Doubleskinfacades

DOUBLE SKIN FACADES

THA1240 Technology 3: Materials and Tectonics

DESISLAVA KUSHELIEVA U1156880 BA(Hons) Architecture 1

PRECEDENTS

Fig1. Helicon Finsbury building, London

Helicon Finsbury Pavement Architect: Sheppard Robson Location of the building: Finsbury Pavement, London Façade Type: Extensive, clear full height inner and outer glazing due to the relatively deep floor plan.

Ventilation of the cavity: Both the origin and destination of the air in the cavity are external. In periods with no solar radiation, the extra skin provides additional thermal insulation. In periods with solar irradiation, the skin is naturally ventilated from/ to the outside by buoyancy (stack) effects - i.e.the air in the cavity rises when heated by the 2

Fig2. Fixings close-up

sun (the solar radiation is absorbed by blinds in the cavity). Solar heat gains are reduced as the warm air is expelled to the outside.

Façade construction – Mirror or solar tinted glass.

Pane type Shading device type Intermediate louvre blades (14% perforation and 70% solar reflectance).

HVAC Building Boasts chilled ceilings and floor based air supply as a lower energy, more comfortable alternative to high capacity VAV and fan coil systems.

In September 1991, Sheppard Robson was commissioned by London & Manchester Assurance to design a landmark building on the corner of Finsbury Pavement and South Place, London EC 2. The result is The Helicon, one of London’s first sustainable buildings to combine retail and offices into a building that is energy-efficient and economical to run

fig3. chilled ceiling in the Helicon building

Zamora Offices

Fig4. Aerial view

baezaArchitects: Alberto Campo

Fig6. Courtyrd

Location of the building: Zamora, Spain Area: 12100.0 m2 Year: 2012 Façade Type: Extensive, clear full height inner and outer glazing Like a greenhouse. With a double facade similar to a Trombe wall. The external skin of the facade is made of glass, each single sheet measuring 600x300x1,2 and all joined together simply with structural silicone and hardly anything else.

Fig5. Interior view of Zamora offices

Fig7. Almost transparent facade

Ventilation of the cavity: This cavity is ventilated to keep the building cool during the summer, preventing a greenhouse effect.

Façade construction – The sheets of glass that make up the exterior of the two-storey building are joined by little more than structural silicone.

HVACsupply as a lower energy, more comfortable alternative to high capacity VAV and fan coil systems.

Frearson, A. (2012, September 15). Offices for Junta de Castilla y León by Alberto Campo Baeza. Retrieved from http://www.dezeen.com/2012/09/15/offices-for-junta-de-castilla-y-leona-by-alberto-campo-baeza/

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HISTORY AND ORIGINS OF THE TECHNOLOGY Double skin facades are relatively new sustainable method that open up new possibilities for creative designs that are well adapted for the climatic conditions. Double skin windows has been long featured in places with cold climate. An example of this technique can be still seen in Switzerland in old farmhouses. Also called as storm windows, they are a combining wood window frame with glass.

With the evolution of glass and steel technology, it seems in retrospect that this system would be combined into a double layered wall. (Crespo, n.d.)

The first example of a double skin curtain wall can be seen as early as 1903 in the Steiff Factory in Giengen, Germany. The building typology is a toy factory and it is designed

by Richard Steiff. The reason behind incorporating the double skin feature are to maximize the daylight gain and take into account the strong winds of the region.

The solution was a three storey steel structure with void 25 cm wide. The only openings the system had were for maintenance purposes.

Because of the success of this construction method, another two additions were

timber instead.

At the same time in Vienna (1903), Austria, Otto Wagner won the competition for post office saving Bank. The building was finished in 1912 and uses double skin as a skylight in order to maximize the light gain in the main hall. The building is still being used.

Post Office Saving Bank

Fig. 10 Fig.10 Steiff Factory

Fig.9 Section of Steif factory

Fig.8 Old Swiss house

erected in 1904 and 1908. However, they were using 4

Another two case studies can be identified at the end of 1920’s although with different priorities in mind. One of them is the communal housing blocks of Narkomfin building(1928). The architect, Moisei Ginzburg, experimented with double skin stripes. Although the project is known to be a manifestation of the communist ideals , Ginzburg was interested with pushing the idea of the window.

Fig.13 Colourful facades

in pushing the idea of the window.

Fig. 11 Narkomfin building

Fig.12 The balconies

The other notable example comes from the Swiss-French architect Le Corbusier, who was designing the Centrosoyus in Moscow. A year later he started designing the Cite de Refuge(1929) and the Immeuble Clarte(1930) in Paris.

