An Introduction To The Design And Application Of Double Skin Facades In North American High-Rise Architecture.

An introduction to the design and application of double skin
facades in North American high-rise architecture.
A Dissertation Submitted in Partial Fulfillment of the Requirements for the
Bachelor of Science (Honours) in Architectural Technology
Department of Architecture, Faculty of Engineering
Cork Institute of Technology
Research conducted by
Benjamin Brown
Submitted on
May 5th, 2016

Abstract
The widespread popularity of highly glazed commercial buildings seems to run with the
same intensity as ‘green’ architecture, or that of the demand for buildings to adopt high standards
of environmental responsibility as a result of improved energy efficiency. As these structures
become increasingly complex in response to the architect’s design intent, client requirements, and
new building legislation, the need for incorporating advanced technologies also continues to grow.
Integration of the double skin facade is not new, however the protective, acoustic, and
thermal performance realized by this technology have initiated a developing interest and a
multitude of new applications. This twin-skin school of thought challenges the way modern
buildings are designed through the construction of a second protective layer, thereby introducing a
‘buffer space’ to mitigate the surrounding environmental conditions. Curiously though, the use of
double skin facades in North America is few and far between.
The intent of this report is to introduce the design principles and function of the double skin
facade in order to investigate why its use has not been widely adopted in North America in
comparison to Europe. Design barriers associated with this system are observed through the case
studies of Canadian and American projects and reinforced by industry commentary. A critical
analysis is further conducted to highlight these barriers, in order to drive a growing discussion on
their application in North American high-rise architecture.

Acknowledgements
This research process has been a challenging, yet always exciting adventure into new ideas
and personal learning experiences. The past few months would not have been nearly as easy (or as
productive) without the unbelievable help of the following people:
Anthony McCauley from Arup in Dublin for taking the time out of his busy schedule to sit down
with me and share his experience,
Pratik Raval from Transsolar in New York for enlightening me on the challenges of North
American double skin design,
My impeccable proofreaders: Gabrielle Bossy, Leanna Lalonde, and Jessica Klunder for their
incredible patience and thorough work,
All those who participated in the industry commentary: your expert opinions were very much
appreciated,
The AT4 Class of 2016, for their constant encouragement and comradery,
and finally,
My parents for their unconditional support from across the Atlantic; this is for you.
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Contents
Abstract i
Acknowledgements ii
Contents iii
List of Figures v
List of Plates vi
Chapter 1: Introduction 1
1.1 Introduction 1
..............................................................................................................................
1.2 Rationale 3
...................................................................................................................................
1.3 Hypothesis 3
................................................................................................................................
1.4 Methodology 4
.............................................................................................................................
1.5 Keywords 4
..................................................................................................................................
Chapter 2: Design Principals & Components 6
2.1 Introduction 6
..............................................................................................................................
2.2 Ventilation Types and Methods 6
................................................................................................
2.3 Protective Skins 8
........................................................................................................................
2.4 Air Cavity Characteristics 9
........................................................................................................
2.5 Solar Shading Devices 10
............................................................................................................
2.6 In Summary 11
............................................................................................................................
Chapter 3: Configurations & Typologies 12
3.1 Introduction 12
............................................................................................................................
3.2 Facade Partitioning 13
.................................................................................................................
3.3 Box Facade 14
.............................................................................................................................
3.4 Shaft-Box Facade 16
...................................................................................................................
3.5 Corridor Facade 18
......................................................................................................................
3.5 Multi-Storey Facade 20
...............................................................................................................
Chapter 4: North American Precedent Studies 22
4.1 Introduction 22
............................................................................................................................
4.2 Overview of North American Climate 23
...................................................................................
4.3 One Niagara Welcome Center 24
................................................................................................
4.4 Seattle Justice Center 27
..............................................................................................................
4.6 Manitoba Hydro Place 29
............................................................................................................
4.6 Riverhouse, One Rockefeller Park 32
.........................................................................................
Chapter 5: North American Challenges 34
5.1 Industry Comments 34
................................................................................................................
5.2 Initial and Required Costs 34
......................................................................................................
5.3 Building Legislation 35
...............................................................................................................
5.4 Performance Data 35
...................................................................................................................
5.5 Client: Developer or Owner 36
...................................................................................................
5.6 Other Compact Solutions 36
.......................................................................................................
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5.7 North American Energy Costs 36
................................................................................................
5.8 In Summary 37
............................................................................................................................
Chapter 6: Conclusions 38
6.1 In Summary 38
............................................................................................................................
6.2 Recommendations for Further Research 38
................................................................................
6.3 Conclusion 39
..............................................................................................................................
Appendix A - Industry Comments 40
Appendix B - Graphs 44
Appendix C - Sketches & Drawings 47
Bibliography 53
Books 53
............................................................................................................................................
Online Journals and Theses 53
..........................................................................................................
Conference Presentations 55
.............................................................................................................
Government Agency Reports 56
.......................................................................................................
Figure Sources 57
..............................................................................................................................
Plate Sources 58
................................................................................................................................
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List of Figures
Figure 2.1 Ventilation methods of a double skin facade.......................................................... 7
Figure 2.2 Location and angle of shading devices in relation to the skins.............................. 11
Figure 3.1 Double skin system classification chart.................................................................. 12
Figure 3.2 Double skin facade partitioning............................................................................. 13
Figure 3.3 Box facade configuration........................................................................................ 14
Figure 3.4 Shaft-box facade configuration............................................................................... 16
Figure 3.5 Corridor facade configuration................................................................................ 18
Figure 3.6 Multi-storey facade configuration............................................................................ 20
Figure 4.1 Location of major double skin facade projects built in North America
(1980-2016)............................................................................................................ 22
Figure 4.2 North America Climate Zones by range of average temperature........................... 23
Figure 4.3 The Occidental Chemical Building double skin..................................................... 24
Figure 4.4 Natural airflows through Manitoba Hydro Place.................................................. 30
Figure 4.5 Airflow through double skin and office space - Manitoba Hydro Place................ 31
Figure 4.6 Riverhouse box facade double skin........................................................................ 33
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List of Plates
Plate 1.1 Close up of the computerized facade on the Al Bahr Towers in Abu Dhabi.......... 2
Plate 1.2 The Al Bahr Towers in Abu Dhabi......................................................................... 2
Plate 4.1 The Occidental Chemical Building West facade.................................................... 24
Plate 4.2 The Occidental Chemical Building South-East corner with pedestrian bridge.... 24
Plate 4.3 The Occidental Chemical Building interstitial space upon completion................ 25
Plate 4.4 The Occidental Chemical Building interstitial space during a site visit in 2006.. 25
Plate 4.5 Seattle Justice Center from the South-West............................................................ 27
Plate 4.6 Seattle Justice Center - Double skin interstitial space........................................... 27
Plate 4.7 Seattle Justice Center - Interior corridor............................................................... 28
Plate 4.8 Manitoba Hydro Place Main facade on Portage Avenue...................................... 29
Plate 4.9 Operable louvers on double skin facade - Manitoba Hydro Place........................ 31
Plate 4.10 Riverhouse at Rockefeller Park from the West....................................................... 32
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Chapter 1: Introduction
1.1 Introduction
A Skin by definition is:
“An outer layer or covering.”
(Oxford English Dictionary, 2015)
Humans have a skin, the Earth has a skin, and buildings too have a skin. It protects the
internal organs, allowing them to function. It regulates and controls temperature and the passage
of moisture. It comes as no surprise then, that the skin has a very important job to perform, and
without properly functioning the internal elements would fail to work.
Before the industrial revolution buildings relied heavily on the external envelope to regulate
the internal environment. It would carefully allow moisture to pass, allow the building to breathe,
and control temperature variations from the outside climate. However, with the introduction of
mechanical heating, ventilation and air-conditioning (HVAC), the role of the skin changed.
Designers paid more attention to reducing air permeability and super insulating walls thereby
allowing mechanical systems to run as efficiently as possible. This increased the reliance of indoor
air quality on the building’s mechanical systems, requiring consistent upkeep and maintenance to
work properly. Subsequently, with the addition of extra maintenance costs and swelling energy
prices (partially to blame from the 1973 oil crisis), buildings ended up becoming incredibly
expensive investments.
In her article Facade Engineering Sara Hart claims:
“The evolution of the building envelope from static wrapper to a complex, active
building system have been partly motivated by the economics of
energy consumption and the promise of sustainability.”
(Hart, 2002)
Agreeably, emphasis of the past four decades has shifted from HVAC efficiency to the
envelope: the skin. The focus now looks to construct buildings that lower their reliance on
mechanical systems by taking advantage of passive design.
One such system gaining momentum is the double skin facade, which is just that: a doubling
of the building facade. First introduced to North America in 1980 in the form of the Occidental
Chemical Building in Niagara Falls, New York, the extra layer introduces a protective air buffer
between the internal conditioned environment and external climate (Enclos Corp., 2016). As
defined by the Belgian Building Research Institute a double skin facade is:
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“ A facade covering one or several storeys constructed with multiple glazed skins. The skins
can be air tight or not. In this kind of facade, the air cavity situated between the
skins is naturally or mechanically ventilated. The air cavity ventilation
strategy may vary with time. Devices and systems are generally integrated in
order to improve the indoor climate with active or passive techniques.”
(Belgian Building Research Institute, 2002)
Doubling the facade indirectly permits designers to meet building regulations that limit the
maximum amount of glazing, by protecting shading devices. Typically these elements would be
mounted to the exterior, blocking the sun to the interior, resulting in an allowance for more
glazing. The devices however, are still exposed to the elements and would eventually require
maintenance. By protecting these elements with a second facade, their lifespan can be lengthen or
at least allow for easier replacement. The second facade will also conform to popular aesthetic
styles of highly glazed ‘modern’ architecture. The air space introduced between the skins can
utilize a maintenance walkway, resulting in the aforementioned cleaning and upkeep, an easily
overlooked but crucial aspect of high-performing buildings.
Performance-based configurations of the double skin facade have emerged, permitting its
use in a variety of environments; from blazing hot desert sun, to driving rain and high-pressure
winds. In warm-weather conditions such as Abu Dhabi the second skin is typically designed as a
highly ventilated sun-shading system (Plate 1.1 and 1.2) in an effort reduce internal solar gain,
thereby decreasing the required cooling load from mechanical units (Boake, 2014). In cold and
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Plate 1.1: Close up of the solar-adaptive facade on the Al Bahr Towers in
the blazing desert sun of Abu Dhabi (Laylin, 2014).
Plate 1.2: Al Bahr Towers in
Abu Dhabi (Laylin, 2014).

