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The effectiveness of enviro-materially actuated kinetic facades: evaluating the thermal performance of thermo-bimetal shading component geometries
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The effectiveness of enviro-materially actuated kinetic facades: evaluating the thermal performance of thermo-bimetal shading component geometries
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2
THE EFFECTIVENESS OF ENVIRO-MATERIALLY ACTUATED KINETIC
FACADES:
Evaluating the Thermal Performance of Thermo-Bimetal Shading Component Geometries
By
Amina Saleh Jambo
A Thesis Proposal
Presented to the
FACULTY OF THE
SCHOOL OF ARCHITECTURE
UNIVERSITY OF SOUTHERN CALIFORNIA
In partial fulfillment of the
Requirements of degree
MASTER OF BUILDING SCIENCE
DECEMBER 2017
3
COMMITTEE
Marc Schiler, FASES, LC
Professor
USC School of Architecture
marcs@usc.edu
213 740 4591
Doris Kim Sung, AIA
Assistant Professor
USC School of Architecture
doris@dosu-arch.com
(310) 722 4458
Anders Carlson, SE, PhD
Assistant Professor
USC School of Architecture
andersca@usc.edu
213 740 1054
4
This page is intentionally blank.
5
Soli deo gloria.
6
ACKNOWLEDGEMENTS
First and foremost, I would like to thank my mother for her continued support and encouragement to
me throughout this thesis writing process. I would also like to thank my committee members Marc
Schiler, Doris Sung, Anders Carlson, for their support and belief in my work and their guidance
throughout the research process. Finally, I would like to thank the MBS faculty and students for
fostering a positive and encouraging working environment.
7
List of Figures
Figure 1-1: Richard Neutra’s brise-soleil on the Los Angeles County Hall of Records
(Kudler 2012) ............................................................................................................................... 19
Figure 1-2: Brise-soleil on the Palace of the Assembly in Chandigarh, India (Asher 2014) ......... 20
Figure 1-3: View of Buckminster Fuller’s Biodome in Montreal for Expo 1967 (ArchDaily) ........ 21
Figure 1-4: View of dynamic apertures of Nouvel’s Insitut du Monde Arab ............................... 22
Figure 1-5: Shades on Al Bahar Towers closing as the sun comes around the façade
(Modlar.com) ............................................................................................................................... 22
Figure 1-6: Static shading devices (Autodesk 2013). ................................................................... 29
Figure 2-2: Doris Sung’s breathing bi-metal assembly (Brownell 2012) ...................................... 34
Figure 2 -3 : Material properties of Thermo-bimetal P675 (EMSClad) ........................................ 35
Figure 2 -4: A view of the effects of heat on the high and low-expansion sides of a thermos-
bimetallic sheet (EMS Clad). ........................................................................................................ 36
Figure 2-5: View of thermo-bimetal strips curling in response to heat (TED.com) ..................... 36
Figure 2-6: (COST) ........................................................................................................................ 38
Figure 2-7: (du Montier et. al. 2013) ........................................................................................... 40
Figure 2- 8(du Montier et. al. 2013) ........................................................................................... 41
Figure 2-9: Energy and lighting performance of different types of movable insulation panels
(du Montier et. al. 2013) ............................................................................................................. 42
Figure 2-10: (Erickson 2013). ....................................................................................................... 44
Figure 3-1: Vertical Mullion System (Author) .............................................................................. 49
Figure 3-2: Brise-soleil Geometry (Author) ................................................................................. 50
Figure 3-3: Research scope workflow overview (Author). .......................................................... 50
Figure 3-4:Component A (Author) ............................................................................................... 51
Figure 3-5: Hot Weather Tilt (Author) ......................................................................................... 56
Figure 3-6: Cold Weather Tilt (Author) ........................................................................................ 51
Figure 3-7: View of Hot Tilt (left) and Cold Tilt (right) in section (Author) .................................. 51
Figure 3- 8: Axonometric view of Hot Tilt (left) and Cold Tilt (right) arrays from the same
vantage point (Author) ................................................................................................................ 52
Figure 3- 9: Axonometric view of Hot Tilt (red) and Cold Tilt (cyan) juxtaposed. (Author). ......... 52
Figure 3-10: Top view of Hot Tilt (red) and Cold Tilt (cyan) mounted on attachment piece
(Author). ...................................................................................................................................... 53
Figure 3-11: View of the attachment plaque alone (Author). ...................................................... 53
Figure 3-12: Section view of the components in Cold Tiilt (cyan) and Hot Tilt (red)
orientation mounted on the plaque (Author). ............................................................................. 54
Figure 3-13: Geometry development notes (Author). ................................................................. 55
Figure 3-14: Workflow diagram of methodology (Author). ........................................................ 56
Figure 3-15: Array of enviro-material components placed in front of a section of south
8
facing wall (Author). ..................................................................................................................... 57
Figure 3-16: Initial testing set up in Revit platform: hot tilt (left) and cold tilt (right)
in front of a south-facing façade. ................................................................................................ 58
Figure 3-17: Histogram of façade surface for shading percentage calculation (Author). ........... 59
Figure 3-18: Overview of color values from which shading percentages were
determined (Author). .................................................................................................................. 60
Figure 3-19 : Heating and cooling degree days for one year in Los Angeles, California
(Pacific Energy Center 2006) ....................................................................................................... 61
Figure 3-20: Range of dry-bulb temperatures and relative humidity levels for
Los Angeles, California as compared to the thermal comfort zone (Author). ............................. 63
Figure 3-21: A sun shading chart for Summer – Fall in Los Angeles, California
displaying times for which shading is necessary (Author). .......................................................... 64
Figure 3-22: Psychometric Chart readings for Los Angeles, California assuming no
mechanical heating or cooling system (Author). ......................................................................... 65
Figure 3-23: Year-round temperature range of Phoenix, Arizona (Author). ............................... 66
Figure 3-24: Average dry-bulb and relative humidity values mapped against comfort
zone for Phoenix, Arizona (Author). ........................................................................................... 67
Figure 3-25: Psychometric Chart readings for Phoenix, Arizona assuming no
mechanical heating or cooling system (Author). ......................................................................... 68
Figure 3-26: A sun shading chart for Summer – Fall in Phoenix, Arizona displaying times
for which shading is necessary (Author). .................................................................................... 69
Figure 3-27: A sun shading chart for Winter – Spring in Phoenix, Arizona displaying times for
which shading is necessary (Author). .......................................................................................... 69
Figure 3-28: Year-round temperature range of Boston, Massachusetts (Author) ...................... 70
Figure 3-29: Range of dry-bulb temperatures and relative humidity levels for Boston,
Massachusetts as compared to the thermal comfort zone (Author) .......................................... 71
Figure 3-30: A sun shading chart for Summer – Fall in Boston, Massachusetts
displaying times for which shading is necessary (Author). .......................................................... 72
Figure 3-31: A sun shading chart for Winter – Spring in Boston, Massachusetts
displaying times for which shading is necessary (Author). ......................................................... 72
Figure 3-32: Psychometric chart data for Cambridge, Massachusetts for the month
of September assuming no mechanical heating or cooling system (Author). ............................. 73
Figure 3-33: Psychometric chart data for Cambridge, Massachusetts for the month
of September assuming no mechanical heating or cooling system (Author). ............................. 73
Figure 3-34: Psychometric chart data for December in Cambridge, Massachusetts
assuming the use of a heating system (Author). ........................................................................ 74
Figure 3-35: Psychometric chart data for Cambridge, Massachusetts for the month
of September assuming no mechanical heating or cooling system (Author). ............................. 75
Figure 3-36: Psychometric chart data for Cambridge, Massachusetts for the month
9
of March assuming no mechanical heating or ventilation system (Author). .............................. 75
Figure 4 -1: (Author) .................................................................................................................... 76
Figure 4- 2: View of the grid template from which components were constructed
in Rhinoceros (Author) ................................................................................................................ 77
Figure 4-3: View of the untrimmed surface Author) ................................................................... 77
Figure 4-4: Hot tilt, cold tilt and surface template of one shading component (Author) ........... 77
Figure 4-5: View of hot and cold tilts superimposed over flat geometries ................................. 78
Figure 4-6: Evolution of morphology ........................................................................................... 78
Figure 4 -7: A front elevation view of an array of element A1 (Author) ...................................... 78
Figure 4-8: Close up view of A1 components (Author) ............................................................... 79
Figure 4-9: A side elevation view of an array of element A1 (Author) ........................................ 79
Figure 4-10: A1 Axonometric View (Author) ............................................................................... 80
Figure 4-11: A front elevation view of an array of element B1 (Author) .................................... 80
Figure 4-12: Close up view of B1 (Author) ................................................................................... 81
Figure 4-13: A side elevation view of an array of element B1 (Author) ...................................... 81
Figure 4-14: B1 Axonometric (Author) ........................................................................................ 82
Figure 4-15: A front elevation view of an array of element B2(Author) ..................................... 82
Figure 4-16: Close up view of B2 (Author) ................................................................................... 83
Figure 4-17: A side elevation view of an array of element B2 (Author) ...................................... 83
Figure 4-18: B2 Axonometric (Author) ........................................................................................ 84
Figure 4-19: A front elevation view of an array of element C1 (Author) ..................................... 84
Figure 4-20: Close up view of C1 (Author) ................................................................................... 85
Figure 4-21: A side elevation view of an array of element C1 (Author) ...................................... 85
Figure 4-22: C1 Axonometric (Author) ........................................................................................ 86
Figure 4-23: Front elevation view of Element G1 (Author) ......................................................... 87
Figure 4-24: (a) Element G1 mounted on the façade (b) Section view of element
mounted on the façade (Author) ............................................................................................... 88
Figure 4-25: A view of shadows cast by the shading element on the façade .............................. 89
Figure 4-26: View of shading profiles of G1 component in Hot Tilt and Cold Tilt
configurations during the Summer Solstice and during the Autumn equinox (Author). ............ 90
Figure 4-27: Front elevation view of Element F1 ........................................................................ 90
Figure 4-28: Views of the F1 and T4 geometries at 3:00pm in the Hot Weather and
Cold Weather tilt configurations (Author). ................................................................................. 91
Figure 4-29: Percentages of shading provided by elements at CW12 in
Cambridge, Massachusetts ......................................................................................................... 92
Figure 4-30: Percentages of shading provided by elements at CW3 in
Cambridge, Massachusetts ......................................................................................................... 92
Figure 4-31: Elevation and shading profiles of components F1, A1, T4, T1, F2 for CW3
orientation ................................................................................................................................... 93
10
Figure 4-32: Trend in shading percentages for all fifteen components across
designated points in time (8:00am, 12:00pm, 3:00pm) .............................................................. 94
Figure 4-33: Percentages of shading provided by elements at HS12 in
Cambridge, Massachusetts ......................................................................................................... 95
Figure 4-34: Shading Profile of Element F1 at HS12 .................................................................... 95
Figure 4-35: T2 Shading Profile of Element A1 at HS12 ............................................................... 96
Figure 4-36: Shading Profile of Element T4 at HS12 ................................................................... 96
Figure 4-37: Shading Profile of Element C2 at HS12 ................................................................... 97
Figure 4-38: Shading Profile of Element B2 at HS12 ................................................................... 97
Figure 4-39: Percentages of shading provided by elements at HS3
in Cambridge, Massachusetts ...................................................................................................... 98
Figure 4-40: T2 Morphology (left) and T4 Morphology (right) .................................................... 98
Figure 4-41: Shading T2 Shading Profile for HS3 ......................................................................... 99
Figure 4-42: Shading Profile for HS3 ........................................................................................... 99
Figure 4-43: Front elevation views of components G1, D1, and D2 .......................................... 100
Figure 4-44: Shading Profile for Element A1 at HS3 with edge conditions ............................... 101
Figure 4-45: Shading Profile of Element B1 at HS3 with edge conditions ................................ 101
Figure 4-46: Shading Profile for Element C1 at HS3 with edge conditions ................................ 102
Figure 4-47: Percentages of shading provided by elements at CA12 in
Cambridge, Massachusetts ....................................................................................................... 103
Figure 4-48: Percentages of shading provided by elements at CA3 in
Cambridge, Massachusetts ....................................................................................................... 103
Figure 4-49: Percentages of shading provided by elements at CW12 in Los Angeles, CA ......... 104
Figure 4-50: Percentages of shading provided by elements at CW3 in Los Angeles, CA ........... 105
Figure 4-51: Percentages of shading provided by elements at HS12 in Los Angeles, CA .......... 105
Figure 4-52: Percentages of shading provided by elements at HS3 in Los Angeles, CA ............ 106
Figure 4-53: Percentages of shading provided by elements at HW12 in Los Angeles, CA ........ 106
Figure 4-54: Percentages of shading provided by elements at HW3 in Los Angeles, CA .......... 107
Figure 4-55: Shading Profile for D1 HW3 Los Angeles, CA ......................................................... 107
Figure 4-56: Shading Profile for E1 HW3 Los Angeles, CA ......................................................... 108
Figure 4-57: Shading Profile for D2 HW3 Los Angeles, CA ......................................................... 108
Figure 4-58: T4 Shading Profile for T3 HW3 Los Angeles, CA .................................................... 109
Figure 4-59: B2 Shading Profile for HW3 Los Angeles ............................................................... 109
Figure 4-60: Percentages of shading provided by elements at CA12 in Los Angeles, CA .......... 110
Figure 4-61: Percentages of shading provided by elements at CA3 in Los Angeles, CA ............ 110
Figure 4-62: Percentages of shading provided by elements at CW12 in Phoenix, AZ ............... 111
Figure 4-63: Percentages of shading provided by elements at CW3 in Phoenix, AZ ................. 111
Figure 4-64: Percentages of shading provided by elements at HW12 in Phoenix, AZ ............... 112
Figure 4-65: Percentages of shading provided by elements at HW3 in Phoenix, AZ ................. 112
11
Figure 4-66: Percentages of shading provided by elements at HS12 in Phoenix, AZ ................ 113
Figure 4-67: Percentages of shading provided by elements at HS3 in Phoenix, AZ .................. 113
Figure 4-68: Percentages of shading provided by elements at CA3 in Phoenix, AZ .................. 114
Figure 4-69: Component G1 with edge conditions ................................................................... 115
Figure 5-1: Front elevation view of small office with enviro-material shading
components mounted (Author) ................................................................................................ 116
Figure 6-1: View of single components, A1, T1, and F2 ............................................................ 121
12
Table of Contents
Chapter 1: Introduction ....................................................................................... 16
1.1 The Changing Face of Buildings .................................................................................................................................... 16
1.2 Reinstating the Role of Facades .................................................................................................................................... 16
1.3 Terms ........................................................................................................................................................................................ 16
1.4 The Field of Adaptive Facades ....................................................................................................................................... 19
1.5 Limitations of the Field ..................................................................................................................................................... 23
1.6 Characterization of Adaptive Facades ........................................................................................................................ 24
1.7 Enviro-material Actuation ............................................................................................................................................... 25
1.8 Explanation of the Exposition ........................................................................................................................................ 25
1.9 Hypothesis Statement ....................................................................................................................................................... 26
1.10 Basic Concepts ................................................................................................................................................................... 26
1.11 Scope of the Work ............................................................................................................................................................ 30
1.12 Chapter Summary ............................................................................................................................................................. 31
1.13 Chapter Structure ............................................................................................................................................................. 32
Chapter 2: Background and Literature Review ............................................. 33
2.1 Chapter Overview ............................................................................................................................................................... 33
2.3 Thermo-bimetals ................................................................................................................................................................. 34
2.4 The Push for Standardization of Adaptive Facades .............................................................................................. 37
2.5 Common Problems in Evaluating Kinetic Façade Components ...................................................................... 39
2.6 Precedent Simulation Studies ........................................................................................................................................ 39
2.7 Chapter Summary ............................................................................................................................................................... 45
Chapter 3: Methodology ...................................................................................... 47
3.1 Chapter Overview ............................................................................................................................................................... 47
3.2 Tools .......................................................................................................................................................................................... 47
3.3 Simulating Environment-Façade Interaction .......................................................................................................... 48
3.4 Establishment of Baselines ............................................................................................................................................. 48
3.5 Geometrical Tests ................................................................................................................................................................ 56
3.6 Evaluation Criteria of Component Orientation ...................................................................................................... 59
3.7 Test Sites ................................................................................................................................................................................. 61
Chapter 4: Results ................................................................................................ 76
4.1 Chapter Overview ............................................................................................................................................................... 76
4.2 Morphology Shading Profiles ......................................................................................................................................... 76
4.3 Results ...................................................................................................................................................................................... 87
4.4 Results for Cambridge, Massachusetts ...................................................................................................................... 92
4.5 Results for Los Angeles, CA ........................................................................................................................................... 104
4.6 Results for Phoenix, AZ ................................................................................................................................................... 111
4.7 Chapter Summary ............................................................................................................................................................. 115
Chapter 5: Analysis ............................................................................................ 116
5.1 Chapter Overview ............................................................................................................................................................. 116
5.2 Solar Radiation Values .................................................................................................................................................... 116
Chapter Summary ..................................................................................................................................................................... 120
Chapter 6: Conclusions ..................................................................................... 121
6.1 Chapter Overview ............................................................................................................................................................. 121
13
6.2 Modifications to the Study ............................................................................................................................................. 122
6.3 Limitations of the Study ................................................................................................................................................. 124
6.4 Chapter Summary ............................................................................................................................................................. 124
Bibliography ......................................................................................................... 126
Appendix A: Description of Elements ........................................................... 129
Appendix A
14
ABSTRACT
Shading devices are perhaps the single most important energy saving component in passively
cooled buildings. If a building is arranged so that the intense rays of the sun are intercepted before they
pass through transparent envelope elements, the cooling load can often be halved (Grondzik and
Kwok 2014). However, many of the shading devices used in buildings today are static, which can
prove counter-productive to maintaining indoor thermal comfort levels during the less extreme points
of the year (i.e. spring and fall). Given the emergence of unique material technologies, it may be
possible to utilize environmentally responsive, or enviro-materially actuated materials to develop more
thermally appropriate shading devices for the built environment. This thesis focuses on the early stage
of design of these dynamic façade components—simulating and evaluating the effectiveness of the
enviro-material shading components in three climate zones. Using currently available modeling and
simulation software, the potential for thermo-bimetals -- sheets of two metal alloys that convert
temperature change into mechanical displacement -- to serve as dynamic shading devices for building
facades was investigated.