Although none of these buildings actually had double skin walls due to inefficiency and budget matters, all of the initial design ideas included what the architect called ‘neutralisant’,a system of ventilated double glazing.

Fig.14 Centrosoyus in Moscow

Little progress was made on double skin glass

Fig.15 Occidental Chemical Building

f a c a d e s til the late

70’s

and

early

u

n 80’s

.

According to Grondzig (2009), one of the first modern examples to be constructed was the Occidental Chemical Building (Niagara Falls, New York, 1980) by Cannon Design. The design was, es-

Fig. 16 Shafts in the intermediate cavity

Fig. 17 Close photo of the edge of the building

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Later, in the 90’s the rising envinmental concerns and the rapid deelipment of hardware and software influences the design of double skin facades and allows for highly complex calculations to shape the exact appearance.

First exmples, both completed in Germany in 1997, are the RWE AG Headquarters by Ingenhoven and the Commerzbank HQ by Foster and Partners.

Fig. 23

Fig. 21 Commerzbank Tower, Frankfurt, Germany Fig.18

Fig. 19

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Fig. 20 RWE AG Headquarters

Fig. 22

Fig. 24

PERFORMANCE WHAT IT DOES ?

The Double-skin facade is a European architectural trend driven mostly bysystem consisting of two skins placed in way that allows the air flow in the intermediate cavity. Harris claims that Compagno, (2002) describes the Double Skin Façade as “an arrangement with a glass skin in front of the actual building façade. Solar control devices are placed in the cavity between these two skins, which protects them from the The Double-skin facade is a European architectural trend driven mostly bysystem consisting of two skins placed in way that allows the air flow in the intermediate cavity. Harris claims that Compagno, (2002) describes the Double Skin Façade as “an arrangement with a glass skin in front of the actual building façade. Solar control devices are placed in the cavity between these two skins, which protects them from the influences of the weather and air pollution a factor of particular importance in high rise buildings or ones situated in the vincity of busy roads.”

The glass skins can be single or double glazing units with a distance from 20 cm up to 2 metres. Often, for protection and heat extraction reasons during

the cooling period, solar shading devices are placed inside the cavity.

The properties of the Double Skin Facade do not differ from the Single Skin one. However, due to the additional skin , a thermal buffer zone is created which reduces the heat losses and enables passive solar gains. During the heating period, the preheated air can be introduced inside the building providing natural ventilation with retained good indoor climate. Different combination of components can result in different purposes of the facade, proving the flexibility of th system and its adaptability to different climates and locations (Poirazis, 2006, p 227)

Fig. 25

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WHY DOUBLE SKIN FACADE ?

• Lower construction cost compared to solutions that can be provided by the use of electrochromic, thermochromic or photochromic panes (their properties change according to climatic or environmental conditions).

• Acoustic Insulation can be seen as one of the main reasons to choose a Double Skin Facade.

Both internal(reducing the transmission from room to room) and external noise pollution(transmission from outdoor sources i.e. heavy traffic) can be dramatically decreased.

•

Thermal insulation: During the winter the

external additional skin provides improved insulation. Reduced speed of air flow and the increased temperature of the air inside the cavity lower the heat transfer rate on the surface of the glass which leads to reduction of heat loss.

During summer the warm air from inside the cavity can be extracted several ways: either mechanically, supported by fan or by natural ventilation. Certain façade types can cause overheating problems. However, a completely openable outer layer can solve the overheating problem during the summer months, but will certainly increase the construction cost.

cavity of the Double Skin Facades they are protected both from wind and rain.

•

Reduction of the wind pressure effects:

The Double Skin Facades around high rise buildings can serve to reduce the effects of wind pressure.

• Fig. 26

Transparency-architectural design: In almost all the literature, the desire of the architects to use larger glazed facades is mentioned.

be energy saving to • Natural Ventilation: One of the main adpre-cool the offices during the night using natural vantages of the Double Skin ventilation.

Façade systems is that they can allow natural (or fan supported) ventilation.

• Energy savings and reduced environmen- Different types can be applied in different climates, tal impacts: In principle, orientations, Double Skin Façades can save energy when properly locations and building types in order to provide designed. Often, fresh air before and during when the conventional insulation of the exterior the working hours. The selection of Double Skin wall is poor, the savings Façade type can be that can be obtained with the additional skin can be crucial for temperatures, the air velocity, and the important. quality of the introduced air inside the building.