temperate climates the system is designed using a highly glazed outer skin, maximizing solar
exposure in order to warm the interstitial air. In both cases, increasing day lighting and outward
views continue to be of high importance.
The biggest challenge for designers occurs when climatic conditions range from hot
summers to cold winters, where the performance objectives vary largely throughout the year.
North America is one such climatic region where these challenges are present and is the location
that this paper is focused.
1.2 Rationale
A preliminary look into the interesting concept of double skin design yields a sparse amount
of discussion, and even less hard data regarding real-world performance. Interestingly, the
majority of information appears from European sources, with repeating case study buildings.
Germany and Austria have shown to be leading the industry with many of their high-rise office
towers acting as the mentioned case studies.
Initial research made it obvious that the adoption of double skin facades is far less prevalent
in Canadian and the United States than in Europe. The minimal information that has been
published merely describes design principles, but fails to put forth any post-occupancy
performance data of double skins. Most of these were published in the early 2000s with very little
new reports following suit. The common consensus of these reports, conferences, and publications
seemed to agree double skins in North America are brushed under the metaphoric design table
mostly due to the extra cost of materials versus a traditional curtain wall (Enclos Corp. 2016).
Additionally, in their conference presentation Emerging applications and trends of double-skin
facades Vagilo et al. (2010) state current (North American) building regulations lack the stringent
requirements such as access to daylight and fresh air in office environments seen in many
European building standards.
Continuing from where these industry reports have left off, this research attempts to analyze
comments such that a discussion may emerge to a point where double skin facades can be a highly
viable environmental design option in North America.
1.3 Hypothesis
The intent of this research is to gain an understanding of the design principles and function
of highly glazed double skin facades, in order to investigate why they are not as prevalent in
Canada and the United States as they are in Europe. Decisions associated with the use of each
configuration are supported by case study North American buildings and reinforced by
observations from industry professionals.
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1.4 Methodology
In an effort to answer the research hypothesis, the following aims have been identified:
• Discuss the individual components of double skin systems through
their physical attributes and effect on the system as a whole,
• Outline the various configurations of the components and for what
application they are most suited,
• Explore the uses of a double skin facade in the North American
context, the designer’s goals and intended results,
• Conduct an investigation of industry professionals to reveal a
possible conclusion to the hypothesis,
• Critically analyze a possible rationale as to why double skin facades
are not as prevalent in North America as they are in Europe.
Given the desired aims, the following chapter objectives have been composed to carry out
the research:
• Chapter 2 and 3 will gather information by means of architectural
papers and science journals, highlighting the system components and
building science behind them.
• Chapter 4 then critiques the current uses of double facades in North
America, through case study buildings.
• Finally, Chapter 5 will deconstruct investigation responses in an effort
to focus on the specific challenges of adopting double skin facades in
North America.
1.5 Keywords
During the course of this research, it was observed that a number of different names were
used for this topic. In general they include:
• Double Skin Facade/System
• Double Facade
• Double Skin Curtain Wall
• Twin Skin Facade/System
• Buffer Facade
• Multi-Skin Facade
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• Second Skin Facade/System
• Active Facade (typically defined when mechanical ventilation is used)
• Passive Facade (typically defined when natural ventilation is used)
• Ventilated Overclad Facade (defined in retrofit projects)
For the simplicity of the research the term Double Skin Facade will be used to refer to the
topic throughout this report.
One thing is for certain: the application and technology behind a double skin system are full
of opportunity to incorporate performance objectives with aesthetic appeal, satisfying the
architect’s ambition, client requirements, and building legislation. Curiously though, the use of
double skin facades in Canada and the United States are few and far between. With that in mind,
the purpose of this paper is to gain an understanding of the design principles and function of a
double skin facade. An evaluation from industry professional is then initiated in order to
investigate why they are not as prevalent in North America as they are in Europe.
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Chapter 2: Design Principals & Components
2.1 Introduction
As in all building construction, basic components are connected to create a larger, more
complex system. To do so effectively requires the knowledge of how each component functions,
such that they compliment each other as a whole.
This chapter aims to thoroughly disassemble the primary components required in double
skin design. Chapter 3 will build on these principles by discussing their various configurations in
establishing each typology.
2.2 Ventilation Types and Methods
The first requirement in double skin design is to determine the desired type and method of
ventilation early on in the project. This decision helps guide the design process of the protective
skins, air cavity geometry and solar shading devices, all of which are crucial for an effective
system.
2.2.1 Type of Ventilation
The types of building ventilation are divided in to 3 main categories:
• Natural Ventilation - Solely the responsibility of thermal buoyancy and
naturally occurring wind patterns to cool the building and ventilate.
• Mechanical Ventilation - Traditionally the most common method of ventilation
requiring mechanical units, a form of energy and regular maintenance.
• Mixed-Mode Ventilation - A hybrid ventilation approach relying on a
combination of both natural and mechanical systems.
Since a natural ventilation strategy is designed without mechanical support, and a
mechanical ventilation strategy relies solely on powered units, a double skin system can be
characterized only by a single ventilation type. If both natural and mechanical systems are
integrated, the system is categorized as mixed-mode. This is an important distinction to be
understood early in the design.
2.2.2 Method of Ventilation
Once the ventilation strategy has been decided, the next step in the design process is to
choose a method of ventilation. Dependent on a number of factors that include thermal, acoustical,
fire, and maintenance requirements, the ventilation method begins to shape the final facade
structure.
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There are 4 main methods of ventilation in a double skin system:
Figure 2.1: Ventilation methods of a double skin facade (Brown, 2016).
Outdoor Air Curtain - Outdoor air infiltrates the cavity and is immediately exhausted through a
different opening. In a traditional outdoor air curtain, cool air is brought in through the bottom of
the flue, utilizes thermal buoyancy and is exhausted through the top, typically located at the front
or back of the parapet. In this method a curtain of air engulfs the external skin, therefore thermal
protection is located on the inner skin. This method does not directly allow air to supply or mix
with the building’s mechanical systems.
Indoor Air Curtain - The reverse of the outdoor air curtain; indoor air infiltrates the cavity before
returning back into the room. In a hybrid ventilation system, a heat recovery unit can utilize the
returning warm air. Typically, operable windows are designed within the inner skin, at the floor
and ceiling level. In this method the curtain of air blankets the inner skin, therefore thermal
protection is located on the external skin. This method also does not directly allow outside air to
supply or mix with the building’s mechanical systems.
Twin-Faced - Ventilation openings are located on both outer and inner skins allowing for the
versatility of both air supply and exhaust to the building. Traditionally the thermal protection is
located on the inner skin.
Air Supply - Ventilation openings are located lower on the outer skin and higher on the
inner skin, allowing cool air to enter the cavity, rise, and enter the building.
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Air Exhaust - Similarly; openings are located higher on the outer and inner skin, allowing
warm internal air to exhaust through the cavity.
Buffer Zone - Both skins are sealed, therefore creating a buffer zone of air between the inside and
outside. This method does not support ventilation, but rather improves thermal performance,
protects internal shading devices, and can be unitized allowing for greater manufacturing quality
and construction speed. For all intents and purposes the twin-faced method can also take on the
properties of a buffer zone if all openings are closed, i.e., in the winter.
2.3 Protective Skins
The basic design of the double facade utilizes two skins separated by an air space. The skins
act as the boundary layers for the air to enter, ventilate, and eventually exhaust. In terms of
materials used, Arons and Glicksman (2001), define the skins simply as “two planar elements that
allow interior or exterior air to move through the system.” More specifically, Terri Boake (2003)
notes the use of “a pair of glass ‘skins’ separated by an air corridor.” While this research focuses
on highly glazed double skin facades, it has been noted that glass is just one of many materials
that can be used.
2.3.1 Materials and Construction
In the extreme climate conditions of North America where this research is focused, the
external layer is typically designed using a single glazed system, tempered or toughened to
withstand wind loading especially in high-rise construction (Lee at al. 2002). The external skin
can be supported in a number of ways depending on the building construction. Individual panels
can be tied back to the internal skin in a stick-framed or unitized fashion, or hung from upper
levels or ground supported as an independent system. Internal layers are interfaced with the
building structure, and subsequently its occupants, therefore choice of frame and finish may vary
to that of the external skin. This layer is similar to a traditional curtain wall system, double or
triple glazed for thermal performance, stick framed or unitized for faster construction, and
connected directly to the building structure.
2.3.2 Thermal Layer
In an effort to maximize building performance, careful consideration is taken when
choosing where the thermal protection is located. Most commonly a single glazed layer will act as
the exterior skin, such as in the outdoor air curtain. If the indoor air curtain is designed, the skins
and therefore their thermal protection are reversed. This arrangement allows warm internal air to
exhaust into the air cavity, but prevents excessive heat losses through the exterior skin.
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In addition, glazing properties can be enhanced to fit the building’s performance
requirement through solar control coatings and . Conventional curtain wall additives for glass
enhancements are not new, though improvements are in constant development.
2.4 Air Cavity Characteristics
It would make sense that the structure of a double skin facade is the most important