A morphology of fifteen components was developed from a single geometry provided by Professor
Doris Sung, the pioneer of this technology, at the University of Southern California. Components
were designed to adopt two discrete configurations: a “hot tilt,” which blocks solar exposure of the
facade, preventing excessive heat gain in warmer temperatures, and a “cold tilt” which admits solar rays
for cooler temperatures, taking advantage of the curling behavior of the thermo-bimetal. That the
components can shift between these two tilts as is appropriate for maintaining thermal comfort for the
interior environment makes a case for the powerful energy-saving implications of incorporating
dynamism of building components into façade design.
Keywords: adaptive building envelope; smart facades; digital simulations; energy savings
15
“I am enthusiastic over humanity’s extraordinary and sometimes very timely ingenuities. If you are in a shipwreck and
all the boats are gone, a piano top buoyant enough to keep you afloat that comes along makes a fortuitous life
preserver. But this is not to say that the best way to design a life preserver is in the form of a piano top. I think that we
are clinging to a great many piano tops in accepting yesterday’s fortuitous contrivings as constituting the only means
for solving a given problem. Our brains deal exclusively with special-case experiences. Only our minds are able to
discover the generalized principles operating without exception in each and every special-experience case which if
detected and mastered will give knowledgeable advantage in all instances.”
– Richard Buckminster Fuller, Operating Manual for Spaceship Earth, 1969
(DesignBoom.com)
16
Chapter 1: Introduction
1.1 The Changing Face of Buildings
Since their implementation in the early 1900s, mechanical ventilation systems have been heavily relied
upon to mitigate the dissociation between popular building materials and those appropriate for
achieving indoor thermal comfort within extreme climate conditions. With building-produced carbon
emissions threatening the predictability of seasonal weather patterns, sea levels, and the availability of
potable water, architects have begun to take more drastic steps toward developing more energy
efficient and climate responsive designs. Consequently, many have targeted the building envelope as
the medium by which to do so.
Although the current state of the built environment is dire, the building façade presents significant
opportunities for the building sector. Building facades hold tremendous potential for improving the
current state of the built environment.
1.2 Reinstating the Role of Facades
The building envelope—“moderator” of energy and comfort separating
an occupant’s experiences from the realities of her external environment—holds the potential to
reduce the significant energy burden placed on mechanical systems to maintain optimal thermal
conditions in indoor environments.
One particular strategy for improving the ability of building facades to adapt to ever-changing
environmental conditions and performance requirements is the incorporation of dynamic elements
into the design of the façade. (Moloney 2011). Allowing buildings to actively interact with the
environmental conditions specific to their situation—whether through material composition, sensor-
based reactivity or otherwise—provides the opportunity for more fluid and effective reduction of
energy use and the ability to achieve energy efficiency independent of user behavior or conscious
decision-making. This holds powerful implications for the future shift of energy-consciousness from
being user-driven to being embedded within the intelligence of the environmental systems they occupy.
1.3 Terms
Before continuing the discussion of the significance of the building facade in accommodating the
variable energy demands of the environments in which they are situated, it is important to define
several terms that will be used throughout this document.
There are a number of terms that are very commonly used imputing facades with an element of
dynamism. As these terms are often used interchangeably, their distinctions are not usually made clear.
For the purpose of this investigation, the following terms will hold the definitions listed below:
17
Adaptive
The term ‘adaptive’, when used in reference to a building façade, describes an envelope that has the
capacity to alter one or more of its physical properties in response to a change in stimulus that usually
results in some improvement in its function. This term is closely related to the term “adaptation”
which implies that the resultant change in structure or function allows the building to be better suited
to its environment.
Dynamic
The term “Dynamic” is defined as that which is active; Resulting in some perceptible and or tangible
change.
Kinetic
Relating to movement; able to undergo motion.
Responsive
Acting in response to some stimulus.
Predictive
Describes an element that is able to determine a course of action or event, and prescriptively respond
to such with a predetermined action.
Actuator
The operator or force which drives action or activates; Motivator.
Control Logic
The governing set of rules according to which a system operates. The control logic defines the
underlying set of responses that can result from activation or operation of the system.
1.3.1 Smart vs. Intelligent Facades
Dynamism in building facades is manifested in one of two categories: “smart” and “intelligent.” It is
important to clarify the difference between smart and intelligent façades, as this will serve as the
foundation for the later discussion of adaptive façade systems.
Smart Facades
In the design disciplines, the term “smart” is most frequently used to refer to materials and surfaces.
According to Addington and Schodek, “smart materials” are those which possess “embedded
technological functions” that involve specific environmental responses. These operate either through
internal changes of some physical property, or through an external exchange of energy. Smart materials
are characterized by: “‘immediacy’ (real-time response), ‘transiency’ (responsive to more than one
environmental state), ‘self-actuation’ (internal intelligence), ‘selectivity’ (a response is discrete and
predictable) and ‘directness’ (a response is local to the activating events).’” (Velikov and Thun 2012).
This means that a smart façade requires no added controls as in the form of sensors or external energy
inputs to elicit a response in the façade.
18
Intelligent Facades
In reference to building skins, the term “intelligent” implies a higher order of organization and
performance than “smart.” In the broadest sense, the goal of an intelligent building skin is to optimize
the building’s systems relative to climate, energy balance and human comfort, typically based on
predictive models and relative to each other. This is often accomplished through building automation
and physically adaptive elements such as louvers, sunshades, operable vents or smart material
assemblies. Brian Atkin, in his book Intelligent Buildings, defines intelligent buildings as those that
“know” what the environmental conditions are both outside and inside, that “decide” how to provide
a convenient and comfortable environment for occupants, and that “respond” promptly to occupant
requests. This is typically achieved using a variety of sensing apparatus that communicate with
building control systems to optimize interior conditions, including computational protocols (for both
the envelope and HVAC equipment) capable of re-balancing the system based on occupant
adjustments (Atkin, 1988).
The biggest difference between the terms “smart” and “intelligent” is that in the former case,
functionality results from intrinsic material properties, whereas in the latter, performance is primarily
controlled through computation and automation. Typically, intelligent facades have a more variable
“performance profile” than that of smart facades which usually have more limited set of responses. The
operation of smart facades is rather limited in control as analog responses are typically continuous in
nature, while the operation of intelligent facades, oftentimes characterized by a binary response,
requires the provision of external power to achieve its goals (Velikov and Thun, 2012). Increasingly
complex adaptive response and reactive envelope systems have allowed the intelligent building to be
compared to biological responses observed in nature” (Wigginton & Harris, 2002).
Despite the use of higher levels of insulation for exterior walls, and improved weatherization practices,
the conventional window remains the weakest thermal link in an otherwise tight environmental barrier
(Muneer, et al 2000). Therefore, there is the need for façade systems that are able to provide more
adaptive accommodation to the energy demands of the external climate forces acting on the building
skin is easily apparent.
The façade system that will be explored in this context can be reasonably considered a smart façade
system as its adaptive response is self-actuated as a result of the material properties and its constituent
geometries. The system further exemplifies a smart technology as it does not have the capacity to
“understand the environment or relationships between multiple systems and how modification to one
may impact the environment and another system’s performance” (Kroner 1997).
19
1.4 The Field of Adaptive Facades
The study of kinetically active, or “adaptive” facades has been ongoing since the 1960s. The earliest
recorded example was a system of vertical and horizontal mullions used on the Los Angeles County
Hall of Record by Richard Neutra: a brise-soleil.
Brise-soleil systems have now come to refer to a variety of permanent sun-shading structures ranging
from the simple patterned concrete walls popularized by Le Corbusier in the Palace of Assembly, to
the elaborate wing-like Burke Brise-Soleil devised by Santiago Calatrava which sits atop the Milwaukee
Art Museum. In these structures, it was the sun itself which acted as the kinetic element, and mullions
were designed such that they took advantage of the varying altitudes of the sun during the winter and
summer months and maximized the amount of exposure of the interior space to the winter sun when
temperatures were typically lower and rejected solar rays in the warmer summer months.
Figure 1- 1: Richard Neutra’s brise-soleil on the Los Angeles County Hall of Records (Kudler 2012)
20
Figure 1- 2: Brise-soleil on the Palace of the Assembly in Chandigarh, India (Asher 2014)
Later examples of dynamic facades introduce actual kinetic elements into their design in order to adapt
more flexibly to the dynamic climate and temperature patterns throughout the year. Two notable
examples of kinetically active façades are Buckminster Fuller’s design for Expo 67 and
Jean Nouvel’s Insitut du Monde Arab.
Arab du Monde is an oft cited example of a dynamic façade—eventually failing due to complexity of
the mechanism and a lack of understanding of how to maintain the components over the course of
time. The building’s south façade uses an aperture-based brise-soileil system, an analog of the
geometric mashrabiya latticeworks prevalent in the Arab world throughout the ages. The system
involves the use of 240 light-sensitive diaphragms (resembling the iris of a camera) controlled by
photosensors that regulate the amount of light that enters the building. In total, the system consists of
113 photosensitive panels with 16,000 moving parts and 30,000 light-sensitive diaphragms of varying
sizes (Millard 2015). As the lenses shift, a series of shifting geometric patterns (squares, circles, and
octagonal shapes) are produced in a fluid motion” as the light is modulated. Thus, solar heat gain is
mitigated by the reduction of the aperture sizes. (Winstanley 2011). It is certainly possible that the
introduction of thermo-bimetals into the construction of the façade could have aided in the
functionality of the façade, reducing the complexity of the system and its reliance on mechanized
functions. From the start, this solution, while novel, was somewhat problematic—in 1987, when
construction was completed, control systems that controlled all of the systems of the building were
quite new, so the operation of the systems experienced issues from the start as heat re-radiated from
the metallic shade.
Bucky Fuller’s biosphere shading system was intended to incorporate pores into the enclosure system
likening it to the pores of the human skin. The geodesic hemisphere entered for the United States
21
Pavillion in the World Expo of 1967 measure 20 stories in height and 250 feet (76.2 meters) in
diameter, and consisted of a spaceframe of steel struts that were welded in tetrahedrons measuring
about 3 feet in depth. “The structural lattice created a spiraling triangular pattern in its outer surface
and a hexagonal mosaic on its inner surface” (Massey 2006). Between these two structural layers, a
“skin” consisting of convex acrylic panels forming a transparent enclosure. Motorized triangular roller
shades controlled automatically by light sensors were attached to a third of the interior surface, thereby
allowing parts of the dome to receive shading as necessary. The combination of the automated shades
with “thermostat controlled conventional air-handling equipment” allowed the pavilion to maintain a
consistent temperature while minimizing fossil fuel use. In this way, the adaptable shading system
allowed the geodesic dome to functionally approximate the body’s homeostatic regulatory system,
sensing the changes in the external environment, and behaving in a manner analogous to the pores on
human skin (Massey 2006). Unfortunately, the shading system failed to work properly and was
eventually disabled.
Figure 1-3: View of Buckminster Fuller’s Biodome in Montreal for Expo 1967 (ArchDaily)
22
Figure 1-4: View of dynamic apertures of Nouvel’s Insitut du Monde Arab (ArchDaily)
Figure 1-5: Shades on Al Bahar Towers closing as the sun comes around the façade (Modlar.com)
23
An example of a highly functional adaptive façade system in use today are the shades on the Al Bahar
Towers in Abu Dhabi. Like the Institut du Monde Arab, the shading apertures incorporate the
mashrabiya into their design, however, this system relies on a series of “transparent umbrella-like”
PTFE components that open and close in response to the sun’s path. (CTBUH 2013).
Each of the two towers is fitted with over one thousand individual shading devices which are
controlled by the building management system. When activated, each of the stretched PTFE
components is “driven by a linear actuator that progressively opens and closes once per day in response
to a pre-programmed sequence that has been calculated to prevent direct sunlight from striking the
façade, and to limit direct solar gain to a maximum of 400 watts per linear meter” (CTBUH 2013). In
the event of strong winds or overcast conditions, a variety of sensors opens the units to protect them
from damage. Reduced glare, improved daylight penetration, less reliance on artificial lighting, and a
significant reduction in solar heat gain and carbon emissions are the reported benefits of this system
(CTBUH 2013).
1.5 Limitations of the Field
Despite these powerful implications and the numerous already realized projects, the development and
realization of adaptive building envelopes is still in fledgling condition at best. “In addition to new
technologies that enable adaptive behavior, simulation tools and suitable testing methods must be
developed; existing norms and regulations must be adapted and holistic concepts to integrate such
facades in the overall building system must be established” (Loonen et. al. 2014).
There is little evidence that these early designers’ application of dynamism to their facades results in an
effective response to the site-specific environmental conditions. Although the projects demonstrate a
kinetic response of the building to dynamic weather, the moving elements in their responsive system
oftentimes experience technical failure due to overly complicated machinations of the façade’s parts.
The push for the architecture discipline as a whole to respond to environmental concerns has spurred
an interest in incorporating kinetic components into their designs.
Kinetic facades are particularly tricky to evaluate due to the wide variety of factors that go into their
design and performance. Their "highly non-steady state behavior" coupled with the fact that their
properties and features change over time, pose huge challenges to manufacturers, designers, and
certification bodies. The parameters usually adopted to label the performances of the facade in terms of
energy behavior (for example, U-values), indoor comfort, durability, structural behavior, etc., are
seldom useful and their assessment becomes tricky or impossible. Furthermore, the experimental and
numerical analysis tools used so far in the design and investigation of static building components
appear to be limited in scope and unsuitable for use in designing adaptive facades. In order to move
toward widespread adoption within the field and eventual improvement of their performance as a
whole, adaptive facades must first be characterized and their performance metrics standardized.
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1.6 Characterization of Adaptive Facades
In his thesis, “Simulation-based support for product development of innovative building envelope
components ”, Roel Loonen at the Eindhoven University of Technology in the Netherlands proposes
characterization of kinetically adaptive facades based on actuation. He lists three groups: those that
utilize a mechanical switch, those that use a centralized control system and those that use a
decentralized control system for actuation, all of which fall under the broader category of mechanical
actuation.
1.6.1 Actuation
Most kinetic facade systems in use today typically rely on one of the three actuating systems listed
above. Yekutiel and Grobman at the Israel Institute of Technology give thorough descriptions of each
type of actuator:
Manual Switch
This form of actuation is rather self-explanatory—the dynamic response of the component geometry is
driven by a mechanical switch which sends a signal to the façade at the user’s request. The effectiveness
of this type of system is largely dependent on the user’s knowledge of appropriate façade
configurations for each time of day over the course of different seasons.
Centralized Control System
“In centralized control systems, each cladding component is connected to a sensor device and collects
information about its immediate environmental conditions. The collected data from the entire façade
is transferred to the main computer where the data processing takes place; as a result, the façade will
perform the necessary kinetic adaption. The kinetic adaption may be different for each cladding
component but will be based on data processing in the main computer” (Yekutiel 2013).
Decentralized control system
“Decentralized control is more complex. By definition, it’s meant to handle multiple conditions and
generate various responses. It is based on local, cheap and less powerful computers or microprocessors,
which are connected to kinetic elements” (Yekutiel 2013). An example of such a decentralized control
system that has gained popularity in recent years is the Arduino—a single-board microcontroller that
can sense and control physical objects.
Each of these actuating systems, whether manual or automated, relies on a specific control system
combined with an input of energy to achieve the desired behavior change. There is, however, another
class of adaptive facades whose system of actuation falls outside of that proposed by Loonen. These
facades are somewhat emergent, not having reached popularity until recently, and are reliant on
the inherent material properties of the facade assembly for their kinetic response rather than the
control of an external actuator. This class of adaptive facades will be referred to from here on out as:
enviro-materially actuated facades.
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1.7 Enviro-material Actuation
Enviro-material actuation is a term developed by the author to describe kinetic facades whose dynamic
response is predicated on the inherent material properties of the façade’s constituent component
geometries. Enviro-material actuation describes activation of building materials that are dependent
upon the inherent material properties of the façade components, the response of which is governed by
the response of the material to a change in the environment (i.e. an increase in dry-bulb temperature,
increase or decrease in relative humidity, etc.). The material governs the behavior of the façade system
and the actuated response is in reaction to a change in environmental stimulus. Hence, the descriptor
“enviro-material” actuation. Examples of materials that can engage in this type of behavior are: wood
veneer, thermostatic bimetallic alloys and shape memory alloys.
These facades do not require the input of additional energy to create movement. Facades of this type
rely on a “natural” control logic that is pre-programmed by nature. For this reason, these types of
façade systems are naturally not predictive, but cumulative (a modified form of reactive). Cumulative
façade elements remain in static until sufficient tension is accumulated to pop them past a tipping
point. They can, by nature of their geometry or the form on which they are hosted, be designed to
increase the amount of time spent in a configuration that maximizes solar exposure during cooler
hours over the course of a day. Because the behavior of enviro-material facade systems varies based on
the environmental stimulus to which their properties respond, they are not technically predictive, but
are predictably responsive to a history of input (temperature) and can thus be used to achieve indoor
thermal comfort.
The system under investigation seeks to achieve indoor thermal comfort by maximizing the amount of
time spent in a configuration that minimizes unwanted solar exposure of the facade to prevent
unwanted heat gain and maximizes solar exposure when solar heat gain is necessary.
1.8 Explanation of the Exposition
This work was both an exercise in simulation of the behavior of enviro-material façade components to
the end of improving the behavior and consequent thermal performance of the geometries, as well as a
study of the effects of geometry of a pattern component on the provision of adequate shading in a
specific climate location. It also investigated the potential for this specific type of façade system to
reduce the amount of unwanted solar heat gain and increase exposure to solar rays during desired
times, year-round. In doing so, the study looked at how the morphology of geometric deviations from
the original pattern component affected the thermal performance of the façade.
The evaluation of the enviro-material façade made use of currently available digital simulation tools
and built a case for the ability of designers and architects to properly evaluate kinetic facade
performance despite the limitations of the existing analytical and digital simulation tools. Ultimately,
this research provides insights and an alternative platform for designers to improve, validate, and make
informed decisions during the early design and development process of adaptive facades of this type. It
also exemplifies ways to explore design options and strategies in realizing kinetic facade designs with
improved thermal performance for specific climate locations.