• Thermal Comfort - temperature of the inNight time ventilation: During the hot • Better protection of the shading or light- ternal wall: Since the air summer days, the interior ing devices: Since the shading inside the Double Skin Façade cavity is warmer •

spaces can easily be overheated. In this case, it may 8

or lighting devices are placed inside the intermediate (compared to the outdoor

air temperature), the interior part of the façade can maintain temperatures that are more close to the thermal comfort levels during the heating period (compared to the single skin facades).

On the other hand, during the summer it is really important that the system is well designed so as the temperatures inside the cavity will not increase dramatically.

WHY NOT DOUBLE SKIN FACADES ?

Fig. 28

•

Fire escape: The glazed space of a Double Skin Façade may be used as a fire escape.

•

Low U-value and G-value: Two advantages

of the Double Skin Façades are the low thermal transmission (U-value) and the low solar heat gain coefficient (g-value) Fig.27 Disadvantages mentioned in different literature sources. Some of the statements are menioned in the text.

• Higher construction costs (compared cavity of a Double Skin Façade can vary from 20 cm to two meters. This to a conventional facade)

results in the loss of useful space. Often the width of • Fire Ecsape: There is not yet very clear the cavity influences the properties inside it (i.e. the deeper the cavity is, whether the Double Skin Facades can be positive or not, concerning the fire the less heat is transmitted by convection when the cavity is closed) and someprotection of a building. times the deeper • Reduction of rentable office space: The the cavity is, the more improved thermal comfort conditions are next to width of the intermediate the external walls.

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increases the weight of the construction which in• Additional Maintenance and opera- creases the cost. tional costs: Comparing the Double Skin and the Single Skin type of façade, one • Daylight: The Double Skin Facades are similar to other types of glazed can realize that the (i.e. single skin façade). However, Oesterle et Double Skin type can have higher costs regarding facades al., (2001) describe, construction, cleaning, that Double facades cause the reduction of the quantity of light entering the rooms as a result of the additional external skin.

• operation, inspection, servicing, and maintenance.

•

Overheating problems: If the Double Skin

\•

Increased air flow velocity: inside the

Acoustic insulation: It is possible that

sound transmission problems (room to room or floor to floor) can take place if the façade is not designed properly.

Façade system is not properly designed it is possible that the temperature of the air in the cavity may increase the overheating of the interior space.

cavity, mostly in multi storeyhigh types. Considerable pressure differences are mentioned between offices in case of natural ventilation via the cavity.

•

Increased construction weight: As it is

expected the additional skin 10

Fig 29. Illustration of a possible way of fire propagation in a VDF

CLASSIFICATIONS The most common way of categorization is according to the geometry(type) of the cavity. It can also classified accordint to he type f ventilation, destination of the airflow and width of the air cavity.

The classification of the Double Skin Facades can also be made according to the:

Type of ventilation ¤ Natural ¤ Fan supported ¤ Mechanical

Origin of the airflow ¤ From inside ¤ From outside

Destination of the airflow ¤ Towards inside ¤ Towards outside

Airflow direction

¤ To the top ¤ To the bottom (only in case of mechanical ventilation)

Fig.29 Tjibaou Cultural Center by Renzo Piano. Its hybrid façade is a system that combines one or more of the basic characteristics of the 3 main typologies to create a new system.

Partitioning

¤ Horizontal (at the level of each storey) ¤ No horizontal partitioning ¤ Vertical

Width of the air cavity ¤ Narrow (10 - 20 cm) ¤ Wide (0.5 – 1m)

Fig.30

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APPROPRIATENESS, AVAILIBILITY AND DISTRIBUTION The cavity between the two skins may be either naturally or mechanically ventilated. In cool climates the solar gain within the cavity may be circulated to the occupied space to offset heating requirements, while in hot climates the cavity may be vented out of the building to mitigate solar gain and decrease the cooling load. In each case the assumption is that a higher isolative value may be achieved by using this glazing configuration over a conventional glazing configuration. Recent studies showed that the energy performance of a building connected to a double-skin facade can be improved both in the cold and the warm season or in cold and warm climates by optimizing the ventilation strategy of the facade Mingotti, Nicola; Chenvidyakarn Torwong, Woods A. W (2010). “The fluid mechanics of the natural ventilation of a narrow-cavity double-skin facade”

Fig.31

Stevensob states that: “ In a cool climate, the solar gain in the cavity can be circulated into the occupied space to offset mechanical ventilation requirements. In a warm climate, the cavity is vented; the hot air rises, vents out and pulls in cooler air behind it. This cooler cavity space reduces cooling requirements within the “ (Stevensob, 2009, p. 1)

Fig.33

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Fig.32 Minerva Tower, London. Nicholas Grimshaw, Architect; Roger Preston & Partners, services engineers. Hybrid mechanical and natural ventilation with double skin façade.