component, however one might be surprised to know the air cavity plays just as crucial a role. The
naturally ventilated double skin system relies heavily on the phenomenon of thermal buoyancy as
its principal method of air movement. When cool air becomes trapped between the two skins,
solar radiation increases its temperature, allowing it to rise through the facade. As the warm air
rises, cooler air rushes in to fill the space, and the process repeats (Baker, 2013). Through this
cycle a very efficient method of natural ventilation emerges.
2.4.1 Tuning Thermal Buoyancy
Designers fine-tune the parameters of thermal buoyancy by modifying the cavity geometry
between internal and external skins. The cavity dimensions will depend on the ventilation function
of each typology; when higher amounts of airflow are required, a larger cavity in both height and
width is used, whereas smaller, restrictive cavities reduce the flow of air, limiting ventilation. This
is an important consideration when employed in high-rise construction, as taller cavity volumes
will increase internal airflow, thereby amplifying the pressure on glazing elements. Thus, narrower
or height-restrictive cavities such as the corridor facade are recommended in these scenarios.
Chapter 3 further discusses partitioning of the air cavity with regard to typologies.
2.4.2 Cavity Geometry
Conventionally, air cavities range from 100 to 300 millimeters or up to 2000 millimeters in
depth where maintenance walkways or internal shading devices are used, with a height between 1
and 3 floors (BBRI 2002). It should be noted however, according to a study by Oesterle et al.
(2001) when a cavity of less than 400 millimeters in width also houses shading devices, internal
airflow will experience significant pressure loss and therefore decrease the effectiveness of natural
ventilation. The study also found cavities designed wider than 400 millimeters do not introduce
any significant airflow resistance.
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2.5 Solar Shading Devices
Included in the shift toward passive environmental strategies are solar gains and day
lighting. When designed properly, buildings can maximize solar exposure for space heating and
natural light. Within a double skin facade, the sun acts as the catalyst for the thermal buoyancy
process. Therefore special attention is required in the design of shading devices. Within a double
facade system, shading devices play important roles in:
• Protecting the building interior from direct solar radiation in the summer months,
• Reducing solar gains, leading to a reduction in overall cooling load on mechanical
systems that further reduce the building’s overall energy requirement.
• Allowing adequate day lighting while reducing glare,
• Allowing thermal buoyancy to occur without restricting airflow.
The application and design of shading devices is vast, involving proper angular calculations,
appropriate finishes to reduce glare or increase reflectivity, and environmental protection. Due to
the scope of this research, their use as defined in this report is focused on the internal air cavity. As
previously mentioned, materials chosen for the skin layers are not always glazed. Some are
external shading devices themselves, where minimizing solar gain is the deciding factor for the
chosen system (Boake 2014).
According to Arup facade engineer Anthony McCauley, one of the main purposes of
designing a double skin, especially in the temperate climates of Europe, is to protect external
shading devices that would otherwise be exposed. The same reason is applicable in North
America. As it turns out, introducing a planar element in close proximity to these devices has
some interesting, though not always wanted, thermodynamic effects that should be carefully
reviewed. Both the location within the air cavity in relation to the skins, as well as the incident
angle of the devices have been shown to have a direct effect on airflow caused by thermal
buoyancy. Figure 2.x depicts some of these basic parameters of solar shading within the cavity.
2.5.1 Location Between Skins
According to the study titled The most efficient position of shading devices in a double-skin
facade by Gratia and De Herde (2007), blinds placed near either glazed layer caused an increase in
temperature on the glazing surface, resulting in heat loss to the outside and heat gain to the inside.
The study tested cavity blinds in 3 location configurations (Figure 2.x):
• Against the windows of the inner skin,
• Against the windows of the outer skin, and
• Placed in the middle of the cavity.
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Figure 2.2: Location and angle of shading devices in relation to the skins (Brown, 2016)
They found the best possible result of thermocirculation to be when a shading device was
placed centrally in the air cavity, where adequate ventilation was found to occur on either side of
the device.
2.5.2 Incident Angle
Similarly, Ji et al. (2007), and later Barbosa and Ip (2014), examined the influence of the
incident angle of shading devices on airflow turbulence using louvers tilted at 0°, 30°, 45°, 60°,
and 80°. Both studies found that louvers angled circa 80° enhanced the effect of thermal
buoyancy, and in the case of Ji et al., resulted in a 35% increase of natural ventilation within the
cavity. Agreeably, the closer a shading device is angled to vertical, the less it will obstruct the
vertical flow of air.
2.6 In Summary
It is key to appreciate how each component performs in relation to each other. Climatic
characteristics should be carefully studied so as to set the desired outcome before approaching the
design. Thermal designation in the location and type of glazing, shading device properties and
angles, ventilation strategies and goals, and air cavity geometry must be finely tuned with an
effective maintenance strategy for the system to thrive.
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Chapter 3: Conﬁgurations & Typologies
3.1 Introduction
As the Chapter 2 has shown, there are many variables to the many individual components of
the double skin system. It is no surprise then, that there is a multitude of construction
configurations available to meet the required parameters of the project.
Using this knowledge, Chapter 3 proceeds by discussing the various configurations to
establish each typology. The attributes associated with each configuration are a direct response to
the design goals laid out during the schematic design phase.
Due to the many variables in double skin design, it is not always easy to classify every
configuration. Each new building uses a mix of past applications for achieving the desired
performance. However, as organized in Figure 3.1, classification of these configurations can be
simplified based on 3 main criteria:
• Type of Ventilation - Natural, mechanical or mixed-mode ventilation.
• Method of Ventilation - Outdoor air curtain, indoor air curtain, twin
faced, or buffer zone.
• Facade partitioning - Cavity geometry defined by its extents, with a
direct effect on the method of ventilation.
Figure 3.1: Double skin system classification chart (Brown, 2016).
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3.2 Facade Partitioning
Once the design team has decided the type and method of ventilation, a decision on cavity
geometry must be made. As noted in Section 2.4, changes in the geometry of the cavity will
directly influence its airflow and therefore effectiveness of its environmental design goals. In their
book Double Skin Facades - Integrated Planning, Oesterle et al. (2001) propose a clear method of
classifying a double skin; by the structure, or cavity partitioning. Rather than confusing an already
complex thermodynamic system, their method simplifies the categorization to 4 main types
(Figure 3.2), and is currently the most widely accepted method by the industry. They are:
• Box Facade
• Shaft-Box Facade
• Corridor Facade
• Multi-Storey Facade
Figure 3.2: Double skin facade partitioning (Brown, 2016).
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3.3 Box Facade
Figure 3.3: Box facade configuration (Brown, 2016).
This configuration uses juxtaposed modules where horizontal and vertical frames govern air
cavity geometry. Horizontal cavity partitions are located at each floor level, and vertical cavity
partitions in plan at a room-by-room or individual window element basis (Barbosa and Ip, 2014).
Both inner and outer skins can be designed with or without fixed or operable openings to take
advantage of an air buffer zone in colder environments and natural ventilation in warmer
environments. This configuration is best suited in high-rise construction where the building is
exposed to extreme environmental conditions, including wind and rain, and where there are
stringent acoustic and fire requirements. It also eliminates the risk of overheating since warm air
can only rise through one storey.
The box facade deconstructed in Figure 3.3 depicts the composition of an outer skin panel,
box partitioning, and inner skin. One “box” can easily be pre-fabricated as a unitized system,
allowing for greater quality control and speed of construction.
Benefits of the box facade according to the Master’s thesis Study of Current Structures in
Double-Skin Facades by Uuttu, S. (2001) are:
• Large reduction in sound transmission between rooms, floors, and from outside,
• Increased protection of interstitial shading devices,
• Interior spaces can utilize natural ventilation if configured in a twin-faced method. In this
method operable windows can also allow occupants to control their environment,
• Mechanical heat recovery can be applied in an indoor air curtain configuration,
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• Can be unitized for quality control and accelerated construction,
• Additional building security versus a traditional curtain wall facade.
Drawbacks of the box facade:
• If not a sealed air cavity (buffer zone), operable panels are required to the interior, limiting
the amount of usable (and rentable) interior floor space, or to the exterior, requiring an
external maintenance strategy,
• Natural ventilation caused by thermal buoyancy is limited to one storey due to cavity
geometry.
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3.4 Shaft-Box Facade
Figure 3.4: Shaft-box facade configuration (Brown, 2016).
The shaft-box configuration is a combination of a multi-storey thermal flue or shaft, and
adjacent box facade units. In this design, vents are located in the sides of the box compartment,
connecting it to the adjacent thermal flue. The vents are located higher in the cavity, incorporated
with the vertical partition. When air trapped within the flue experiences thermal buoyancy, it rises
and is replaced by air from the box compartment. Intake vents in the lower portions of the thermal
flue and box compartment replenish both air cavities as the process continues.
Similar to the box facade, vertical partitions of both the thermal flue and box compartment
can be located in plan at a room-by-room or individual window element basis (Schiefer et al.,
2008). The inner skin of the box compartment can be designed with or without operable openings
to take advantage of the natural ventilation. The inner skin of the thermal flue is typically not
designed with operable windows, as its purpose is to facilitate rising hot air, but access for
maintenance is still a concern.
This configuration is logical for natural ventilation and is best suited in low to mid-rise
construction, so as not to cause overheating in the upper levels of the thermal flue. However,
according to the comprehensive report BESTFACADE by Schiefer et al. (2008), if multiple shafts
are stacked vertically and divided by horizontal partitions every few floors, it can be a viable
option in high-rise construction. Unlike the box facade, the thermal flue creates an issue for
acoustic transmission and fire spread between floors.
!16

