduction in
carbon emissions if applied as a façade or structural system. However, not all wood material can sequester
carbon since it depends on the type of wood and its sourcing. It is important to note that carbon sequestration
could benefit the built environment if forest area increases and building construction increases wood usage
(Lugt 2019). There is potential in climate change mitigation using (HWP) harvested wood products
(Aryapratama and Pauliuk 2019). 1.6 Gt of carbon emissions occur every year because of the deforestation
in tropical areas and 0.5 Gt of carbon emissions occur every year due to the burning of fossil fuels (Lugt
2019). The carbon cycle can improve if less fossil fuels are burned, deforestation is stopped, forest
22

conservation has better management, and more durable wood products are used for construction (Lugt
2019).

2.5 Retrofit existing building façades
2.5.1 CO 2 and energy demands
Given the findings of CO 2 emissions and material alternatives, façade retrofit is simultaneously
examined. Façade systems are also considered since retrofit strategies can decrease energy consumption up
to 31%. Material values are also explored in the retrofit process. Energy efficient materials and minimal
construction waste can reduce both CO 2 and energy demands appropriately.

2.5.2 Building façade
The building façade is the primary source of heat entering the building. If heat enters the building,
HVAC systems and energy consumption will generally rise. In order to reduce the site’s energy use intensity
(EUI), the building façade systems need to prevent heat from transferring through walls and windows. Heat
transfer during the summer includes, heat entering the building and heating the interior of the rooms.
However, heat transfer during the winter is heat exiting the building due to conduction and convection.
Building systems for this reason need to consider reducing heat transfer through façade systems to lower
the use of HVAC systems. Through implementing newer façade technology of solar reflection and
absorption, buildings can stay warmer during the winter without using as much of the mechanical heating
or air-conditioning during the summer. Newer technologies of window glazing similar to low-e glazing,
insulation, and solar shading can be useful to the reduction of heat transfer. Increased heat transfer can also
cause uncomfortable indoor environments if heat transfers through the building materials and is not
mitigated (see Fig. 2.2).

23

Figure 2.2 Building façade heat transfer (Author 2019) (Attic Insulation Kingston - Cellulose Fibre Insulation 2015)
(The Westin Bonaventure 2019)

2.5.3 Air leakage
Similar to heat transfer in buildings, air leakage is also a common building problem. Outside air
can enter uncontrollably through cracks and openings, causing infiltration. Air leakage also referred to as
air infiltration, is air that typically filters through cracks in the building envelope and changes the interior
temperature of the building. If outside air is filtered into the building then hot or cold air can change the
indoor air quality (IAQ). If the IAQ changes, the interior of the building can feel warmer or colder than it
was intended. 40% of the total heat loss in buildings can be attributed to air leakage (Mélois et al. 2019)
(Tamura 1975). HVAC systems allow the room temperature to be controlled through thermostats, but if the
24

building temperature is compromised with outside air the thermostat temperature cannot be achieved. Air
infiltration and exfiltration should be mitigated also due to smoke from fires that commonly occur in Los
Angeles. Smoke can enter the building and cause health complications or cause the building to smell like
smoke. Many countries throughout the world are starting to require mitigation in air leakage due to the
amount of energy that is lost in buildings (Leprince, Carrie, and Kapsalaki 2017). Air tightness is highly
recommended for these reasons and should be implemented in any façade retrofit strategy. In addition,
based on this observation these following façade variables are considered; insulation, window glazing, air
tightness, and solar shading.

2.6 Façade strategies
A case study presented by Ardente et al. mentions that by retrofitting a building’s insulation,
lighting, and glazing, efficient energy performance increased (Ardente et al. 2011) (Farmer et al. 2016).
The conducted research of Farmer et al. also states that the reduction of U-values decreased the demand for
heat in the building (Farmer et al. 2016). There is an overall necessity to change the variables in retrofit
design to achieve an energy efficient building. Further studies by El-Darwish and Mohamed Gomaa show
that a five-story building at Tanta University, an Arab Academy for Science Technology (AAST), and a
six-story institute building at Beheira Governorate (BHI) can reduce an average of 23% of energy
consumption with solar shading (El-Darwish and Gomaa 2017). Meanwhile, 8% of energy consumption
can also be reduced with selected glazing variables. With this conducted research, the façade variables
selected will be compared with the existing material properties and the changed values.

2.6.1 Insulation
In El-Darwish and Mohamed Gomaa’s case study, Expanded Polystyrene System (EPS) was found
to improve energy efficiency (El-Darwish and Gomaa 2017). The study applied a 0.05m of added insulation
to the AAST and decreased the energy by 386.95 W h/m2 (shown in Table 2.4). In using this insulation,
the performance increased slightly and changes did show.

25

Table 2.4 Energy breakdown (W h/m2) (El-Darwish and Gomaa 2017)

Retrofit strategy Base
case
Double
glazing
Air
tightness
External wall
insulation
Solar
shading
Tanta University 3843.01 3414.92 3322.88 3270.17 2876.47
BHI 6714.55 6081.63 6126.44 6164.18 3205.78
AAST 4665.96 4422.25 4321.35 4279.01 3597.61
Average Energy
Consumption
5077 4640 4590 4571 3227

2.6.2 Embodied and operational energy
Although operational energy is significant in decreasing building CO 2 emissions, decreasing
embodied energy is likewise essential. Even if operational CO 2 is reduced, additional embodied energy can
be applied when the building is demolished. To achieve a reduction in CO 2 emissions and energy
consumption, both operational CO 2 and embodied energy need to decrease. Operational energy can
decrease when demolishing an existing building and constructing a new building with energy efficient
technology; yet, the embodied energy will also increase. Decreasing operational energy will not save energy
consumption in the long term. Operational energy will continue to emit CO 2 throughout the years while
embodied energy is static and emits CO 2 during construction. CO 2 emitted from operational energy is
combined with the original embodied energy, which is used to build the existing building (see Fig. 2.3). By
demolishing the existing building, the demolition energy will be added to any newly produced embodied
energy (Chow 2010). The original embodied energy will be wasted when the building is demolished and
newly produced embodied energy will be added.
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Figure 2.3 Embodied and operational energy (Chow 2010)

Further studies of similar façade strategies are suggested to retrofit an existing building. Overall,
façade retrofit is expected to reduce additional embodied energy and emit less CO 2 due to the limited
construction.

2.6.3 Window glazing
In addition, improving the existing building glazing values are recommended to decrease energy
consumption. Additional research in El-Darwish and Mohamed Gomaa’s case study found that single-
glazed windows are commonly used throughout the world (El-Darwish and Gomaa 2017). Although single
glazing is common, energy efficiency is lower due to the higher U-values and lack of insulation. Lower U-
values will be adjusted to decrease the heat transfer through the glazing material. In changing the window
glazing variables from single glazed to double glazed, energy usage is expected to decrease (see Table 2.5).

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Table 2.5 Reduced energy (%) (El-Darwish and Gomaa 2017)

Retrofit strategy Base
case
Double
glazing
Air
tightness
External wall
insulation
Solar
shading
Tanta University – 11% 14% 15% 25%
BHI – 5% 7% 8% 23%
AAST – 9% 9% 8% 52%
Achieved Reduction % – 8% 10% 10% 33%

El-Darwish and Mohamed Gomaa studies show a reduction of energy consumption from 3800 W
h/m2 to approximately 2900 W h/m2 in Tanta University (El-Darwish and Gomaa 2017). Variables that
changed for Tanta University include; glazing, wall, insulation, and solar shading. A similar finding was
found in the BHI and AAST buildings. There was an overall decrease in energy consumption after the three
case study façades were retrofitted.

2.6.4 Air tightness
Air tightness is necessary as the moisture that develops through infiltration can impact the
building’s structural integrity. Air infiltration can then cause future structural problems as well as long-term
performance (Younes, Shdid, and Bitsuamlak 2011). Air infiltration can be responsible for as much as 15%
of the heating loads, which can fluctuate the indoor temperature of commercial buildings (Younes, Shdid,
and Bitsuamlak 2011). Air tightness can mitigate the amount of air infiltration and exfiltration that is
transferring through the building façade system and interior partitions. By using façade systems that
incorporate air tightness, less energy will be needed for the conditioning of the building’s interior. The
façade system can also lose energy through insulation and linear thermal bridging (Younes, Shdid, and
Bitsuamlak 2011). If energy loss from façade systems are addressed, additional energy savings can result.

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Figure 2.4 Air infiltration (Younes, Shdid, and Bitsuamlak 2011)

2.6.5 Solar shading
Solar shading systems are a common device used to block heat from entering the building. By using
this shading system, energy performance improved (shown in Table 2.5). Louvers and overhangs can be
used as a shading device, in addition to, improved insulation and window glazing. Solely adding louvers
and overhangs will unfortunately not provide an immense reduction in site energy usage. Solar shading;
however, is an optimal façade system for windows and curtain walls to mitigate solar radiation. Insulation,
window glazing, and solar shading would need to be added and changed as a scheme to achieve at least ¼
of energy savings.

2.6.6 CO 2 and façade strategies
Based on these façade strategies, CO 2 emissions are considered. CO 2 emissions can significantly
decrease after retrofitting an existing building compared to building a new building. New buildings emit
more CO 2 through deconstruction than new construction. In retrofitting existing buildings with minimal
construction changes, less CO 2 is also emitted. According to El-Darwish and Mohamed Gomaa study,
glazing variable changes reduced energy to 8% on average (El-Darwish and Gomaa 2017). Meanwhile solar
shading reduced almost a ¼ of the energy savings dependent on the placement of the solar shading. Overall,
29

this study demonstrates that a significant amount of energy reduction is possible without deconstructing a
majority of the building. Yet, these results apply only to the building in this case study. It is expected that
a ¼ energy savings can be achieved through this reference.

2.7 Summary
Insulation, window glazing, and solar shading were the main outlined categories used to decrease
EUI, and overall reduced energy up to 31% energy savings. Rather than end a building service life,
retrofitting an existing building can decrease CO 2 emissions and energy consumption. Embodied CO 2,
operations related CO 2, and demolition are all significant factors in analyzing the CO 2 emittance in this
thesis. Through this understanding of how CO2 is emitted, limited construction is necessary for the least
amount of CO 2 emissions.
Material selection is additionally considered as it contributes to embodied CO 2. With the selection
of materials measured for the Westin Bonaventure Hotel, the embodied and demolition energy is expected
to decrease significantly. In order to improve energy performance and decrease CO 2 emittance of an existing
building, materials applied to the façade strategies are valuable to the building analysis. Building materials,
insulation, window glazing, and solar shading can allow for a substantial decrease in energy and carbon
emissions. Thus, by decreasing CO 2 and energy consumption through insulation, window glazing, solar
shading, and selective materials – retrofitting existing buildings is recommended. The Westin Bonaventure
Hotel is a case study building proposing strategies for unique buildings lacking this data and can be applied
to the Renaissance Center and Westin Peachtree Plaza.

30

3. METHODOLOGY

The Westin Bonaventure Hotel in Los Angeles is a case study building with strong indications of
wear. As the hotel is a 1970s building, with outdated glass – newer façade technologies are suggested. First
the existing building’s current conditions are analyzed, and then the circular geometry of the case study is
defined. After defining the circular geometry, one case study room referencing the Bonaventure Hotel is
modeled in Revit and later simulated in IES-VE to ultimately find retrofit resolutions.
Normally, baseline data is compared to the retrofitted results and offers valuable information about
the reduction in energy consumption. In this case, the baseline data was not available and the following
results are retrofit studies that have the potential of reducing the Bonaventure Hotel’s energy consumption
by 40%.
To start the Revit model process, building data is needed. Documenting architectural drawings,
examining façade strategies, and recording material limitations are necessary. A site visit to the
Bonaventure Hotel is also helpful when collecting photograph documentation of the current conditions. In
addition, this visit to the hotel explored the idea of placing Onset HOBO data loggers in one of the south
facing hotel rooms. By doing this, a possibility arose that the temperature gathered from the data logger can
report any uncomfortable heating or cooling conditions in the room. Since the intent is to understand the
current energy performance of the hotel, using HOBO’s could have been an ideal resolution. Yet, in using
these HOBO’s as a beginner in HOBO research – the results did not clearly eliminate the possibility of
HVAC interference. HOBO’s can report the peak temperature, relative humidity and more. However, in
the case that there isn’t additional data for when the HVAC systems are turned on or off – the analysis of
these results are not as useful. The HOBO’s are only explored in this study but does not continue in this
research.
After conducting an overview study of the Bonaventure Hotel, 30 façade alternatives are considered
with a variety of material options and façade systems. The façade alternatives are listed to then compare
31

each of the façade options. The list is later used to make combinatorial façade options, using a ZWICKY
chart. This ZWICKY chart allowed 300 façade systems to be interchangeable, suggesting new systems. Out
of the 300 façade options 200 are selected through the ZWICKY chart. The data selection system allowed
for a systematical based selection that is not derived from personal preference. By using this system-based
selection, 200 façade options are used for future analysis. The thesis contains the following research
methods:
- Case study analysis,
- Retrofit façade, reduce energy consumption, and CO 2 emissions,
- Examine façade strategies and current limitations,
- Façade options selected through the ZWICKY chart,
- Eliminate façade alternatives,
- Building 3D model in Revit,
- Software energy simulation in IES-VE,
- Data analysis and evaluate results,
- Re-design and find retrofit resolutions.
The main objective of this study is to analyze the energy performance of an existing building, retrofit its
façade, consider CO 2 emissions, energy consumption, and enhance environmental sustainability. Embodied
carbon, façade limitations, and combinatorial iterations were all design suggestions in the Revit simulation.
Wall type, placement, and model testing are also considered in the application and testing re-design.
Strategies are analyzed to suggest resolutions for the façade retrofit of the Bonaventure.
The Revit software is a 3D modeling tool to analyze the existing physical building of the Bonaventure
Hotel in 3D digital form. It is used as an analytical device to examine the circular geometry of the building
and its unique glazing design. By using this Revit modeling software, the existing building is examined
through modeling its glazing, interior walls, floor slab, and interior core. To explore the effects of façade
retrofit on energy consumption and CO 2 emissions, an existing unique hotel tower with an aging façade
will be examined, and a set of alternative interventions proposed are analyzed.
32

3.1 Methodology diagram

Figure 3.1 Method diagram (Author 2019)

33

3.2 Case study
3.2.1 HOBO data
In exploring HOBO data, the recorded results were not useful. As a beginner using HOBO’s for
this research, the information acquired was not clear to continue this analysis. Usually, when HOBO data
is acquired the information exports temperature data that informs the researcher an accurate peak
temperature, relative humidity and more. However, the Bonaventure hotel room in this case study was
supplied with a running HVAC system and the information exported combined the temperature from the
HVAC unit. Mechanical systems that are used during the data logging process can interfere with the data
collected since the actual average room temperature is manipulated. The room temperature is unknown in
this study, as the HVAC systems were not monitored for comparison. The HOBO information was only
tested and was not continued in this research work.
If the analyzed room’s air conditioning system was turned off for the study period, then the HOBO
results could offer more valuable information of the true room temperature. The importance of knowing the
interior temperature of the room leads to the intent of knowing how much energy is used to supply the
room’s HVAC system. If the building’s interior environment is too hot or cold due to the façade envelope
performance specifically, then the HVAC is needed to overrun and use more energy than necessary.
Overall, since the HOBO’s were only able to report temperature data that included the HVAC system then
the HOBO’s were not further used. The photographs below show the location where the HOBO’s were
placed and the graphs include the HVAC system data.

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Figure 3.2 HOBO at window sill (Author 2019) Figure 3.3 HOBO 5ft from sill and center (Author 2019)
Figure 3HOBO 5ft from sill and center (Author 2019)

Figure 3.4 HOBO in HVAC unit (Author 2019) Figure 3.5 HOBO at back of room (Author 2019)

35

Figure 3.6 HOBO at window sill (Author 2019)

Figure 3.7 HOBO 5ft from window sill (Author 2019)

Figure 3.8 HOBO at center (Author 2019)
36

Figure 3.9 HOBO back of room (Author 2019)

HOBO information is provided above as one of the initial steps before modeling in Revit and was
not used to continue the future studies. HOBO information would be more useful if the room did not have
air conditioning in-use.

3.2.2 Building geometry
There are three steps in analyzing the existing case study building. The first step is defining the
building geometry through length, width, height, and shape. Another is by developing the Revit model
based on the findings. Third is running simulation studies to analyze the results.
First, existing plans and architectural drawings are needed to define the building geometry. The
existing plans include “lobby level, one level below lobby, level 2-california ballroom, and level 3.” A
detailed plan, a color-coded evacuation plan, and a hotel room plan are also needed for reference. The floor
plans are a useful tool to understand the existing program per floor, while the detailed plans inform the
circulation and orientation of the building. The evacuation plan is specifically used to identify the colored
towers position on the site and the hotel room layout. The evacuation plan is compared based on orientation
and the red tower is also the south tower. Once the plans are collected, architectural drawings related to
sections and axonometric drawings are also recommended for reference. The 10
th
floor in the red tower is
37

selected in this research to be modeled and analyzed. The red tower is the south facing tower most valuable
in analyzing the most solar heat gain.