ROBUST DETAILS POST TOWER OFFICE, BONN, GERMANY

Fig. 35 Section through nine-story segment of multistory facade, showing principle of staggering air-intake and extract openings distributed over the height of the building.

Fig. 34 Photo of model of proposed Post Office headquar- Fig. 36 Diagramatic section through north facade and space to rear, ters tower. showing ventilation and air-condditioning elements.

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PROCESS AND MANUFACTURE

Fig. 37 View of the Olympic Park in Munich

Fig.38 Vertical and horizontal section through facade support construction for tower block at Olymoic Park in Munich: using system fixing fins

Fig.39 Site photo assembly of the prefabricated facade elements

Fig.40 Principle of lifting equipment with which the prefabricated elements are hoisted into position for assembly. Example: Bussiness Tower, Nuremberg.

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Fig.40 Bussiness Tower, Nuremberg

COST

MAINTENANCE AND AFTERCARE ly of cleaning and repairing. The maintenance cost are varying depending to the glass skins. The cost is higher due to the presence of 4 surfaces to be cleaned. The source of ventilation air passing through the cavity plays a role as well. In case of cavity ventilated with outside air, the cost rise.

Another factor for the frequency of cleaning is the level of pollution in the chosen environment. Also, shading devices situated between the two skins will be beneficial if you are in favour of rarer cleaning.

As a guide to gleaning costs for glazed facades, the following prices apply for large areas:

Fig.41 Cleaning the outer glazed facade

The construction and maintenance costs of the double skin facades is, without any doubt, higher than a single skin one. However, if the facade is designed properly, it’s possible to reduce the energy consumption mainly from heating, cooling and ventilating the building. However there are many contradictory opinions on the effectiveness of this system. Some theorists Lstiburek claim that many “green buildings don’t save energy. He also describes them as ‘leaky to air’ and ‘fraught with thermal bridges’ (2008, p. 1) A well thought design has to take into account many different parameters like biulding scheme and type, orientation, occupancy schedule,equipment etc. It also has to consider the location(climate, daylight availibility, temperature, site and obstructions,

lattitude and atmospheric conditions).

Jager, (2003) presented constructional and maintenance costs for Standard and Double Skin Facades. According to him: “Investments (in Central Europe) • Standard façade 300 to 500 Euro/ m² • Double Skin Standard 600 to 800 Euro/ m² • Double Skin with adjustable air in and outlet 700 to 1000 Euro/ m² • Double Skin with openable exterior sashes 800 to 1300 Euro/ m² Double Skin Façades for Office Buildings 76 Running Costs (in Central Europe) • Standard façade 2.5 to 3.5 Euro/ m² and cleaning operation • Double Skin façade 4 to 7.5 Euro/ m² and cleaning operation”.

The maintenance of such facades consist main-

Source: Oesterle, E. (2001). Double-skin facades: Integrated planning : building physics, construction, aerophysics, air-conditioning, economic viability. Munich:

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REGULATIONS

by SKANSKA HVAC (Heating, Ventilating, and Air Conditioning) is the system that maintains desired environmental conditions in a space in most modern buildings. In almost every application, several options are available to satisfy this basic goal. In the selection and combination of these options several criteria have to be considered to achieve the functional requirements associated with the goal.

The goal is to fulfill certain indoor air quality, thermal comfort and energy use

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KEY MANUFACTURERS

REFERENCING Oesterle, E. (2001). Double-skin facades: Integrated planning : building physics, construction, aerophysics, air-conditioning, economic viability. Munich: Prestel.

Offices for Junta de Castilla y León by Alberto Campo Baeza. (2012x). Retrieved from http://www.dezeen. com/2012/09/15/offices-for-junta-de-castilla-y-leona-by-alberto-campo-baeza/ Crespo, A. (n.d.). 3x2:Three takes on double skins”,. Retrieved from Harvard University website: http://www.civil.uwaterloo.ca/beg/ArchTech/History%20of%20Double%20Skin.pdf pic1 Collins, A. (2010). Swiss Architecture at a Glance. Retrieved from http://seeingdesign.com/places/swiss-architectureat-a-glance/ website: http://seeingdesign.com/places/swiss-architecture-at-a-glance/ pic2 MY STEIFF LIFE. (2010). Retrieved from blogspot.co.uk website: http://mysteifflife.blogspot.co.uk/2010_11_01_archive.html Wagner’s Postal Savings Bank:. (n.d.). Retrieved from http://projects.ecfs.org/bome/cities/hband2004/vienna/SKendall/ Postal%20Savings%20Bank.html Poirazis, H. (2006). double skin facades (43). Apex.