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1.9 Hypothesis Statement
Due to their adaptive capabilities, enviro-materially actuated facade systems can provide better thermal
comfort than static facades in the same climate location. More specifically, enviro-materially actuated
facades can take advantage of solar exposure for heat gain and heat prevention for more periods of time
throughout the year than static facade systems due to their temperature-dependent behavior. As a
corollary, these experiments investigated whether reliance on temperature-adjusted behavior proves for
more effective shading than static positioning based on sun position throughout the year.
1.10 Basic Concepts
1.10.1 Heat Gain
Given the building envelope’s role as mediator between internal and external environments, one of the
most influential indicators of its effectiveness is how resistant it is to heat transfer. Due to the
complexities of a building envelope’s construction, there are a number of factors that influence the way
heat flows across it. Each material from which a building envelope is constructed has associated with it
a characteristic rate at which heat flows through it. This property is referred to as conductivity and is
measured in Btu in./h ft2 F. In the context of building envelope design, conductivity affects the rate at
which heat is conducted from a material to the surrounding air. This idea is important to understand
as the proceeding experiments are related to indoor environmental control and thermal comfort
(Grondzik and Kwok 2014).
Heat flow through a building envelope is highly variable. It varies broadly by season and hour (as
temperature, relative humidity, and solar radiation impact). A designer who aims to provide thermal
comfort in an energy-efficient and environmentally responsible manner must consider these
complexities and design accordingly. In order to determine how best to design for optimal heat flow
through the building envelope, it is important to be cognizant of the different means by which heat is
transferred to a space. Conduction, convection, and radiation are three terms which describe means by
which this heat transfer occurs.
Conduction
According to Grondzik and Kwok, conduction is the heat transferred directly from molecule to
molecule, within or between materials, with proximity of molecules (material density) playing a critical
role in the extent of heat transfer (Grondzik and Kwok 2014).
In the context of the built environment, conduction can be expected to occur between the shading
element and the façade upon which it is attached.
Convection
Convection refers to heat exchanged between “a fluid (typically air) and a solid, with the motion of the
fluid occurring due to heating or cooling (playing a role in the extent of heat transfer” (Grondzik and
Kwok 2014).
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Radiation
“Radiation refers to heat flows via electromagnetic waves from hotter” surfaces to detached, colder
surfaces—even across empty space and potentially great distance (Grondzik and Kwok 2014). This
method of heat transfer does not rely upon any contact between the heat source and the heated object
as is the case with conduction and convection. Some examples of this type of heat gain are the heat
from the solar rays or the heat released from the filament of a light bulb (EDInformatics 1999).
For the purposes of this study, only the radiative component of heat gain was considered and any
convection and conduction occurring through the façade was temporarily ignored for the sake of
simplicity. This is because the geometries were evaluated on the basis of their ability to prevent solar
radiation during undesirable times and to allow solar radiation to penetrate the façade behind the
shade assembly during desirable times depending on the temperature history of the location. Radiation
is the largest component of heat gain that occurs in the system—both from the solar direct gain
received from the sun onto the shading elements and from the heat that is re-radiated from the
elements to the façade behind the shading array. While the enviro-material components do experience
convective heat gain, the amount by which this occurs varies depending on the distance of the
components from the façade. As the distance of the components from the façade increases, so, too,
does the amount of air flow around the shading components, thus increasing the amount of cooling
that occurs on the surface and around the elements. Conduction is rather minimal, as it occurs only
through the transfer of heat from the element to the mount, and the mount to the bridge, effectively
creating a thermal bridge.
1.10.2 Solar Heat Gain
The sun’s position, angle of incidence, and intensity play a large role in the variability of this heat flow
throughout the day across seasons. The intensity of the sun varies by the clarity of the atmosphere and
the angle at which the sun strikes a surface. This is called the “incident angle”. The closer the sun ray
angle is to the perpendicular to a surface, the more heat and light energy that surface will receive, per
unit area. The incident solar radiation is the amount of solar radiation energy received on a given
surface during a given time (also called insolation). Insolation is often given in units of energy per area
(W/m
2
or BTU/hr/ft
2
) or can be quoted in terms of energy accumulated per day or per year
(kWh/m
2
/day or kWh/m
2
/year) (Grondzik and Kwok 2014).
1.10.3 Sun Path
The sun's path varies throughout the year and plays an important role in the shadow angles that result
from incident sunlight on shading devices of different lengths and shapes. In the summer, the sun is
higher in the sky and rises much earlier and sets much later in the summer than in the winter
(Autodesk 2013). Important to note is the fact that on the summer solstice, the sun reaches its highest
noon altitude for the year. The solstices reflect the extremes of the sun's position, while the equinoxes
reflect the average sun position. Summer solstice in the Northern hemisphere occurs on the 21st of
June, when the sun is at its highest noon altitude. Winter solstice during the 21st of December, the is
sun at its lowest noon altitude. Autumn equinox, 21st of September, when the sun rises due east and
sets due west and Spring Equinox, the sun rises due east and sets due west.
Winter studies can reveal how to maximize the sun to passively heat the building, and summer studies
can show how to minimize the sun to passively cool the building. This is because the total solar energy
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incident on a south-facing window is actually greater during the winter than in the summer. Although
the sun rises earlier during the summer months, it remains East or West of the south-facing façade for
the majority of its path before it sets in the afternoon. When it does reach the southern façade, it is
higher and more oblique to the surface, thereby minimizing the amount of direct gain incident on the
surface. In the winter, the opposite occurs and the South façade receives direct sunlight for the entirety
of the day. Thus, south-facing façades are subject to incident solar radiation for the entire length of the
solar day. During the summer solstice, a building in Los Angeles, California with a latitude of 33° 48’
will experience fourteen hours of daylight (from about 5:30am to 7:30pm) only seven hours of which
will yield incident solar radiation for a south-facing façade (from 8:30am to 3:30pm). During the
winter solstice, however, the south-facing façade will have incident sunlight for all ten of the ten
daylight hours of the season (between 7:30am and 5:30pm) (Toossi 2008).
This information, in addition to the typical hours of occupancy for a small office building, played a
major role in influencing the design of the experiment which will be explained in greater detail in
Chapter 3.
It is also worthwhile to study how this influences providing means of shading for specific times of day.
In the morning, the sun is low in the sky and the sun's energy can be captured to warm up spaces
(however, it is important to note that glare can also occur during this time). At noon*, the sun is
generally strongest and highest in the sky and it is useful to block the hot midday sun to reduce
cooling loads in some areas. In the next section, traditional types of shading devices will be explained
in order to provide a lens through which an understanding of this study’s enviro-material shading
elements can be understanding.
*Sometimes noon is not the highest altitude angle. This is because of the difference between solar time (which is determined by the
position of the sun) and local time (which is determined by the time zone.)
1.10.4 Shading
Shading devices are perhaps the single most important energy-related component for passively cooled
buildings. If a building is arranged to intercept the intense rays of the sun before they pass through the
transparent envelope elements, the cooling load can often be halved. Effective external shading rejects
about 80% of solar energy, whereas internal shading absorbs what it blocks and releases it inside the
space. The absorbed energy can be released can occur by convection or re-radiation of the energy from
the shading devices into the space or back into the atmosphere. This speaks to the importance of the
role of the building envelope in participating in the reduction of excessive energy loads placed on
mechanical conditioning systems (Grondzik and Kwok 2014).
In order to balance solar heat gain rejection and visibility, sunshades typically project outwards from
the windows they are designed to protect. “These exterior projections become highly visible elements
of facades and tempt some designers to impose formal aesthetic criteria that can be damaging to the
solar control functions” (Grondzik and Kwok 2014). A frequent example is the application of the same
sunshade geometry to all facades of a building. When the sunshades are in fixed positions, this often
helps one facade, but is ineffective for the other orientations.
Fixed sun shading devices are very common as they are simple and require almost no maintenance
which is not the case with many kinetic shading decides that have numerous complicated
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machinations that can be expensive and troublesome. During the less extreme points in the year, (i.e.
the spring and fall), fixed sun shading devices can pose a dilemma as to block the sun on any elevation
in September would also block it in March which may be counter-productive or detrimental to
maintaining indoor thermal comfort levels for many locations in more temperate climates where
spring can oftentimes have cold temperatures (Grondzik and Kwok 2014).
The design of static shading devices has allowed designers and architects to prevent excess heat gain for
specific times of day over the course of different seasons to effectively prevent unwanted heat gain for
years. Horizontal static shades can be quite effective at selectively allowing the sun’s light and heat into
the building. The most common element manipulated to achieve effective shading is the shade
depth—designing louvers wide enough that the sun’s rays are blocked without significantly
compromising visual transmissivity during the summer months when the solar azimuth is at its peak,
and allowing for sunlight during the winter months when the azimuth is lower has continually been an
effective strategy of providing shading.
Figure 1-6: Static shading devices (Autodesk 2013).
What makes adaptive shading components powerful tools is their ability to adapt to this variable heat
flow and respond with the appropriate configuration across the façade surface.
1.10.6 Horizontal and Vertical Shadow Angles
An understanding of horizontal and vertical shadow angles is also critical to the design of effective
shading devices. The vertical shadow angle is particularly important for the design of horizontal shades
as it determines the required projection length. Horizontal and vertical angles differ depending on the
date, time, location as well as the orientation and tilt angles of the surface casting the shadow. In order
to design an effective shading device, one must understand what these angles are in order to block heat
gain at unwanted times (when the sun is more intense) and allow heat gain during the cooler periods
of the day. These angles depend both on the position of the sun and the orientation of the façade.
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The horizontal shading angle (HSA) is relevant for vertical shading devices such as fins, and is
relatively easy to determine: the angle between the normal of the window pane and the azimuth of the
sun.
HSA = azimuth - orientation angle
(Grondzik and Kwok 2014)
The vertical shadow angle (VSA) is a bit more difficult to determine and is required when designing
horizontal shading devices such as overhangs.
VSA = arctan (tan (altitude) / cos (HSA))
(Grondzik and Kwok 2014)
This information is useful not only in designing static shading devices, but also in optimizing shading
profile of kinetic shading devices. The next section will elaborate on how this information was useful
in preliminary tests of component geometry performance for the latitude and longitude chosen.
1.11 Scope of the Work
1.11.1 Evaluation Criteria
As this research is primarily concerned with evaluating the shading performance of adaptive facade
components compared to static components within a similar location, it is important to establish the
evaluation criteria.
The first metric of evaluation is the continuity of shadows on the surface of a façade. If a component
geometry can provide continuous shading across the surface of the façade it clads, during times when
shading is desired, it is considered effective. The method of evaluating shadow continuity will be
described in greater detailed in Chapter 3. It will be assumed that the continuity of shadows across the
façade surface corresponds to how effectively the geometry is able to prevent unwanted solar radiative
heat gain. This reduction of transmitted heat may be translated as a potential decrease in the cooling
load on the interior of the space in question assuming that the space is unoccupied and contains no
electrical equipment.
It is important to establish the conditions under which energy loads will be calculated. In addition to
the design variables that affect design heat loss (i.e. envelope assembly, U-factor, surface area,
temperature difference, and airflow rate), the following variables also affect “design cooling load”
(Loonen et al. 2014):
• Orientation (north, south, east, west, etc.)
• Tilt (vertical, horizontal, inclined)
• Surface reflectance
• Thermal capacity
• Solar heat gain coefficient (if the assembly is transparent/translucent)
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• Shading devices
• Heat gain
o Sensible and latent from occupants
o Lighting and appliances
o Sensible and latent from equipment
Of these, the criteria upon which this research is based are the orientation (of the façade surface
receiving sunlight), tilt (of component geometries), type of shading devices (specific geometrical forms
being tested) and the relationship between the component shapes being tested and the amount of
sensible heat gain able to the façade’s surface in their respective tilts.
Of all the factors that influence building design, human occupancy poses the largest challenge to
developing effective strategies for energy savings. Depending on the perceived comfort conditions of
the occupant or occupants, the desired indoor thermal conditions can be vastly different from external
thermal conditions.
“Humans do not share a uniform response to environmental stimuli (light, temperature, noise,
moisture, etc.), but respond in a non-deterministic manner influenced by personal preferences,
physiology, culture, and expectations. Because of the diverse perceptions of what comfort is, comfort
standards are more likely to be reflections of a society’s beliefs, values, experiences and aspirations”
(Cooper 1982). Thus, for the purpose of this study, user preferences and thermal comfort perceptions
were standardized based on the psychometric chart in order to maximize the building’s response to
external climate conditions.
1.11.2 Deliverables
A morphology of these enviro-material facade components was developed based on a single
geometrical model provided to the author by Professor Doris Sung at the University of Southern
California. The morphology consisted of fifteen geometries that were evaluated for their ability to shift
between one of two tilts that either blocks solar radiation during unwanted points in the day or admits
solar radiation when desired. The results of this evaluation reveal which geometries within the
morphology provide more continuous shading given incident sunlight at particular angles/times.
However, as component behavior is linked to external temperatures the study ultimately shows which
of the geometries lend themselves to higher or lower effectiveness in achieving indoor thermal comfort
by means of admission or prevention of solar radiative heat gain for the locations selected.
Through the simulations and experiments performed, a workflow is presented as a new approach to
evaluating the thermal performance of kinetic façade components during the early design phase. This
workflow demonstrates a method of evaluating kinetic façade components to understand the
challenges and problems before the actual facades are constructed and installed in the building.
1.12 Chapter Summary
The process of designing an adaptive facade is quite complex as it involves developing effective kinetic
elements, testing the effectiveness of these elements, determining appropriate material choice, and
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evaluating the facade performance periodically during different points of the design process.
To design adaptive shading geometries to perform optimally for specific climate locations, it is
important for designers to be able to prototype, simulate, and evaluate the behaviors early in the design
process. The next chapter will discuss several experimental methods of effectively simulating and
evaluating kinetic facade components for specific climate locations. These simulations rely on the
capabilities of the software and depend on the temperature ranges and weather patterns stored within
the software databases for accuracy.
1.13 Chapter Structure
Chapter 1 introduces the reader to the current state of the use of adaptive facades in the field of
architecture—their developments and pitfalls and why the author has decided to focus on the specific
type of kinetic facades she has.
Chapter 2 discusses different types of enviro-materially active facades that are currently under
development and introduces different methods of simulating and evaluating the performance of
kinetic facade component geometries as defined by scholars in their published investigations.
Chapter 3 exposits the methods by which the author has chosen to evaluate the specific component
geometries in question—how these geometries were decided upon, the metrics of evaluation, measures
of success, and specific tools used to perform the analysis.
Chapter 4, the results of the tests are disclosed in full and the findings made during the execution of
the tests described in Chapter 3 are summarized.
Chapter 5 analyzes the results of the experiments and tests performed in the previous chapter.
Chapter 6 concludes the exposition.
Chapter 7 extrapolates the data and explains its implications for the field and future studies.
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Chapter 2: Background and Literature Review
2.1 Chapter Overview
As was mentioned earlier in the exposition, simulation, evaluation, and standardization of kinetic
facades are the major barriers to their widespread adoption in the field today. As such, there is not a
rich body of literature available on effective means of simulating and evaluating the performance of the
dynamic components of adaptive facades. The studies featured in this chapter are those that have some
intersection with the investigation of the comparative performance of adaptive vs. static shading
devices featured in this study.
2.2 Enviro-material Shading Devices
Enviro-material facades have begun to gain traction in the architecture field, with architects engaging
in collaboration with materials scientists and engineers earlier in the design process. Two pioneers of
enviro-materially actuated facade design techniques are Achim Menges of the University of Stuttgart's
Institute for Computational Design and Doris Sung at the University of Southern California.
Menges used a series of wood veneer panels to create a “Meteorosensitive Pavilion” which he exhibited
at the Pompidou Center in Paris in 2015. Through parametric software, parameterizes the direction of
wood grain, the relative humidity, the absolute humidity, length to width thickness ratio of the wood
panels, layout of the natural and synthetic composite, and to predict the material response to the
amount of humidity in the air. The façade was created by digitally fabricating four thousand
geometrically unique elements in Grasshopper which were then constructed via robotic arm (as
opposed to manually due to the precision and discretization of the wood paneling). The composite
system elements were programmed to compute different shapes for the material according to the
amount of humidity in the atmosphere.
Figure 2-1: Achim Menges’s responsive
wood veneer surfaces at different
temperatures (Universitat Stuttgart
2006)
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Sung uses thermo-bimetal sheets – sheets comprised of two different alloys with vastly different
thermal coefficients of expansion annealed together – to create geometries with systems of elements
that curl in response to high temperatures.
Figure 2-2: Doris Sung’s breathing bi-metal assembly (Brownell 2012)
The enviro-material components being tested in this work are constructed from this same class of
metals: thermostatic bimetallic alloys.
2.3 Thermo-bimetals
As mentioned previously, thermostatic bimetals are a class of metals resulting from two sheets of metal
alloys being combined under high temperature and pressure. These metal alloys both have unique
metallic properties, and when combined through a process called metal cladding, can create a
composite sheet called a bimetal layer which has modified properties of both. In many cases, the
annealing of metal alloys results in increased strength or ductility of the resultant material.
2.3.1 A Closer Look at Metal Cladding
The process of cladding involves combining two or more metal alloys by using extremely high
temperature and pressure. More specifically, large rollers are used to compress the metal layers together,
and under such compressive force, the electrons are essentially “squeezed” together.
Process of Manufacturing Bimetal:
1. Start with a clean surface
– Strips of metal are chemically or mechanically cleaned to provide contaminant-free surface
2. Rolling mill
- Rolls exert immense pressure on the strip that reduces the thickness of the strip and creates a
metallurgical bond as the atomic lattices of the different metals merge into a common structure.
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The resulting composite {a composite metal} derives integrity from the shared electron interface.
- High pressure produces massive deformation of the material which causes sharing of their electrons at
the interface, which produces a bond on the atomic level.
The type of metal that Doris Sung uses in her work is known as P675. P675 is a bimetal composite
consisting of one sheet of low expansion alloy (containing 64% Iron and 36% Nickel), and one sheet
of high expansion alloy (72% Manganese, 18% Copper, and 10% Nickel). Thermally and structurally
P675 is very similar to a metal composite called Invar.