Figure 3.10 Westin: Plans (The Westin Bonaventure Hotel and Suites, Los Angeles 2019)

Figure 3.11 Westin: Plans (The Westin Bonaventure Hotel and Suites, Los Angeles 2019)

38

Figure 3.12 Westin: Plan (John Portman, Westin Bonaventure Hotel 2011)

Figure 3.13 Westin: Evacuation plan (Evacuation Plan 2017)
Figure 3.14 Westin: Hotel room plan (The Westin Bonaventure 2019)

39

Figure 3.15 Westin: Hotel room layout plan (Hogan 2009)

The drawings as a collective are intended to later construct the analytical model. Exterior
photographs of the Bonaventure Hotel are also recommended to analyze the appearance of the building.

3.2.3 Revit
Revit is a modeling software for architects, landscape architects, structural engineers, designers, and
similar professions (Revit: BIM Software 2020). The software is also used to model in 3D and draft drawings
in 2D. Revit offers a variety of tools including objects placed in “families.” The families are classified as
system, loadable, and in-place families. These can be used in model making, but in this research the most
common family used is the system families. The system families that will be described are walls, floors,
and ceilings. Once the drawings and photographs are gathered – one room from the Bonaventure Hotel will
be built in Revit. Revit 2019 was used in this thesis. Below is a summary of the steps:
• Step 1: Gather the existing plans and architectural drawings
• Step 2: Model a room on the 10
th
floor of the red tower in Revit
• Step 3: Export the room model as a gbXML file
40

• Step 4: Simulate the South (S), SE, E, NE, N, NW, W, and SW room in IES-VE
• Step 5: Analyze the simulation
• Step 6: Save the energy analysis
• Step 7: Use the energy analysis to re-design the 10
th
floor in Revit
• Step 8: Model the 10
th
floor of the red tower in Revit and re-design
• Step 9: Export the original 10
th
floor model and the re-design as a gbXML file
• Step 10: Simulate the 10
th
floor model and the re-design in IES-VE
• Step 11: Analyze the simulation
• Step 12: Save the energy analysis
• Step 13: Find a façade system retrofit resolution

3.2.4 Model the south room
Build the south room in the red tower in Revit. First, insert the “hotel room plan” in the Revit
software and scale the image to a more accurate dimension to obtain the length and width of the room. The
insert image button will be located in the Revit toolbar that states “image.” Once the “image” button is
selected, a pop-up will allow the image to import into Revit. After the image is inserted in the level 1 plan
the image can be scaled. By referencing the door drawn in the plan, the image can be scaled until the door
is 3’ wide. After the image is scaled and the door is 3’ wide, the interior and exterior dimensions of the
room can be acquired. The dimensions gathered for the south hotel room should be 27’ in length, 7’ in
interior width and 19’ in exterior width.

41

Figure 3.16 Insert hotel room plan (Author 2020)

Figure 3.17 Scale hotel room plan (Author 2020)

After the image is scaled, the dimensions gathered can be used to construct the walls, floor, and
ceiling of the hotel room. The dimensions used for the model should be approximately 27’ in length, 7’ in
interior width and 19’ in exterior width. When constructing the room model, the exterior wall can be flat
rather than curved. In a previous analysis, the curved wall and the flat wall were the same in energy
performance. For the simplicity of the model and offering the same information, a flat exterior wall will be
built in Revit.
42

In order to construct the model in Revit an additional image needs to be imported. The “hotel room
layout plan” is necessary to build the room model and follow the orientation of the floor plan. The layout
plan also allows the built room to follow the hotel layout of the south red tower and consider the rooms
adjacent.
Insert the “hotel room layout” image and scale it up or down until the interior wall is 27’. Once
done, lock the image and add (3) 6 ⅛” interior partition walls tracing the placed image. Below are images
showing this process.

Figure 3.18 Insert hotel room layout plan (Author 2020)

43

Figure 3.19 Scale plan to 27’ (Author 2020)

Figure 3.20 Construct wall (Author 2020)

To build a wall, the wall tool is under the “architecture tab.” Construct a wall following the hotel
room layout image and then follow and build the other (3) interior walls. The walls should also be set to a
top constraint of 10’. Typically, the standard height in Revit is 10’ and up to level 2. If the height is not 10’,
44

the top constraint can be changed to “unconnected” and the number can be changed to 10’. A 10’ height
constraint will be used in this research with references to diagrammatic sections found of the Bonaventure
Hotel.
Once the walls are traced on the image, at a length of 27’ and an interior width of 7’ the wall
material can be changed to the interior partition wall. Select the wall or walls and change the material to 6
⅛” interior partition (2-hr). The 6 ⅛” interior partition walls are found in the basic wall properties settings.
Use this same wall tracing technique to build a flat basic wall on the south side of the room.

Figure 3.21 Construct interior partition walls (Author 2020)

The next step involves drawing a basic wall. To draw a basic wall, change the material to a curtain
wall system. The curtain wall option can be found in the properties toolbar at the bottom of the materials.
The overall dimensions should again be, approximately 27’ in length, 7’ in interior width, and 19’ in exterior
width.
45

Figure 3.22 Add curtain wall (Author 2020)

Next, the floor and ceiling can be constructed. To build the floor, the floor option will be in the top
toolbar in the “architecture” tab where it states “floor.” Select the floor button and construct a 12” concrete
floor slab on top of the architectural plan. Then, build the ceiling. The ceiling button is located next to the
floor button in the same toolbar.

Figure 3.23 Add floor (Author 2020)

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Figure 3.24 Add floor and ceiling (Author 2020)

After the room model is completed, the Revit model can be saved for later use. Data collection will now
begin to determine what façade strategies will be used to retrofit the Bonaventure Hotel.

3.3 Data collection
For data collection, the following tools are necessary:
• Façade strategies
• Material limitations
• ZWICKY chart
• Energy Use Intensity (EUI)

Façade strategies are used to explore multiple iterations on the Bonaventure Hotel. These strategies are
implemented by listing the existing façade materials, analyzing 300 new façade systems, and determining
their limitations. The limitations result in whether the new façade systems can be applied. Limitations
include, resistance from the Westin management team and changes too drastic from the original.
47

3.3.1 Existing façade building materials
To suggest alternative façade strategies and determine the material limitation, the existing materials
should be recorded first. The existing materials found are through visual analysis of the Bonaventure and
comparison of other façade systems. With these findings of existing materials through visual representation,
a list is created. A dataset list using a Microsoft Word chart is created to identify all the existing materials
of the Westin Bonaventure. Based on this list, existing materials are compared by material, system, and
condition. Conditions are determined by a visual appearance assessment. The assessment is based on a basic
(B), poor (P), and fair (F) evaluation. The following chart is generated:

Table 3.1 Existing façade materials

Façade material System Condition
1 Glass, single glazed, tinted
mirrored
Curtainwall P
2 Steel Mullions F
3 Concrete Wall P

3.3.2 Athena
Athena software is a recommended program management tool that helps select sustainable
materials during construction (Athena LCA Software Tools 2020). The Athena software includes the life
cycle assessment (LCA) data and aims to increase sustainability in construction. Architects, engineers,
builders, and manufacturers can use Athena to get accurate information about their building footprint
(Athena LCA Software Tools 2020). The software allows builders to make environmental decisions during
their design process. The materials selected will be considered as a life cycle process and how these
materials impact the environment after demolition. Athena includes carbon footprint and product
declarations that help the process of implementing sustainable materials on a new or existing building.
Athena is not used in this research but is suggested for future work.
48

Athena could be used in future work to assess two of the LCA factors. Athena also considers the
demolition process of sustainable materials. Athena is not used in this thesis to manage the CO 2 emitted by
burned fossil fuels but is highly recommended for the future. Athena can help architects and engineers in
selecting materials for building retrofit and construction. This software would be essential in selecting
materials for the retrofit strategies explored in this thesis. Retrofit strategies are the first step and the next
step would be to pick the material of the retrofit façade systems.
Athena is ISO (International Organization for Standards) code compliant and assets the process in
selecting up-to-date materials. The Athena Institute software allows construction professionals to compare
building designs with a variety of sustainable materials (Athena LCA Software Tools 2020). The software
is currently available for free and allows the builders to make significant environmental decisions. Athena
Institute has four softwares available for the life cycle inventory of building materials; Impact Estimator,
Pavement, EcoCalculator for commercial, and EcoCalculator for residential. These softwares allow the
building life cycle materials to be examined by the choice of products, transportation, construction, and
demolition. The Athena software does not require the software users to be LCA proficient and is user-
friendly.
The Athena Impact Estimator for Buildings and the EcoCalculator for Assemblies allow the
designers to have an estimate building design footprint. However, the Impact Estimator is more accurate in
providing the building carbon footprint information. The Impact Estimator allows users to apply their
energy simulation results, calculate their façade strategies of operating and embodied effects (Athena LCA
Software Tools 2020). The Pavement LCA is mainly used to measure roadway design impacts to the
environment. Overall, Athena is a tool that complies with the LCA and the ISO 14040 standards. The
Athena Institute as of now has developed over 300 LCA studies using construction products and materials
(Athena LCA Software Tools 2020).

49

3.3.3 Modeling and analysis tools
After listing the existing materials of the building, energy modeling softwares are compared. The
following softwares are considered, and one is selected for the modeling analysis. Skill levels are based on
the users proficiency in the listed softwares, through the scale of user-friendly, intermediate, and advanced.
HEED and Design Builder are both user-friendly, yet HEED is limited to energy analysis for residential
models. IES-VE 2019 is then selected for the purpose of this research.

Table 3.2 Modeling software

Software Skill level Building type Capability Selected software
Design Builder User-friendly Commercial and
residential
Limited
EQuest Intermediate Commercial and
residential
Detailed/flexible
HEED User-friendly Residential Limited
IES-VE Intermediate Commercial and
residential
Detailed X
DIVA Advanced Commercial Detailed
Energy Plus Intermediate Commercial Detailed
ESP-r Advanced Commercial Detailed
TRNSYS Advanced Commercial Detailed

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3.3.4 ZWICKY chart
A ZWICKY chart is an information organizing technique that can identify possible combinations
that can be found in the various façade systems. By listing 30 façade systems, combinations are made
finding new façade alternatives. A cross-consistency assessment allows connective relationships to be
found. Rather than assigning a glazing technique with a solar shading system one-by-one, the ZWICKY
chart is a multi-dimensional analysis that suggests more façade combinations. Through the combination of
façade systems, 300 are found as new façade alternatives that can be used on the Bonaventure Hotel. With
the limitations of applying certain façades on the Bonaventure, façade systems are then eliminated. In
eliminating façade systems, the remaining façade options are then analyzed and further eliminations are
necessary. Limitations from the Westin management and changes too drastic from the original, are the main
objections in applying certain façade systems on the Bonaventure. Yet, material limitations and carbon
emissions are also considered. Before eliminating any façade systems, the ZWICKY chart needs to be
created.
The ZWICKY chart is used to identify combinatorial alternatives to apply retrofit strategies to the
Bonaventure’s façade. The façade systems below are used in the ZWICKY chart:
51

Figure 3.25 ZWICKY chart (Author 2019)

After finding these 300 combinations, process of elimination begins. The 300 systems that are
related to high density solar shading is not applicable and is too distracting for the public and the Westin
will not approve. 100 of the 300 systems are not applicable to the Bonaventure since some of the façade
strategies were drastically different from the current façade system and the selected materials manufacturing
process emits a significant amount of CO 2. As the objective of this research is to reduce CO 2 emissions and
energy consumption – the selected façade systems should limit the emittance of CO 2 and assist in improving
energy efficiency. With this considered, the remaining 200 façade system combinations from the ZWICKY
chart are further analyzed.

3.3.5 Energy Use Intensity (EUI)
These 200 façade systems are analyzed through building materials, embodied energy, and carbon
emissions. Since energy efficient materials reduces CO 2 and energy demands significantly, these tools are
52

considered in the elimination process. 200 of the 300 are then selected as probable façade alternatives for
the Westin Bonaventure. The façade systems are also less energy intensive and emits less CO 2. The façade
systems with overhangs, vertical fins, and horizontal louvers that emits less CO 2 through the selected
material process are then constructed in Revit.

3.4 Façade alternatives
3.4.1 Application
Before applying new façade strategies to one room of Westin Bonaventure’s 10
th
floor – the Revit
model with the existing materials are simulated first in IES-VE. Next, the façade retrofit strategies are
simulated.
Before simulating in IES-VE, the façade alternatives are each placed on the south facing room of
the Westin in Revit. Once each of the façade options are placed on the Bonaventure Hotel room, the file
should be saved as different retrofit versions. For example, once the Westin south room file is created in
Revit and the façade retrofit is applied – the file should be re-saved with a new name. The file should then
be re-saved as “Westin_Insert Façade System Type_v1.” The façade system name can change depending
on the façade iteration that was made in the file. The version numbers also change as the versions increase.
To begin, only 23 façade strategies are needed in Revit to analyze the 200 ZWICKY chart façade
options. Most of the 23 façade systems will be simulated with different glazing properties. When doing so,
there will be more façade combinations per Revit file. The glazing systems that will be combined with some
of the façade systems are single, double, and triple glazed. In addition, some strategies will include air,
argon, or krypton-filler depending on the pattern of better energy performance.

In this order the 23 façade systems can be applied:
1. Curtain Wall
2. 6” Concrete Wall
3. Overhang – 1’ depth
4. Overhang – 1’ depth, 1’ below roof line
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5. Overhang – 2’ depth
6. Overhang – 3’ depth
7. Overhang – 2’ depth, 75-degree angle
8. Overhang – 3’ depth, 75-degree angle
9. Vertical fins – 1’ depth, 1’ spacing
10. Vertical fins – 1’ depth, 1’ spacing, 75-degree angle
11. Vertical fins – 1’ 6” depth, 1’ spacing
12. Vertical fins – 2’ depth, 1’ spacing
13. Vertical fins – 2’ depth, 2’ spacing
14. Vertical fins – 2’ depth, 2’ spacing, 75-degree angle
15. Vertical fins – 2’ depth, 2’ spacing, 65-degree angle
16. Vertical fins – 2’ depth, 1’ spacing, 11’ internal space
17. Vertical fins – 3’ depth, 1’ spacing
18. Vertical fins – 3’ depth, 1’ spacing, 75-degree angle
19. Horizontal louvers – 1’ depth, 1’ spacing,
20. Horizontal louvers – 1’ depth, 1’ spacing, slanted angle
21. (2) Horizontal louvers – 1’ depth, 1’ spacing, slanted angle
22. Brise Soleil – 1’ depth, 3 sides
23. Brise Soleil – 1’ depth, 4 sides

After all 23 façade strategies are placed on the south façade of the Bonaventure hotel, there should be
23 Revit files in total. There should be an original south room file with a curtain wall system and 22 new
façade iteration files. The original Westin south room file should not overwrite, and the retrofit files should
be saved with new names. Once these files are attained, all 23 Revit files should be exported in gbXML.
Below are the façade strategies:

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Figure 3.26 Revit façade retrofit strategies (Author 2019)

3.4.2 gbXML export
To export a gbXML (Green Building XML), first a space needs to be created at the level 1 floor
plan of the room model. The room file selected for this example is, “Westin_Flat Wall_Louvers v6.” Once
the chosen Revit file is open, then the space tool can be used. With this space tool, the interior room is
selected in plan view and the space is then placed. Following, change the viewport to a 3D view so, the file
can then be exported to gbXML.

55

Figure 3.27 Revit space placement (Author 2020)

If the viewport is not in 3D view, the model will not export into gbXML. After the viewport is in
3D view, go to “file,” “export,” then “gbXML.” A pop-up should pop on the screen and say “use energy
settings” or “use room/space volumes.” Select “use room/space volumes” and another pop-up should show.

Figure 3.28 Revit gbXML export (Author 2020)

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Figure 3.29 Revit gbXML export (Author 2020)

This step should allow the selection of the following parameter values:
• Building type: Hotel
• Location: Los Angeles, CA
• Export category: Spaces
• Building service: Split System (or another system that is available)

Typically, a split system is not used for a hotel. However, this HVAC system was selected in this
research to study one room of the hotel. It is important to note that another type of HVAC system could be
used for this research analysis. Since the purpose of this study is to analyze the difference of energy
consumption and carbon emissions, and compare the retrofit model to the base case, any of the listed Revit
HVAC systems can be applied. Yet, carefully note that the base case HVAC system needs to be the same
system for the retrofit model. A different system on a base case and retrofit model, will not supply adequate
results. Applying different HVAC systems can increase or decrease the energy consumption depending on
the air-conditioning system selected. If this occurs, the results will be inaccurate and the façade retrofit will
appear to perform better or worse than it is actually performing. The retrofit performance results could show
that the façade retrofit is performing better than it actually is, if the HVAC system is also improving the
57

energy performance. By applying the same standard HVAC systems on the base case and retrofit model,
the energy savings for only the glazing and façade retrofits can be compared.

Figure 3.30 Revit gbXML export (Author 2020)

After the values are input, the gbXML file can be checked for errors before exporting to IES-VE.
The errors can be checked by selecting “details” on the top left tab next to “general” in the export gbXML
settings. When the details tab is selected the “analytical surfaces” should be clicked on next. The yellow
exclamation icon symbol is an error symbol that is shown if there is an error in the model. This step should
be checked before moving to the next step of exporting to IES-VE. If there is an error in the model the
gbXML will still export, but the imported surfaces may cause additional errors in IES-VE. Checking the
details tab in Revit for errors can limit future errors that can occur in IES-VE. Click “next” to save the
gbXML file.