The shaft-box facade deconstructed in Figure 3.4 depicts the composition of a thermal flue
and box compartment, both constructed with an outer skin panel, air cavity partitioning, and inner
skin. Unitized box compartments can also be used in this configuration.
Benefits of the shaft-box facade according to Uuttu, S. (2001):
• Reduction in sound transmission between rooms, floors, and from outside,
• Can utilize natural ventilation through the box compartment if configured in a twin-faced
method. In this method operable windows can allow occupants to control their
environment,
• Mechanical heat recovery can be applied at the top of the thermal flue to further aid in
energy use reduction,
• Can be unitized for quality control and accelerated construction,
• Additional building security versus a traditional curtain wall facade.
Drawbacks of the shaft-box facade:
• If not a sealed air cavity (buffer zone), operable panels are required to the interior, limiting
the amount of usable (and rentable) interior floor space, or to the exterior, requiring an
external maintenance strategy,
• Thermal flue can create a fire-spread, and acoustic transmission concern.
!17

3.5 Corridor Facade
Figure 3.5: Corridor facade configuration (Brown, 2016).
The corridor configuration is much simpler to that of the box or shaft-box facade. In this
design, vents are located close to the floor, and ceiling of the outer skin, and staggered from bay to
bay so as to encourage separate intake and exhaust. Thermal buoyancy is not as strong in this
configuration as in the shaft-box due to the limited vertical height.
In the case of indoor air-curtain design such as that found in Manitoba Hydro Place (Chapter
4), the thermal layer is placed on the outer skin. This configuration is logical for natural
ventilation and is best suited in high-rise construction, as overheating in the upper levels due to
thermal buoyancy is not an issue. Unlike the shaft-box façade, the physical partition of the air
cavity at each level decreased acoustic transmission and fire spread between floors, as well as
facilitating maintenance access.
The corridor façade deconstructed in Figure 3.5 depicts the composition of the per-floor
compartments, constructed with an outer skin panel, air cavity partitioning, and inner skin.
Unitized outer skin panels can also be used in this configuration as they would in traditional
curtain wall construction.
Benefits of the corridor façade according to a Uuttu, S. (2001):
• Increased reduction in sound transmission between floors and from outside.
• Can utilize natural ventilation if configured in a twin-faced method. In this method
operable windows on the inner skin can allow occupants to control their environment,
!18