Grondzik, Walter T.; Alison G. Kwok, Benjamin Stein, John S. Reynolds (2009). Mechanical and Electrical Equipment for Buildings. John Wiley and Sons. p. 133.

Poirazis, H. (2006). Double Skin Facades (43). Retrieved from IEA SHC website: http://www.ecbcs.org/docs/Annex_43_ Task34-Double_Skin_Facades_A_Literature_Review.pdf Lstiburek, J. (2008). Why Green Can Be Wash. Retrieved from ASRAE website: http://www.smacna.org/pdf/ACF222B. pdf Mingotti, Nicola; Chenvidyakarn Torwong, Woods A. W (2010). “The fluid mechanics of the natural ventilation of a narrow-cavity double-skin facade” Stevensob, A. (2009, August 9). DOUBLE SKIN FACADES [Graph]. Retrieved from http://http://architecturenotes. wordpress.com/2009/08/09/double-skin-facades/ Mei, L., Infield, D., Eicker, U., & Fux, V. (2003). Thermal Modeling of a Building with an Integrated Ventilated PV Façade. Energy and Buildings 35(2003) 605-617.

Kragh, M. (2000).Building Envelopes and Environmental Systems. Paper presented at Modern Façades of Office Buildings Delft Technical University, the Netherlands Web address: http://www.permasteelisa.com/upload/docs/pub _TUD02001.pdf Jager, W. (2003). Double Skin Facades – Sustainable Concepts. Presentation of Hydro for Syd Bygg 2003, Malmo, Sweden.

Crespo, A.M.L. History of the Double Skin Façades.

Web address: http://envelopes.cdi.harvard.edu/envelopes/content/ resources/PDF/doubleskins.pdf Arons, D.M.M., & Glicksman, L.R. (2001). Double Skin, Airflow Facades: will the Popular European Model work in the USA?, Proceedings of ICBEST 2001, International Conference on Building Envelope Systems and Technologies, Ottawa, Canada, vol. 1, pp. 203207.

Askar, H., Probert, S. D., and Batty, W. J., (2001).

“Windows for Buildings in Hot Arid Countries”, Applied Energy, Vol. 70, pp. 77-101.

LIST OF FIGURES Fig.1 Grundy, P. (2008). Helicon Building, an example of what Curtis B. Wayne calls “The Fourth Architecture”. Image Courtesy of Paul Grundy, bdonline.co.uk [photo]. Retrieved from http://www.archdaily.com/418605/toward-a-fourth-architecture/ Fig2 Chow WK, Hung WY. Effect of cavity depth on smoke spreading of double-skin façade. Building and Environment 2006; 41(7):970–979.

Fig3 Façade: la peau se double. http://www.crit.archi.fr/produits%20innovants/FICHES/Fiche6/presentation.html Fig4 Sevilla, J. (2012, December 13). Alberto Campo Baeza [photograph]. Retrieved from http://www.archdaily. mx/178682/oficinas-zamora-alberto-campo-baeza/ Fig5 Sevilla, J. (2012, December 13). Alberto Campo Baeza [photograph]. Retrieved from http://www.archdaily. mx/178682/oficinas-zamora-alberto-campo-baeza/ Fig6 Sevilla, J. (2012, December 13). Alberto Campo Baeza [photograph]. Retrieved from http://www.archdaily. mx/178682/oficinas-zamora-alberto-campo-baeza/ Fig7 Wouters, Peter: Les différents types de façades doubles. Avantages, inconvénients, modes de fonctionnement, exemples. Journée d’étude SRBII (Belgium) - 02/05/2000 Fig8 Collins, A. (2010, October 13). Swiss Architecture at a Glance [photo]. Retrieved from http://seeingdesign.com/ page/7/ Fig9 Chow CL, Chow WK. Fire safety aspects of refuge floors in supertall buildings with computational fluid dynamics.

Journal of Civil Engineering and Management 2009; 15(3):225–236.