Below is a more complete listing of physical properties of P675, courtesy of EMS Clad:
Figure 2 -3 : Material properties of Thermo-bimetal P675 (EMSClad)
The coefficient of thermal expansion of the high expansion side results in a much higher degree of
distortion of this side than that of the low expansion side, which creates the curved response of the
metal to heat. The coefficient of thermal expansion predicts the increase in the dimension resultant
from an increase in temperature. Because the two sides have been bound together, the differential
expansion causes curvature, a natural response, (high expansion side convex) as is shown in the image
below:
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Figure 2 -4: A view of the effects of heat on the high and low-expansion sides of a thermo-
bimetallic sheet (EMS Clad).
The high expansion side deforms at a faster rate than the low expansion side and as a result, the high
expansion side (in this case, side A) is forced into compression, being bound to the low expansion side.
This results in the high expansion side being the convex surface.
Sung has used this type of metal in several of her projects with interesting results. One such project,
Bloom, a foot structure that consists of 14,000 parametric components of this type which result in a
shading effect.
Figure 2-5: View of thermo-bimetal strips curling in response to heat (TED.com)
What is beneficial about these types of systems is the reduced need for maintenance that comes with
mechanical controls of kinetic façade components. To predict the curling behavior of a strip of
37
thermo-bimetal, one can use a formula which relates the radius of curvature of the strip to the
thickness of the components in question:
(EMS Clad)
2.4 The Push for Standardization of Adaptive Facades
In their thesis completed at the University of Sao Paulo, Celani and Sperling break the movement of
dynamic façade components into the following categories based on the type of movement they employ.
They list: Diaphragm systems, Pivoting systems, Telescopic systems, Scissor Systems, Folding Plate
and Umbrella Type Systems. While this system of categorization is useful for understanding the
mechanism by which the adaptive components achieve dynamism, it fails to take in account other
qualities which are important in understanding the function of an adaptive façade system and where it
may be appropriately used.
Creating a standardized system of categorization for actuators of kinetic facades is worthwhile because
it allows for the projection of energy savings for façades in specific regions and aids in the planning
process during the pre-design phase. Being able to test the materials and create mock-ups or prototypes
of the kinetic façade components can provide designers with an understanding of the design factors,
fabrication techniques, and potential problems to consider when scaling up to a full-sized model of the
façade system.
Currently, in research of adaptive building envelopes there is a lack of knowledge transfer between the
individual research institutes between one another and the industry. In response to this issue, several
European research institutes formed the COST Action TU1403 Adaptive Facades Network in order
to mitigate the discrepancy in information between disseminated. COST Action TU1403 is a non-
profit intergovernmental organization with 120 participants across 26 European countries and exists to
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share technological knowledge on adaptive facades on a European level to the end of generating ideas
for new innovative technologies. This is intended to lead to “increased knowledge shading between the
various European research centers and the industry at large, the development of new technologies and
concepts for adaptive facades, new knowledge such as methods or tools for effectively evaluating
adaptive facades, and the start of new collaborations and research projects in the area of adaptive
façade technologies” (Knaack et. al 2016).
The standardization methods proposed by this group was deemed a more than adequate starting point
from which to begin the process of standardization for adaptive facades, and thus will be explained
briefly in the following section in the hopes of extending this system to adaptive facades in the United
States and other regions of the world.
The association has published their collected research and separated them into four “work groups,”
each having its own mission (set of goals) within the larger mission of standardizing and collecting
information about adaptive facades. Work Group 1 is of particular interest in light of this study, as it
proposes a categorization matrix through which effectively all adaptive facades can be categorized. This
could reasonably allow for the standardization of evaluation methods for adaptive facades on a global
scale. The matrix in Figure 2-6 below breaks up the facades into purpose, adaptive features, responsive
function, and operation.
Figure 2-6 (COST)
WGI’s adaptive façade characterization matrix makes for a comprehensive means of categorizing
dynamic façade of various types. Enviro-material facades are distinct from most other types of kinetic
facades in use today in that their operation is intrinsic as a result of their material properties (the
difference in expansion in the two sides of the bimetal sheet causing the curl), and the lack of a need
for a mechanical or sensor-based motivator. Following the COST characterization matrix, the degree
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of this type of façade system is considered “gradual,” and the responsive function is to “reject”. Finally,
the purpose would be “thermal comfort” and “energy savings”.
2.5 Common Problems in Evaluating Kinetic Façade Components
As was mentioned previously, lack of standardization of evaluation methods for assessing kinetic
facades makes it difficult to evaluate one’s performance relative to another even under similar
conditions in terms of situation, building orientation and occupancy, and internal loads.
There are two main obstacles to providing meaningful industry-wide evaluation of adaptive facades
today:
1. No standardization—A lack of performance metrics by which to evaluate facades. This means
that even if a façade system is evaluated, it is difficult to understand what this performance
value mIeans in comparison to another facade of comparable performance—or how to even
determine whether another façade system is comparable in construction.
2. The complexity of buildings themselves. Buildings are highly complex entities, and once their
orientation, program, mechanical system efficiencies and climate location are taken into
consideration, evaluating one façade system against another that exists under similar conditions
can be daunting to say the least.
While the focus of this study is not to propose a universal framework by which to evaluate adaptive
facades, it does provide a fairly simple, yet effective method by which designers can understand the
performance of a shading system of this time early on in the design process. This allows for the
improvement of the design through various iterations.
2.6 Precedent Simulation Studies
Although designs of kinetic components abound, there is a veritable lack of available data as to their
performance. Furthermore, there is no available standard by which designers or architects evaluate the
thermal performance of facade systems.
Of the data available to the general public, and other research on adaptive building envelopes, the
majority has been protected by numerous nationally funded projects and there is an unfortunate lack
of knowledge transfer between the individual research institutes between one another and the industry.
The studies listed below were relevant enough to the specific subject being tested and performed with
enough rigor that they seemed sufficient to form the baseline for the experiments conducted in this
investigation.
2.6.1 Sharaidin RMIT Melbourne, Australia
The first precedent study was conducted at RMIT in Melbourne, Australia by Dr. Kamil Sharaidin
who looked specifically at means of aiding designers in making decisions concerning the design of
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adaptive facades during the early design stage. He found that creating physical prototypes was very
helpful in that it allowed the designers to get a sense of the actual behavior of their systems and what
could be done to improve the effectiveness of the facade. However, not all designers will have the time
or access to conduct physical prototypes, which is why simulation software can be so powerful in the
early design process. By mimicking the behavior of the façade systems as closely as possible, it is
possible to predict, evaluate and ultimately improve the behavior of a façade system by doing a
theoretical simulation study. Sharaidin looked at several different types of systems, increasing in
complexity, and evaluated their performance using different software interfaces.
This investigation focuses on the early design stages where crucial decisions regarding the kinetic
façade are made. It is at this stage where simulation and prototyping are most crucial to the
development of effective façade systems. Sharaidin’s research efforts explore “the design and
performance of kinetic strategies through physical prototyping with the integration of physical
computing and digital software” (Sharaidin 2013).
Sharaidin suggests that design should be finalized only after “a thorough exploration of the
requirements of the kinetic pattern and mechanism of the façade in response to the environmental
conditions” (Sharaidin 2013). This is so that a more informed decision can be made in the early stage
of design with regards to the requirements for the facade to be made as early as possible.
2.6.2 Cedric du Montier et. al at University Laval School of Architecture
Cedric du Montier at the University Laval School of Architecture evaluated the potential for moveable
insulation panels (MIPs) to conserve energy for a small office building in Nordic climate (du Montier
et. al. 2013). In carrying out their evaluation, the team used the IES-VE software suite to measure a
reference model of a small office building against a simulation model that used the MIPs. Several
configurations of MIPs were measured against each other to determine which orientation was the most
effective in reducing energy consumption for a 24-hour period (including both occupied and un-
occupied hours in the schedule). The figure below (reproduced from their study) shows the two
models measured against one another:
Figure 2-7 (du Montier et. al. 2013)
Montier and his team chose to simulate three main forms and movement types for analysis: a sliding
panel, a vertical folding panel which folds along the vertical axis, and a horizontal folding panel (an
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experimental theoretical model developed by the team for evaluation purposes) which folds along the
horizontal axis to create an exterior light shelf. The moveable insulation panel types simulated in the
experiment were based on real-world analogs readily available from Josuma Inc. A diagram displaying
all three panel types has been reproduced from their study below:
Figure 2-8 (du Montier et. al. 2013)
The team chose to evaluate the panels based on an optimal configuration that they established upon
the panels’ performance in the following metrics:
(1) “Energy consumption per floor area (kWh/m²) compared with the reference case is used to develop
an energy optimal scenario.
(2) An adaptation of the Useful Daylight Index, suggested by Nabil & Mardaljevic is used to
assess the lighting potential of MIPs and to develop a lighting optimal scenario”
(du Montier et. al. 2013).
Their studies showed that from an opening percentage standpoint, the respective optimal scenarios for
all types of moveable insulation panels were generally similar. However, the energy and lighting
performance results of each panel were vastly different.
Simulation Strategy
This research team chose to use IES-VE for the modeling of their panel behavior.
Because IES-VE does not allow for the adaptive modeling of the shading elements, the team modeled
the panels as four stationary positions with different opening levels (25%, 50%, 75% and 100% as
shown in figure two above) over the course of one year. An opening position of 100% would represent
a fully open panel and 25% is chosen as the minimum aperture size to allow for sufficient daylighting
for occupant activities.
Discussion of Results
The results of this study indicate that the most effective use of moveable insulation panels results
during the wintertime, when energy savings of up to 46% were observed and increases of lighting
performance of up to 73% were observed. Significant energy savings could also be made during the
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autumn equinox; however, energy performance was not significant during the summer solstice. Based
on the metrics use for evaluating the panels in the experiments, there are fewer solar gains when the
sun is high in the sky than when the sun is lower in the sky. The MIP type that resulted in the best
compromise between energy and lighting performance was the vertical folding panel.
Figure 2-9: Energy and lighting performance of different types of movable insulation panels (du Montier et.
al. 2013)
Figure 2-9 shows a compilation of the energy performance for type of MIP where the horizontal axis
represents the energy performance and the vertical axis represents the lighting performance. The first
quadrant is the quadrant where an improvement of both energy and lighting performance is observed
as compared to the static shading device, whereas the third quadrant shows a regression performance.
Comparing types of MIPS, the vertical folding panel yields the best overall performance in terms of
both lighting levels and energy savings. From an energy standpoint, the sliding panel yields energy
savings that are in some cases higher than those of the vertical folding panel, but in many cases, those
scenarios also describe the worst lighting performance. Overall, the horizontal folding panel scenarios
describe the worst energy performances as compared to the other MIPS. Certain types of panels can
clearly be associated to a particular season according to its performance, and although each type of
MIP can modify its position “relative to daily and hourly conditions, the results ultimately show that
an adaptation of the form on a seasonal basis could be of benefit” (Montier et. al. 2013).
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These results indicate that the use of enviro-materially actuated adaptive façade components
could be of use due to their seasonal and temperature-related behavior.
2.6.3 James Erickson, PhD University of Arizona
James Erickson of the University of Arizona conducted a study on the effectiveness of adaptive facades
in saving energy for a small office as defined by Title 24 baseline standards (Erickson 2013). The
objective of Erickson’s research was to simulate an adaptive building envelope’s (ABE’s) behavioral
response to changing weather conditions in an effort to reduce indoor energy use without
compromising occupant comfort as measured by PPD (Predicted Percentage Dissatisfied).
An ABE, or adaptive building envelope, as defined by Davies in 1981 as a polyvalent wall, has
increasingly garnered attention in the field of architecture as technological advances have made their
construction and execution more feasible. ABEs have the potential to reduce the energy used to
maintain comfortable indoor climates in wide range of locations with varying climates and weather
extremes. They also hold the potential to improve indoor environmental quality by reducing reliance
on mechanical ventilation systems and “offer a form of resiliency to weather and climate conditions
that static envelopes are incapable of matching” (Erickson 2016). Modeling the functionality of these
dynamic systems has been virtually impossible until recently as computer simulation techniques have
advanced to be able to simulate some of their functional complexities (Erickson 2016).
Building designs that depend on climatic design principles have long been shown to significantly
reduce the dependence on mechanical climate control systems resulting in lower energy use while
achieving quality indoor conditions for their occupants (Olgyay, 1963, Zhai and Previtali, 2010).
However, this successful design approach traditionally employs relatively static responses to meet
changing weather and occupant behavior, and internal loads to exploit positive energy exchanges
between the indoor and outdoor environments. Inserting an adaptive envelope between indoor and
outdoor climates creates a negotiator that pursues a desirable energy transfer and seeks to satisfy
objectives such as reducing energy use, controlling glare, and providing fresh air. If an ABE is designed
so that its environmental barrier characteristics (e.g. properties concerned with controlling the flow of
thermal energy, air, water vapor, and solar radiation) are able to respond with selective exclusion or
inclusion of specific environmental variables, then it is possible to examine which adaptive responses
are preferred in responding to prevailing weather conditions and occupant needs.
A simulation program structure was developed to determine optimal configurations for the simulated
envelope on an hourly basis, mimicking possible responses to the ABEs changing context. Current
building energy simulation (BES) software does not yet have the ability to optimize building variables
by time interval (e.g. minute, hour, day, etc.) in sequential steps requiring the creation of a composite
algorithm. Differences in ABEs behavior during the weekends and weekdays when unoccupied were
attributed in part to changes in occupancy and internal loads, lighting levels, ad thermostat setbacks.
All schedules were unchanged from the original Commercial Reference Buildings .idf files that indicate
low occupancy levels during the weekends, but regular lighting, heating and cooling levels.
Erickson defines optimization as “the regimentation of design into mathematical system that seeks to
minimize or maximize the cost function or functions based on a user defined set of criteria. The
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optimization process relies on constructed mathematical relationships between variables and constants
that are solved for in the pursuit of the solution that best satisfies the objective criteria from all feasible
solutions” (Erickson 2013).
“Due to the nature of wicked problems, no true optimum solution is possible because of the
complexities of the system” (Diakaki, Grigorondis, & Kolokotsa, 2008). However, the designer may
choose to isolate specific systems from within the larger problem and solve those independently using
carefully chosen criteria and gaps. Although this does not result in any form of an optimized solution
within the context of a wicked problem, it does provide a feasible solution within a reduced solution
space that can be used to fulfill the design process by comparing output to design objects.
In order to accurately model the functionality of the building envelope, Erickson developed an
algorithm to simulate an adaptable building envelope (ABE) responding to hourly changes in weather
conditions and occupant loads that reduced indoor energy use without compromising occupant
comfort as measured by the Predicted Percentage Dissatisfied metric (PPD) established by ASRAE.
Erickson uses a three-step process involved Energy Plus, GenOpt and a custom PHP script
modification of the Energy Plus software to create the algorithmic determination of optimal behavioral
response settings for the adaptive envelope.
Figure 2-10 (Erickson 2013).
When the outdoor climate is approximate to the indoor thermal comfort range, AEM and OBM
scenarios display similar energy use, typically observed during the autumn weeks when there is little
thermal stress between indoor and outdoor climates for the regions chosen. AEM scenarios
demonstrate the means to manipulate energy transfer through the envelope in ways that change the
needed HVAC response.
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Discussion of Results
In contrast to Erickson’s study, the adaptive components’ ability to reduce the need for mitigation of
thermal discomfort via mechanical heating and ventilation systems in the building will be evaluated
simply as a function of the amount of solar radiant heat that is prevented from being transmitted
through the façade. This method of evaluation is simple, straightforward, and is intended to build a
cast for the components’ enviro-materially actuated shading capabilities and how well-suited the
elements are for certain environments.
R-values for glass can vary by construction and appropriateness for climate. Thus, the focus will be on
how effective each component geometry is able to provide shading- what elements of a geometry
contribute to more appropriate shading given the curling potential of the material.
2.6.4 Azadeh Omidfar Harvard Graduate School of Design
Investigation Methods
In her thesis, The Role of Digital Tools in Computational Analysis of Site-Specific Architecture,”
Omidfar pursues the investigation of opportunities for “high-performance ‘low-tech’ formal solutions
in built structures.” She makes the claim that with digital tools, architects now have the power to
optimize building performance by targeting performance optimization. The problem lies in the set
interface of the tools available today—for employing high technology in the design phases allows
architectural form to perform as co-mate systems, thereby reducing the need for mechanical and
electrical technologies during the lifetime of the building. Using well-integrated design processes and
employing basic principles of physics in the designs (aerodynamics, optics, and thermodynamics)
Omidar also cites digital tools as means by which architects can reverse the trend of handing off the
analysis and design of low-energy use from architects to engineers, referencing tools such as Ecotect,
TRNSYS, DesignBuilder, and IES. A problem with the use of these tools, however, is the fact that the
associated output diagrams and graphs are often assumed to be scientifically accurate in spite of two
underlying issues: the reliance of digital tools on mathematical models, which represent reality thought
a limited set of variables, and human error—the incorrect assumptions made by the design as the base
information they provide for the settings of their designs.
In this investigation, the enviro-material shading components were evaluated using a series of currently
accessible digital tools and software programs which made possible the modeling and simulation of
component performance under dynamic conditions. The study does not assume infallibility of the
software and tools chosen, rather it regards them as an effective means for providing designers and
architects with a basis on which to develop quantitative analyses of their shading components’
performance. The specific limitations of the software used and potential means for mitigating issues in
future studies are elaborated upon further in Chapter 6.
2.7 Chapter Summary
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For simplification purposes, and because U-values, insulation values, etc. are highly variable for input
into traditional building simulation and evaluation software, these factors will not be taken into
consideration, rather the facade will be evaluated from a more theoretical standpoint and more weight
will be placed on the ability of the component geometries to block unwanted solar radiation and admit
solar radiation during desired times. Because of the assumed temperature dependent behavior of the
facade system, based on the behavior of a comparable panel constructed from thermostatic bimetallic
alloy, the author is able to make these assumptions for the purpose of evaluation. Visual evaluation is
beneficial for facade systems of this type because it bypasses the need to alter software that does not
have the capability to input dynamic motion over time and because it requires less on the part of the
designer to create an accurate simulation of the panel’s behavior and response to light over the course
of seasons. Sun position and component position are two factors that are changing throughout this
simulation, and seem to have an immediate response to evaluate based on the shadow pattern cast on
the facade allows for straightforward and relatively simple evaluation after the code has been
established. However, the importance of quantitative results for this study lies in the ability of these
results to provide better understanding of how the components work and consequently, where
improvements can be made.