• Allows for maintenance space within air cavity,
• Mechanical heat recovery can be applied within ceiling space to further aid in energy use
reduction,
• Outer skin can be unitized for quality control and accelerated construction.
• Additional building security versus a traditional curtain wall façade.
Drawbacks of the corridor façade:
• Divided at each level or every few levels therefore limited thermal buoyancy,
• Air cavity corridor can create acoustic transmission issue between rooms on the same
floor.
!19

3.5 Multi-Storey Facade
Figure 3.6: Multi-storey facade configuration (Brown, 2016).
The final classification as proposed by Oesterle et al. (2001) is the multi-storey façade. As
the simplest configuration, it is no wonder the majority of double skin projects in North America
have chosen to use it (Vagilo et al., 2010). Twelve of the twenty major double skin projects located
in Chapter 4 - Figure 4.1 utilize this design. Though a full list of design information is unavailable
for these projects, it can be speculated that a multi-storey façade was chosen for its simple yet
effective attributes.
Unlike the box, shaft-box and corridor façade, the multi-storey façade is not physically
partitioned vertically or horizontally, but rather forming one large cavity volume. A lightweight
structure supports the outer glazed skin, and is generally wide enough to permit a grated
maintenance walkway (Schiefer et al., 2008). In this configuration it is also possible to design the
air cavity to run uninterrupted around the building. As this configuration relies highly on natural
ventilation and will be exposed to the elements, the thermal layer is placed on the inner skin.
This system is logical for naturally ventilated, low to mid-rise construction, so as not to
cause overheating in the upper levels.
The multi-storey façade deconstructed in Figure 3.6 depicts the simplistic composition of
the lightweight structure connected to outer skin panels, air cavity volume, and inner skin.
Unitized outer skin panels can also be used in this configuration as they would in traditional
single-glazed curtain wall construction.
!20

Benefits of the multi-storey façade according to a Uuttu, S. (2001):
• Excellent reduction in sound transmission from outside noise,
• Logical for natural ventilation if configured in a twin-faced method. In this method
operable windows on the inner skin can allow occupants to control their environment,
• Allows for maintenance space within air cavity,
• Mechanical heat recovery can be applied at the roof level to further aid in energy use
reduction,
• Outer skin can be unitized for quality control and accelerated construction,
• Additional building security versus a traditional curtain wall façade.
Drawbacks of the multi-storey façade:
• Undivided air cavity both horizontally and vertically allows for the potential of acoustic
transmission and fire spread between rooms and floors.
• Limited in air cavity height due to the risk of overheating at upper levels.
!21

Chapter 4: North American Precedent Studies
4.1 Introduction
By now it is clearly evident double skin facades are complex systems with many parameters
and design decisions driving their effectiveness and therefore performance. These design decisions
are not only based on the project goals and statutory requirements, such as natural ventilation or
reduction in solar gains, but also the microclimate experienced by the location. As with any
properly designed building, attention and acknowledgment of these microclimate conditions can
amplify or diminish its actual performance.
This chapter aims to demonstrate 4 North American buildings that use double skin facades,
their project goals and the result of their chosen system. The projects range from the first double
skin facade in North America in 1980, to a highly advanced office tower built in 2008. The
projects are located in Seattle, Washington; Winnipeg, Manitoba; Niagara Falls, New York and
New York City, New York (Figure 4.1). The choice of project locations allows for a range of
climatic regions to be explored.
!22
Figure 4.1: Location of 20 major double skin facade projects built in North America (1980-2016) (Brown, 2016).

4.2 Overview of North American Climate
The scope of this research will briefly examine the climatic conditions of North America to
outline the many microclimates designers face in the region.
As the third largest continent on the planet it is expected North America will experience an
extreme range of weather patterns across the landscape. Temperatures range from Arctic cold to
blazing desert heat and everything in between (Figure 4.2). Severe thunderstorms are common
across the continent in the spring and summer months, while devastating tornadoes can occur in
the central United States, and hurricanes affecting the Gulf of Mexico (World Atlas, 2015).
According to the comprehensive report Climate Change 2007: Synthesis Report by The
Intergovernmental Panel on Climate Change (2007) “confidence has increased that some weather
events and extremes will become more frequent, more widespread or more intense during the 21st
century.” It is clear that the attention to local climate will continue to grow for designers looking
to optimize their building performance.
!23
Figure 4.2: North America Climate Zones by range of average temperature (Landry, 2012).

4.3 One Niagara Welcome Center
(Formerly called Occidental Chemical Building) Niagara Falls, New York
As the first building to use a double skin in North America
(Wigginton and Harris, 2013), the Occidental Chemical Building (now
called One Niagara Welcome Center) is heavily referenced when
studying this type of facade system in a North American context. In her
very thorough reports on the building, Professor of Architecture at the
University of Waterloo Terri Boake describes it as “one of the oldest
examples of the “modern” double-skin building” (Boake et al., 2002, p.
2). She states the architects were “trying to design a building that was
!24
Plate 4.1: The Occidental Chemical Building
West facade (Harrison, 2001).
Plate 4.2: South-East corner with pedestrian bridge
(Harrison, 2001).
Figure 4.3: Wall section
showing air flow
(Harrison, 2001).
Project Profile
Architect: CanonDesign Inc.
Client (original): Hooker Chemical & Plastics Corporation
Type, size and cost: Corporate office, 20,000m2 and USD $12.5
million
Year built: 1980
Double skin design: Naturally ventilated, 9-storey outdoor air
curtain (Figure 4.2), with maintenance walkways at each level,
motorized intake and exhaust louvres can also create a trapped
air buffer zone. Sensor-controlled shading louvers are located
close to the inner skin.

both highly energy efficient and also highly transparent.” In this design, natural ventilation for the
occupants was not chosen, and therefore the inner skin is non-operable fixed glazing.
“It was (for its time) perhaps the largest passive solar collector in the world, and possibly the
most energy efficient office building in its climate zone (a latitude of about 43 degrees,
the same as Marseilles [France], but with the climatic characteristics of the
American continental land mass and very cold in winter.”
(Wigginton, 1996)
Unfortunately, at the time of their case study, Boake et al. (2002), describe multiple system
components no longer functioning, including the sensors that control the shading devices, which
were fixed in a horizontal position and “filthy.” The motorized dampers that allow fresh air to fill
the cavity had been covered with plywood, and glass panels appeared to be clouded, a result of
seal breaks on the double glazed units. As it turns out, last minute program changes and an
inadequate maintenance strategy turned this once award-winning building into disrepair. A site
visit in 2006 noticed the shading devices had been removed (Plate 4.4) and as of 2012, Millard
(2015) states the building is nearly empty.
!25
Plate 4.3: The interstitial space upon completion
(King, 2013).
Plate 4.4: The interstitial space during a site visit in
2006 (Boake, 2006).