58

Figure 3.31 Revit: gbXML export (Author 2020)

3.4.3 IES-VE
IES-VE is an integrated environmental solutions software for the virtual environment (Unrivalled
Modelling and BIM Interoperability 2019). It is also an energy analysis and performance modeling software
for engineers and architects. The software allows designers to identify passive solutions, renewable
technologies, energy usage, and CO 2 emissions. It is an integrative process that allows projects to
incorporate sustainable building approaches. IES-VE 2019 is used for the purpose of these simulations.

3.4.4 Climate zone selection
When the gbXML file is imported into IES-VE, the climate zone location should appear
automatically. At the bottom toolbar of the IES-VE software, it should state “Los Angeles Usc Campus
(ASHRAE Climate Zone)”. Once this is verified, glazing values per façade retrofit strategies can be
changed.

59

Figure 3.32 IES-VE climate location (Author 2020)
3.4.5 Glazing values
After exporting the 23 façade systems as a gbXML file, each façade option file can be imported in
IES-VE. Once one of the strategies is imported into IES-VE, the glazing values can be updated. The glazing
values used per system are listed below:

Figure 3.33 IES-VE single-glazed values (Author 2020)

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Figure 3.34 IES-VE double-glazed air values (Author 2020)

Figure 3.35 IES-VE double-glazed argon values (Author 2020)

61

Figure 3.36 IES-VE double-glazed krypton values (Author 2020)

Figure 3.37 IES-VE triple-glazed air values (Author 2020)

62

Figure 3.38 IES-VE triple-glazed argon values (Author 2020)

Figure 3.39 IES-VE triple-glazed krypton values (Author 2020)

Applying each of the glazing options on all 23 of the façade options, will offer at least 160 façade
opportunities. There are 7 glazing options that are used in this research, below is the list and above are the
63

glazing values that can be used. The values are determined through researching the existing glazing
manufacturers and applying the existing values into IES-VE. All values needed for the IES-VE glazing
construction might not be available to the public, but the U-values can be achieved through manipulation
of each material category. For instance, conductivity, convection and resistance may not be offered for
public use – yet, an educated guess can be used to achieve the same U-value that is provided by the glazing
manufacturer. The 7 glazing options that can be applied to the 23 façade strategies are listed below:
1. Single glazed
2. Double glazed, air
3. Double glazed, argon
4. Double glazed, krypton
5. Triple glazed, air
6. Triple glazed, argon
7. Triple glazed, krypton
Below are a few façade combination examples:

Figure 3.40 Façade retrofit iterations (Author 2019)

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Figure 3.41 Façade retrofit iterations (Author 2019)

Before simulating more glazing façades with krypton, it is important to export the energy
consumption data with krypton first. It is possible that the hotel room’s energy consumption will increase
rather than decrease after applying krypton to the façade system iterations. Krypton is known to have better
energy efficiency compared to air and argon, yet when additional retrofit systems are applied the energy
consumption can increase. If krypton is applied as only a glazing system without additional retrofit
65

strategies of overhangs or louvers, then krypton can possibly perform better than air and argon-fillers. At
first when this research started, applying krypton to a retrofit system was expected to perform even better
than the other comparable gas-fillers. Yet, the results showed that krypton performed worse after applying
all of the façade retrofit strategies. A pattern in the results suggested that argon or air should instead be
applied for the continued research. Argon was later chosen as a better gas-filler with the retrofit strategies
compared to air.

3.4.6 Adjacent buildings
Adding adjacent buildings are necessary to limit air infiltration from the east, west, and north sides
of the south hotel room. Since the Bonaventure Hotel is analyzed first as a room, there should not be air
infiltration coming from the (3) sides of the hotel room. The “adjacent buildings” command will be used
for air tightness and will be modeled in IES-VE. These adjacent buildings will be constructed as
neighboring hotel rooms since the selected hotel room for analysis has neighboring rooms on the east and
west sides. There is also a hallway on the north of the analyzed hotel room and the hallway will be modeled
in IES-VE as a neighbor. The following images will illustrate how a neighboring room or hotel hallway can
be built in IES-VE:

Figure 3.42 Construction lines (Author 2020)

In order to draw a neighboring room or hallway, the adjacent building command is necessary. To
build a neighboring room, construction lines can be used to guide the shape of the room. The construction
button can be found at the top tool bar, labeled “construction lines.”

66

Figure 3.43 Construction lines: plan view (Author 2020)

After the construction line button is selected, the outline of the room can be traced. The dimensions
are also shown for guidance. Once the construction lines are drawn, the neighboring room can be built using
the “draw extruded shape” command. The “draw extruded shape” command allows the room or hallway to
be built in IES-VE and then changed to a neighboring/adjacent room. Attempting to build the neighboring
room in Revit first, did not allow the room to be changed to adjacent building easily in IES-VE. It is
recommended that the adjacent room is constructed in IES-VE.

Figure 3.44 Draw extruded shape (Author 2020)

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Figure 3.45 Shape trace (Author 2020)

The room can be constructed following the construction lines. These construction lines are helpful
in outlining the adjacent shapes surrounding the analyzed room. Once the adjacent room is constructed, the
height of the room and plane level can be adjusted. The plane is the plan level that the room will sit on.
This plane level can be -10 ft below the analyzed room, 10 ft above the analyzed room, or at the floor level
of the analyzed room at 0ft. 0ft is the standard level the Revit models are inserted in. Those levels can be
adjusted if additional floor levels are added. In the next step, the room will be changed to an adjacent room.

68

Figure 3.46 Model to adjacent building (Author 2020)

If the room model is automatically listed as a “model” then the model can be changed to “adjacent
building.” To determine if the room is selected as “model,” the room that was built can be selected in 3D
and checked in the spaces toolbar. After verifying that the room is a model, the model can be changed to
adjacent building. To make this model change, select the room that was created in the space category under
the applications tab selection. Once selected, right-click to edit properties and a properties pop-up should
appear. In the properties pop-up, the object type can be changed from building space to adjacent building.

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Figure 3.47 Model to adjacent building (Author 2020)

Figure 3.48 Model to adjacent building (Author 2020)

The images above can be used to model the hotel hallway or room as an adjacent building. The
construction lines can also be deleted once done.
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After these following steps are completed the simulation, can begin:
• Step 1: Gather the existing plans and architectural drawings
• Step 2: Model a room on the 10
th
floor of the red tower in Revit
• Step 3: Export a room model as a gbXML file
• Step 4: Apply the varied glazing materials in the IES-VE file
• Step 5: Construct the adjacent buildings

The next steps are:
• Step 6: Run the SunCast tool
• Step 7: Export total energy
• Step 8: Calculate operational CO 2
• Step 9: Export CO 2 data
• Step 10: Orientation simulations
• Step 11: Energy consumption and CO 2 comparison
• Step 12: Model the 10
th
floor of the red tower in Revit and re-design

3.4.7 SunCast
To start the simulation process, the SunCast tool is used to cast shade onto the room. If the SunCast
tool is not used, the data acquired will not be accurate. The solar shading devices intended to cast shade
onto the room will not be simulated, if the SunCast tool is not used before simulation. The SunCast button
can be found in the “applications” tab then under the “solar” tab. This tool is used for analyzing solar
shading and will be used before simulating the Bonaventure 3D models.

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Figure 3.49 IES-VE sun cast (Author 2020)

Figure 3.50 IES-VE sun cast (Author 2020)

3.4.8 Export total energy data
The energy usage data in IES-VE gives the total energy per month and for the year. To compare
the total energy savings per façade system, the summed total will be compared. The total energy data should
be exported after each simulation is done. To locate the energy data, it will be in the “VistaPro” tab under
“energy.” Once the total energy data is acquired the total energy should be listed at the bottom of the chart.
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The total energy consumption chart should then be saved for documentation. The energy consumption data
will then be analyzed and compared to the other façade retrofit’s energy consumption results. In this
research, each retrofit strategy will be simulated individually and the data will be exported once the
simulation is complete. To efficiently analyze the data, the file names and folders should be organized
carefully. The organization process can help the location of files.
Batch simulation could be used to simulate multiple models, yet as a beginner in this research study
– individual simulations were tested.

Figure 3.51 IES-VE energy usage (Author 2020)

3.4.9 Base case calculation
To calculate the base case operational CO 2, a formula can first be used. The formula that will be
used for this research is the annual energy use and CO 2 footprint formula. There are other formula iterations
that can calculate operational CO 2, but the below calculation will be used.
Annual energy use and CO 2 footprint:
1MBTU = 1,000,000 BTU 1BTU = 2.931 MWh
1MBTU = 0.2931 MWh LADWP CO 2 intensity = 1200 LBS CO 2 / MWh

Annual electricity consumption (in MWh) x carbon intensity = Annual electricity CO 2 footprint
47 MBTU x 0.2931 = 13.78 MWh
13.78 MWh / year x 1200 LBS CO 2e / MWh = 16,536 LBS CO2
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An additional calculation that can similarly calculate operational CO2 is below:
CO 2 emissions of operational energy:
1BTU = 0.000293071 kWh
1MBTU = 293.07107 kWh

△OE = 0.79 LBS Co2/kWh x Saved (kWh)
Saved (kWh) = 35.73 MBTU x 293.07kWh = 10, 471 kWh
△OE =0.79 LBS CO 2kWh x 10, 471 kWh = 8, 272 LBS CO 2

Saved (kWh) is the total energy (MBTU) converted to kWh.

3.4.10 Retrofit calculation
Similar to the base calculation, the retrofit calculation can be used. The example for the operational
energy CO 2 emissions is shown below:
Annual energy use and CO 2 footprint:
1MBTU = 1,000,000 BTU 1BTU = 2.931 MWh
1MBTU = 0.2931 MWh LADWP CO 2 intensity = 1200 LBS CO 2 / MWh

Annual electricity consumption (in MWh) x carbon intensity = Annual electricity CO 2 footprint
40 MBTU x 0.2931 = 11.72 MWh
11.72 MWh / year x 1200 LBS CO 2e / MWh = 14,064 LBS CO2

3.4.11 Export CO 2 data
After calculating the operational CO 2, the monthly and total operational CO 2 can be exported from
IES-VE for comparison. The CO 2 data can be exported from the same location the total energy data was
exported. The total CO 2 data exported can be compared to the above calculations of total operational CO 2.

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Figure 3.52 IES-VE total carbon (Author 2020)

3.4.12 Orientation simulations
Once the energy consumption and CO 2 data is exported for the south room first, then other
orientations can also be simulated. The data should be exported simultaneously when simulating, to then
review any patterns that may appear. The façade strategies that were attempted above showed a pattern of
vertical fins and horizontal louvers at 1’ depth and 1’ spacing to perform better than the other façade
systems. With this analysis, attempting these façade systems on the orientations of SE, E, NE, N, NW, W,
and SW are significant to also try. Although, the vertical fins and horizontal louvers appear to perform
better on the south façade other façade systems might perform better on the SE, E, NE, N, NW, W, and
SW. Simulating different iterations while also analyzing each of the energy consumptions and determining
if there is a pattern, can assist in which façade systems should be revised or applied differently. If 3’
spacings are showing an increase or decrease in energy consumption, then 4’ spacings or 2’ spacings can
be tried. Yet, if 3’ spacings are showing a significant increase in consumption – then 2’ spacings may be
more appropriate to decrease energy consumption. Evaluating the energy consumption patterns after each
simulation, adjustments to the façade strategies can be made. In addition, it is important to note that the
façade systems that may perform better on the SE will not perform better on the NE. As well as, overhangs
or louvers on the north are not necessary due to minimal solar heat gain. Façade strategies for the S, SE, E,
NE, N, NW, W, and SW will all be simulated and compared in IES-VE.

75

Figure 3.53 IES-VE orientations (Author 2019)

3.4.13 Energy consumption and carbon comparison
After the base case file and retrofit files are each simulated, the data should be analyzed thoroughly.
The energy consumption and carbon data can be analyzed through documenting the energy and carbon
savings. These results will then show that horizontal louvers and vertical fins performed more efficiently
than the other façade strategies tested. Horizontal louvers and vertical fins will be selected as a preferable
façade retrofit option.

3.5 10
th
floor Revit model
Once the preferable options are selected, the façade retrofit systems can be applied to all the
orientations on the 10
th
floor. The 10
th
floor will have varied façade retrofit options depending on which
systems perform better on each orientation. The south façade will have a different façade iteration compared
to the east and north orientation. Modifying the transition from a vertical façade system to a horizontal
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system will be analyzed once the 10
th
floor has all façade systems placed on each orientation. To visualize
the south to north façade appearance, analyzing the 10
th
floor with all the façade systems applied is
necessary. One façade system will not be applied on all façade orientations, since each orientation performs
differently with varied solar heat gains. The results for the 10
th
floor will show the transition of the vertical
fins, horizontal louvers, and without louvers and fins applied.

Figure 3.54 10
th
floor Revit model (Author 2019)

Figure 3.55 10
th
floor Revit model: plan (Author 2019)
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3.6 Summary
Out of the 300 façade options 200 were selected through the ZWICKY chart. The data selection
system allowed for a systematical based selection that is not derived from personal preference. These
strategies were implemented by listing the existing façade materials, 300 new façade systems, and
determining their limitations. The limitations result in the probability that the new façade systems can be
applied. Limitations include, resistance from the Westin management team and changes too drastic from
the original. By using this system-based selection, 5 façade options were used for future analysis. The
façade options used for future analysis are the combinations of 1’ depth vertical fins and horizontal louvers
at 1’, 2’, 3’, spacing with double-glazed argon gas-filler.
Horizontal louvers and vertical fins are the selected systems for the 1970s façade. However,
horizontal louvers and vertical fins will not be selected for the north façade, since there is minimal solar
heat gain and the north performs proficiently without attached façade systems. Double glazing will be
considered for replacing the original single glazing of the north façade.
The main objective of this study is to analyze the energy performance of an existing building,
retrofit its façade, and consider CO 2 emissions and energy consumption. Embodied carbon, façade
limitations, and combinatorial iterations were all design suggestions in the Revit simulation. Wall type,
placement, and model testing are also considered in the application and testing re-design. Strategies are
analyzed to suggest resolutions for the façade retrofit of the Bonaventure.

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4. RESULTS

Over 300 façade retrofit alternative studies have been completed for this research, comparing a
variety of horizontal louvers, vertical fins, brise soleils, and overhangs. 200 façade strategies were first
simulated in IES-VE to compare the room’s total energy consumption and operational CO 2. Any systems
related to high density solar shading were later eliminated. High density solar shading increases energy
consumption instead of decreasing energy consumption. Solar shading is beneficial when it is shading an
accurate amount of the building or room. When there is too much shading, the room or building can become
dark and energy consumption can increase. Daylighting is as significant as shading, with limited daylight
then artificial light is required and energy usage will increase. Mitigating solar heat gain can be
accomplished with façade strategies, but understanding how much solar shading is beneficial per orientation
and room is important. The results showed that 1’ depth and 1’ spaced horizontal louvers and vertical fins
gave a significant amount of solar shading without requiring additional artificial lighting per room.
100 of the 300 ZWICKY chart options were not applicable since some of the façade strategies were
drastically different from the current façade system and the selected materials had a significant amount of
embodied CO 2. Since the objective of this research is to reduce CO 2 emissions and energy consumption –
the selected façade systems should limit the emittance of CO 2 and assist in improving energy efficiency.
The 1’ depth and 1’ spaced horizontal louvers and vertical fins were the selected systems for the
study of the Westin Bonaventure Hotel. Overhangs, horizontal louvers, vertical fins, and brise soleils were
the primary façade systems explored in the ZWICKY chart. Since overhangs, horizontal louvers, vertical
fins, and brise soleils are widely available and are popular façade shading devices, these systems will be
examined in this study. Out of the 200 studies that were simulated, vertical fins, horizontal louvers, and a
concrete wall performed the best. Vertical fins were simulated with various depths and spacing iterations.
The vertical fins were examined in 1’, 2’, 3’ depth and 1’, 1’ 6”, 2’, 3’ spacing. Horizontal louvers were
explored with 1’, 1’ 6”, 2’ depths and spacings. The vertical fins and horizontal louvers at 1’ depth and 1’
79

spacing showed to have better energy savings than the other façade strategies that were simulated. 3’
spacings for the horizontal louvers were not tested since a pattern showed that 2’ spacings performed worse
than 1’ spacings. Examining the energy consumption data for each façade system before simulating more
was necessary to understand a pattern. The pattern showed how each façade systems depths, spacings, and
strategy type were impacting the total energy consumption. If the 2’ spacing performed worse than the 3’
spacing, then it is understood that the 3’ spacing would also perform worse than the 1’ spacing. These
patterns can suggest which strategies should be analyzed more thoroughly and which ones can be excluded
from more tests.
The strategies were first analyzed on the south (S) orientation, then analyzed on the SE, E, NE, N,
NW, W, and SW orientations. Testing the orientations in increments resulted in discovering which façade
strategies perform better in each orientation. In doing this, the data shows which façade strategies should
be applied per orientation on the 10
th
floor. There are many façade combinations that can be applied to a
façade orientation, since each façade has different amounts of solar heat gain. A façade strategy that might
perform better on the south might not perform better on the west. The following façade systems are explored
in this study:

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Figure 4.1 Façade retrofit iterations (Author 2019)

4.1 South façade
Normally, on the south façade, horizontal louvers are known to perform more efficiently compared
to vertical fins. Yet, in this research vertical fins saved 4% more energy than horizontal louvers with single
glazing. Vertical fins saved a total of 8% of the room’s energy from January to December meanwhile
horizontal louvers saved 4% total energy. This resulted in 1’ depth 1’ spaced vertical fins performing better
on the south façade of the Bonaventure Hotel than horizontal louvers. However, either horizontal louvers
or vertical fins can be applied on the Bonaventure and the retrofit design can be determined by hotel
management.