Quantitative results are crucial to the establishment of the significance of design decisions made in the
development of these types of adaptive façade components and, if isolated carefully, allow designers to
track how much influence a particular design element has on the overall outcome of a component’s
use—in this study, this outcome would manifest as the amount of solar direct gain prevented or
admitted from penetrating the façade.
Quantitative evaluation of these façade components allows for the comparison of one geometry
performs to another and how much solar radiant heat gain is blocked by each morphology in each
location. The quantitative results provide a base from which further improvements can be made on the
enviro-material façade and allows progress to be measured and tracked.
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Chapter 3: Methodology
3.1 Chapter Overview
The investigation unfolded through a deductive approach of reasoning, with subsequent experiments
and tests being predicated on the results of the initial experiments.
Two main elements formed the basis for the hypothesis:
1) motivator
2) range of motion through which the kinetic panel moves
To conceptualize the movement of the enviro-material components as a series of target geometries
allowed the author to understand how to maximize the panel’s effectiveness over a defined temporal
range. To determine what geometrical configurations provided the least and most exposure to solar
rays over the course of a year target geometries, the components were simulated during the most
extreme solar positions in a year: the summer solstice (the period of time during which the solar
altitude is highest and direct solar rays are the most intense) and the winter solstice (the period of time
when the solar altitude is lowest and the azimuth has the shortest range).
Determining the end positions of the geometry provides a range of motion through which the
movement of these kinetic facades can occur, but allows for the selection of two configurations (tilt
angles, overall shape, aspect ratio) that would perform better for solar adjustment than a single static
shading component in the same climate location.
3.2 Tools
Rhinoceros 3D
Rhinoceros 3D, or “Rhino”, is a commercial 3D computer graphic and computer-aided design
application developed by Robert McNeel & Associates. It is based on NURBS mathematical modeling,
which focuses on generating a mathematically precise representation of curve and freeform surfaces
within computer graphics as different to polygon mesh-based application
1
Grasshopper
Grasshopper is a visual programming language developed by David Ritten at Robert McNeel &
Associates. It operates within Rhinoceros 3D modeler, which offers the visual algorithms and affords
parametric modeling. This program is capable of accepting custom designed programs that can extend
the functionality. Various types of analysis range from sound, structural, design optimization ad
controlling Arduino are just a few tasks that can be performed within the software.
Autodesk Revit 2016
Revit is a Building Information Modeling software specifically built for the modeling of architectural
design, MEP and structural engineering, and construction.
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ImageJ
ImageJ is a public domain image-processing program based in Java developed at the National
Institutes of Health (NIH) for the reading and scientific analysis of multidimensional images. It has
the capability to run either as a downloadable application or an online applet on any computer with a
Java 1.4 or later virtual machine.
3.3 Simulating Environment-Façade Interaction
One of the most obvious benefits of using building information modeling software to simulate the
response of the façade system to the changing sun position is its ability to program specific material
characteristics of the component geometries. Revit allows for customization of the R-values, U-values
and other such material characteristics of any components that are developed in the software provided
they are not in-place masses. When paired with an analysis plug-in like Ecotect (no longer available to
the public as of spring 2015), this provides a powerful tool by which to more accurately evaluate the
effects of solar heat exposure on the façade assembly over different spans of time.
This investigation used two distinct methods of software integration to achieve analysis of the façade
components’ performance under dynamic environmental conditions, generation of parametric surfaces,
and validation of the effectiveness of the enviro-material shading devices in thermal performance.
The benefit of using a static component is that the use of imported shading devices from geometries
from the Rhinoceros interface can be easily transferred into Revit. Autodesk’s model can show the
resulting influence of these surfaces on the building’s estimated heating/cooling performance. While
not being able to simulate a variable fully dynamic surface, the final objective of this method was to
validate the performance of the component geometry. The beginning and end conditions could be
examined separately, if desired.
3.4 Establishment of Baselines
3.4.1 Static Parametric Design and Simulation
Initially a simple experiment on static component geometry was carried out on the Revit platform.
With a static system, the process can begin with traditional mass modeling methods as shown below:
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This initial study used a simple vertical mullion array in front of a continuous surface, subject to
variable solar exposure. The model was scaled at two stories, and analysis was executed based on the
shadows cast on the facade surface. Continuous shading of the façade behind represented a more
effective pattern geometry capable of providing maximum thermal shading and preventing unwanted
solar heat gain in summer months when the sun exposure is undesirable. The vertical mullions were 3
inches thick, 1.2 feet (0.4 m) deep and spaced 1.2 feet (0.45 m) apart. The overall array was 15 feet
wide and 15 feet (4.57 m) high.
In the tests, shadows cast onto the façade by the component geometries were observed and it was
noted when the geometries provided continuous shading onto the façade. After this benchmark was
completed, another simulation model was created to test a slightly more complicated geometry—the
brise-soleil system. Two mullions— horizontal and vertical were 2.5 inches thick, 1 foot (0.33 m) deep
and spaced 1 5/8 inches between vertical mullions. The entire array was 15 feet (4.57 m) wide.
Figure 3- 1: Vertical Mullion System (Author)
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At this point in the study, the author had the option to continue observing the effectiveness of static
geometries at different orientations (north, northwest, west, southwest, etc.), or to continue testing of
the effect of variations in elements of the component geometries on solar radiation of a south facing
wall. The latter option was pursued, but the former workflow may be investigated in a future study.
Figure 3- 3: Research scope workflow overview (Author).
Once these baselines were established, the shadow studies were conducted using a more complex
geometry provided by Professor Doris Sung detailed in the figures below. This is an element under
consideration for a built test case by Professor Sung’s firm.
Figure 3- 2: Brise-soleil Geometry (Author)
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Figure 3- 4:Component A (Author)
Figure 3- 5: Hot Weather Tilt (Author) Figure 3- 6:Cold Weather Tilt (Author)
Figure 3-7: View of Hot Tilt (left) and Cold Tilt (right) in section (Author)
52
Figure 3- 8: Axonometric view of Hot Tilt (left) and Cold Tilt (right) arrays from the same vantage point
(Author)
Figure 3- 9: Axonometric view of Hot Tilt (red) and Cold Tilt (cyan) juxtaposed. Both components are
situated on the plaque which connects the elements to the façade (Author).
53
As the behavior of the enviro-material component geometry was discretized for ease of modeling in the
software, the component was assumed to have two set end positions: one for “hot” temperatures and
another for “cold” temperatures which have been discretized for the purpose of this study. At
temperatures below 70 degrees Fahrenheit, the component would assume the “Cold Tilt” (Figure 3-6)
to maximize the exposure of the interior space to solar rays. Above 70 degrees, the panel assumes the
“Hot Tilt” configuration (Figure 3-5) to block solar radiation and prevent unwanted heat gain.
The components are constructed with a notch in the center-most point as shown in the figure below:
Figure 3-10: Top view of Hot Tilt (red) and Cold Tilt (cyan) mounted on attachment piece (Author).
The pieces were placed on a plaque which serves to attach them to the façade. The dimensions of the
plaque are shown below in Figure 3-11.
Figure 3-11: View of the attachment plaque alone (Author).
Thus, the distance between the bottom edge of the hot tilt and the facade is ½” and the distance
between the top edge of the cold tilt and the facade is ½”. The distance between the shading
component and the wall is indirectly important because of the convection cooling that occurs from air
passing behind the shading devices.
1 ¼”
½” ½”
½”
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Figure 3-12: Section view of the components in Cold Tiilt (cyan) and Hot Tilt (red) orientation mounted on
the plaque (Author).
Hot and cold tilts align on the top edge of the attachment point to the façade, however for the
purposes of simplicity, the geometries were tested without the attachment plaque to fully gauge how
well each geometry lent itself to shading. The component was placed in an array of elements
overlapping as shown below and the ability of the two tilts to accept and block solar radiation as
needed was tested at three points in time: 8:00AM, 12:00PM, and 3:00PM for the winter and summer
solstices as well as the autumn equinox. These times were chosen for two reasons:
1. Typically, facade studies are conducted at times symmetrical to the 12PM position, but as
shadow studies would be evaluated on the basis of the amount of shade provided to the
building, creating symmetry about the afternoon sun would result in redundancy of values for
the daylight hours with shading percentages being equal about daylight.
2. Considering the fact that this shading system would likely be for use on a commercial building,
taking into consideration the period of time for which the building would typically be
occupied was paramount in the study. This is due to the intent to reduce the need to use
mechanical heating or ventilation to keep the interior within the range of thermal comfort.
Thus, 8:00AM was chosen as the starting point—a time during which full occupancy of office
spaces typically begins. 12:00PM reflects the highest point of the sun’s altitude during the day,
and 3:00PM is typically when temperatures are the most extreme.
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Once the shading profiles for the Cold Weather Tilt and Hot Weather Tilt were determined
respectively, it became time to test ways to improve the performance of these geometries. Improved
component performance was defined as having a geometry that provides the most continuous shading
to a vertical façade surface in the Hot Tilt, and allows for the maximum amount of solar exposure to
the façade surface in its Cold Tilt configuration. In order to identify this geometry, the following
workflow was employed to carry out tests in a controlled and methodical fashion:
Figure 3-13: Geometry development notes (Author).
1. Modify tilt angles for Hot Tilt and Cold Tilt configurations across a range from xx to yy
2. Deform original geometry using control points
3. Continue deformation of specific points based on the results of shadow studies
4. Track the geometry and tilt angle combinations that provide better shading/solar exposure as is
evidenced by reported percentages of façade surface area in shadow
5. Calculate surface area shading provided by each geometry using ImageJ
6. Compare shading performance of geometries across three different points in the day (8:00AM,
12:00PM, 3:00PM)
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Figure 3-14: Workflow diagram of methodology (Author).
3.5 Geometrical Tests
3.5.1 Tilt Angle Modification
In the Rhinoceros software platform, a single component was selected and the tilt angle was modified
keeping the curve in the x-and y-dimensions constant. No deformations of the geometry itself were
made at this stage: Only the effects of tilt angle on the shading capability of the component were tested.
Tilt modifications were made in 15 degree increments, using Rhino’s angle command. To calculate the
tilt angle, a proxy in the form of a two-dimensional rectangle was created, and tilted alongside the
component geometry.
3.5.2 Geometrical Deformation
A single component was selected in Rhino and exported as a .sat file with ACIS solids format for use in
the Revit-ImageJ workflow.
Using NURBS-based control points, specific points on the geometry were altered (allowing a
maximum of two points moved per new geometry and maintaining symmetry about the y-axis).
Each element spans 4 inches in width (end-to-end on the x-axis), and 1.25 inches in height. Hot tilts
were oriented -125 degrees from horizontal. When creating the cold tilt orientation, elements were
rotated 180 degrees about a vertical axis and tilted -45 degrees from horizontal to match the hot and
cold tilts angles of the original component geometry provided by Professor Sung. Ultimately, for the
sake of simplicity, the difference in tilt angles between the Cold Weather and Hot Weather Tilt
geometries were used to represent the difference in curvature resulting from the heat-triggered
deformation of the geometry between the tilts. This is because any change in tilt angle is inextricably
linked to the deformation of the geometry as it responds to the heat of its environment.
Each geometry was then exported into the Revit workspace and arrayed in the fourteen-row pattern
shown above in Figure 3-7 where shadow studies were conducted to observe the shading profile of the
geometry.
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Figure 3-15: Array of enviro-material components placed in front of a section of south facing wall (Author).
3.5.3 Shadow Study Process
As mentioned previously, the behavior of the façade components was treated as discrete for the
purposes of evaluating the component tilts against one another depending on shadow production first
during the summer solstice, winter solstice and later during the autumn equinox.
Discretizing the movement of the shading components allowed for the accurate determination of the
amount of solar radiation that would be blocked when shading occurred or when solar radiation was
admitted. This research allowed us to understand how much shading could be expected from a fully
open panel at a temperature below 60F and for a fully closed panel (at a temperature above or equal to
80F. At 80 degrees, components are at full hot tilt shading angles, and at 60 degrees, components are
at full cold tilt shading angles. The flip in orientation occurs at 70 degrees Fahrenheit.
Shadow studies were conducted at three points in the day: 8:00AM, 12:00PM and 3:00PM. Three
times were chosen to represent a range of different sun intensities based on the angle of solar incidence
onto the surface of the component array.
The following process was employed for observing the shading profiles of the component geometries:
58
1) Place hot tilt component array onto façade surface
2) South-facing
3) Turn on sun-path diagram
4) Turn on shadows
5) Set location to weather station at one of three locations (e.g 42.36,-71.06 for Cambridge,
Massachusetts)
6) Test shading profiles at 8:00AM, 12:00PM. 3:00PM on December 21
st
and June 21
st
7) Record observations
8) Repeat for cold tilt component
9) Repeat entire process for modified geometry
A total of fifteen walls were developed in Revit and the component arrays were placed on each wall
such that they attached to the corresponding points on each façade. Using BIM software for this
process was extremely useful as it has the capability to recognize the position of the wall relative to the
sun (south-facing, west-facing, etc.) and also recognizes the distance of the component arrays from the
wall.
Figure 3-16: Initial testing set up in Revit platform: hot tilt (left) and cold tilt (right)in front of a south-facing
façade (Author).
After the shadow studies were conducted for the different component geometries, images of each
component array in front of a façade surface 30 m
2
(10 meters wide x 6 meters deep x 3 meters high)
were generated in Rhino and imported into the ImageJ program for processing. In Figure 3-16, the
component array is shown situated in front of the façade. The figure displays the shadow testing set-up
for the initial testing phase where the distance between the façade and the shading elements is much
larger than it was in actual testing phase. For the final experiments, the distance between the shading
components and the building façade is ½”.
59
3.6 Evaluation Criteria of Component Orientation
In the ImageJ platform, a histogram analysis was used to determine the percentage of the façade
surface in shadow during each of the three points in the day on the summer solstice, winter solstice
and autumn equinox, resulting in a total of 270 images processed. This percentage was used as a
metric by which to evaluate how effective the component configuration was for each solar condition
during the year: summer tilt vs. winter tilt for the south-facing façade.
Determining the percentage of shaded façade area from the ImageJ histogram analysis required first
converting the images to 8-bit grayscale color. This enabled the conversion of all color values in the
image from 0 to 255 to correspond to different levels of “whiteness” or “blackness,” with 0 being black
and 255 being white.
Figure 3-17: Histogram of façade surface for shading percentage calculation (Author).
These values were then imported into an Excel database, and percentages were calculated based on a
threshold value from which shading percentages were determined.
Sets of fifteen images (one image per component) were then batch processed and analyzed via
histogram. The histogram was divided into a series of color values and the frequency of values that
corresponded to each color value was used to determine which components qualified as shading. It was
important to be sure that the values chosen to represent shadows in each image actually corresponded
to shadow in the image. This was confirmed via a mouse-over of the image in the ImageJ platform.
ImageJ allows users to see the color value associated with each pixel upon mouse-over of an image. A
threshold value was chosen for each set of data to determine which values corresponded to shadows,
and which did not.
60
In the initial shading percentage calculations, a problem occurred in which identical color values were
reported for the façade and some areas of the elements themselves which resulted in inaccurate
percentages for each geometry. This was later remedied by reproducing images in Revit with higher
contrast which better distinguished the shading components from the façade.
Figure 3-18: Overview of color values from which shading percentages were determined (Author).
The total number of pixels in each core region, or region of interest (ROI) was 1624616 pixels. Images
were cropped to 1876 x 866 pixels to maintain consistency for the comparison of shading percentages.
It was assumed that the percentages of shading corresponding to each component geometry could be
mapped to the energy transfer through the building envelope in the form of solar radiant heat gain.
Each shading percentage corresponding to an element’s shading profile for a given point of time
reflected how much solar radiation could be predicted to have been blocked at a certain point in time.
These percentages of admittance were ultimately used as the performance metric by which each
geometry was evaluated.
Due to the variability of factors that influence the means of optimizing a building’s thermal
performance, the model chosen to represent the small office building on which these elements would
be rested remained a generic mass in the Revit platform.
According to Erickson, designing an effective energy-efficient envelope requires a clear
definition of indoor comfort as a benchmark for the design process as well as known indoor and
outdoor environmental conditions in order to understand the stresses that the envelope will endure.
(Erickson 2013). For this reason, three different sites were selected as the basis for evaluating these
enviro-material shading components. Thermal comfort was defined according to California’s Title 24
Standards as is displayed on the psychometric charts available in Climate Consultant for the climate
zone considered. For the purposes of this study, indoor thermal comfort range will be based off
61
standards set by the psychometric chart. It was assumed for the purposes of this study that thermal
comfort exists between 68F and 80F, but it is recognized that optimal thermal comfort varies between
individuals and is a function of the relationship between dry-bulb temperature and relative humidity.
The test was designed such that the minimum number of variables was tested to purely evaluate the
effectiveness of the enviro-material shading component as a shading and energy reduction device. As a
result, glare was not considered in this analysis, for the sake of simplicity and eliminating variables. It
was also assumed that the more solar radiant heat gain blocked during unwanted times, the less energy
will be used to drive a mechanical ventilation system to remove this heat through forced air or other
such heat mitigating systems. The ability for the components to respond appropriately to the
environment must be simulated and evaluated in terms of how much solar radiation is blocked and
eventually how much energy that will save from being placed on any mechanical heating and
ventilation systems in the climates chosen.
3.7 Test Sites
The three locations chosen for this simulation were Los Angeles, California; Phoenix, Arizona; and
Cambridge, Massachusetts.
Heating Degree Days (HDD)
Figure 3-19 : Heating and cooling degree days for one year in Los Angeles, California (Pacific Energy Center
2006)
A Heating Degree Day (HDD) is the difference between the average outdoor dry bulb temperature
during the day and a base temperature that is selected below which it is assumed that the indoor space
62
will require heating. While the base or reference temperature is usually 65F, base reference
temperatures of 60F, 55F, and 50F are also used to estimate the winter energy heating loads of spaces
such as parking garages, warehouses. This measurement provides an understanding of whether a
climate is heating dominant, meaning that for the majority of the year it requires heating to bring
spaces to a level of thermal comfort or “cooling dominant,” meaning that it requires cooling for the
majority of the year to keep indoor spaces at level of thermal comfort. Cooling degree days (CDD) are
measured by recording how many days the average outdoor temperature is above the reference
temperature. Historically, the cooling degree day reference temperature was set at 80F, but it has been
moved to 65F, coinciding with the HDD reference temperature.