While the Occidental Chemical Building remains a poster child for the design and
application of double skin facades in North America, it also stands as a reminder of how important
integrated design and maintenance is to architecture. Unfortunately, subsequent owners failed to
buy into the maintenance plan, such as regular interstitial cleaning of shading devices. Clearly, as
dust and debris collected in the space, mechanical breakdown forced the shading devices to fail,
leading to eventual overheating. It is important that clients are also on board with their
responsibilities when it comes to program changes; in this case switching an office space program
into a research facility with occupant hours stretching into the late evening (Millard, 2015). Since
the original program called for specific heating and cooling requirements it is clear the designed
facade system was not prepared to handle the extra load of the new program.
It is important to note the Occidental Chemical Center was the project of a specific type of
client; an owner/occupier, not a developer. This distinction will be a subject of discussion in
Chapter 5.
!26

4.4 Seattle Justice Center
Seattle, Washington
From inception the client required the project to achieve LEED Silver certification at a
minimum, therefore a naturally ventilated double skin, green roof with water harvesting, and
highly recyclable materials were used. The project was to aimed at displaying the openness of a
!27
Plate 4.5: Seattle Justice Center from the South-
West (TDSA Architecture, 2004).
Plate 4.6: The double skin interstitial space
(TDSA Architecture, 2004).
Project Profile
Architect: NBBJ architects
Client: City of Seattle
Type, size and cost: Public services, 27,870 m2 and USD $90 million
Year built: 2002
Double skin design: Naturally ventilated, 9-storey outdoor air curtain, with 750 mm wide
maintenance walkways at each level (Plate 4.6), and motorized intake and exhaust louvers to
create a trapped air buffer zone in the winter. A light shelf is placed inside the building at 2.4
m above the floor to throw natural light deep into the offices (Plate 4.7).

courthouse and the authority of a police station, to replace the 50-year-old existing Public Safety
Office.
Interestingly, even though the project did achieve LEED Silver, the design does not allow
for natural ventilation into the building. This is an important distinction to be made when
compared to building in the European context, where natural ventilation is a main driver for these
types of facades. More will be discussed on this topic in Chapter 5.
Plate 4.7: Seattle Justice Center interior corridor (NBBJ Architecture, 2002)
!28

4.6 Manitoba Hydro Place
Winnipeg, Manitoba
Touted as “a game changer” and “radical by North American standards” (SAB Mag, 2010)
Manitoba Hydro Place had high performance written on it from project inception. Early on the
team decided to approach the project using the Integrated Design Process for full collaboration
from the start of the design phase. This allowed for a diversity of ideas and approaches,
“[harmonizing] elements related to energy, materials, site, climate, construction, economics,
culture and society” (Manitoba Hydro Place, 2009).
The building features bioclimatic and energy efficiency through a 115 m solar chimney, the
largest geo-thermal array in Manitoba, under-floor ventilation, and several atria with 24 m
!29
Project Profile
Architect: KPMB Architects
Executive Architect: Smith Carter
Energy/Climate Engineer: Transsolar
Client: Manitoba Hydro
Type, size and cost: Office, 64, 590 m2 and CAD $278 million.
Year built: 2008
Double skin design: A twin-faced corridor facade with computer controlled operable
windows on the exterior skin (Plate 4.9), and occupant controlled windows on the interior
skin. Interestingly the thermal layer is placed in the exterior skin, technically categorizing it as
an indoor air curtain when the exterior skin is sealed.
Plate 4.8: Manitoba Hydro Place main facade on Portage Avenue (Hueber, 2008).

waterfalls acting as humidity controls (Figure 4.4) (Manitoba Hydro Place, 2009). Thanks to a
highly advanced building control system “no single feature is more important than any other, as
the entire building is designed to simulate a living organism” (SAB Mag, 2010). In addition,
occupants can enjoy 100% natural ventilation 24 hours a day all year, regardless of the extreme
temperature fluctuations of -35° C to +34° C Winnipeg experiences (CTBUH, 2011).
Figure 4.4: Natural airflows through Manitoba Hydro Place (Christie, 2009).
“Manitoba Hydro Place stands out as the next generation of sustainable buildings that use simple,
time-tested and repeatable concepts in conjunction with science and technology to achieve a
‘living building’that interprets and reacts to its physical environment.”
(CTBUH, 2009).
Post occupancy performance data resulted in a 64.9% energy savings compared to the
average Canadian office tower, 85% of the total building area that is day lit (See Appendix C -
Drawing 1), and the 280 geothermal boreholes provide 60% of the total heating load (Manitoba
Hydro Place, 2009). In 2009 the project was recognized as the Best Tall Building - Americas by
the Council on Tall Buildings and Urban Habitat (CTBUH, 2011).
!30

Figure 4.5: Airflow through double skin and office space - Manitoba Hydro Place (Christie, 2009).
In terms of the type of double skin chosen for
this project, it can be argued that the corridor facade
chosen by the design team was the best choice. The
multitude of other environmental elements, such as
the solar chimney, work in conjunction with the level-
by-level intake of the corridor facade. A multi-storey
facade would be the next best choice for this project,
however since all levels would be connected via the
air cavity, a second solar chimney would appear. As
the built solar chimney is designed in such a way as to
pull air through the floors, a multi-storey facade
would diminish its effectiveness.
!31
Plate 4.9: Operable louvers on double skin
facade (Arban, 2009).

4.6 Riverhouse, One Rockefeller Park
New York City, New York
Plate 4.10: Riverhouse at Rockefeller Park from the West (Ennead Architecture, 2009).
The Riverhouse at One Rockefeller Park is the first residential building in North America to
use a double skin facade as part of its energy strategy (Ennead Architects, 2009). As of their
article, Green Home NYC (2009) states the 264-unit tower has been designed with highest
percentage of green roof space in New York City.
The project was awarded LEED Gold, however access to other construction information has
been limited due to the nature of the private client. Interestingly, in 2010 a lawsuit hoped to
!32
Project Profile
Architect: Ennead Architects
Client: LG Fairmont Group
Type, size and cost: Residential, 46,450 m2 and undisclosed cost.
Year built: 2009
Double skin design: Naturally ventilated, per-window box facade, protected roller shade and
intake and exhaust dampers to create a trapped air buffer zone in the winter (Figure 4.4 - Next
page). An operable panel in the lower portion of the window allows for natural ventilation.

recover $1.5 million in damages, after the occupants claimed “the building’s much-heralded
‘green’ heating system consistently fails to provide adequate heat” (Percio, 2010). The suit
continued by detailing a number of defects in the facade such as cold drafts and insufficient heat.
As of this report no further development had been pursued.
In terms of the type of double skin chosen for this project, it can be argued that the unitized
box facade was the best choice. Since the Riverhouse is a residential building, acoustic
transmission and fire spread prevention is of high importance both to its occupants and building
regulations. Oppositely, as the lawsuit claims, the unitized box facade failure introduces possible
issues with every single other unit; a very costly repair.
Figure 4.6: Riverhouse box facade double skin (Ennead Architecture, 2009).
!33