4.1.1 Retrofit application
The graph below shows a decrease in the room’s energy consumption after vertical fins were
applied to a single-glazed system on the south façade.

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Figure 4.2 South façade (Author 2019)

There is a visible decrease in energy consumption after vertical fins were applied to the south
façade. The vertical fins’ total energy consumption was initially compared to the base case model’s total
energy consumption. The base case model was simulated as a preliminary step to determine the potential
energy savings for the 1’ depth 1’ spacing vertical fins. By comparing the single-glazed vertical fin façade
with the base case model, it provided insight on how the vertical fins were performing without improved
glazing. To identify the energy savings per system, comparing the base case model is necessary. If double
glazing was applied to the vertical fins system and not analyzed with single glazing, then the results would
only show the energy savings of the façade combination. Applying vertical fins to a single-glazed façade
provided an energy performance analysis for only the vertical fins without the double-glazed combination.
This analysis resulted in 90-degree angle vertical fins with single glazing saving 8% of the room’s
energy consumption and 90-degree angle horizontal louvers with single glazing saving 4% of the room’s
energy consumption. Both façade systems have the same depth and spacing, but the vertical fins have
proven to save more energy on the south façade.
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4.1.2 Additional retrofit strategies
The ZWICKY chart study and IES-VE simulations suggested further analysis in applying a
combination of double and triple glazing to the retrofit strategies. The double and triple-glazing systems
that were tested included argon, air, and krypton. However, after noticing a pattern that krypton performed
less efficiently with vertical fins or louvers, argon and air were further analyzed. Argon was ultimately
chosen as a better gas-filler with the tested retrofit strategies compared to air. The following chart shows
the room models simulated in IES-VE and the energy saving results:

Table 4.1 Energy savings per façade system (%) – south façade
# Retrofit strategy Energy
savings (%)
# Retrofit strategy Energy
savings
(%)

1

Single Glazed

Base Case

2

Double Glazed + Air

12%

3

Double Glazed + Argon

11%

4

Double Glazed
+ Krypton

8%

5

Triple Glazed
+ Air

9%

6

Triple Glazed
+ Argon

8%

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7

Triple Glazed
+ Krypton

4%

8

6” Concrete Wall

35%

9

1’ Depth, 1’ Space,
Louvers + Single Glazed

4%

10

1’ Depth, 1’ Space,
Louvers + Double Glazed
+ Air

15%

11

1’ Depth, 1’ Space,
Louvers + Double
Glazed + Argon

14%

12

1’ Depth, 1’ Space,
Louvers + Double Glazed
+ Krypton

12%

13

1’ Depth, 1’ Space,
Louvers + Triple Glazed
+ Air

12%

14

1’ Depth, 1’ Space,
Louvers + Triple Glazed +
Argon

11%

15

1’ Depth, 1’ Space,
Louvers + Triple Glazed
+ Krypton

8%

16

1’ Depth, 1’ Space, Fins +
Single Glazed

8%
84

17

1’ Depth, 1’ Space, Fins
+ Double Glazed + Air

17%

18

1’ Depth, 1’ Space, Fins +
Double Glazed + Argon

16%

19

1’ Depth, 1’ Space, Fins
+ Double Glazed +
Krypton

14%

20

1’ Depth, 1’ Space, Fins +
Triple Glazed + Air

14%

21

1’ Depth, 1’ Space, Fins
+ Triple Glazed + Argon

13%

22

1’ Depth, 1’ Space, Fins +
Triple Glazed + Krypton

11%

23

Brise Soleil + Single
Glazed

0%

24

Brise Soleil + Double
Glazed +Argon

11%

25

Single Glazed + 2’
Overhang

0%

26

Double Glazed + 2’
Overhang + Argon

11%

27

1’ Depth, 2’ Space, Fins
+ Single Glazed

0%

28

1’ Depth, 2’ Space, Fins +
Double Glazed + Argon

11%

85

29

1’ Depth, 3’ Space,
Fins, 75 Deg. Angle +
Double Glazed + Argon

11%

30

1’ Depth, 3’ Space,
Fins, 75 Deg. Angle +
Triple Glazed + Argon

8%

31

1’ Depth, 3’ Space,
Fins, 75 Deg. Angle +
Double Glazed +
Krypton

9%

32

1’ Depth, 3’ Space,
Fins, 75 Deg. Angle +
Triple Glazed + Krypton

5%

33

2’ Depth, 1’ 6” Space,
Fins + Double Glazed +
Argon

12%

34

2’ Depth, 1’ 6” Space,
Fins + Triple Glazed +
Argon

10%

35

2’ Depth, 3’ Space,
Fins, 75 Deg. Angle +
Double Glazed + Argon

11%

36

2’ Depth, 3’ Space,
Fins, 75 Deg. Angle +
Triple Glazed + Argon

8%

37

2’ Depth, 1’ 6” Space,
11’ Internal Space,
Fins+ Single Glazed

1%

38

3’ Depth, 1’ 6” Space, Fins
+ Single Glazed

4%
86

39

3’ Depth, 1’ 6” Space,
Fins + Double Glazed +
Argon

14%

40

3’ Depth, 1’ 6” Space,
Fins + Triple Glazed +
Argon

10%

41

3’ Depth, 1’ 6 Space,
Fins, 75 Deg. Angle +
Single Glazed

4%

42

3’ Depth, 1’ 6 Space,
Fins, 75 Deg. Angle +
Double Glazed + Argon

13%

43

3’ Depth, 1’ 6 Space,
Fins, 75 Deg. Angle +
Triple Glazed + Argon

11%

44

3’ Depth, 3’ Space,
Fins, 75 Deg. Angle +
Triple Glazed + Argon

8%

Before simulating more façade strategies, the base case model is compared to each retrofit façade
system simultaneously. The base case model is a single-glazed façade system without louvers or fins. The
retrofit strategies studied are horizontal louvers, vertical fins, overhangs, and brise soleils with single,
double, and triple-glazed façades. The façade retrofit strategies total energy consumption is exported from
IES-VE and then compared to the base case model’s total energy consumption to determine potential energy
savings. Once the data is exported and analyzed, façade systems that are performing inefficiently or
efficiently will be determined. In this study, the analyzed data of the various façade strategies showed a 0-
35% total energy savings after all the chosen retrofit iterations were tested. The chart below demonstrates
the 5 façade systems that performed better than all the façade iterations tested on the south.

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Table 4.2 Energy savings per façade system (%) – south façade
Façade system Energy savings
(%)
6” Concrete wall

35%
Double glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle + air

17%
Double glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle + argon 16%
Double glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle + air

15%
Double glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle + argon

14%

The 6” concrete wall performed the best out of the 5 listed iterations, with 35% energy savings.
The double-glazed 1’ depth 1’ space vertical fins performed better with 14-18% energy savings compared
to horizontal louvers with 12-15% energy savings. Although the 6” concrete wall is more energy efficient,
horizontal louvers and vertical fins are more suitable as a hotel façade iteration. The concrete wall wouldn’t
be appropriate for the Bonaventure Hotel since it will limit valuable exterior views and natural ventilation.
Additional façade retrofit strategies were examined, exploring a variety of single, double, and triple-glazed
façade iterations.

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Table 4.3 Energy savings per façade system (%) – south façade
Version
(#)
Single glazed – façade system

Energy
savings (%)
S – v1 Single glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

4%
S – v2 Single glazed, 1’ depth, 1’ space horizontal louvers, 75 deg. angle

3%
S – v3 Single glazed, 1’ depth, 2’ space horizontal louvers, 75 deg. angle

0%
S – v4 Single glazed, 1’ depth, 1’ space horizontal louvers, 45 deg. angle

3%
S – v5 Single glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

8%
S – v6 Single glazed, 1’ depth, 1’ space vertical fins, 75 deg. angle

9%
S – v7 Single glazed, 1’ depth, 1’ space vertical fins, 45 deg. angle

11%

Version
(#)
Double and triple glazed – façade system Air Argon Krypton

S – v8 Double glazed (without louvers or fins) 12% 11% 8%
S – v9 Double glazed, 1’ depth, 1’ space horizontal louvers, 90 deg.
angle

15% 14% 12%
S – v10 Double glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

17% 16% 14%
S – v11 Double glazed, 1’ depth, 1’ space vertical fins, 75 deg. angle

18% 17% 15%
S – v12 Triple glazed (without louvers or fins) 9% 8% 4%
S – v13 Triple glazed, 1’ depth, 1’ space horizontal louvers, 90 deg.
angle

12% 11% 8%
S – v14 Triple glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

14% 13% 11%

First, horizontal louvers, vertical fins, overhangs, and brise soleils were applied to a single-glazed
system then double and triple-glazed system. A double and triple-glazed model was constructed without
horizontal louvers and fins, to determine if double or triple glazing performed efficiently without additional
systems. Unexpectedly, the double-glazed façade systems performed better than triple glazed. Double-
glazed 1’ spaced façade systems performed more efficiently than double-glazed 2’ spaced. Horizontal
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louvers with a 90-degree angle performed the same as a 75-degree angle. After analyzing this data, double-
glazed systems performed better than single and triple-glazed systems on the south room façade.
In all, vertical fins with a 1’ depth, 1’ spacing, and a 75-degree angle saved 9% of the room’s total
energy and vertical fins at a 90-degree angle saved 8% with single glazing. Since the 75-degree angle didn’t
perform at least 2% more efficiently at a slanted angle, the 90-degree vertical fin or the 75-degree vertical
fin system can be applied to the Bonaventure with the same energy savings. Although 45-degree fins could
perform more efficiently at 1’ depth 1’ spacing, the 45-degree angles can block exterior views from the
hotel guest room. The 75-degree fins were tested further to determine their energy performance.
It is important to note that the simulation results for the double and triple-glazed systems are based
on the U-values applied. There are many U-values that could have been used, based on the glazing
manufacturer values, yet the average U-value was used in this study. The U-values used for double-glazed
air is 0.41, argon is 0.32, and krypton is 0.22.
In addition, since the double-glazed façade systems performed better than the triple-glazed systems,
this probably reflects the daytime direct gains and the significant nighttime conductive/convective loss of
the triple-glazed system. Triple glazing could have performed efficiently during the day, yet lost heat during
the night. In this study double glazing performed better than triple glazing; however, this might not apply
to all buildings.
The south room façade results showed that double-glazed air-filler performed better than argon and
krypton. Yet, the double-glazed air façade only saved 1% more energy than argon. Considering the average
U-value applied, the average energy savings for air is slightly the same as argon in this study.
Although, air and argon performed the same, air contains moisture and can condense on the inside
of the glass units. Filling the glazing unit with air can cause the glazed façade to appear cloudy or develop
mold if not properly cleaned. Argon is equally efficient in this research study and does not develop
excessive moisture. Since argon does not develop excessive moisture and saves the same amount of energy
as air, argon continued in this study.
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The data illustrated in this research showed a decrease in energy consumption after adding vertical
fins with 1’ depth 1’ spacing. There was also an increase in energy savings after horizontal louvers and
vertical fins were applied to a double-glazed system. Based on the façade systems studied, the highest
energy savings for the south façade was 18%.

Figure 4.3 South façade – versions 1 to 14 (Author 2020)

A double-glazed system with 1’ depth 1’ spacing vertical fins and a 75-degree angle performed the
best out of the 50 versions tested on the south façade, with 15-18% energy savings. In the above graph,
versions 8 through 14 were tested with air, argon, and krypton-filler. Air is illustrated on the plotted graph
for the double-glazed versions (v1-14).
As seen in table 4.3, air saved 17% of the room’s total energy with a similar vertical fin system as
v11. Air saved slightly the same amount of energy as argon in all the tested façade systems. Argon
unexpectedly performed better than krypton saving 2-4% more energy. Although, krypton was expected to
perform better in this research with lower U-values, krypton was not tested in the future studies. Krypton
performed less efficiently than air and argon. It is possible that krypton and air, in this study, allowed the
glazing system to perform efficiently during the day yet had a significant conductive/convective loss during
the night.
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The following façade strategies of argon gas-filler will be compared, to determine the better
performing double-glazed argon façade system.

Table 4.4 Energy savings per façade system (%) – south façade
Version
(#)
Double glazed – façade system Argon
S – v8 Double glazed (without louvers or vertical fins) 11%
S – v10 Double glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

16%
S – v15 Double glazed, 1’ depth, 2’ space vertical fins, 90 deg. angle

11%
S – v16 Double glazed, 1’ depth, 3’ space vertical fins, 75 deg. angle 11%
S – v17 Double glazed, 2’ depth, 1’ space vertical fins, 90 deg. angle 12%
S – v18 Double glazed, 2’ depth, 1’ space vertical fins, 75 deg. angle 13%
S – v19 Double glazed, 2’ depth, 3’ space vertical fins, 75 deg. angle 11%
S – v20 Double glazed, 2’ overhang at roof line 11%
S – v21 Double glazed, 1’ depth brise soleil 11%
S – v22 Double glazed, 3’ depth, 1’ 6” space vertical fins, 90 deg. angle 14%

Vertical fins improved the room’s energy savings by 5% once applied to the double-glazed system.
Brise soleils didn’t increase the double-glazed energy performance, and the energy savings didn’t improve.
The façade systems with a 11% energy savings performed identical to the double-glazed system without
louvers or fins.
Once the double-glazed, 1’ depth, 1’ space, vertical fins and double-glazed (without louvers or
vertical fins) were simulated with argon, additional strategies were explored. The façade versions listed
above are illustrated in the below graph. The graph shows that the additional façade studies examined did
not perform more efficiently. Double-glazed, 3’ depth, 1’ 6” space, vertical fins performed at a 2%
difference from version 10.

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Figure 4.4 South façade – versions 15 to 22 (Author 2020)

The double-glazed 1’ depth 1’ spaced vertical fins, version 10, performed better than the 22
analyzed versions of double-glazed systems.

4.1.3 South façade – summary
The 6” concrete wall performed the best out of all the south façade iterations, with 35% energy
savings. The double-glazed 1’ depth 1’ spaced vertical fins performed efficiently with 14-18% energy
savings compared to horizontal louvers with 12-15% energy savings. Although the 6” concrete wall is more
energy efficient, horizontal louvers and vertical fins are more suitable as a hotel façade retrofit strategy.
The concrete wall wouldn’t be appropriate for the Bonaventure Hotel since it will limit valuable exterior
views and natural ventilation.
Although energy savings were expected to increase after applying triple glazing to the south façade,
the results showed the opposite. Unexpectedly, triple glazing performed poor compared to double glazing.
Without adding horizontal louvers or vertical fins, the examined triple-glazed air façade only saved 9% of
energy compared to the double-glazed façade that saved 12%. It is possible that the triple-glazed façade
didn’t allow enough natural sunlight and reduced transmissivity in the visual spectrum. In addition,
additional layers to a glazing system can reduce the transmission of incoming solar radiation (Mears 1998).
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An additional analysis, after applying vertical fins to a triple-glazed system the room’s energy
savings increased to 14% from 9%. It is assumed that the vertical fins increased the triple-glazing’s energy
savings since the fins efficiently filter sunlight and can provide shading. Triple glazing was also tested on
the southeast façade to determine if there is a pattern of triple glazing performing less efficiently than double
glazing. In the following sections, the SE, E, NE, N, NW, W, and SW orientations were all tested
individually and analyzed.

4.2 Southeast façade
The (SE) southeast façade was analyzed next, with vertical fins and horizontal louvers. A 6”
concrete wall was not tested on the following orientations since the concrete wall was not selected as a
façade strategy. However, vertical fins were again compared to the single-glazing system to determine if
the vertical fins would improve the room’s energy consumption. The graph below shows that the vertical
fins can decrease the room’s energy consumption significantly after comparing to the base case model.

Figure 4.5 Southeast façade (Author 2019)

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Applying horizontal louvers to the SE façade also decreased the room’s energy consumption, but
vertical fins performed better. There is a slight decrease of energy consumption illustrated with horizontal
louvers, but the vertical fins performed 3% more efficiently on the southeast façade similar to the south
façade.