Winter indoor design conditions for spaces occupied for extended periods of time (office, schools,
stores, residential spaces, etc.) typically require no heating until the temperature outside falls below
65F. This is because of the internal heat gains in the space from occupants, lights, and loads from
appliances which will offset the transfer heat losses through the building envelope (walls, windows,
roofs). A base temperature of 65F assumes that the space will not require heating unless the average
outdoor temperature falls below this reference temperature. (Pennsylvania State University 2017)
Cooling Degree Days (CDD), then are the difference between the average outdoor dry bulb
temperature during the day and a base temperature that is selected above which it is assumed that the
indoor space will require cooling. A base temperature of 65F is typically used to determine Cooling
Degree Days. (Pennsylvania State University 2017)
3.7.1 Los Angeles, California
Los Angeles is characterized by a rather temperate climate and resides within Climate Zone 8 (or 3B
according to ASHRAE climate zone characteristics). This means that it is rather dry and over the
course of the year it can expect to receive less extreme temperatures, thereby causing more component
flipping from one orientation to another within a season. (Pacific Energy Center)
Below are charts of the temperature history of Los Angeles in different seasons—winter, summer, fall,
and spring which indicated when the components can be expected to take on certain configurations.
There is a sharp increase in temperature and decrease in humidity as one leaves the coast. Sunshine is
plentiful year-round, so solar heating is very advantageous in this climate zone. Climate Zone 8 is a
very comfortable place to live and therefore requires the least energy of any region in California to
achieve thermal comfort levels.
Climatic design priorities according to Climate Consultant are to insulate, reduce infiltration and
utilize passive solar gain in the wintertime, and to shade, make use of natural ventilation and distribute
thermal mass in the summertime to achieve thermal comfort.
63
Figure 3-20: Range of dry-bulb temperatures and relative humidity levels for Los Angeles, California as
compared to the thermal comfort zone (Author).
Figure 3-19 above illustrates how mild Los Angeles’s climate actually is. Dry-bulb temperatures dip
barely below the thermal comfort zone in the winter months, with values rarely hitting temperatures
below 50F, and seldom reach above 80F. With temperatures being so close to the comfort zone
already, enviro-material shading components with a response to temperature should be quite effective
at keeping indoor thermal comfort levels within range, for the short periods of time that the
temperatures dip outside of the range.
64
Figure 3-21: A sun shading chart for Summer – Fall in Los Angeles, California displaying times for which
shading is necessary (Author).
For the Summer-Fall months (between June 21
st
and December 21
st
), Climate Consultant predicted a
need for shade for 907 hours during which temperatures exceed 75F. For 762 hours, shade would be
helpful, but not necessary for maintaining comfort as temperatures are above 68F, just in the range of
thermal comfort. Then, for 929 hours during this period, shade would be needed when temperatures
dip below 68F. It is important to note that these estimates are given for daylight hours only (between
6AM and 5PM in the summer months and 8AM and 5PM in the winter months) as can be observed
by the scales on the outer and innermost legends along the winter and summer curves.
65
Figure 3-22: Psychometric Chart readings for Los Angeles, California assuming no mechanical heating or
cooling system (Author).
In Revit, the specific weather station chosen from which to base the shadow studies had the following
characteristics:
Weather Station 7780
Year: 2004
Latitude: 34.033
Longitude: -118.245
Elevation: 350.00ft
3.7.2 Phoenix, Arizona
Phoenix, Arizona falls under the ASHRAE category 2B, meaning it is considered a hot, arid climate
and temperatures are usually on the higher end of the range. As such, Phoenix is considered a cooling
dominant city, with cooling being required for the majority of the year.
The weather station chosen at this location has the following specifications according to Revit’s
database:
Weather Station: 99071
Year: 2006
Latitude 33.448
Longitude: – 112.026
Elevation: 392.00 ft
66
Figure 3-23: Year-round temperature range of Phoenix, Arizona (Author).
Phoenix typically experiences temperatures that are well above the thermal comfort zone, with summer
temperatures reaching above 110 degrees Fahrenheit. In the winter months, temperatures can dip
slightly below 40F according to Figure 3-23, above.
67
Figure 3-24: Average dry-bulb and relative humidity values mapped against comfort zone for Phoenix,
Arizona (Author).
In Figure 3-24, the frequency with which temperatures are outside of the thermal comfort zone is
more easily distinguishable, with dry-bulb temperatures spiking above the thermal comfort zone seven
months out of twelve. In such a climate, the need to block unwanted solar radiant heat gain to prevent
overheating of indoor spaces seems rather high, and the enviro-materially actuated components would
likely perform quite well here. The lack of extreme cold in this climate could allow the admission of
direct normal solar radiation to contribute rather significantly to the perception of thermal comfort in
indoor spaces (especially when coupled with the high solar radiation values that will be shown later in
Chapter 5).
68
Figure 3-25: Psychometric Chart readings for Phoenix, Arizona assuming no mechanical heating or cooling
system (Author).
According to the psychometric chart data in Figure 3-25 above, Phoenix remains within the range of
thermal comfort for 74.8% of the time (6553 out of 8760 hours) over the course of a year barring use
of mechanical heating and cooling systems. Traditional sun shades are said to contribute 26.5% to
thermal comfort levels in this climate zone. Figures 3-26 and 3-27 below provide data concerning
shading needs for a small office construction throughout the year. In Figure 3-26, which details the
summer-fall months (June 21
st
to December 21
st
), shading is estimated to be required for 1992 hours
of the year when temperatures are above 75F. This would coincide with when the enviro-material
shading components would assume the hot tilt configuration. For 210 hours of the year, “shade helps,”
meaning that shading is not absolutely necessary, as temperatures fall within the range of thermal
comfort being greater than 68F. Finally, for 384 hours of the year, sun is needed as temperatures fall
below 68F, outside of the range of thermal comfort. These are the hours that coincide with the
component assuming the cold tilt configuration allowing solar radiation to penetrate the façade behind
the array. In the following figure, Figure 3-27, the winter-spring months are analyzed with estimates
for months between December 21
st
and June 21
st
.
69
Figure 3-26: A sun shading chart for Summer – Fall in Phoenix, Arizona displaying times for which shading
is necessary (Author).
Figure 3-27: A sun shading chart for Winter – Spring in Phoenix, Arizona displaying times for which shading
is necessary (Author).
70
3.7.3 Cambridge, Massachusetts
Cambridge, Massachusetts falls under Climate Zone 5a classification and is considered a heating
dominant city. Boston is the most extreme climate of the three chosen for this study. Temperatures
can dip as low as -5F in the winter months and exceed 95F in the summer months (see July).
According to the psychometric charts in Figure 3-28 and Figure 3-29 below, traditional shading
methods would have 21.8% effectivity for maintaining thermal comfort in June and 14.7% effectivity
in September.
Figure 3-28: Year-round temperature range of Boston, Massachusetts (Author)
71
Figure 3-29: Range of dry-bulb temperatures and relative humidity levels for Boston, Massachusetts as
compared to the thermal comfort zone (Author)
For much of the year Boston’s average temperatures fall well below the range of thermal comfort
which distinguishes it from the other two cities selected for this study.
72
Figure 3-30: A sun shading chart for Summer – Fall in Boston, Massachusetts displaying times for which
shading is necessary (Author).
Figure 3-31: A sun shading chart for Winter – Spring in Boston, Massachusetts displaying times for which
shading is necessary (Author).
73
Figure 3-32: Psychometric chart data for Cambridge, Massachusetts for the month of September assuming
no mechanical heating or cooling system (Author).
Figure 3-33: Psychometric chart data for Cambridge, Massachusetts for the month of September assuming
no mechanical heating or cooling system (Author).
74
As is evidenced by Figure 3-33 above, without the use of heating and humidification systems, a
building in Cambridge is only able to reach indoor thermal comfort 10.9% of the time in December
(81 out of 744 hours). In contrast, during the month of June, 81.3% of hours are comfortable
assuming wind protection of outdoor spaces, natural ventilation cooling, and excluding mechanical
heating and cooling systems. For this month, Climate Consultant predicts that sun shading will have a
21.8% contribution to achieving thermal comfort, and passive solar direct gain will have a 10.1% to
14.4% contribution-both strategies that result from using the enviro-materially actuated shading
component detailed for this study.
While the predictions and relative weights of the strategies projected by Climate Consultant are simply
estimates, they provide a powerful starting point from which to begin to consider how effective the
enviro-material shading components will be in each location. It is useful to consider the month-by-
month breakdown of effectiveness as well, as in choosing a particular geometry for their shading array,
designers will want to consider the factors they will want to prioritize: prevention of solar direct gain in
undesirable times, or maximization of solar direct gain in desired times. As will be demonstrated in the
following section, each component geometry has a tradeoff between its performance in the two tilts—
many of the components that block higher amounts of radiation in the hot tilt configuration also
block relatively high amounts of radiation in the cold tilt configuration.
Figure 3-34: Psychometric chart data for December in Cambridge, Massachusetts assuming the use of a
heating system (Author).
75
Figure 3-35: Psychometric chart data for Cambridge, Massachusetts for the month of September assuming
no mechanical heating or cooling system (Author).
Figure 3-36: Psychometric chart data for Cambridge, Massachusetts for the month of March assuming no
mechanical heating or ventilation system (Author).
76
Chapter 4: Results
4.1 Chapter Overview
This evaluation is based on a uniform grid and excludes the edge conditions. Assuming sufficient
overlap allows greater accuracy and extrapolation of the results to other cases. The position and size of
the shaded region is directly related to the size of the wall, distance of the components on the wall, and
relative position of the components on the facade. Therefore, the shading percentages are a direct
result of the specific values chosen for the evaluation. In order to derive more accurate results, the
author chose to eliminate the edge condition and evaluate the component geometries based on a core
region of petal components. See Figure 4-1 below. A morphology of fifteen component geometries was
created in the Rhino interface and imported into Revit for testing of their shading capabilities. Due to
Revit’s proficiency as a building information modeling program, it was able to provide accurate
shadow patterns for the location, azimuth and height of the wall that was being considered.
4.2 Morphology Shading Profiles
The fifteen morphologies created in total: A1, B1, B2, C1, C2, D1, D2, E1, F1, F2, G1, T1, T2, T3,
and T4, were developed by using a grid system which defined the six points that needed to remain
constant across geometries.
Figure 4 -1: (Author)
The grid, pictured in Figure 4-2 below, measures 4 inches in total width .212 inches in y
77
.500 inches in x. An envelope was developed to bound the region according to the dimensions of the
original component geometry.
Figure 4- 2: View of the grid template from which components were constructed in Rhinoceros (Author)
Figure 4-3: View of the untrimmed surface (Author)
The original geometry was “untrimmed” in Rhino, and the resulting rectangular bent pieces were
superimposed over the new geometries to recreate the bends necessary for the cold and hot tilt
components.
Figure 4-4: Hot tilt, cold tilt and surface template of one shading component (Author)
78
Figure 4-5: View of hot and cold tilts superimposed over flat geometries (Author)
Figure 4-6: Evolution of morphology (Author)
The figures below show the geometries in elevation and axonometric view:
Figure 4 -7: A front elevation view of an array of element A1 (Author)
T3
F1
T1
A1
F2
C1 B1
G1
T4
E1
B2
Original geometry
T2
D2
D1 C2
79
Figure 4-8: Close up view of A1 components (Author)
Figure 4-9: A side elevation view of an array of element A1 (Author)
80
Figure 4-10: A1 Axonometric View (Author)
B1
Figure 4-11: A front elevation view of an array of element B1 (Author)
81
Figure 4-12: Close up view of B1 (Author)
Figure 4-13: A side elevation view of an array of element B1 (Author)
82
Figure 4-14: B1 Axonometric (Author)
Figure 4-15: A front elevation view of an array of element B2(Author)
83
Figure 4-16: Close up view of B2 (Author)
Figure 4-17: A side elevation view of an array of element B2 (Author)
84
Figure 4-18: B2 Axonometric (Author)
C1
Figure 4-19: A front elevation view of an array of element C1 (Author)
85
Figure 4-20: Close up view of C1 (Author)
Figure 4-21: A side elevation view of an array of element C1 (Author)
86
Figure 4-22: C1 Axonometric (Author)
A series of views of the eleven remaining elements can be found in Appendix A.
The elements are arrayed such that there is a distance of 4” between the midpoint of each notch. The
distance from the outer most point right and let of the center of each slot measures 2 inches. The y-
distances between the top of each component and the top of the next measures ¾”. The components
attach to the façade via a notch which allows them to be mounted onto a series of attachment plaques.
During the simulations, the plaques were omitted from the array to focus the analysis on the shading
capabilities of the geometries themselves.
Over the course of the study, it was found that there was no immediately obvious single geometry that
resulted in optimal conditions for both summer and winter. In other words, geometries that resulted
in 100% shading for the summer conditions also had varying effectiveness of admission of solar
radiation in the winter conditions. This was a rather interesting observation because it implies that
some compromise must be reached in order to obtain performance better suited to the particular
location in which these enviro-material components are being used.
Some geometries were extremely effective at allowing high levels of solar radiation to infiltrate the
façade at desired times (when temperatures were below levels of thermal comfort)
The total number of pixels for the crop region was 1624616 pixels from a crop region of 1866 x 876
pixels for each core region.
87
The following section details the performance of the two tilts at three different points in time, for the
winter and summer solstice.
4.3 Results
A nomenclature was developed to more easily organize the results that corresponded to each tilt during
the time of day and time of year.
The Hot Weather Tilt is the orientation of the component at a temperature above 70 F. The Cold
Weather Tilt reflects the orientation of the component at a temperature below 70 F, which could
occur on the same day and at the same sun angle. This is a notable feature of the bimetal—the ability
to provide adaptable and appropriate shading of a facade depending on the temperature.
HW# refers to the Hot Weather Tilt during the winter solstice at some time of day (e.g. 8:00am).
CW# refers to the Cold Weather Tilt during the winter solstice
HS# refers to the Hot Weather Tilt during the summer solstice at some time of day
CS# refers to the Cold Weather Tilt during the summer solstice at some time of day
HA# refers to the Hot Weather Tilt during the *autumn equinox at some time of day
CA# refers to the Cold Weather Tilt during the autumn equinox at some time of day
*because the sun hits the components at essentially the same angle during the autumn and spring
equinoxes, shadows were observed for only one of the equinoxes to avoid redundancy.
Figure 4-23: Front elevation view of Element G1 (Author)
88
Figure 4-24: (a) Element G1 mounted on the façade (b) Section view of element mounted on the façade
(Author)
89
Figure 4-25: A view of shadows cast by the shading element on the façade (Author)
The shading profiles created by each element on the façade are represented in images such as that
shown in Figure 4-25. For the hot tilt elements, the view was oriented such that the wall was visible
from an angle. The view angle has been represented by a grey cube to the right of the element’s
shadow profile.
G1 HS3 Cambridge, MA G1 CW3 Cambridge, MA
(Element G1, Hot Weather Tilt, Summer (Element G1, Cold Weather Tilt, Summer
solstice, 3:00 pm, Cambridge, MA) solstice, 3:00 pm, Cambridge, MA)
Shading Element
Façade behind element
Shadow cast by element
90
G1 HA 3 Cambridge, MA G1 CA 3 Cambridge, MA
(Element G1, Hot Weather Tilt, Autumn (Element G1, Cold Weather Tile, Autumn
equinox, 3:00 pm, Cambridge, MA) equinox, 3:00 pm, Cambridge, MA)
Figure 4-26: View of shading profiles of G1 component in Hot Tilt and Cold Tilt configurations during the
Summer Solstice and during the Autumn equinox (Author).
One component geometry that allowed for highest level of solar radiation admitted in its cold tilt
orientation was the FI morphology:
Figure 4-27: Front elevation view of Element F1
F1 HS3 Cambridge, MA F1 CW3 Cambridge, MA
(Element F1, Hot Weather Tilt, Summer (Element F1, Cold Weather Tilt, Winter
Solstice, 3:00 pm, Cambridge, MA) solstice, 3:00 pm, Cambridge, MA)
This geometry also seemed to block the least amount of light of the morphologies, however, the
amount blocked was not appreciably far from 100%.
91
F1 HA3 Cambridge, MA F1 CA3 Cambridge, MA
(Element F1, Hot Weather Tilt, Autumn (Element F1, Cold Weather Tilt, Autumn
Equinox, 3:00 pm, Cambridge, MA) equinox, 3:00 pm, Cambridge, MA)
T4 HS3 Cambridge, MA T4 CW3 Cambridge, MA
(Element T4, Hot Weather Tilt, Summer (Element T4, Cold Weather Tilt, Winter
Solstice, 3:00 pm, Cambridge, MA) solstice, 3:00 pm, Cambridge, MA)
Figure 4-28: Views of the F1 and T4 geometries at 3:00pm in the Hot Weather and Cold Weather tilt
configurations (Author).
The different tilts combined with the solar azimuth result in different amounts of shading as was
appropriate for the external temperature conditions. This is unique to enviro-material shading
components and allows them to provide adaptive shading as is appropriate for external thermal
conditions thereby providing more effective support) to keep indoor temperatures in the range of
thermal comfort.
92
4.4 Results for Cambridge, Massachusetts
4.4.1 Cold Tilt - Winter Solstice
Figure 4-29: Percentages of shading provided by elements at CW12 in Cambridge, Massachusetts
Figure 4-30: Percentages of shading provided by elements at CW3 in Cambridge, Massachusetts
For Cambridge, Massachusetts the top five performing components were F1, A1, T4, T1 and F2. The
geometries that seemed to provide more continuous shading in the summer months resulted in lower
performance during the winter solstice when the objective was to admit as much solar radiation as
possible to account for the lower external temperatures.