Chapter 5: North American Challenges
In designing for various locations, clearly there will be differences based on climate,
building regulations, intended use, and local material choice, however the reason for
implementing a highly glazed double skin remains the same. The system offers protection from
the elements for shading devices. Its external skin deflects direct wind allowing occupants access
to natural ventilation. The vertical flue initiates the thermal buoyancy process. Its air cavity can
allow for a maintenance walkway for ease of cleaning. The extra glazing means spectrally
selective coatings can be used to improve performance against solar radiation. It is curious then,
why these facades are far less prevalent in Canada and the United States, than they are in Europe.
5.1 Industry Comments
A closer look at the preceding case study buildings, and those mentioned earlier in Chapter
4, demonstrate double skin design is and has been feasible in North America for over thirty years.
Nonetheless there are important distinctions that should be emphasized when compared to their
European counterparts. As a means to examine real-world challenges, a discussion with the
industry was required. Found in Appendix A, 8 questions were presented to 13 professionals in the
architecture and engineering field focusing on their encounters with double skin facades in North
America. As it turns out, the architects and environmental engineers of the Chapter 4 precedent
study projects were not available for comment, leaving 5 responses from other professionals.
Since the number of respondents is proportionally small, the research acknowledges the following
comments are not a representative view of the industry. The responses do however allow a
continued conversation of the challenges these professionals face when proposing double skin
facades in North America.
5.2 Initial and Required Costs
First and foremost all 5 responses ascertain initial material cost as a main deciding factor for
the addition of ‘new’ or advanced technologies, or building features that would otherwise be
deemed ‘extras.’ Lee at al (2002) agree by noting “all too often a building element that is more
expensive to [purchase and] install…works better and reduces operating, maintenance and
replacement costs in the future use of the building.” Equally in both Europe and North America,
cost will always drive the project, especially when it includes double the amount of material. Both
regions are affected by this constraint, however as of 2000 Lang and Herzog state the system is
twice as expensive in Europe, and up to five times as expensive in North America, when
!34

compared to a ‘regular’ clad facade. Likewise, the 2008 report BESTFACADE by Schiefer et al.
suggests double skin costs of “20-80% higher compared to single glazed facades, and about
100-150% higher compared to opaque facades with windows” (See Appendix B - Graph 2).
Clearly the industry responses agree with preceding research, and reinforce that initial cost is still
a design challenge in North America.
5.3 Building Legislation
For the purpose of the responses, cost has been divided between statutory requirements and
performance benefits. At the time of this report there are currently no regulations that requires a
double skin facade to be used in North American architecture. There are also no requirements in
European regulations that specifically make the system a requirement. Within the scope of this
research specific legislation will not be explored, however as stated in the BEST FACADE report
by Schiefer et al. (2008) a growing number of regions in Europe are acting on energy and
occupant comfort goals. Requirements include access to daylight, outward views, natural
ventilation, and demanding building energy performance. These requirements open the door for
the regular use of double skin facades, with examples from Germany and Austria as industry
leaders (Schiefer et al., 2008). All of the industry responses received agree that the lack of strict
energy and occupant comfort regulations in North America have hindered double skin use in the
region.
5.4 Performance Data
Requirements aside, if a technology has proven its benefit offsets its cost, then it could make
sense for a project to use it. Insulation is a great example of where the benefit highly outweighs
the cost and therefore it is widely used. As it turns out, the multiple industry reports agree there is
very limited real-world data on double skin performance, especially in North America, to justify
the extra cost and embodied carbon. Doebber and McClintock of Arup (2006) fault the limited and
inconsistent performance records on double skins being applied in locations they are not well
suited, and for improper design. They comment further by admitting that as of their presentation
date, they are very aware of the lack of resources designated for designing double skin facades.
Further, in 2014 Professor of Architecture at the University of Waterloo Terri Boake
observes there is still very little published data (especially in North America) concerning operating
energy benefits of the system. She continues by explaining that in cases where energy data has
been published, credit for the system or systems responsible for the improved performance has not
been specified (Boake, 2014). Instead, only the overall energy use is provided. This in itself is a
!35

roadblock designers face when proposing the system, as accurate real-world performance is not
available to be used as a rational for the design.
5.5 Client: Developer or Owner
When asked if clients are open to conducting a post-occupancy performance evaluation on
their buildings, all responses replied neither yes nor no. Unanimously they answered that the
situation varies from client to client, project to project. This introduces the idea that there may be a
certain type of client or project that is more likely to allow a post-occupancy performance
evaluation, and more specifically one that is interested in the actual performance of the building.
A discussion with Associate Director and Facade Engineer at Arup Anthony McCauley
sheds light on the topic; a speculative developer is less likely to sign off for a performance
evaluation than an owner / occupier (See Appendix C - Sketches). This leads to the belief that a
developer, rather than an owner / occupier is also less likely to be on board with energy saving or
environmentally responsible building elements. The developer client in this case is more interested
in low initial cost, construction speed, and quick leasing than in long-term maintenance and
energy costs. In a commercially driven industry like North America, where developers demand
maximum rentable area in their buildings, it would make sense that the extra space taken up by
systems like a double skin will not be accepted. As a result, it can be established that clients who
are owner / occupiers, such as the City of Seattle and Manitoba Hydro as seen in Chapter 4, are
much more likely to build with double skin facades. Though not discussed in detail in this report,
it can be observed that these clients seem to be more active in promoting their projects as ‘green’
or environmentally friendly, when compared to their developer counterparts.
5.6 Other Compact Solutions
In relation to maximizing leasable floor space in commercial buildings, one response
received mentions emerging technology in glazing that offers a more compact facade solution.
Spectrally selective films, low-e coatings, and triple and quadruple glazing all seem more
attractive to developers when compared to the space that cannot be rented when occupied by a
double skin.
5.7 North American Energy Costs
Finally, the low cost of energy enjoyed by North Americans could also play a role in the
decision to use technologies such as a double skin facade. As mentioned earlier, the clients less in
favour of the system are also more likely to accept mechanical heating, ventilation and air
!36

conditioning options due to cheap energy prices (California Energy Commission, 2014). One
industry response stated this as a possible deterrent for implementing the more expensive,
naturally ventilated solution in North America. As it turns out, limited resources on the specifics of
this data as a possible barrier in North America forces this research to simply speculate on its
actual impact.
5.8 In Summary
Taking a step back it can now be established that there are multiple barriers to the
implementation of double skin facades in North America. Questions presented to industry
professionals affirm the points noted by previously published reports, outlining continual design
barriers. Cheap energy costs and other compact building solutions persuade developer-type clients
to continue maximizing rentable floor space and lowering initial costs. A lack of real-world data
suitable for buildings in specific regions setback designers forcing them to reevaluate their chosen
system. Finally, as stated by the multiple sources preceding this report and the industry responses,
the main barriers the North American industry seems to face are initial cost and a lack of
environmentally conscious building legislation. These factors eliminate the stringent requirements
seen in the European industry and increase the cost of extra materials, resulting in a minimized
number of projects utilizing a double skin facade.
!37