Figure 4.6 Southeast façade (Author 2019)

Since the vertical fins performed better on the south and southeast façade, the 1’ depth 1’ spaced
vertical fins and horizontal louvers were further investigated in this study. 75-degree angles were also
explored in this study to determine if the 75-degree vertical fins would perform better on the southeast
façade similar to the south façade results. The SE façade analysis showed that 75-degree angles saved the
same amount of energy as the 90-degree vertical fins with double glazing. The southeast façade systems
explored are listed below:

Table 4.5 Energy savings per façade system (%) – southeast façade
Version
(#)
Single glazed – façade system

Energy
savings (%)
SE – v1 Single glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

4%
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SE – v2 Single glazed, 1’ depth, 1’ space horizontal louvers, 75 deg. angle

3%
SE – v3 Single glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

7%
SE – v4 Single glazed, 1’ depth, 1’ space vertical fins, 75 deg. angle

7%

Version
(#)
Double glazed – façade system

Air Argon
SE – v5 Double glazed (without louvers or vertical fins) 12% 11%
SE – v6 Double glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

14% 13%
SE – v7 Double glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

16% 15%
SE – v8 Double glazed, 1’ depth, 1’ space vertical fins, 75 deg. angle 17% 16%
SE – v9 Triple glazed (without louvers or vertical fins) 8% 8%
SE – v10 Triple glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

12% 10%
SE – v11 Triple glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

14% 13%

Double-glazed systems with air-filler performed 0-1% better than argon gas-filler with the
examined façade systems. The single-glazed systems are compared to the double-glazed systems to analyze
the difference in energy performance and savings. Double-glazed 1’ depth 1’ spaced vertical fins with a 75-
degree angle performed the best on the SE façade, with air and argon. The 1’ depth 1’ spaced vertical fins
with a 75-degree angle saved 17% of the SE room’s energy with air-filler and 16% with argon. Double-
glazed air and argon façade systems are compared to the single-glazed systems in the following graphs:
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Figure 4.7 Southeast façade – versions 1 to 11(Author 2020)

Figure 4.8 Southeast façade – versions 5 to 11 (Author 2020)

4.2.1 Southeast façade – summary
After comparing air and argon energy savings, surprisingly, air saves the same amount of total
energy as argon. Since krypton is a more expensive gas-filler compared to argon and argon saves 2-4%
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more energy, krypton did not continue in this research. A more economical gas-filler will be used for further
studies. Argon will be used for the future double-glazed research studies and triple glazing will not be used.
Triple-glazed systems are performing less efficiently than double glazing. Double glazing compared to
single glazing will continue in this analysis.

4.3 East façade
After analyzing the southeast façade, the east (E) façade retrofit iterations were studied. For the
east façade, vertical fins continued to perform better than horizontal louvers. Vertical fins saved 1-3% more
energy consumption than horizontal louvers. Although, the energy savings comparing vertical fins and
horizontal louvers are not drastically different from each other, vertical fins are proven to perform better
than louvers by 3% on the south façade with a 75-degree angle. The graph below illustrates the reduction
of energy consumption with the application of single glazing without louvers or fins, vertical fins with
single glazing, and vertical fins with double glazing. Double glazing with vertical fins performed better
than vertical fins with single glazing.

Figure 4.9 East façade (Author 2019)

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Figure 4.10 East façade (Author 2019)

The graphs showed a significant decrease of energy consumption when double-glazed argon was
applied to the vertical fin façade iteration. The single-glazed vertical fin system also showed a decrease in
energy consumption by 6% and the double-glazed system with vertical fins saved an additional 8% of
energy. The single-glazed vertical fins saved 6% of total energy and double glazing saved 14%. The double-
glazed systems have proven to perform better than single glazed.

Table 4.6 Energy savings per façade system (%) – east façade
Version
(#)
Single glazed – façade system

Energy
savings (%)
E – v1 Single glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

3%
E – v2 Single glazed, 1’ depth, 1’ space horizontal louvers, 75 deg. angle

4%
E – v3 Single glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

6%
E – v4 Single glazed, 1’ depth, 1’ space vertical fins, 75 deg. angle

6%

Version
(#)
Double glazed – façade system

Argon
E – v5 Double glazed (without louvers or vertical fins) 10%
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E – v6 Double glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

12%
E – v7 Double glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

13%
E – v8 Double glazed, 1’ depth, 1’ space vertical fins, 75 deg. angle

14%

Figure 4.11 East façade – versions 1 to 8 (Author 2020)

The graph above shows an increase in energy savings from version 1 to 8. Façade version 8, double-
glazed 1’ depth 1’ spaced vertical fins at 75-degree angle had the highest energy savings on the east façade
with 14% total energy savings. Although, vertical fins at a 75-degree angle is not a drastic angle to shade
the hotel room – the angle was tested to analyze the energy savings compared to a 90-degree angled vertical
fin. Initially, vertical fins with a 90-degree angle were tested and the 75-degree angle saved more energy in
this research study.

4.3.1 East façade – summary
The double-glazed 1’ depth 1’ spaced vertical fins at a 75-degree angle performed better than the
8 tested façade iterations. Vertical fins at a 75-degree angle saved 14% of the room’s total energy and the
90-degree angled vertical fins (v7) saved 13%. Since the 75-degree angled vertical fins saved slightly the
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same amount of total energy as the 90-degree angles, the 75-degree angle or the 90-degree angle façade
system can either be selected for the east room of the Bonaventure Hotel.

4.4 Northeast façade
The next façade examined is the northeast (NE) façade. In the northeast orientation 1-12% energy
savings were achieved compared to the east room of 3-14% energy savings. Since there is less solar heat
gain on the north compared to the south, east, and west façades – north façades are less likely to achieve
drastic energy savings due to minimal solar heat gain. The north façades are also known to perform more
efficiently than the S, E, and W façades, without requiring additional retrofit resolutions. There was a slight
reduction of energy consumption after vertical fins were applied to the NE single-glazed façade.

Figure 4.12 Northeast façade (Author 2019)

This study found that if vertical fins were applied to a single-glazed system on the northeast façade
only 5% of the room’s energy consumption can be saved. If horizontal louvers with 1’ depth and 1’ spacing
was applied to a single-glazed system only 1% of energy savings can be achieved. A double-glazed argon
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façade system performed more efficiently with 8% energy savings and 12% savings with vertical fins at a
75-degree angle. The Bonaventure Hotel management can determine if the northeast, north, and northwest
façades should include louver or fin or double-glazed applications since the rooms can perform efficiently
without the systems.

Table 4.7 Energy savings per façade system (%) – northeast façade
Version
(#)
Single glazed – façade system

Energy
savings (%)
NE – v1 Single glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

1%
NE – v2 Single glazed, 1’ depth, 1’ space horizontal louvers, 75 deg. angle

1%
NE – v3 Single glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

5%
NE – v4 Single glazed, 1’ depth, 1’ space vertical fins, 75 deg. angle

5%

Version
(#)
Double glazed – façade system

Argon
NE – v5 Double glazed (without louvers or vertical fins) 8%
NE – v6 Double glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

9%
NE – v7 Double glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

11%
NE – v8 Double glazed, 1’ depth, 1’ space vertical fins, 75 deg. angle

12%

The data gathered from the table above was used to illustrate the graph below. NE version 8 had
the highest energy savings of 12%, only 1% more than version 7. Either version 7 or 8 can be implemented
on the northeast façade of the Bonaventure hotel room.
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Figure 4.13 Northeast façade – versions 1 to 8 (Author 2020)

4.4.1 Northeast façade – summary
Although many façade iterations were tested on the NE façade, applying a single-glazed vertical
fin system to the NE façade isn’t cost effective. The vertical fin systems tested with a single-glazed façade
only saved 5% of the room’s total energy consumption. If a retrofit strategy is applied to the northeast
façade, a double-glazed façade system would be recommended. The most cost effective and energy efficient
solution for the northeast façade is applying double glazing without louvers or fins. Only applying double
glazing to the northeast façade can save 8% of the total energy without the additional cost of louvers or
fins. To save an additional 3% of energy savings, fins could be applied.

4.5 North façade
The north (N) façade was also tested in this research and it is performing efficiently without
additional façade retrofit systems. The highest achievable energy savings for the north façade was the
horizontal louvers and vertical fins double-glazed systems with 8-9% savings. Since the horizontal louvers
or vertical fins resulted in the same amount of saved energy, the retrofit application could be dependent on
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aesthetic preference. The Bonaventure hotel management has the choice of applying double glazing to the
north room and save 7% of the room’s total energy without the additional cost of louvers or fins.
The chart below shows a slight decrease in energy consumption after vertical fins were applied to
the single-glazed north façade. Since there is only a 3% reduction in energy consumption for the north
room, it does not seem necessary to apply horizontal louvers or vertical fins.

Figure 4.14 North façade (Author 2019)

The following table shows minimal energy savings after testing 5 façade strategies on the north façade.

Table 4.8 Energy savings per façade system (%) – north façade
Version
(#)
Single glazed – façade system

Energy
savings (%)
N – v1 Single glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

1%
N – v2 Single glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

3%

Version
(#)
Double glazed – façade system

Argon
N – v3 Double glazed (without louvers or vertical fins) 7%
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N – v4 Double glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

8%
N – v5 Double glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

9%

Double-glazed 1’ depth 1’ spaced horizontal louvers can reduce energy consumption by 8% and
vertical fins can reduce 9% of energy consumption. Single-glazed systems with horizontal louvers and
vertical fins are not recommended since they can only achieve a maximum of 3% energy savings with the
tested iterations. A single-glazed north façade with horizontal louvers also only saved 1% of energy savings.
1% energy savings is not a significant amount of reduced energy to apply horizontal louvers. The cost to
apply horizontal louvers to a single-glazed system is not worth 1% of energy savings.

Figure 4.15 North façade – versions 1 to 5 (Author 2020)

4.5.1 North façade – summary
A double-glazed façade could be applied to the north façade and save 7% of the room’s energy and
save the additional cost of applying horizontal louvers and vertical fins. The horizontal louver double-
glazed system only saved 8% of energy, similar to the double-glazed system without louvers. Vertical fins
also only saved 9% of energy consumption, 2% more than the double-glazed system without louvers or
fins. Double glazing could be applied to the north façade as a façade retrofit design without louvers and
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fins and save 7% of the room’s total energy for a year. A double-glazed façade system is recommended for
the north rooms of the Bonaventure Hotel.

4.6 Northwest façade

After analyzing the north façade, the (NW) northwest façade was analyzed. The NW retrofit results
were similar to the north façade. The horizontal louvers saved 1% of the room’s total energy and will not
be recommended for application to the northwest façade. However, the vertical fins saved 5% of the total
energy consumption with a 75-degree angle and a 90-degree angle. Either vertical fin systems with a 75-
or 90-degree angle could be applied to the NW façade and save the same amount of energy.
The graph below illustrates a similar reduction of energy consumption compared to the N façade,
with a slight decrease in total energy consumption once a single-glazed vertical fin façade system was
applied. There are greater savings with a double-glazed vertical fin system than a single-glazed system.
Double glazing is the recommended resolution for the NW façade retrofit, with or without vertical fins that
can save 9-12% of the room’s energy consumption.

Figure 4.16 Northwest façade (Author 2019)
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Double-glazed systems are performing more efficiently than single-glazed systems. The façade
iterations tested below includes the same façade iteration with single and double glazing. After applying
double glazing to the single-glazed façade iteration, the energy savings increased by 4-7%. The strategies
listed below are explored on the NW façade:

Table 4.9 Energy savings per façade system (%) – northwest façade
Version
(#)
Single glazed – façade system

Energy
savings (%)
NW – v1 Single glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

1%
NW – v2 Single glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

5%
NW – v3 Single glazed, 1’ depth, 1’ space vertical fins, 75 deg. angle

5%

Version
(#)
Double glazed – façade system

Argon
NW – v4 Double glazed (without louvers or vertical fins) 9%
NW – v5 Double glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

9%
NW – v6 Double glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

12%
NW – v7 Double glazed, 1’ depth, 1’ space vertical fins, 75 deg. angle

9%

The data gathered from the above list is plotted on the graph below.

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Figure 4.17 Northwest façade – versions 1 to 7 (Author 2020)

4.6.1 Northwest façade – summary
Energy savings increased after double-glazed systems were applied to the northwest façade. On the
north façade the maximum savings with single glazing was 3% and the northwest façade was 5%. The north
and northwest façade had identical façade retrofit systems with 2% energy savings difference. Although
single-glazed systems on the N and NW façade saved 3-5% of the room’s total energy, single glazing is not
recommended in this study. Double-glazed systems on the NW façade can save 9% of the room’s total
energy without the application of louvers or fins. With the application of louvers and fins, the horizontal
louvers can only save 9% of the total energy and vertical fins can save 12%. Since horizontal louvers are
less efficient at blocking low afternoon sun during peak heat gain periods, the louvers could therefore be
performing less efficiently than vertical fins (Prowler 2016). A double-glazed system without horizontal
louvers or vertical fins is recommended for the Bonaventure Hotel’s NW façade. Double glazing with argon
is also recommended. Argon is an efficient and more affordable gas-filler.

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4.7 West façade
The west (W) façade was analyzed next. Energy savings increased after horizontal louvers and
vertical fins were applied to the west façade. The west façade had greater energy savings than the northwest
and north façade. Horizontal louvers can save 3% of the room’s total energy compared to 1% in the N and
NW orientations. The energy savings for the west orientation is increasing since there is more solar heat
gain absorbed in the glazing insulation than on the N. The south orientation is known to have the most solar
heat gain and orientations closer to the south will have higher solar heat gains. Compared to the north
façade, the west façades can save 5% more energy with an updated façade retrofit system.
The west façade can save 8% of the room’s total energy if vertical fins were applied to a single-
glazed façade. If the vertical fins were installed with a 75-degree angle, the energy savings would not
increase. The energy savings for the double-glazed 75-degree fin system was the same as the 90-degree fin
system. Adjusting the vertical fins to a 45-degree angle might be a cost-effective retrofit resolution since
the 45-degree fins saved 2% more energy than the 90-degree vertical fins. Yet, the 45-degree fins at 1’
depth spacing could block exterior views from the hotel guest room. 2’-3’ spacing would be ideal for 45-
degree angle fins, however; 2’ spacing was proven to not perform efficiently in the room studies. The
recommended system for single glazing on the west façade is the 1’ depth, 1’ spaced vertical fins at 90-
degrees. Below are the additional façade systems explored for the west façade:

Table 4.10 Energy savings per façade system (%) – west façade
Version
(#)
Single glazed – façade system

Energy
savings (%)
W – v1 Single glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

3%
W – v2 Single glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

8%
W – v3 Single glazed, 1’ depth, 1’ space vertical fins, 75 deg. angle

5%

Version
(#)
Double glazed – façade system

Argon
W – v4 Double glazed (without louvers or vertical fins) 10%
W – v5 Double glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

13%
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W – v6 Double glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

14%
W – v7 Double glazed, 1’ depth, 1’ space vertical fins, 75 deg. angle

14%
W – v8 Double glazed, 1’ depth, 1’ space vertical fins, 45 deg. angle

16%

The graph below illustrates the energy savings per façade system listed above.

Figure 4.18 West façade – versions 1 to 8 (Author 2020)

After applying a double-glazed system with argon to the W façade, an increase in energy savings
can be achieved. Horizontal louvers and vertical fins have the same energy savings with only 1% savings
difference with double glazing. Vertical fins and horizontal louvers can either be applied on the west façade
of the Bonaventure Hotel.

4.7.1 West façade – summary
Double-glazed, vertical fins with argon or horizontal louvers at 90-degrees are suggested for the
west façade retrofit. The 75-degree vertical fins are not necessary for application on the west façade since
the savings are identical to the 90-degree angles. Adjusting the louvers to a 75-degree angle might not be a
cost-effective retrofit resolution since the 90-degree angles don’t need additional mechanics to rotate to 75-
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degrees. The Bonaventure Hotel management can determine if horizontal louvers, vertical fins, and vertical
fins with a 75-degree angle should be applied since the façade systems save the same amount of energy on
the west façade.

4.8 Southwest façade
Lastly, the southwest façade was analyzed. The S, SE, E, NE, N, NW, W, and SW orientations
were all analyzed first before the energy savings for 10
th
floor was examined. The energy savings for the
southwest room were similar to the south room’s energy savings. The S and SW rooms saved 4% of the
room’s total energy consumption after horizontal louvers were applied to the single-glazed façade system.
7% of the room’s total energy was saved after vertical fins were applied. The vertical fins at a 75-degree
angle on the SW façade saved 8% of the room’s total energy meanwhile 9% total energy was saved on the
S. There is a 1% increase in energy savings from the S and SW façades. However, the 1% energy savings
difference is expected since there is more solar heat gain on the S. Single and double-glazed façade systems
are listed below.

Table 4.11 Energy savings per façade system (%) – southwest façade
Version
(#)
Single glazed – façade system

Energy
savings (%)
SW – v1 Single glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

4%
SW – v2 Single glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

7%
SW – v3 Single glazed, 1’ depth, 1’ space vertical fins, 75 deg. angle

8%

Version
(#)
Double glazed – façade system

Argon
SW – v4 Double glazed (without louvers or vertical fins) 11%
SW – v5 Double glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle

14%
SW – v6 Double glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle

16%
SW – v7 Double glazed, 1’ depth, 1’ space vertical fins, 75 deg. angle

16%

The façade systems analyzed above are illustrated below.
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Figure 4.19 Southwest façade – versions 1 to 7 (Author 2020)

4.8.1 Southwest façade – summary
Double-glazed façades have proven to perform more efficiently on the Bonaventure Hotel. The
rooms that were tested on the S, SE, E, NE, N, NW, W, and SW orientations show a significant amount of
energy savings after double-glazing systems were applied. Compared to the base case model, the double-
glazed iterations with argon can save 11-16% of the room’s energy on the southwest façade. The double-
glazed, 1’ depth, 1’ spaced horizontal louvers and vertical fins are recommended for the southwest façade,
saving 14-16% of the room’s total energy.