11.54%
16.90%
21.75%
19.02%
19.49%
30.50%
26.14%
28.81%
10.67%
15.06%
22.99%
14.36%
18.25%
22.43%
12.90%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%
35.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
CW12 - CAMBRIDGE, MA
15.35%
22.24%
27.92%
24.33%
25.46%
38.26%
34.10%
37.12%
14.66%
19.83%
29.44%
18.90%
23.75%
28.38%
17.29%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%
35.00%
40.00%
45.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILES
CW3- Cambridge, MA
93
Visual representations of the shading profiles of the top five morphologies have been reproduced
below:
Front elevation view and shading profile of component F1 in CW3 orientation
Front elevation view and shading profile of component A1 CW3
Front elevation view and shading profile of component T4 CW3
Front elevation view and shading profile of component T1 CW3
Front elevation view and shading profile of component F2 CW3
Figure 4-31: Elevation and shading profiles of components F1, A1, T4, T1, F2 for CW3 orientation
94
Figure 4-32: Trend in shading percentages for all fifteen components across designated points in time
(8:00am, 12:00pm, 3:00pm)
For the cold tilts, better performance is linked to shading profiles with lower percentages, as these are
reflective of geometries that allow more solar radiation through the façade during wanted times (at low
temperatures).
The trends in component shading performance is consistent across times for a given day, but the same
cannot be said of the patterns observed across seasons, which is to be expected given the difference in
solar azimuth.
4.4.2 Hot Tilt - Summer Solstice
For the summer months, the panels that result in the most shading of the façade are
B2, C1, C2, D1, D2, E1, G1, and T3 result in virtually full shading of the façade for the summer
solstice 3pm (HS3) condition.
16.06%
10.86%
15.35%
23.28%
16.06%
22.24%
29.58%
20.11%
27.92%
25.51%
17.54%
24.33%
26.62%
18.08%
25.46%
40.11%
28.00%
38.26%
35.02%
24.57%
34.10%
38.96%
26.54%
37.12%
15.23%
10.21%
14.66%
20.33%
14.15%
19.83%
30.07%
21.14%
29.44%
19.85%
13.56%
18.90%
25.40%
17.00%
23.75%
30.37%
20.82%
28.38%
18.28%
12.47%
17.29%
1 2 3
COLD TILT SHADING PROFILES - DECEMBER 21ST
A1 B1 B2 C1 C2
D1 D2 E1 F1 F2
G1 T1 T2 T3 T4
8
1
3
95
Figure 4-33: Percentages of shading provided by elements at HS12 in Cambridge, Massachusetts
The geometries that block the lowest amounts of solar radiation for the HS12 condition are: F1, A1,
T4, C2 and B2. It is interesting to note that components that perform most effectively for the Cold
Weather Tilt condition prove to be less effective under the Hot Weather Tilt condition as a result of
the width of the components in y-direction of the lateral portion of the wings. Wings larger in this
area of the geometry block large portions of solar radiation when the components are in the Cold Tilt
configuration.
Figure 4-34: Shading Profile of Element F1 at HS12
79.38%
86.15%
85.03%
88.72%
84.37%
88.13%
88.78%
88.05%
72.24%
86.05%
89.24%
87.78% 88.03% 88.22%
83.67%
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
90.00%
100.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
HS12 - Cambridge, MA
96
Figure 4-35: T2 Shading Profile of Element A1 at HS12
Figure 4-36: Shading Profile of Element T4 at HS12
97
Figure 4-37: Shading Profile of Element C2 at HS12
Figure 4-38: Shading Profile of Element B2 at HS12
98
Figure 4-39: Percentages of shading provided by elements at HS3 in Cambridge, Massachusetts
For the summertime 3pm and 8am case, all components can be expected to provide roughly 100%
shading in the shaded region excluding the edge condition. However, for a wall of size 3 meters by 10
meters the following shading percentages were observed when the components were situated roughly
one half inch from the facade.
The T2 morphology, while not able to provide complete shading of the façade, performs better than
the T4 geometry due to increased surface area at its bottom edge: The T4 component’s comparatively
poor performance at this time most likely stems from the triangular shaped opening at its bottom edge:
T2 Morphology T4 Morphology
Figure 4-40: T2 Morphology (left) and T4 Morphology (right)
98.02%
98.94%
99.87%
99.43%
99.76%
99.99%
99.98%
99.92%
96.59%
98.91%
99.46%
98.20%
99.86%
100.00%
96.77%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
HS3 - CAMBRIDGE, MA
99
Figure 4-41: Shading T2 Shading Profile for HS3
Figure 4-42: Shading Profile for HS3
These results seem to indicate that geometries with wider lateral wings in the y-direction allow for
better shading in the summer months when the solar azimuth angle is larger. Components G1, D1,
and D2 are good examples of this principle. When in the Cold Tilt configuration, these same
geometries seem to allow less solar radiation to penetrate the façade behind.
100
Front elevation view of component G1
Front elevation view of component D1
Front elevation view of component D2
Figure 4-43: Front elevation views of components G1, D1, and D2
It is important to note that for the summer conditions the size of the shaded region does change
somewhat significantly between geometries, and although this does not influence the percentages used
to create shading profiles of each morphology, it does have important implications for designers while
making design decisions for their facades. Designers should keep in mind that facades to which these
enviro-material components will be applied should be large enough that the sun hits each of the
components equally, thus creating a larger shading region for the façade over the course of the year.
101
Figure 4-44: Shading Profile for Element A1 at HS3 with edge conditions
Figure 4-45: Shading Profile of Element B1 at HS3 with edge conditions
102
Figure 4-46: Shading Profile for Element C1 at HS3 with edge conditions
The edge conditions reveal vastly different information about the shadows cast by these geometries,
but are only representative of the specific conditions for this particular façade (wall size, distance of
elements from the façade, etc.). The results cannot necessarily be scaled up to larger walls unless we
isolate the core condition as has been done to produce the results of this research. Thus, final
calculations would consider the particular wall size, shading panel overlap at the edges and distance
from the wall being shaded. The best value would be the full overlap.
103
4.4.3 Cold Tilt - Autumn Equinox
Figure 4-47: Percentages of shading provided by elements at CA12 in Cambridge, Massachusetts
Figure 4-48: Percentages of shading provided by elements at CA3 in Cambridge, Massachusetts
1.28%
2.03%
3.23%
2.89%
3.11%
4.48%
3.65%
4.16%
1.29%
2.25%
3.54%
1.47%
1.98%
2.82%
1.57%
0.00%
0.50%
1.00%
1.50%
2.00%
2.50%
3.00%
3.50%
4.00%
4.50%
5.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
CA12 - CAMBRIDGE, MA
6.61%
7.52%
10.14%
9.91%
10.72%
15.39%
12.78%
15.06%
5.27%
8.38%
13.13%
4.52%
7.32%
10.43%
4.64%
0.00%
2.00%
4.00%
6.00%
8.00%
10.00%
12.00%
14.00%
16.00%
18.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
CA3 - CAMBRIDGE, MA
104
4.5 Results for Los Angeles, CA
Because Los Angeles is a more temperate climate, one can expect to see a wider range of tilt responses
over the course of a year. For example, in Cambridge, the components will almost never take on the
hot tilt configuration in the winter time, simply because temperatures almost never exceed 70 degrees
in the wintertime. In contrast, Los Angeles can see temperatures above 70 degrees in what is typically
considered winter—especially in the fall season.
It is more likely that the enviro-material façade will assume Hot Tilt configuration in the winter season
for those regions in lower latitudes given their temperature histories.
Thus, the HW and HA configurations are more likely to be observed in Los Angeles and Phoenix than
in Cambridge, where it is very unlikely that temperatures will hit 70F during the winter months.
4.5.1 Cold Tilt - Winter Solstice
Figure 4-49: Percentages of shading provided by elements at CW12 in Los Angeles, CA
7.76%
11.27%
14.04%
12.66%
11.83%
19.71%
17.59%
18.55%
6.65%
9.43%
14.55%
8.80%
11.35%
14.20%
8.52%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
CW12 Los Angeles, CA
105
Figure 4-50: Percentages of shading provided by elements at CW3 in Los Angeles, CA
4.5.2 Hot Tilt - Summer Solstice
Figure 4-51: Percentages of shading provided by elements at HS12 in–Los Angeles, CA
11.45%
17.05%
22.03%
18.92%
19.55%
30.51%
26.22%
28.85%
10.42%
14.88%
22.86%
14.36%
18.12%
21.49%
12.98%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%
35.00%
A1 B1 B2 C1 C2 D1 D1 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
CW3 - Los Angeles, CA
97.76%
97.56%
97.13%
99.84%
97.33%
99.97%
99.29%
99.95%
90.40%
99.46%
99.98%
97.43%
97.14%
99.60%
96.48%
84.00%
86.00%
88.00%
90.00%
92.00%
94.00%
96.00%
98.00%
100.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILES
HS12 - Los Angeles, CA
106
Figure 4-52: Percentages of shading provided by elements at HS3 in Los Angeles, CA
4.5.3 Hot Tilt - Winter Solstice
Figure 4-53: Percentages of shading provided by elements at HW12 in Los Angeles, CA
100.00% 100.00% 100.00% 99.99% 100.00% 100.00%
98.17% 98.17% 98.17% 98.17% 98.17% 98.17% 98.17% 98.17% 98.17%
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
90.00%
100.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILES
HS3 - Los Angeles, CA
35.31%
52.65%
60.75%
53.27%
55.65%
71.13%
66.51%
67.59%
33.54%
45.23%
56.90%
44.02%
53.71%
65.73%
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
HW12 - Los Angeles, CA
107
Figure 4-54: Percentages of shading provided by elements at HW3 in Los Angeles, CA
The five geometries that result in the most shading for the Hot Weather Tilt Winter Solstice
configuration at 3:00pm are: D1, E1, D2, T3, and B2.
Figure 4-55: Shading Profile for D1 HW3 Los Angeles, CA
32.39%
47.60%
56.46%
48.56%
51.42%
67.74%
63.54%
64.04%
30.12%
41.22%
50.62%
39.45%
47.68%
59.24%
36.55%
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
HW3 - Los Angeles, CA
108
Figure 4-56: Shading Profile for E1 HW3 Los Angeles, CA
Figure 4-57: Shading Profile for D2 HW3 Los Angeles, CA
109
Figure 4-58: T4 Shading Profile for T3 HW3 Los Angeles, CA
Figure 4-59: B2 Shading Profile for HW3 Los Angeles
110
4.5.4 Cold Tilt - Autumn Equinox
Figure 4-60: Percentages of shading provided by elements at CA12 in Los Angeles, CA
Figure 4-61: Percentages of shading provided by elements at CA3 in Los Angeles, CA
10.29%
14.92%
19.28%
17.01%
17.52%
27.11%
23.42%
25.85%
9.91%
14.06%
20.65%
12.51%
15.77%
19.80%
11.87%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
CA12 - LOS ANGELES, CA
12.10%
16.29%
20.32%
18.74%
19.48%
29.40%
25.37%
28.27%
11.23%
16.05%
23.48%
13.05%
17.06%
21.54%
12.44%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%
35.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
CA3 - LOS ANGELES, CA
111
4.6 Results for Phoenix, AZ
Results for Phoenix and Los Angeles were expected to be rather similar, as compared to
Cambridge, Massachusetts given their temperature histories and similar latitudes.
4.6.1 Cold Tilt - Winter Solstice
Figure 4-62: Percentages of shading provided by elements at CW12 in Phoenix, AZ
Figure 4-63: Percentages of shading provided by elements at CW3 in Phoenix, AZ
–
7.51%
10.09%
13.17%
11.25%
11.64%
18.50%
16.03%
17.45%
5.67%
8.88%
13.67%
8.35%
10.64%
13.38%
7.51%
0.00%
2.00%
4.00%
6.00%
8.00%
10.00%
12.00%
14.00%
16.00%
18.00%
20.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
CW12 - PHOENIX, AZ
9.67%
14.55%
18.64%
15.88%
16.60%
25.64%
22.04%
24.09%
9.23%
12.76%
19.35%
12.30%
15.33%
19.44%
11.23%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
CW3 - PHOENIX, AZ
112
4.6.2 Hot Tilt - Winter Solstice
Figure 4-64: Percentages of shading provided by elements at HW12 in Phoenix, AZ
Figure 4-65: Percentages of shading provided by elements at HW3 in Phoenix, AZ
36.14%
53.37%
60.41%
54.65%
55.67%
71.92%
67.18%
68.23%
34.38%
45.77%
57.44%
45.04%
55.16%
66.10%
41.62%
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
HW12 - PHOENIX, AZ
51.93%
87.04%
84.70%
66.28%
66.89%
75.81% 75.37%
72.80%
46.93%
56.87%
62.56%
58.74%
63.70%
71.53%
55.57%
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
90.00%
100.00%
SHADING PROFILE
HW3 PHOENIX, AZ
113
4.6.3 Hot Tilt - Summer Solstice
Figure 4-66: Percentages of shading provided by elements at HS12 in Phoenix, AZ
Figure 4-67: Percentages of shading provided by elements at HS3 in Phoenix, AZ
98.81%
98.19%
97.96%
99.50%
97.69%
99.97%
99.81%
99.97%
94.56%
99.46%
99.99%
97.88%
98.08%
99.98%
95.00%
91.00%
92.00%
93.00%
94.00%
95.00%
96.00%
97.00%
98.00%
99.00%
100.00%
101.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
HS12 - PHOENIX, AZ
97.98%
98.74%
98.55%
98.09%
98.36%
98.80%
98.70%
98.37%
98.16%
98.17%
98.16%
99.83%
98.76%
98.83%
98.31%
97.00%
97.50%
98.00%
98.50%
99.00%
99.50%
100.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
HS3 - Phoenix, AZ
114
4.6.4 Cold Tilt - Autumn Equinox
Figure 4-68: Percentages of shading provided by elements at CA3 in Phoenix, AZ
11.30%
16.76%
21.30%
18.55%
19.65%
29.91%
25.98%
28.60%
11.04%
15.55%
23.01%
14.12%
17.93%
21.95%
13.32%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%
35.00%
A1 B1 B2 C1 C2 D1 D2 E1 F1 F2 G1 T1 T2 T3 T4
SHADING PROFILE
CA3 - PHOENIX, AZ
115
4.7 Chapter Summary
Although the edge conditions were omitted for the purpose of evaluating the geometries across seasons,
they still yield important revelations about the installation of the panels and situation on the façade.
Figure 4-69: Component G1 with edge conditions
Designers may choose to situate components such that at the most extreme sun angles, they can
provide the most shading possible while employing the smallest number of components in their array.
Depending on how far away the panels are placed from the wall, the edge conditions will play a larger
or smaller role in the amount of shading that the façade receives.
In Figure 4-59 above, one can see that the component provides shading almost to the bottom of the
wall, and is able to eliminate the need to place several additional rows of components to provide the
same amount of shading during this time of day. The most drastic shading will occur at noon on
summer solstice (the highest amount of wall coverage will be seen for the hot tilt). To eliminate the
edge conditions completely, a designer may choose to extend the components such that they remain
larger than the size of the façade.
116
Chapter 5: Analysis
5.1 Chapter Overview
As was mentioned previously in Chapter 3, the thermal zone in this study is based upon the US
Department of Energy’s Commercial Reference Building’s dimensions for a small single-story office
building. A similar model was used as the basis for Erickson’s adaptive façade study at the University
of Arizona.
Figure 5-1: Front elevation view of small office with enviro-material shading components mounted (Author)
The mass measures 6 meters deep, 3 meters high, and 10 meters wide, and it is assumed that other
than the south-facing façade, all other surfaces are adiabatic. It is also assumed that non-adiabatic
façade is largely fenestration.
As evidenced by the results in the previous chapter, summer solstice conditions left little room for
improvement in terms of performance between the geometries. For the summer condition, shading
performance between geometries had little variance, if any at the 12:00pm and 3:00pm solar angles,
with percentage of façade in shadow hovering between 98% and 100%. The true test of the geometries’
effectiveness came into play for the solar radiation admittance capabilities of the Cold Weather Tilt
during the winter solstice and spring/autumn equinoxes.
Panels should be able to achieve a balance between blocking as much solar radiation as possible when
in Hot Tilt configuration when temperatures are high and allowing as much solar radiation to
penetrate the façade when in Cold Tilt configuration in colder temperatures.
5.2 Solar Radiation Values
The data used to determine the solar radiation values for each hour measured were sourced from
Typical Meteorological Year (TMY) Files provided by the National Renewable Energy Lab in
California. Typical Meteorological Year files are sets of data that detail expected dry bulb temperature,
solar radiation values, and much more information for a particular location based on the observed data.
The expected percentages of solar radiation blocked in each season are as follows:
117
Summer Solstice Radiation Values
Los Angeles, CA
Los Angeles International Airport
6/21/02
8:00 AM 12:00PM 3:00PM
6 W/m
2
162 W/m
2
391 W/m
2
These values have been reported with an uncertainty of 15% which most likely results from the
presence of cloud cover during the time of measurement.
Phoenix, AZ
6/21/86
8:00 AM 12:00PM 3:00PM
296 W/ m
2
609 W/ m
2
753 W m
2
Cambridge, MA
6/21/02
8:00 AM 12:00PM 3:00PM
551 W/m
2
721 W/m
2
631 W/m
2
15% uncertainty
Winter Solstice direct normal irradiance values for each of the three cities are as follows:
Winter Solstice Radiation Values
Los Angeles International Airport
12/21/86
8:00 AM 12:00PM 3:00PM
216 W/m
2
691 W/m
2
780 W/m
2
21% uncertainty
Phoenix, AZ
12/21/01
8:00 AM 12:00PM 3:00PM
28 W/m
2
808 W/m
2
636 W/m
2
Cambridge, MA
12/21/86
8:00 AM 12:00PM 3:00PM
0 W/m
2
379 W/m
2
34 W/m
2
21% uncertainty
**For Cambridge, Massachusetts values for Boston, Massachusetts were used and assumed to be
reasonably similar given the close proximities of the two cities.
118
Because the enviro-material shading components are temperature dependent instead of sun-dependent,
not only will they activate during these solar extreme conditions, but they will also become active
when temperatures are high, but the sun is not at its most extreme, for example at points during the
spring and autumn equinoxes.