Chapter 6: Conclusions
6.1 In Summary
The design and use of a highly glazed double skin facade is not new, however the protective,
acoustic, and thermal performance realized by this technology have initiated a developing interest
and a multitude of new applications. Curiously though, initial research made it obvious that the
adoption of double skin facades is far less prevalent in Canadian and the United States than in
Europe. The minimal information that had been published merely describes design principles, but
fails to put forth any post-occupancy performance data of the double skin system. Most of these
were published in the early 2000s with very little new reports following suit.
The intent of this report has been to introduce the design principles, component functions,
and configurations of double skin facades in order to further understand their design challenges in
North America. Examination of the ventilation types and methods, protective skins, air cavity
characteristics, and solar shading devices has been conveyed to form a foundation of knowledge.
Building on this information the various component configurations were assembled along with
their intended and best-suited building applications.
By presenting enquires to industry professionals, this report has outlined North American
design challenges in an attempt to drive a growing dialogue. The research acknowledges the
collected responses are not a representative view of the industry, but they coincide with preceding
research when noting initial material cost and a lack of environmentally conscious building
legislation as primary design barriers. The low cost of energy enjoyed by North Americans is
noted as an incentive to use energy efficient mechanical systems rather than their more expensive
natural alternatives such as a double skin. They continue by agreeing that a limited amount of
post-occupancy performance data fails to back up design proposals, leading to minimal adoption
of the system in the commercially driven North American market. As a result of this commercial
market the responses mention more compact, space saving solutions such as spectrally selective
films for triple and quadruple glazing are more attractive in projects with developer-type clients.
6.2 Recommendations for Further Research
The report has been aimed at driving a discussion on the minimal adoption of double skin
facades in North America, and has outlines barriers to their design. Based on these barriers, the
research emphasizes the lack of environmentally conscious building legislation in Canada and the
United States. Building regulations so prominent in European regions have the ability to influence
the use of natural ventilation, access to views and day lighting for building occupants elsewhere in
!38

the world. As a result, designers will be required to integrate these ‘green’ functions, and
developer-type clients will need to accept them in their budget.
Further, closer attention to post-occupancy performance evaluations and double skin design
tools should be considered. Every project is unique, therefore specifics should be included in these
energy data reports for future buildings to take advantage of the lessons learned.
6.3 Conclusion
In conclusion, the growing popularity of highly glazed commercial buildings seems to run
with the same intensity as ‘green’ architecture, or that of the demand for buildings to adopt high
standards of environmental responsibility as a result of improved energy efficiency. As these
structures become increasingly complex in response to the architect’s design intent, client
requirements, and new building legislation, the need for incorporating advanced technologies also
continues to grow. However, these factors require a focus on the future and a focus on the source
of potential barriers.
Double skin facades have shown to be highly effective systems in Europe, a result of
stringent energy standards, material costs and client requirements. Gradually, the North American
adoption of these factors is occurring, along with a growing dialogue about the future of high-rise
architecture.
!39

Appendix A - Industry Comments
The survey was conducted between March 1st, 2016 and April 22nd, 2016 and focused on
the architects and environmental engineers of the 4 precedent study buildings found in Chapter 4.
In addition, meetings with Anthony McCauley, Associate Director of Arup in Dublin on March
23rd, 2016 (See Appendix C - Sketches) and Pratik Raval, Associate Director of Transsolar
KlimaEngineering in New York on March 29th, 2016 were also attended. As the meetings were
informal, no transcripts were recorded for either. Below are the questions and responses to the
industry commentary portion of the research found in Chapter 5.
1. What is your professional title, and which region [North America or other] are your
projects located?
2. What category best describes your scope of work?
!40
Both
60%
Europe
20%
North America
20%
Responses:
• Architect (Registered, OAA) - Both North America
and Europe.
• Architect (Registered, OAA) - Both North America
and Europe.
• Architectural Technologist (Dipl Arch Tech) - Both
North America and Europe.
• Associate Director (Environmental Engineering) -
North America.
• Associate Director (Facade Engineering) - Europe.
Environmental Engineering
40%
Architectural design
60%
Responses:
• Architectural design and architectural contract documents.
• Architectural design and contract administration.
• Architectural design.
• Environmental engineering.
• Environmental engineering.

3. In your professional opinion, are advanced technologies a requirement for truly high-
performing facade such as a double skin system, or are they achievable with basic
components?
4. In your experience, who typically initiates the decision to use a double skin system?
!41
No - Not required
100%
Responses:
• No - Basic components can be used. Insulating qualities can be provided within the glass
itself (ie. Coatings, triple glazing). Daylighting control strategies can also be employed.
• No - Basic components can be used. However, truly high performing facades require
advanced technologies (photovoltaics / ITO coatings / window cavity fill - argon).
• No - Very wide and difficult question. What is called [an] advanced technology in some
cities, [might] actually be very simple in Toronto or London [UK].
• No.
• No.
Facade engineer
40%
Design architect
60%
Responses:
• Design architect.
• Design architect.
• Design architect and the client budget.
• Facade Engineer / Consultant.
• Facade Engineer / Consultant.

5. In your experience, what is (typically) the deciding factor or factors for using a double
skin system in North America?
6. Conversely, what factors might be deterrents to the use of double skin systems in North
America as compared to Europe?
!42
Architectural aesthetics
20%
Natural ventilation
20%
Thermal performance
60%
Responses:
• Thermal performance attributes, acoustics.
• Natural ventilation, protection of shading
devices, and architectural aesthetics.
• Architectural aesthetics.
• Natural ventilation, thermal performance
attributes, and acoustics.
• Natural ventilation and protection of shading
devices.
N/A
20%
Cost - Construction
27%
Cost - Material
27%
Cost - Design time
27%
Responses:
• Added time / cost to design, material cost, construction cost / extended construction time,
cheap energy in North America - mechanical systems opted for.
• Added time / cost to design, material cost, construction cost / extended construction time.
• N/A.
• Material cost, construction cost / extended construction time.
• Material cost, construction cost / extended construction time.

7. In your experience, is there a predominant type of double skin system used in North
America, and if so which is it?
8. In your experience, has a post-occupancy performance evaluation been proposed, and if
so have the client/tenants agreed or disagreed?
!43
N/A
20%
No - Varies
80%
Responses:
• No - It varies and depends on the desired project outcome.
• No - it varies and depends on the desired project outcome.
• N/A.
Varies
100%
Responses:
• Varies - Completely depends on the project/client.

Appendix B - Graphs
Appendix B - Graphs
Graph 1 - “Cost of DSF compared to conventional facades.”
Graph represents multiple sources collected by the BESTFACADE report.
Source:
Schiefer, C., Heimrath, R., Hengsberger, H., Mach, T., Streicher, W., Santamouris, M., Farou, I.,
Erhorn, H., Erhorn-Kluttig, H., de Matos, M., Duarte, R., Blomsterberg, Å. (2008)
‘BESTFACADE: Best Practice for Double Skin Facades’, BESTFACADE, Intelligent
Energy Europe. p. 24 Available at: http://www.bestfacade.com/textde/
05_results_downloads_gesamt.htm [Accessed October 2015].
!44

Appendix B - Graphs
Graph 2 - “Subsidies for renewable energy as a percentage of the retail electricity price in
selected European countries, 2009 to 2012.”
Source:
Webster, R. (2014) How the cost of energy in the UK compares to other European countries,
in five graphs. Available at: http://www.carbonbrief.org/how-the-cost-of-energy-in-the-uk-
compares-to-other-european-countries-in-five-graphs [Accessed 26 April 2016]
!45

Appendix B - Graphs
Graph 3 - “Map of natural ventilation and its connections.”
Source:
California Energy Commission (2014) ‘Natural ventilation for energy savings in California
commercial buildings’, California, p.145. Available at: http://escholarship.org/uc/item/
4cd386s7#page-1 [Accessed April 2016].
!46

Appendix C - Sketches & Drawings
Sketches 1 - Explanatory sketches provided by Anthony McCauley, Associate Director at Arup,
Dublin, during a meeting on March 23rd, 2016. For academic purposes only.
!47

!48

!49

!50

!51

Drawing 1 - “Manitoba Hydro Place - Typical Tower Office Section”
Source:
KPMB (2009) ‘Typical Tower Office Section’, Available at: http://manitobahydroplace.com/
integrated-elements/ie-details/?rid=32 [Accessed April 2016].
!52

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Figure 2.2 Brown, B. (2016) Location and angle of shading devices in relation to the skins
[Diagram].
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Figure 3.2 Brown, B. (2016) Double skin facade partitioning [Diagram].
Figure 3.3 Brown, B. (2016) Box facade configuration [Diagram].
Figure 3.4 Brown, B. (2016) Shaft-box facade configuration [Diagram].
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!58

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