4.9 S, SE, E, NE, N, NW, W, and SW summary
Out of the 200 studies that were simulated, vertical fins, horizontal louvers, and a concrete wall
performed the best. Vertical fins were simulated with various depths and spacing iterations. The vertical
fins were examined in 1’, 2’, 3’ depth and 1’, 1’ 6”, 2’, 3’ spacing. Horizontal louvers were also explored
with 1’, 1’ 6”, 2’ depths and spacings. The vertical fins and horizontal louvers at 1’ depth and 1’ spacing
showed to have better energy savings than the other façade strategies that were simulated. 3’ spacings for
the horizontal louvers were not tested since a pattern showed that 2’ spacings performed worse than 1’
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spacings. Examining the energy consumption data for each façade system before simulating more was
necessary to understand a pattern. The pattern showed how each façade systems depths, spacings, and
strategy type was impacting the total energy consumption. These patterns suggested which strategies should
be analyzed more thoroughly, and which ones can be excluded from more tests.
Vertical fins with 1’ depth 1’ spacing at a 90-degree angle and a 75-degree angle, performed more
efficiently on all the S, SE, E, NE, N, NW, W, and SW orientations. However, since the north façade can
perform efficiently without additional louver and fin systems, louvers and fins are not recommended for
the application of the north façade. In addition, since double-glazed systems proved to perform more
efficiently than single and triple-glazed systems – double glazing can be applied as a retrofit strategy on all
the façade orientations.
For each of the rooms that were simulated the energy savings varied. The S, SE, E, and NE façade
performed efficiently with a 75-degree and 90-degree vertical fin system. In the W and SW orientations,
the vertical fins at a 75-degree and a 90-degree angle performed the same. The 75-degree angle vertical fins
did not provide additionally shading on the NW, W, and SW orientations, yet performed slightly better on
the S, SE, E, and NE orientations. Before applying the façade strategies onto the 10
th
floor retrofit model,
an analysis of the better performing retrofit strategies per orientation were studied. Below is a summary of
the better performing façades with argon per orientation:

Table 4.12 Energy savings per façade system (%) – S, SE, E, NE, N, NW, W, and SW orientations
Orientation Retrofit system Argon energy
savings (%)
Retrofit system Argon energy
savings (%)
(S) South Double glazed, 1’ depth, 1’
space vertical fins, 75 deg.
angle

17% Double glazed, 1’ depth, 1’
space vertical fins, 90 deg.
angle
16%
(SE)
Southeast
Double glazed, 1’ depth, 1’
space vertical fins, 75 deg.
angle

16% Double glazed, 1’ depth, 1’
space vertical fins, 90 deg.
angle

15%
(E) East Double glazed, 1’ depth, 1’
space vertical fins, 75 deg.
angle

14% Double glazed, 1’ depth, 1’
space vertical fins, 90 deg.
angle

13%
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(NE)
Northeast
Double glazed, 1’ depth, 1’
space vertical fins, 75 deg.
angle

12% Double glazed, 1’ depth, 1’
space vertical fins, 90 deg.
angle

11%
(N) North Double glazed, 1’ depth, 1’
space vertical fins, 90 deg.
angle

9%

Double glazed (without
louvers or vertical fins)
7%
(NW)
Northwest

Double glazed, 1’ depth, 1’
space vertical fins, 90 deg.
angle

12% Double glazed, 1’ depth, 1’
space vertical fins, 75 deg.
angle

9%
(W) West

Double glazed, 1’ depth, 1’
space vertical fins, 75 deg.
angle
14%

Double glazed, 1’ depth, 1’
space vertical fins, 90 deg.
angle

14%
(SW)
Southwest

Double glazed, 1’ depth, 1’
space vertical fins, 75 deg.
16% Double glazed, 1’ depth, 1’
space vertical fins
16%

The data above is illustrated in the diagram below.

Figure 4.20 Façade retrofit energy savings (Author 2020)

The façade retrofit strategies on the south (S), saved the most energy at a total of 17%. In the SE
and SW orientations, the façade studies saved the same amount of energy at a total of 16%. For the NE and
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NW façades, the same amount of energy was also saved at a total of 12%. However, the N façade only
saved 9% of the room’s total energy.
Simulating each façade orientation was necessary in analyzing the performance of the S to SW
façades individually. The Bonaventure Hotel has 8 façade orientations, and in order to retrofit an entire
floor’s façade, determining the energy performance of each façade is significant. A façade that is
performing better on the S might not perform better on the N. By analyzing the façade orientations, the
application of the façade system can be determined by each of the room’s energy performance.
The following retrofit strategies will include the analysis from the room simulation studies. The
façade retrofit strategies that performed the best will be applied to the 10
th
floor façade model. Since the
double-glazed 1’ depth 1’ space vertical fins were one of the better performing systems on the S to NE and
W to SW, the 1’ depth 1’ space vertical fins will be tested on all the orientations on 10
th
floor except the N.

4.10 10
th
floor – façade retrofit design
After analyzing each room’s energy usage in the S, SE, E, NE, N, NW, W, and SW orientations,
the entire 10
th
floor’s façades were designed. The façade retrofit design implemented the results from the
room orientation analysis and applied it to all the orientations on the 10
th
floor. Two of the primary design
iterations applied were double-glazed, 1’ depth, 1’ spaced, horizontal louvers and vertical fins. Since
horizontal louvers and vertical fins performed better than all of the iterations tested on the room model, the
same systems were explored on the 10
th
story façade model. Although the 6” concrete wall is more energy
efficient than all the tested room iterations, horizontal louvers and vertical fins are more suitable as a hotel
façade system. The concrete wall wouldn’t be appropriate for the Bonaventure Hotel since it will limit
valuable exterior views and natural ventilation. Horizontal louvers and vertical fins at 1’ depth and 1’
spacing was applied to the 10
th
story of the Bonaventure Hotel.
The retrofit strategies for the 10
th
story was modeled in Revit and exported as a gbXML file. The
gbXML file is imported into IES-VE and simulated for total energy and operational CO 2 data. The results
showed that 1’ depth 1’ spaced horizontal louvers and fins were performing efficiently with double and
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triple glazing. The total energy consumption decreased significantly after 1’ depth 1’ spaced retrofit
strategies were applied. In order to decrease and analyze the energy consumption for the 10
th
story, more
retrofit design iterations were tested. This phase of testing included studies from the room orientation
simulations. The retrofit strategies for the 10
th
story included, spacings of 1’ and 2’. Instead of testing only
1’ spacings, wider spacings of 2’ were analyzed in this study. The results later showed that double-glazed
1’ spaced vertical fins performed better than 2’ spaced vertical fins. Applying only double glazing to all the
façade orientations also performed the same as triple glazing, in this study.
Similar to the simulations of each room’s façade, the 1’ depth 1’ spaced retrofit systems performed
better on the 10
th
story model. Adding 2’ spacing in-between the fin system with a 45-degree angle also
improved the energy performance of the façade story model. To note, any systems without efficient solar
shading did not perform as well. 1’ spaced systems performed the best providing shading for the building
and room. Mitigating solar heat gain can be accomplished with façade strategies and understanding how
much solar shading is beneficial per orientation and room is important.
To begin, a base case story model and multiple retrofit models are exported as a gbXML file from
Revit. Once exported, the gbXML story models are imported into IES-VE for total energy and operational
CO 2 simulations. The Revit and IES-VE steps applied for the room model simulations can be used for the
10
th
story façade model. The following figures show how the Revit models are exported and imported.
Interior partition walls were used for reference but were not simulated to acquire the energy consumption
and CO 2 results.
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Figure 4.21 Revit 10
th
story design gbXML export (Author 2020)

Figure 4.22 IES-VE 10
th
story design gbXML import (Author 2020)

The following façade systems were tested on the 10
th
story and showed a significant decrease in
energy consumption after a double-glazed argon façade was applied to all orientations on the façade model.
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The design iterations tested for the 10
th
floor façade model was compared to the single-glazed base case
model. Comparing the base case model to the retrofit strategy, provided an analysis in the story’s total
energy savings. The total energy for the base case model was exported first, indicating the total energy for
the base case as 915.84 MBTU. After a double-glazed system was applied as a design iteration, the total
energy significantly decreased to 714.81 MBTU, suggesting potential savings of 22%.
The following strategies include the façade iterations from the room study. There are 20 design
versions studied on the 10
th
story model.

Table 4.13 Energy savings per façade system (%) – 10
th
floor façade model
Design
Version (#)
Façade system (Double glazed gas-filler: argon) Total energy
savings (%)
Base Case Single glazed -
Design v1 Double glazed (without louvers or fins) 22%
Design v2 Double glazed, 1’ depth, 1’ space horizontal louvers and vertical fins, 90
deg. angles

24%
Design v3 Double glazed, 1’ depth, 1’ space vertical fins, 90 deg. angles 24%
Design v4 Double glazed, 1’ depth, 2’ space horizontal louvers and vertical fins, 90
deg. angles

22%
Design v5 Double glazed, 1’ depth, 2’ space 90 deg. angle horizontal louvers and 45
deg. angle vertical fins

22%
Design v6 Double glazed, 1’ depth, 2’ space 45 deg. angle horizontal louvers and 45
deg. angle vertical fins

22%
Design v7 Double glazed, 1’ depth, 2’ space vertical fins 90 deg. angle and 45 deg.
angle vertical fins

23%
Design v8 Double glazed, 1’ depth, 2’ space vertical fins, 90 deg. angle 22%
Design v9 Double glazed, 1’ depth, 2’ and 3’ space vertical fins, 90 deg. angles 22%
Design v10 Double glazed, 1’ depth, 1’ space horizontal louvers, 90 deg. angle 23%
Design v11 Double glazed, 1’ depth, 2’ space horizontal louvers, 90 deg. angle 22%
Design v12 Double glazed, 2’ depth, 2’ space horizontal louvers, 90 deg. angle 22%
Design v13 Double glazed, 2’ depth, 1’ space vertical fins, 90 deg. angle 24%
Design v14 Double glazed, 2’ depth, 2’ space vertical fins, 90 deg. angle 22%
Design v15 Double glazed, 2’ depth overhang 22%
Design v16 Triple glazed (without louvers or vertical fins) 22%
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Design v17 Triple glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle 24%
Design v18 Double glazed, egg crate, 1’ depth, 1’ space vertical fins and horizontal
louvers, 90 deg. angles

28%
Design v19 Double glazed, egg crate, 1’ depth, 1’ space vertical fins and 2’ space
horizontal louvers, 90 deg. angles

23%
Design v20 Double glazed, egg crate, 1’ depth, 2’ space vertical fins and horizontal
louvers, 90 deg. angles

22%

The double-glazed, egg crate, 1’ depth 1’ spaced fins and louvers performed the best, decreasing
the total energy from 915.84 MBTU to 656.33 MBTU, and saving 28% total energy. The triple-glazed
system 1’ depth 1’ space vertical fins also decreased the façade floor model’s energy consumption
significantly by 24%, yet similar to design v2, v3, and v13. The triple-glazed system 1’ depth 1’ space fins
are similar to the studies of double-glazed 1’ depth 1’ space fins, double-glazed 1’ depth 1’ space louvers
and fins, and double-glazed 2’ depth 1’ space fins. This resulting in only 2% more savings than double-
glazed (without louvers or fins) and triple-glazed (without louvers or vertical fins). The double-glazed
system and triple-glazed system are performing the same in the 10
th
story model. Again, the triple-glazed
façade is not performing more efficiently than the double-glazed façade system. Since double-glazed
systems cost less than triple-glazed systems and are performing better, double-glazed systems are
recommended for the application of the Bonaventure Hotel.
The double-glazed iterations that performed the second best are the design versions v2, v3, and
v13. These systems include 1’ depth 1’ spacing, saving 24% total energy. The third best energy savings in
this study are v7, v10, and v19, saving 23% total energy. Although, v7 is combined with a 45- and 90-
degree angled vertical fin system the total energy savings are the same as v10 and v19. Design version v10
are 1’ spaced horizontal louvers and v19 is an egg crate with 1’ spaced vertical fins and 2’ spaced horizontal
louvers. Since v7 includes 2’ spaced vertical fins, design v7 is more suitable for a hotel façade than v10 or
19 because it can offer wider views in-between the 2’ vertical spacing. Implementing 1’ spacing in a façade
retrofit design for the Bonaventure Hotel can be dependent on hotel management. The 1’ depth 1’ spaced
systems have proven to perform better than all the louver and fin façade iterations tested.
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Louvers and fins applied to the double-glazed façade did increase the 10
th
story model’s energy
savings. The highest total energy savings found with a double-glazed vertical fin and louvers system is
design v18. If a double-glazed system without louvers or fins was applied to the 10
th
floor, 22% of the total
energy savings could be achieved. There are designs that were also tested that did not increase the energy
savings after applying the façade strategy to a double-glazed façade system. The systems listed with 22%
savings with additional strategies to the double-glazed system did not improve the energy performance. A
double-glazed system (without louvers or fins), or design version v7 that has 2’ spacing with valuable
exterior views are recommended as a possible façade retrofit resolution for the Bonaventure Hotel.
Applying horizontal louvers and vertical fins to the tested glazing systems decreased the energy
consumption significantly on 8 of the 10
th
story façade iterations. The story design versions analyzed above
are illustrated below.

Figure 4.23 Story designs (Author 2020)

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Figure 4.24 Story designs (Author 2020)

Design versions 2, 3, 4, 8, 9, and 20 are shown below:

Figure 4.25 Design v2 (Author 2020)

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Figure 4.26 Design v3 (Author 2020)

Figure 4.27 Design v4 (Author 2020)

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Figure 4.28 Design v8 (Author 2020)

Figure 4.29 Design v9 (Author 2020)

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Figure 4.30 Design v20 (Author 2020)

After the better performing systems were selected, the façade retrofit operational CO 2 was
compared to the base case operational CO 2. The objective of this research is to reduce CO 2 emissions and
energy consumption.

4.10.1 Operational CO 2 calculation
Operational CO 2 is significant in the carbon footprint analysis since producing the energy used in
the HVAC systems and artificial lighting produces a substantial amount of CO 2. Mitigating the building’s
solar heat gain can help reduce operational CO 2 of overperforming HVAC and lighting systems. Applying
efficient retrofit strategies on the Bonaventure Hotel can decrease operational CO 2 emissions with an
updated façade technology. The main objective of this study is to analyze the energy performance of an
existing building, retrofit its façade, and consider CO 2 emissions and energy consumption. In order to
decrease the hotel’s carbon footprint and energy consumption, the operational energy produced should be
examined.
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To determine the base case model’s operational CO 2, a base case calculation was used. The
operational CO 2 calculated was used to compare to the retrofit calculation. The retrofit calculation and the
base case calculation for 4 selected strategies showed a decrease in 22-28% operational CO 2.
The base case operational CO 2 calculation is shown below. The formula that was used for this
research is the annual energy use and CO 2 footprint formula. The annual electricity consumption in MWh
units are necessary to achieve the annual electricity CO 2 footprint for the base case model. The total energy
MBTU data gathered from the simulations were converted to MWh and then applied to the annual energy
use and CO 2 footprint formula based on the carbon footprint listed for the LADWP. The LADWP carbon
intensity found was 1200 LBS CO 2 (Greenhouse Gas Emissions 2017). An example of the base case
calculation is shown below:
Annual electricity consumption (in MWh) x LADWP carbon intensity = Annual electricity CO 2 footprint
915.84 MBTU x 0.2931 = 268.43Wh
268.43 MWh / year x 1200 lbs CO 2e / MWh = 322,116 lbs CO2

For comparison, an example of the façade retrofit calculation is shown below:
Annual electricity consumption (in MWh) x LADWP carbon intensity = Annual electricity CO 2 footprint
714.81 x 0.2931 = 209.51 MWh
209.51 MWh / year x 1200 lbs CO 2e / MWh = 251,412 lbs CO2

Design version 1, 3, 7, 18 were analyzed further, comparing the operational CO 2 saved. The double-
glazed egg crate design saved the most operational CO 2 , decreasing the 322,116 lbs of CO 2 for the 10
th

story to 230,844 lbs of CO 2.

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Table 4.14 Operational CO 2 per façade system (%) – 10
th
floor façade model
Design
Version (#)
Façade system (Double glazed gas-filler: argon) Operational CO2
(lbs CO2)
Base Case Single glazed 322,116
Design v1 Double glazed (without louvers or fins), argon 251,412
Design v3 Double glazed, 1’ depth, 1’ space vertical fins, 90 deg. angle 245,772
Design v7 Double glazed, 1’ depth, 1’ space 90 deg. angle vertical fins and 2’ space 45
deg. angle vertical fins

248,256
Design v18 Double glazed, egg crate, 1’ depth, 1’ space vertical fins and horizontal
louvers, 90 deg. angles

230,844

Applying the varied façade iterations to the Bonaventure Hotel significantly decreased the
operations CO 2 emissions by 22 – 28%. Embodied energy was considered in this research but will be
applied in future work.

4.11 Summary
The Bonaventure Hotel has an outdated façade that has a likely energy liability. Computer modeling
confirmed this, indicating that the single-glazed hotel energy efficiency could be substantially improved.
The Bonaventure Hotel can perform more efficiently with the retrofit strategies tested. A detailed chart of
façade retrofit possibilities was created. For these reasons, widely available façade applications, low
embodied energy from materiality, and strategies known to perform efficiently, a subset of 300 alternative
schemes were proposed. Each façade analyzed was modeled in Revit and simulated in IES-VE.
Out of all the retrofit systems that were tested, a 6” concrete wall, horizontal louvers, and vertical
fins saved the most energy and operational CO 2 for the Bonaventure Hotel. After analyzing 200
combinations of façade strategies, 195 strategies performed inefficiently compared to the remaining 5
façades. The results showed that 1’ depth 1’ spaced vertical fins perform efficiently in the room simulations
and the 10
th
story façade model. The 1’ depth 1’ spaced systems were performing better than the 2’ spaced
systems. After applying a 45-degree angled fin system to the 2’ spaced iteration, the 2’ spacing performed
efficiently, saving 23% with design v7. The 10
th
story model resulted in new assumptions, that double-
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glazed systems were already performing efficiently and added louver or fin systems would only improve
the story’s total energy savings by 1-2%. If an egg crate retrofit design with 1’ depth 1’ spacing was applied
to the entire floor’s façade, then 6% total energy savings can be achieved with double glazing. Since the
energy savings for the 10
th
story already achieved 22% total energy savings, to increase the savings with
louvers and fins was difficult to accomplish. There are 8 façade iterations that increased the 22% double-
glazed savings, but 11 façade iterations could not be increased more. It is assumed that since the story model
is already performing better with a high-performing glazing material, some iterations with louvers or fins
might not be as drastic. After analyzing these results, a double-glazed system without louvers or fins and a
double-glazed system with 1’ depth 1’ spaced vertical fins and 2’ spaced 45-degree vertical fins would be
recommended for the Bonaventure façade retrofit.