Autumn Equinox Radiation Values
Los Angeles International Airport
9/21/77
8:00 AM 12:00PM 3:00PM
283 W/m^2 674 W/m^2 621 W/m^2
9% uncertainty 13% uncertainty 9% uncertainty
Phoenix, AZ
9/21/87
8:00 AM 12:00PM 3:00PM
208 W/m^2 551 W/m^2 425 W//m^2
9% uncertainty
Cambridge, MA
9/21/76
8:00 AM 12:00PM 3:00PM
47 W/m^2 408 W/m^2 29 W/m^2
9% 13% 9%
Spring Equinox Radiation Values
Los Angeles International Airport
3/21/87
8:00 AM 12:00PM 3:00PM
1 W/m^2 5 W/m^2 193 W/m^2
9% uncertainty
Phoenix, AZ
3/21/00
8:00 AM 12:00PM 3:00PM
168 W/m^2 376 W/m^2 697 W/m^2
Cambridge, MA
3/21/81
8:00 AM 12:00PM 3:00PM
1 W/m^2 6 W/m^2 1 W/m^2
9% uncertainty
Given the dimensions of a typical small office construction upon which the mass was based the
expected incident solar radiation onto the south-facing façade can be easily estimated using the TMY
values listed above. For example, on the summer solstice at 12:00pm in Los Angeles, one could
reasonably expect ~162 watts of solar radiation incident on every square meter of the façade (note: this
119
value was provided with an uncertainty of fifteen percent). For a façade measuring 30 square meters,
one would expect 4260 watts of direct solar radiation incident on the surface. This number does not
reflect the solar heat gain into the interior of the space, however, as that is dependent on the thermal
transmittance of the façade—a number which reflects how readily heat is passes through the façade as
a result of its insulation capacity. According to the Department of Energy standards for a small office
construction, an example of a U-value for fenestration of a small office construction in Los Angeles is
3.241 W/m
2
-K.
In order to determine the amount of solar radiation incident on the façade surface at each time of day
measured, one would simply multiply the dimensions of the façade (30 m) by the expected solar
radiation values at the time and the percentage of admitted solar radiation (1 – percentage of shading
provided by the component at that time) to get the value. An example of this calculation has been
provided below:
In Los Angeles at 12:00PM, the amount of solar radiation expected (according to the NREL TMY3
values) on the winter solstice is 691 W/m
2
. Across the 30 square meter façade, this would lead to
20730 watts of solar radiation. If a designer made the decision to use Element G1 as the enviro-
material shading component for this façade, she could expect a shading percentage of 56.90%
(meaning 43.10% of the façade would receive solar radiation) if the temperature were above 70
degrees, or 3.67% (which translates to 86.33% of the façade receiving solar radiation) if the
temperature were below 70 degrees. For a temperature above 70 degrees, this means that the facade
would receive 8934.63 watts of solar radiation incident on the surface and below 70 degrees, the
façade would receive 17896.21 watts of solar radiation.
691 watts/sq. meter * 30 m
2
* (1 - .569)
[solar radiation value] * [area of the façade] * [percentage of façade not shaded by the components]
Assuming a U-value of 3.241 Watts/m
2
-K, this would mean that
The accurate calculation of the solar heat gain requires the consideration of the effects of solar angular
and spectral dependence as well as complex glass types and the effects of the shading devices on the
admission of solar radiation. This is quite a complex task. (ASHRAE 2005). According to a study out
of Deakin University, Australia, this justifies the need for a standardized format of results based upon
solar angle of incidence as well as these other solar components (direct beam, diffuse and reflected
radiation). The problem lies, in the words of Luther, M.B. et al, with the “need for designers to have a
rigorous, yet simple-to-use tool” that allows them to asses a specific glazing system for a given climate
in a desired orientation over the course of the day (Luther, M.B. et al. 2014).
The solar heat gain coefficient is the fraction of solar radiation external to the façade system, that is
transmitted and admitted through inward flowing surface radiation and convection. The coefficient is
dependent on solar angle and varies according to the incident angle of the source (whether direct beam,
diffuse, or the reflected component of solar radiation). The WINDOW 6.0 program developed by the
Lawrence Berkeley National Laboratory (LBNL) is used to provide the SHGC values for a wide range
of glazing systems.
120
Chapter Summary
The determination of the amount of energy saved by enviro-material shading components is
dependent on a confluence of factors—the complexity of which would render specific calculations
almost inapplicable to other cases. It is for this reason, that surface irradiance was used as the metric by
which shading components were evaluated. In future studies, it may be possible to more accurately
model the incident solar irradiance and consequently, the direct solar gain to a space given the latitude
and longitude of the site, incident solar angles at specific times, and amount of diffuse radiation that
the façade receives. However, because the purpose of this study was to evaluate the relationship
between the temperature-dependent nature of the enviro-material components and their geometries on
their ability to reduce unwanted solar heat gain (and perhaps as a result, the use of the mechanical air
conditioning systems within a small office space), a priority was placed on the amount of surface
irradiance allowed to reach the façade on which they were mounted. The effectiveness of each shading
element is therefore inextricably linked to the climate, location (altitude, latitude, longitude), and time
of day in which the components are activated.
121
Chapter 6: Conclusions
6.1 Chapter Overview
Through the simulations and models tested through this thesis, one can conclude with reasonable
confidence that due to the ability of the enviro-material panels to respond to the temperature of a
given climate location, they are able to exhibit more thermally effective performance and can lend
themselves to a significant reduction of the cooling load of a building in a variety of climate zones.
Most geometries had a clear bent to their performance in the hot tilt and in the cold tilt. Higher levels
of shading in the hot tilt usually resulted in less solar radiation being admitted in the cold tilt.
Specifically, the tests have revealed that shading components are most effective at blocking solar
radiation when they have a shape for the lateral wings that maximizes the width in the y-direction at
the outer edge. Components with this shape typically block more solar radiation in their cold tilt as
well, thereby preventing the admission of high levels of solar radiation to warm up the interior space.
For admitting solar radiation, geometries that have a small y-distance from the peak to the bottom of
the attachment notch tend to result in more effective performance.
There were not many geometries that were able to achieve a balance between admission of solar
irradiance in the colder temperatures and prevention of solar direct gain in warmer temperatures, but
elements A1, T1, and F2 appeared to be rather effective based on the results in Chapter 4 above.
A1
T1
F2
Figure 6-1: View of single components, A1, T1, and F2
These components represent the average performance of the fifteen components—with none
providing the most or least shading in the hot or cold tilt configuration for the times of the year
measured.
122
Where a static building envelope provides the ability to control indoor environments, for the benefit of
health and comfort or its occupants, the adaptive, responsive, and predictive abilities that enviro-
material actuation could provide would significantly improve a building’s ability to control energy use
and reduce environmental stress, enhancing the structure’s ability to maintain a steady state for
comfort and occupant health.
6.2 Modifications to the Study
Increasing the efficiency of enviro-materially active façade systems allows buildings to more effectively
participate in the reduction of energy usage to maintain thermal comfort. Enviro-material actuation
eliminates the need for external energy input into the system to maintain a level of thermal comfort
and uses the natural response of the material as the driver for kinetic response. It can also allow for the
reduction of UV coatings and consequently allow a greater range of color spectrum for the viewer.
This system also retains visibility at all times unlike standard blinds.
Another factor to be explored further is the impact of material choice for thermally active façade
systems on the absorption of heat gain into the building’s interior. Developing a kinetic façade
assembly with a higher level of emissivity on the outward facing surface may be more effective at re-
radiating absorbed heat, thereby decreasing the amount of energy that would contribute to cooling
loads in hot-humid and hot-arid climates during the summer. Temperate climates would likely benefit
from this material choice during the summer months as well.
This study only evaluated the performance of the panels on a south-facing façade, and thus leaves the
north, northwest, east, etc. (all other orientations) to be examined for future studies. It would be
interesting to understand how the orientation of the façade would affect the design of the panels and
the need for particular shapes to maximize or minimize shading for each orientation in different
climate zones.
Changing the size of the components is another subject for future study—perhaps creating larger
components to provide shading would improve shading abilities—but one would also need to consider
how the size of the components affects its curling abilities—whether or not a more or less intense curl
would result from particular sizes could be calculated from the formula provided in Chapter 2 above.
When taking into consideration the amount of glare or other visual disturbance would result from
certain tilt angles, it is also important to consider the amount of heat that would be re-radiated to the
façade behind the shading array due to conduction. The amount of glare might also be affected by the
application of color to the units.
An interesting application of this work would be to estimate how much energy each geometry could
save for building—Shading percentages could be mapped to a window schedule in an energy modeling
software such as IES-VE and based on the standard equipment, R-values and U-values specific to their
project, one could easily begin to estimate energy savings for their particular building and office
schedule.
123
Another interesting application for future study is the programming of these panels to tilt in such a
way that they would provide predictive or preemptive heating and cooling of the building for the
office schedule in question. For example, if an office was expected to be occupied at 8AM, in a hot arid
climate, how might a designer want to program a building such that the building could be kept cool
for the longest amount of time possible. Perhaps the elements could be set to tilt in such a way that at
certain temperatures, they pre-emptively closed even while cool in anticipation of the warmer
temperatures to come. Fortunately, it is possible to control the temperature at which the shading
components flip given that the temperatures are specified before manufacture. In colder regions, it
is possible to trigger the flip at lower temperatures and in hotter regions, trigger a flip at higher
temperatures.
Another factor that was ignored for the purpose of simplicity in this study was the amount of heat that
the components would absorb throughout the day and transmit through radiant heating to the façade
behind. The material on which they were situated would also play a role in how much absorbed heat
was reradiated to the façade behind. The distance of the components from the wall would indirectly
play a role in how much convection would allow for the prevention of unwanted reradiated heat from
the metals panels to the façade, as this distance would directly influence the amount of air that
circulates between the shading elements and the façade behind, thereby cooling down the surface of
the elements and decreasing the amount of heat that would be reradiated to the façade surface.
A set distance was determined by Professor Sung and her team, but it might be worthwhile to pursue
further investigation of this distance to determine the optimal range to allow for adequate shading and
prevention of unwanted radiated heat gain.
For the scope of this research, the performance of the components was tested only on a south-facing
façade at three different points in a day 8:00AM, 12:00PM, and 3:00PM. In future studies, it will be
important to study the performance of the components on facades of other orientations (particularly
southwest and west-facing as these directions receive more severe levels of solar radiation at later points
in the day (between 3:00pm and 5:00PM). It is also important to determine how much energy savings
can be projected to receive for these other orientations and the temperature dependence of the enviro-
material shading components can contribute to the effectiveness of the system.
The results of this experiment seem to indicate that the geometries that have larger wings on the lateral
sides (larger lateral components) seem to result in better shading performance on the summer solstice.
Designers of future experiments may choose to apply this observation to the design of new
components which take this into consideration.
Another consideration in designing these enviro-material geometries is the optimization of visual
transmittance. Panels should be designed such that shading can be achieved, but view should not be
completely obstructed during this time. As such, it may be useful to experiment with different tilt
angles for the hot tilt and exploring what angles are beneficial for the trade-off between view and
thermal protection of the facade behind.
124
Another point for future study is heat gain from conduction and heat loss from convection in the
design of these shading components. For the sake of simplicity, these factors were not considered in
this evaluation, but will certainly play an important role in maximizing the amount of energy saved the
amount of heat that will be reradiated to the façade
Given the current global warming trends, it may be possible that temperatures in colder climates such
as Cambridge, Massachusetts may eventually exceed 70F, but it will be many years before this kind of
change becomes evident. Even in those cases, because of their temperature-dependent responses, these
enviro-material facades will adapt to the change and assist in bringing interior temperatures to levels of
thermal comfort.
This experiment was only concerned with the behavior of the petals during daylight hours and
therefore ignored component behavior when the sun was not up or when the wall became self-shading
which occurred after 3:30pm in the summer azimuths.
6.3 Limitations of the Study
As was addressed in the study conducted by Omidfar in Chapter 2, one of the limitations of this study
include the limitation of the software to model dynamic/adaptive systems. Working around this by
studying the movement of the panels has a set of discrete positions (studying the end-point behaviors)
will reveal the capabilities of each geometry in the most extreme cases.
Building a case for this dynamic system does not classify as an intelligent system and functions better
than the static case which only responds to sunlight and not temperature.
ARUP has recently partnered with Integrated Environmental Solutions (IES) and Argos Analytics to
develop an online tool called WeatherShift which generates predicted future climate weather data
based on climate simulations. Improving the climate predictions for sites can allow for more accurate
simulations of these enviro-materially actuated facades and can give more accurate understanding of
the percentage of time for which they would assume a certain configuration (hot tilt vs cold tilt) as well
as the amount of solar radiation that would be blocked at particular times of the year. These
predictions are based on the Intergovernmental Panel on Climate Change Fifth Assessment Report
IPCC AR5) and are publicly accessible at www.weathershift.com.
6.4 Chapter Summary
The results of this experiment seem to indicate that the hypothesis stated earlier is in fact correct: the
temperature dependent behavior of these components lends itself to more effective temperature
moderation of the indoor environment, as the shading components are able to respond to higher
temperatures with a reduction in solar radiation being admitted through the façade which is not
possible with static components.
125
Varying the shapes of the elements in this study revealed that components with a greater width in the
y-direction can block a large amount of solar radiant heat gain while in their Hot Tilt configuration,
especially for the summer solstice. Across all cities tested, Phoenix, Arizona, Los Angeles, California
and Cambridge, Massachusetts, the amount of shading that could be achieved by each component was
above 98% with rather insignificant differences between the geometries. The most appreciable
differences occurred during the winter solstice for each city and during the autumn and spring
equinoxes.
According to Climate Consultant, in Cambridge, Massachusetts, a city that experiences very harsh
winters, the admission of solar radiant heat gain can only make up for about 11% of thermal comfort.
This is also dependent on factors such as the mass of the construction (whether it is low mass or high
mass) the rating of the insulation, the orientation of the building, window-to-wall ratio of the
fenestration and the program of the building. It is possible that the combination of internal heat gain
from lights and appliances, the room for adjustment of clo units of the occupants and other factors
could allow for further increase of the effectiveness of solar direct gain alone on improve wintertime
thermal comfort levels for occupants, but because these are highly dependent on variables that were
not considered within the study no conclusion will be drawn about these matters.
In climates such as Los Angeles or Phoenix where components would take on Hot Tilt in the
wintertime due to the relatively high temperatures that the locations experience, the Hot Tilt behavior
of the components becomes very important in assessing which geometries suit the building's needs
better. A building that is situated in a location where winter temperatures are above 70 degrees may
place less importance on Cold Tilt behaviors and allowing heat gain to penetrate the façade, than on
blocking heat. This would certainly be the case for Phoenix, Arizona.
The most significant opportunities for these enviro-material components to show their effectiveness,
however, is spring and autumn equinoxes when temperatures are more highly variable and less extreme,
there is greater potential for energy savings. During these times, because the components are allowed
to freely adjust their configuration to block or allow solar direct gain as needed they almost certainly
out-perform static shading components which are effectively obsolete during these times because of
their dependence on the position of the sun.
Ultimately it is the decision of the designer to determine which panels work best for their purposes.
According to the results of this study, it is possible to determine which set of elements blocks more
solar radiation in hot temperatures and allows more solar radiant heat gain in colder temperatures by
employing a comparative sequence such as demonstrated above. It is important to note, that for proper
convective cooling of the enviro-material component array to occur, it should be placed further from
the façade it is screening. A minimum distance of four inches should be employed for experimentation
Through future studies with further experimentation on shading capabilities of different geometries,
varying the times during which shading is tested (both seasonally and number of hours over which the
components are tested), additional evidence can be gathered about how the geometry of an enviro-
material components such as these can affect both its shading potential and ability to reduce energy
usage or loads on mechanical ventilations systems.
126
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Appendix A: Description of Elements
C2
:
C2 Plan View
130
C2 Side Elevation View
C2 Axonometric View
131
D1
D1 Plan View
132
D1 Side Elevation View
D1 Axonometric View
133
D2
D2 Plan View
134
D2 Side Elevation View
D2 Axonometric View
135
E1
E1 Plan View
136
E1 Side Elevation View
E1 Axonometric View
137
F1
F1 Plan View
138
F1 Side Elevation View
139
F1 Axonometric View
F2
140
F2 Plan View
F2 Side Elevation View
141
F2 Axonometric View
G1
142
G1 Plan View
G1 Side Elevation View
143
G1 Axonometric View
T1
144
T1 Plan View
T1 Side Elevation View
145
T1 Axonometric View
T2
146
T2 Plan View
T2 Side Elevation View
147
T2 Axonometric View
T3
148
T3 Plan View
T3 Side Elevation View
149
T3 Axonometric View
T4
150
T4 Plan View
T4 Side Elevation View
151
:
T4 Axonometric View
Abstract (if available)
Abstract
Shading devices are perhaps the single most important energy saving component in passively cooled buildings. If a building is arranged so that the intense rays of the sun are intercepted before they pass through transparent envelope elements, the cooling load can often be halved (Grondzik and Kwok 2014). However, many of the shading devices used in buildings today are static, which can prove counter-productive to maintaining indoor thermal comfort levels during the less extreme points of the year (i.e. spring and fall). Given the emergence of unique material technologies, it may be possible to utilize environmentally responsive, or enviro-materially actuated materials to develop more thermally appropriate shading devices for the built environment. This thesis focuses on the early stage of design of these dynamic façade components—simulating and evaluating the effectiveness of the enviro-material shading components in three climate zones. Using currently available modeling and simulation software, the potential for thermo-bimetals—sheets of two metal alloys that convert temperature change into mechanical displacement—to serve as dynamic shading devices for building facades was investigated. ❧ A morphology of fifteen components was developed from a single geometry provided by Professor Doris Sung, the pioneer of this technology, at the University of Southern California. Components were designed to adopt two discrete configurations: a “hot tilt,” which blocks solar exposure of the facade, preventing excessive heat gain in warmer temperatures, and a “cold tilt” which admits solar rays for cooler temperatures, taking advantage of the curling behavior of the thermo-bimetal. That the components can shift between these two tilts as is appropriate for maintaining thermal comfort for the interior environment makes a case for the powerful energy-saving implications of incorporating dynamism of building components into façade design.
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Jambo, Amina Saleh Amanda
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Core Title
The effectiveness of enviro-materially actuated kinetic facades: evaluating the thermal performance of thermo-bimetal shading component geometries
School
School of Architecture
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Master of Building Science
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Building Science
Publication Date
11/20/2017
Defense Date
04/28/2017
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