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5. DISCUSSION

The results found reinforce the significance of façade retrofit on existing buildings and the
Bonaventure. There are buildings similar to the Bonaventure Hotel that could benefit from these façade
retrofit resolutions, through the results found in this study. Although these results were analyzed for the
Bonaventure Hotel in Los Angeles, other similar buildings can learn from the studies conducted. In this
study, double-glazed façades are more efficient than single and triple glazed. Horizontal louvers and vertical
fins are also more effective façades than brise soleils. This research also shows a reduction in operational
CO 2 and energy consumption. If reducing CO 2 and energy consumption is important worldwide, then less
buildings should be demolished and existing buildings should be retrofitted. Instead of demolishing an
existing building, the existing building can be re-examined to reduce demolition CO 2 and embodied energy
CO 2. If buildings are not retrofitted, then the existing building’s energy consumption and operational CO 2
can remain excessive.
Buildings prior to the 1990s were constructed with inefficient façades and many existing buildings
are lacking in energy efficiency. Façade systems have evolved since the 1990s and a building as early as
the 1970s can benefit from current 2020 technology without demolition. There is an opportunity to save on
construction costs, energy consumption, and carbon footprint by implementing new façade strategies.
Demolishing a building before attempting a strategy that can reduce energy consumption is environmentally
harmful with increased carbon emissions. Before choosing to demolish future buildings, first implementing
these researched façade strategies can reduce the building’s energy costs and carbon emissions.
Since heating, cooling, and lighting is a key contributor to the energy consumption in a building,
the façade strategies selected can decrease the heat transfer through the building with the double-glazed
systems. This thesis analyzed efficient façade strategies for the Bonaventure’s façade. The process included
applying current façade technologies onto the existing 1970s building. The main objective was to
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implement an updated façade technology of the 2000 era onto a 1970s building. The façade strategies
incorporated the current glazing envelope with a new efficient technology.
It could be argued that existing buildings are an energy liability and demolishing the existing
building to construct a new one is the best resolution. However, older buildings have the opportunity to
achieve efficient energy performance. In addition, buildings’ have a historical significance that impacts the
people of the community and the carbon footprint if demolished. If the goal is to reduce energy consumption
and carbon footprint then demolishing a building is not necessarily a better resolution for the environmental
problem. By first replacing the main contributor in increasing HVAC costs, the façade system, increased
energy performance and cost savings can be expected.
Existing buildings similar to the Bonaventure have the opportunity to become a new 2020 building.
With the application of an updated façade, the Bonaventure was tested with a modern hybrid façade system.
This case study and others can benefit from this research with a retrofitted façade, to reduce CO 2 emissions
and current energy consumption. The Renaissance Center and Westin Peachtree Plaza Hotel can likewise
benefit from this study. Although the buildings suggested are in different states, the circular floor shapes
are similar to the Bonaventure Hotel. Both, the Renaissance Center and Westin Peachtree Plaza have
outdated glass and can gather new data from a similar façade retrofit analysis.

5.1 Evaluation of the workflows
In the beginning stages of this research, architectural drawings and literature-based information
were predominantly useful in the façade retrofit studies of the Bonaventure. The architectural drawings and
literature information available allowed a beginner in façade research to study the hotel at a micro-level.
Yet, further studies were not implemented due to the limitations of skill and inability to obtain baseline
energy usage data. During the early stages of research, background information was necessary to understand
which retrofit strategies could be implemented. The Bonaventure is a hotel with architectural history to the
community of Los Angeles. Considering that the building is an iconic landmark in Los Angeles, there were
design constraints for the new façade retrofit. The new façade retrofit was intended to be a 2020 technology,
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but to combine the old and the new. In this study, there were façade retrofit studies conducted to find a
façade resolution for a 1970s building.

5.1.1 ZWICKY chart
A total of 300 façade retrofit studies were analyzed using a ZWICKY chart, comparing a variety
of horizontal louvers, vertical fins, brise soleils, and overhangs. 50 of the façade strategies from the chart
could not be applied since the façade systems were drastically different from the current Bonaventure
design. The original Bonaventure Hotel design is a modern futuristic building with highly reflective glazing
material. As an example, one of the façade strategies listed on the ZWICKY chart was a red glazing material
and was eliminated from the conducted research. Since red glazing is an opposite design approach for the
Bonaventure’s historical context, 50 of the façade strategies from the ZWICKY chart were eliminated.
Although horizontal louvers and vertical fins can be argued as a drastic design approach to the Bonaventure
Hotel it is not as drastic as red film. Louvers and fins are shading devices that can be integrated in the
modern retrofit design and include the 1970s glazing transparency and reflectance. The red color glazing
material was eliminated in the façade strategy process due to its impact on the historic context of the
building. The design approach for the hotel was not to be identical to the original, but to keep its modern
qualities of transparency and include an updated 2020 technology.
In total, 100 of the 300 ZWICKY chart options were not applicable since some of the façade
strategies were drastically different from the original Bonaventure design and the selected materials had a
significant amount of embodied CO 2. Since the objective of this research is to reduce CO 2 emissions and
energy consumption – the selected façade systems should limit the emittance of CO 2 and assist in improving
energy efficiency.

5.1.2 Revit room modeling
The base case Revit model was built after the ZWICKY chart was created. Existing façade materials
were also listed to analyze the existing model and determine if the new façade retrofit systems could be
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applied. To suggest alternative façade strategies and determine the material limitation, the existing materials
were recorded first. The existing materials found were through visual analysis of the Bonaventure and
comparison of other façade systems. With these findings of existing materials through visual representation,
a list was established. The assessment was based on a basic (B), poor (P), and fair (F) evaluation. The
single-glazed, tinted mirrored curtain wall was in poor condition and could benefit from a new system.
Following these façade strategy assessments, the strategies found from the ZWICKY chart were applied to
the Revit room models.

5.1.3 IES-VE room simulations
After the Revit room models were constructed, 200 façade strategies were then simulated in IES-
VE to compare the room’s total energy consumption and operational CO 2. Façade systems related to high
density solar shading were also eliminated during the process. Following the study, the simulations results
showed that 1’ depth and 1’ spacing horizontal louvers and vertical fins gave a significant amount of solar
shading without requiring additional artificial lighting per room.

5.2 Comparison of results
The strategies were first analyzed on the south (S) orientation, then analyzed on the SE, E, NE, N,
NW, W, and SW orientations. Testing the orientations in increments resulted in discovering which façade
strategies perform better in each orientation. In doing this, the data showed which façade strategies should
be applied per orientation on the 10
th
story model. A façade strategy that might perform better on the south
might not perform better on the west.
The double and triple-glazing systems that were tested included argon, air, and krypton. After
noticing a pattern in the data, krypton performed less efficiently than argon and air. Argon and air were
further analyzed and argon was ultimately chosen as a better gas-filler with the tested retrofit strategies
compared to air. In following sections, louver and fin façade strategies were applied to the S, SE, E, NE,
N, NW, W, and SW orientations individually.
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5.2.1 South façade
On the south (S) façade, horizontal louvers are known to usually perform more efficiently compared
to vertical fins. Yet, in this research vertical fins saved 4% more energy than horizontal louvers with single
glazing. This resulted in a double-glazing study with vertical fins and horizontal louvers. After applying
double glazing to the 1’ depth 1’ spacing vertical fins façade, the vertical fins performed better than
horizontal louvers. The double-glazed, 1’ depth, 1’ space, vertical fins saved 16% of energy with argon and
horizontal louvers saved 14% of energy with argon. Vertical fins saved 2% more energy than horizontal
louvers on the south façade. Vertical fins are a recommended façade resolution for the south façade, with
double-glazed argon. However, either horizontal louvers or vertical fins can be applied on the Bonaventure
and the retrofit design can be determined by hotel management.
As mentioned previously, a 6” concrete wall performed the best out of all the iterations tested with
35% energy savings. Although the 6” concrete wall is more energy efficient, horizontal louvers and vertical
fins are more suitable as a hotel façade iteration. The concrete wall wouldn’t be appropriate for the
Bonaventure Hotel since it will limit valuable exterior views and natural ventilation. Additional façade
retrofit strategies were examined, exploring a variety of single, double, and triple-glazed façade iterations.
Although energy savings were expected to increase after applying triple glazing to the south façade,
the results showed the opposite. Unexpectedly, triple glazing performed poor compared to double glazing.
Double glazing is recommended as a façade iteration in this study.

5.2.2 Southeast façade
Unexpectedly, vertical fins performed better on the south and southeast (SE) façade. The façade
strategies with 1’ depth 1’ spacing vertical fins and horizontal louvers were further investigated. 75-degree
angles were also explored in this study to determine if the 75-degree vertical fins would perform better on
the southeast façade. The SE façade analysis showed that the 75- and 90-degree vertical fins saved the same
amount of energy with double glazing. A double-glazing system with 90-degree vertical fins could be
applied to the southeast façade if 75-degree vertical fins are unavailable.
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In addition, argon was also recommended in this study since argon saved 2-4% more total energy
than krypton, with louver and fin systems. Since krypton is a more expensive gas-filler compared to argon
and argon saves 2-4% more energy, krypton did not continue in this research. Triple glazing was also not
applied since triple glazing performed less efficiently than double glazing. Double glazing and single
glazing were analyzed for all orientations, since the single-glazed iterations were used for base case studies.

5.2.3 East façade
For the east (E) façade, double-glazed 1’ depth 1’ spaced vertical fins at a 75-degree angle with
argon performed better than 8 of the tested façade iterations. Vertical fins at a 75-degree angle saved 14%
of the east room’s total energy and 90-degree vertical fins saved 13% (v7). Since the 75-degree vertical fins
saved the same amount of energy as the 90-degree fins, either the 75- or 90-degree system could be used
for the east room of the Bonaventure Hotel. These results are only for the orientation addressed in this
section.

5.2.4 Northeast façade
On the northeast (NE) façade, applying a single-glazed vertical fin system to the NE façade isn’t
cost effective. The vertical fin systems tested with a single-glazing façade only saved 5% of the room’s
total energy consumption. If a retrofit strategy is applied to the northeast façade, a double-glazed façade
system would be recommended. The most cost effective and energy efficient resolution for the northeast
façade is applying double glazing without louvers or fins. Applying double glazing to the northeast façade
can save 8% of the total energy without the additional cost of louvers or fins. To save an additional 3% of
energy savings, louvers and fins could be applied.

5.2.5 North façade
In the north (N) orientation, a double-glazed façade could save 7% of room’s energy and also save
the cost of applying horizontal louvers and vertical fins. The horizontal louver double-glazed system only
saved 8% of energy, identical to the double-glazing system without louvers. Vertical fins also only saved
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9% of energy consumption, 2% more than the double-glazing system without louvers or fins. Double
glazing could be applied to the north façade as a façade retrofit design without louvers and fins and save
7% of the room’s total energy for a year. A double-glazed façade system without louvers or fins is
recommended for the north room of the Bonaventure Hotel.

5.2.6 Northwest façade
Compared to the north façade, the northwest (NW) façade’s energy savings increased after double-
glazed systems were applied. The north and northwest façade had identical façade retrofit systems with 2%
energy savings difference. Double-glazed systems on the NW façade could save 9% of the room’s total
energy without the application of louvers or fins. With the application of louvers and fins, the horizontal
louvers can only save 9% of the total energy and vertical fins can save 12%. A double-glazing system
without horizontal louvers or vertical fins is recommended for the Bonaventure Hotel’s NW façade, saving
the additional cost of louvers or fin application.

5.2.7 West façade
On the west (W) façade, a double-glazed system with 90-, 75-, or 45-degree vertical fins are
suggested for the west façade retrofit. Horizontal louvers are not necessary for application on the west
façade since the savings are similar to the vertical fins savings. However, adjusting the vertical fins to a 45-
degree angle might be a cost-effective retrofit resolution since 45-degree fins saved 2% more energy than
90-degree fins. The Bonaventure Hotel management can determine if louvers, fins, and fins with a 45-
degree angle should be applied to the west façade systems since the systems save slightly the same amount
of energy.

5.2.8 Southwest façade
Compared to the southwest (SW) base case model, the double-glazed iterations with argon saved
11-16% of the room’s energy on the southwest façade. The double-glazed, 1’ depth, 1’ spaced, horizontal
louvers and vertical fins are recommended for the southwest façade, saving 14-16% of the room’s total
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energy. Double-glazed façades have been proven to perform more efficiently on the Bonaventure Hotel.
The rooms that were tested on the S, SE, E, NE, N, NW, W, and SW orientations show a significant amount
of energy savings after double glazing systems were applied.

5.2.9 S, SE, E, NE, N, NW, W, and SW
Vertical fins with 1’ depth 1’ spacing at a 90- and 75- degree angle performed more efficiently on
all the S, SE, E, NE, N, NW, W, and SW orientations. However, since the north façade can perform
efficiently without additional louver and fin systems, louvers and fins are not recommended for the
application of the north façade. In addition, since double-glazed systems proved to perform more efficiently
than single and triple-glazed systems – double glazing can be on all the façade orientations.
For each of the rooms that were simulated the energy savings varied. The S, SE, and E façade the
75-degree vertical fins performed the same as the 90-degree fins. In the NW, W, and SW orientations, the
90-degree fins performed 0-3% better than the 75-degree fins. However, in all, the 75-degree vertical fins
performed almost the same as the 90-degree angles in all orientations. Before applying the façade strategies
onto the 10
th
story retrofit model, an analysis of the better performing retrofit strategies per orientation were
studied. The following graph shows highest energy savings for all orientations.

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Figure 5.1 10
th
floor façade retrofit results (Author 2020)

The façade retrofit strategies on the south (S), saved the most energy at a total of 17%. In the SE
and SW orientations, the façade studies saved the same amount of energy at a total of 16%. For the NE and
NW façades, the same amount of energy was also saved at a total of 12%. However, the N façade only
saved 9% of the room’s total energy.
Simulating each façade orientation was necessary in analyzing the S to SW façades individually.
The Bonaventure Hotel has 8 façade orientations, and in order to retrofit an entire floor’s façade,
determining the energy performance of each façade is significant. A façade that is performing better on the
S might not perform better on the N. After analyzing the façade orientations, the façade systems can be
applied depending on each of the room’s energy performance.
The retrofit strategies studied on the 10
th
story included the analysis of the room simulation studies.
The façade retrofit strategies that performed the best were then applied to the 10
th
floor façade model. Since
the double-glazed 1’ depth 1’ space vertical fins were one of the better performing systems on the S to NE
and W to SW, the 1’ depth 1’ space vertical fins were tested on all the orientations on 10
th
floor except the
N.
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5.2.10 10
th
floor – façade retrofit design
After analyzing each room’s energy usage in the S, SE, E, NE, N, NW, W, and SW orientations,
the entire 10
th
floor’s façades were designed and simulated together. The façade retrofit design implemented
the results from the room orientation analysis and applied it to all the orientations on the 10
th
story. Two of
the primary design iterations examined were double-glazed, 1’ depth, 1’ spaced, horizontal louvers and
vertical fins. Since horizontal louvers and vertical fins performed better than all of the iterations tested on
the room model, the same systems were explored on the 10
th
story façade model.
20 façade systems were tested on the 10
th
floor façade model and showed a significant decrease in
energy consumption after double-glazed argon-filler was applied. The design iterations tested for the 10
th
story model were compared to the single-glazed base case model. Comparing the base case model to the
selected retrofit strategy, provided an analysis in the story’s total energy savings. The total energy for the
base case model was exported first, resulting in a total of 915.84 MBTU. After double glazing was applied,
the total energy significantly decreased, suggesting potential savings of 22%.
The double-glazed, egg crate, 1’ depth 1’ spaced fins and louvers performed the best, decreasing
the total energy from 915.84 MBTU to 656.33 MBTU, and saving 28% total energy. The triple-glazed
system did not save more energy. Triple and double glazing saved the same amount of total energy. The
triple-glazed system with 1’ depth 1’ space fins had the same results as the double-glazed 1’ depth 1’ space
fins, double-glazed 1’ depth 1’ space louvers and fins, and the double-glazed 2’ depth 1’ space fins. The 1’
space, 1’ depth and 2’ depth systems only saved 2% more savings than the double-glazed without louvers
or fins and triple-glazed without louvers or fins. The double and triple-glazed system are performing the
same in the 10
th
story model. The triple-glazed façade is not performing more efficiently than the double-
glazed system. Since double-glazed systems cost less than triple-glazed systems and are performing better,
double-glazed systems are recommended for the application of the Bonaventure Hotel.
The double-glazed iterations that performed the second best are the design versions v2, v3, and
v13. These systems include 1’ depth 1’ spacing, saving 24% total energy. The third best energy savings in
this study are v7, v10, and v19, saving 23% total energy. Although, v7 is combined with 45- and 90-degree
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vertical fin systems, the total energy savings are the same as design v10 and v19. Design v10 are 1’ spaced
horizontal louvers and v19 is an egg crate with 1’ spaced vertical fins and 2’ spaced horizontal louvers.
Since v7 includes 2’ spaced vertical fins, design v7 is more suitable for a hotel façade than v10 or 19.
Design v7 provides wider views in-between the 2’ vertical spacing. Implementing 1’ spacing in a façade
retrofit design for the Bonaventure Hotel can be dependent on hotel management. The 1’ depth 1’ spaced
systems have proven to perform better with all the louver and fin façade iterations tested.

Figure 5.2 10
th
floor façade retrofit results (Author 2020)

Louvers and fins applied to the double-glazed façade did increase the 10
th
story model’s energy
savings. The highest total energy savings found with a double-glazed vertical fin and louver system is
design v18. If a double-glazed system without louvers or fins was applied to the 10
th
floor, 22% of the total
energy savings could be achieved. A double-glazed system (without louvers or fins), or design version v7
that has 2’ spacing with valuable exterior views are recommended as a possible façade retrofit resolution
for the Bonaventure Hotel.
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5.2.11 Operational CO 2
The operational CO 2 calculated included a base case model’s operational CO 2. A base case
calculation was compared to the retrofit calculation. The retrofit calculation and the base case calculation
for 4 selected strategies showed a significant decrease of operational CO 2. Applying the varied façade
iterations to the Bonaventure Hotel decreased the operations CO 2 emissions by 22-28%.

5.3 Summary
Currently, glazing materials similar to the 1970s glazing is lacking in energy efficiency and we can
gain knowledge from the 2000s era glazing technology. By updating the glazing system of the Westin
Bonaventure and similar buildings, an increase of energy performance is expected. The Bonaventure Hotel
can perform more efficiently with the retrofit strategies tested.
Out of all the retrofit systems that were tested, a 6” concrete wall study, horizontal louver study,
and vertical fin study saved the most energy and operational CO 2 for the Bonaventure Hotel. After analyzing
combinations of 200 façade strategies, 195 strategies did not perform as efficiently as the remaining 5
façades. The results showed that 1’ depth 1’ spaced vertical fins performed efficiently in the room
simulations and on the 10
th
story façade model. The 1’ depth 1’ spaced systems were performing better than
the 2’ spaced systems. After applying 45-degree fins to the 2’ spaced iteration, the 2’ spacing performed
efficiently, saving 23% with design v7. The third best energy savings in this study were v7, v10, and v19,
saving 23% total energy. The double-glazing iterations that performed the second best are design versions
v2, v3, and v13. These systems include 1’ depth 1’ spacing, saving 24% total energy.
If an egg crate with 1’ depth 1’ spacing was applied to the entire floor’s façade then 28% total
energy savings can be achieved with double glazing, saving the most energy. Since the energy savings for
the 10
th
story already achieved 22% total energy savings, increasing the savings with louvers and fins was
difficult to accomplish. There were 8 façade iterations that increased the 22% double-glazed savings, but
11 façade iterations could not be increased more. After analyzing these results, a double-glazed system
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without louvers or fins, a double-glazed system with 1’ depth 1’ spaced vertical fins, and 2’ spaced 45-
degree vertical fins would be a potential resolution for the Bonaventure façade retrofit and buildings similar.
The results also showed that vertical fins were more efficient on all of the cylinder’s façade
orientations. The Bonaventure Hotel has to determine which façade retrofit strategies could be applied. This
study is useful in understanding the benefits of façade retrofit applications on existing buildings, and the
worldwide environmental problem of CO 2 emissions from the building sector. Buildings are being
demolished so new 2020 buildings could be built. Fortunately, existing buildings with stable structures do
not require demolition and can be retrofitted with a new façade technology. An existing building with a
new façade system can be perceived as a new building. The appearance of the existing Bonaventure can
appear brand new with a 2020 façade, and still have the building footprint intact. Existing buildings
shouldn’t be demolished to decrease energy consumption and carbon emissions. The results in this research
show that there is an opportunity to apply façade retrofits on 1970s buildings, meet goals of reduced energy
consumption, and objectives for carbon emissions. Façade retrofits can decrease operational CO 2 and
energy consumption by 28%.

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6. CONCLUSION AND FUTURE WORK

6.1 Conclusion
This thesis explored hundreds of façade retrofit opportunities that the Bonaventure Hotel and other
similar buildings could gain knowledge from. There is a trend of demolishing existing buildings without
considering the demolition and embodied energy CO 2. If these carbon emissions are considered before
demolition, then carbon footprint could decrease by solely preserving the existing building. However, in
order to decrease energy consumption, retrofitting existing façade systems should be considered. Façade
retrofits have the ability to not only decrease carbon footprint compared to constructing a new building, but
also decrease current and future energy consumption. The current energy consumption of a 1970s building
is expected to be inefficient and could be retrofitted with new technology. By retrofitting an existing
buildings façade, the building can perform more efficiently than before.
Unfortunately, the Westin Bonaventure Hotel and similar buildings built in the 1970s show strong
indications of wear and are visually outdated. Rather than demolish an existing building, and construct a
new building, the Westin Bonaventure can be re-used. Building demolition is common in the building
industry and significant CO 2 emissions are released during demolition.
The existing building can be re-used and avoid additional material waste. Carbon footprint and
energy consumption can decrease after an existing façade is retrofitted. Since existing building façades can
allow up to approximately ¼ of energy savings, façade systems were analyzed. The retrofit façade strategies
included insulation, glazing, solar shading, and lower CO 2 emissions through materiality. In addressing
these façade options, a reduction in energy consumption was expected for the Bonaventure Hotel.
Increasing the current insulation of the building, examining different layers of glazing, and placing solar
shading decreased energy consumption.
Although the Bonaventure Hotel was expected to decrease 40% of total energy and 20% of the
carbon footprint, the results showed that the energy consumption decreased by 22% and thus operational
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CO 2 also by 22%. Reducing the energy consumption of the building simultaneously decreased the
operational CO 2 emissions equally. These results are impactful for the broad understanding of façade
retrofit, energy consumption and carbon footprint.
The Bonaventure Hotel has the potential to be a part of the 2020’s modern style façade system with
better energy performance. The research process considered the application of façade retrofit strategies on
existing buildings and updating existing technology. However, the Bonaventure Hotel management can
determine the façade strategies that should be applied.

6.2 Evaluation of methodology
To examine the Bonaventure’s façade system, collecting literature information and architectural
drawings were necessary for beginner’s research. Unfortunately, there were limited resources and obtaining
current energy usage of the Bonaventure Hotel was difficult to gather. Obtaining energy usage data in the
initial research steps would have been useful in determining the actual reduction of energy consumption.
Collaborating with the Bonaventure Hotel management could have provided valuable information for future
façade retrofit applications.
The research conducted began with beginner’s knowledge in IES-VE simulations, HOBO data, and
energy usage consumption. The information gathered is highly valuable to façade retrofit exploration on
unique 1970s buildings. These results showed horizontal louvers and vertical fins having similar energy
savings on the south façade. Generally, horizontal louvers perform better on the south façades and vertical
fins perform better on the east and west façades. These findings provided significant information confirming
that general statements are not always true. It is possible that other aspect ratios of horizontal louvers and
vertical spacing would have proven more effective, but a broad range was attempted. Although horizontal
louvers have often proven to save more energy than vertical fins on the south façade, in this research,
vertical fins have shown to save the same amount of energy. This research is useful to the building industry
and the façade system engineers that apply façade iterations on current, existing, and future façades.

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6.2.1 Improvements to current workflow
Valuable façade retrofit strategies were provided in this thesis, and if more studies are assessed, the
information could enhance this research on the Bonaventure. Since the Bonaventure Hotel was simulated
with only considering one guest room, existing neighboring rooms and a story, the results could differ if
neighboring buildings adjacent to the Bonaventure were modeled. Energy savings could vary if an adjacent
building was modeled in this research and shaded a portion of the rooms or stories. As an example, if a
building across the street from the Bonaventure Hotel was modeled in IES-VE, changes to the data could
differ. The retrofitted strategies can have lower or higher energy savings if the Bonaventure Hotel was
shaded by neighboring buildings.
Modeling neighboring buildings in IES-VE was not initially investigated since the intent was to
analyze only the façade retrofit strategies without any influence from neighboring buildings. If the
neighboring buildings across the street from the south facing room were simulated first, then the results
wouldn’t determine how much savings were from the façade strategies. However, if the simulations were
studied with and without the neighboring buildings, the data can be analyzed comparing the total energy
savings for both files. Overall, the objective of this research was to study the energy savings from façade
retrofits without the neighboring building’s shading influence.
As a beginner in IES-VE software, the simulation process was also difficult since the skill level
didn’t allow the use of “batch simulation”. IES-VE batch simulation is a tool that can simulate multiple 3D
models at once. In this research, each gbXML model imported was simulated individually in separate files
in IES-VE. Normally, multiple 3D gbXML models are in one IES-VE file and then the results would export
as a batch of results. Below is an example of the batch simulation option in IES-VE.

Figure 6.1 IES-VE batch simulation (Author 2020)

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There were also various strategies not tested in this study which could have resulted in better energy
savings or carbon footprint.

6.2.2 Façade variation strategy
Louvers and fins were applied to all orientations except the N. The louvers and fin systems
transitioned around the façade of the Bonaventure, from S to E and S to W façades, and double-glazing
without louvers or fins were placed on the N. The façade iterations tested explored façade location and
placement. More studies could be tested to find the best transition of façade studies. Below are diagrams
showing the façade strategy.

Figure 6.2 Façade variation strategy (Author 2020)
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If a horizontal fin systems performed better on the S and vertical fins performed better on the E and W
façades, the façades would vary around the Bonaventure’s cylinder tower. The location of façade placement
was dependent on the performance results. The transition of façade changes could be studied in future work
as there is a design opportunity to blend the façade edges.

6.2.3 Future work
For future research, a variety of façade iterations with neighboring buildings could be analyzed
further. There could be a neighboring building base case file that is compared to a non-neighboring building
base case file. Comparing the files can show how the neighboring buildings impact the existing site. This
study of future work can determine the façade strategies performance with the shade from the neighboring
buildings. Future steps include façade retrofit strategies with neighboring buildings and the actual energy
saved from the shade of the adjacent building.
Façade iterations with and without neighboring buildings could be tested with the IES-VE batch
simulation. A few strategies that were not tested include changes in emissivity, various egg crate models,
wider spacing in-between louvers or fins, and more iterations with a 45-degree angle. There are many façade
strategies that could be applied on the Bonaventure for further analysis.
Obtaining actual energy usage data from the Bonaventure Hotel is also useful in the façade
iterations batch simulation. Acquiring the annual energy usage data can suggest or confirm if the base case
model results are accurate. Since the annual energy data was unavailable for this study, the research
gathered compared possible façade retrofit resolutions. Although the base case model was not benchmarked
to the actual annual data that exists, the information found in this study is still valuable for percentage
savings and common knowledge. The results found could be used for future façade designs concepts, and
then analyzed further. Future benchmark data iterations tested could also help façade researchers apply
better façade strategies on the Bonaventure.
Athena software could also be applied in assessing the demolition process of sustainable materials
and calculate embodied energy of the materials. Though Athena is not used in this thesis to manage the
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embodied energy CO 2, it is highly recommended for future research. Athena can assist in the selection of
materials for building retrofit and construction.
Climate zone conditions can additionally be tested when analyzing varied design iterations. The
façade iterations that were recommended for the Bonaventure in Los Angles can also be analyzed in a
different city or state. There is potential for the future work of this study to advance, with countless façade
opportunities, valuable insight for the Bonaventure Hotel, and examination of similar buildings.

6.3 Summary
IES-VE and Revit were the primary softwares used in this research study. 200 façade strategies
were simulated in IES-VE, comparing the room’s total energy consumption and operational CO 2.
Subsequently, the 10
th
story model was simulated to export total energy and CO 2 data. The study continued,
resulting in 1’ depth 1’ spaced horizontal louvers and vertical fins giving a significant amount of solar
shading with double-glazed argon.
Although, glazing systems are commonly used in architecture, single glazing is unfortunately
lacking energy efficiency due to the higher U-values and minimal insulation. Single-glazed systems should
be re-evaluated for the purpose of improving energy efficiency. As common as glazing systems are in 2000s
architecture and existing buildings, 1900s buildings can benefit from the updated system. Currently, the
1970s glazing material is lacking energy efficiency and can gain knowledge from the 2000s era glazing
technology. The glazing technology as of now, can perform with embedded insulation that was not applied
during the construction of the 1970s. By updating the glazing system of the Westin Bonaventure and similar
case study buildings – an increase of energy performance is expected. Window glazing can similarly
decrease the use of HVAC systems and lighting.
In this research, material selection was additionally considered as it contributes to embodied CO 2.
A thorough selection of materials was analyzed for the Bonaventure Hotel’s façade retrofit, to decrease
embodied energy. In order to improve energy performance and decrease CO 2 emissions of an existing
building, material selection is valuable to the building analysis. Building materials, insulation, glazing, and
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solar shading can significantly decrease energy consumption and carbon emissions. By decreasing CO 2
emissions and energy consumption through the application of improved insulation, glazing, solar shading
and selective materials, retrofitting existing buildings is suggested. The Bonaventure Hotel was a façade
retrofit case study proposing new strategies for unique buildings lacking this data and can be applicable to
the Renaissance Center and Westin Peachtree Plaza.
Embodied CO 2, operations related CO 2, and demolition were all significant factors in analyzing
CO 2 emissions. The 1’ depth and 1’ spacing horizontal louvers and vertical fins were the selected systems
for the study of the Westin Bonaventure Hotel. Overhangs, horizontal louvers, vertical fins, and brise soleils
were the primary façade systems explored in the ZWICKY chart. The façade retrofit strategies that
performed the best in the room simulations were applied to the 10
th
story model. Since the double-glazed
1’ depth 1’ spaced vertical fins were one of the better performing systems on the S to NE and W to SW, the
1’ depth 1’ spaced vertical fins were tested on all the orientations on 10
th
floor except the N. Louvers and
fins varied around the Bonaventure’s S, E, and W façade and double glazing without louvers or fins were
placed on the N. The placement of façade strategies were dependent on the performance results. The studies
included horizontal louvers or vertical fins on the S and vertical fins on the E and W.
An additional study explored was a 45-degree vertical fin system on the E and W, with 2’ spacing.
The 2’ spacing application with the 45-degree fins improved the energy performance of the story model
significantly. After exploring multiple iterations on the 10
th
story, a 22-28% reduction in energy
consumption was achieved with double glazing horizontal louvers and vertical fins at 1’ depth 1’ space, or
1’ depth and 2’ space with a 45- or 90-degree angle.
Following the analysis of these results, a double-glazed system (without louvers or fins) or a 2’
spaced 45-degree fin system could be a potential resolution for the Bonaventure façade retrofit and
buildings similar. These results emphasize the importance of façade retrofit strategies on existing buildings
and a potential return on investment (ROI). Façade retrofits have proven to save at least 22% of total energy
and CO 2 emissions.
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There are buildings similar to the Bonaventure that could benefit from these façade retrofit
resolutions. Insulation, window glazing, and solar shading were the main façade strategies used to decrease
energy consumption, and resulted in reducing energy and operational CO 2 up to 28%.

148

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Abstract (if available)

Abstract As buildings age, they can be perceived outdated compared to their more modern counterparts with regards to sustainability and energy. The state of art in building envelopes continues to advance and new technologies are developed. A building that is merely 50 years old might have energy and daylighting profiles that compare unfavorably to modern buildings. Demolishing and replacing buildings can improve their energy consumption, but the financial costs can be excessive. Sometimes the costs and implications of demolition outweigh the advantages of the energy improvements. Embodied energy costs of new materials, transportation, construction, and disposal are additional costs that should be considered when designing architecture. Often it can make economic sense to rehabilitate or upgrade the envelope of a structurally and spatially sound building. A unique building in downtown Los Angeles has been selected as a testbed for various hypothetical façade replacement strategies implementing energy and carbon control. This iconic building that is well-known to residents of the region will be re-examined for façade retrofit instead of demolition. The study will propose and analyze a small set of design alternatives for the Westin Bonaventure Hotel in Los Angeles.

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Asset Metadata

Creator Solomon, Alexxa (author)

Core Title A proposal for building envelope retrofit on the Bonaventure Hotel: a case study examining energy and carbon

School School of Architecture

Degree Master of Building Science

Degree Program Building Science

Publication Date 05/18/2020

Defense Date 03/23/2020

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

Tag building envelope,Carbon,Energy,facade retrofit,glass façades,OAI-PMH Harvest,sustainable façades

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Noble, Douglas (committee chair), Choi, Joon-Ho (committee member), Schiler, Marc (committee member)

Creator Email alexxaso@usc.edu

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c89-311960

Unique identifier UC11663653

Identifier etd-SolomonAle-8542.pdf (filename),usctheses-c89-311960 (legacy record id)

Legacy Identifier etd-SolomonAle-8542.pdf

Dmrecord 311960

Document Type Thesis

Rights Solomon, Alexxa

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