Fig10 Exam Part [photo]. (n.d.). Retrieved from http://funpoper.com/wagner-post-office-savings-bank-loos-ller-house. html Fig11 Kate Harrison: Extract Air Façade Diagram Fig12 Doppelfassaden. http://www.reteg.de/e040/internet/reteg/retegwebgate.nsf/ContentByKey/BBAR-4Q6J57DE-p Fig13 Verification of Dynamic Buffer Zone (DBZ) Wall Assembly Performance Using Infrared Photography. Antonio Colantonio, Public Works and Government Services Canada, Technology Directorate, Rick Quirouette, Quirouette Building Specialists Limited. 2002. p. 3 Fig14 Sevilla, J. (2012, December 13). Alberto Campo Baeza [photograph]. Retrieved from http://www.archdaily. mx/178682/oficinas-zamora-alberto-campo-baeza/ Fig15 Sevilla, J. (2012, December 13). Alberto Campo Baeza [photograph]. Retrieved from http://www.archdaily. mx/178682/oficinas-zamora-alberto-campo-baeza/ Fig16 CCBR University of Toronto. Double Façade Report Draft. April 2002. Behnisch, Behnish & Partner with Architects Alliance. p. 4 Fig17 Yahiaoui: Integration of control and building performance simulation software by run-time coupling. Eight International IBPSA Conference, Eindhoven, Netherlands, August 11-14, 2003, p 1435 - 1441 Fig18 Hui, S. (2001, August 6). ext4 [photo]. Retrieved from http://www.mech.hku.hk/sbe/case_study/case/ger/RWE_ Tower/rwe_index.html Fig19 Hui, S. (2001, August 6). ext3[photo]. Retrieved from http://www.mech.hku.hk/sbe/case_study/case/ger/RWE_ Tower/rwe_index.html Fig20 Hui, S. (2001, August 6). ext2 [photo]. Retrieved from http://www.mech.hku.hk/sbe/case_study/case/ger/RWE_ Tower/rwe_index.html Fig21, 22, 23, 24 Commerzbank Headquarters, Frankfurt, Germany [photos]. (2007). Retrieved from https://my.news. yahoo.com/the-12-architectural-must-see-by-foster---partners-083809480.html?page=all Fig25 Fig26 Price, & Myers (2004). Innovations in Façade Technology [diagram]. Retrieved from http://www.theislingtonestate. com/SOA-present.htm

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Fig27 Façade: la peau se double. http://www.crit.archi.fr/produits%20innovants/FICHES/Fiche6/presentation.html Fig28 Das Stadttor Düsseldorf. CCI.print InfoSystem GebäudeTechnik, http://www.zentfrenger. de/download/fachaufsaetze/199910_cci_das_stadttor_duesseldorf.pdf Fig29,30,31 Illustration of a possible way of fire propagation in a VDF [diagram]. (2004, November). Retrieved from http://http://www.bbri.be/activefacades/new/index.cfm?cat=4_tech_aspects_perfor&sub=2_safety_case_fire Fig32 Francisco, A. (2008, March 24). SEGUNDA-FEIRA. Retrieved from http://http://almadaumavisaoparaofuturo.blogs.sapo.pt/2008/03 Fig33 McGrattan K (ed.). Fire Dynamics Simulator (Version 4.0.6) Technical Reference Guide. NIST Special Publication 1018. Fire Research Division, Building and Fire Research Laboratory, National Institute of Standards and Technology: USA, 2006.

Fig34 History of the Double Skin Facade. Building Envelopes.org - Harvard University Fig35 British Standards Institution. BS 6262 Part 4 Code of Practice for Glazing for Buildings—Safety Related to Human Impact. British Standard Institution: UK, 1994.

Fig36 Chow WK. Use of computational fluid dynamics for simulating enclosure fires. Journal of Fire Sciences 1995; 13(4):300–334.

Fig37 Klinkenberg, F. (2009, November 24). Olympiahalle, Munich. Retrieved from http://http://www.rocktimes.de/gesamt/r/rammstein/muenchen09.htmt Fig38 Law M. Fire safety of external building elements—the design approach. American Institute of Steel Construction (AISC). Engineering Journal 1978; Second quarter: 59–74.

Fig39 McGrattan K (ed.). Fire Dynamics Simulator (Version 4.0.6) Technical Reference Guide. NIST Special Publication 1018. Fire Research Division, Building and Fire Research Laboratory, National Institute of Standards and Technology: USA, 2006.

Fig40 View of Nuremberg. (2014, April 1). Retrieved from http://www.tourismus.nuernberg.de/v04/mod/bilder/B_B_BusinessTower_20070117120452.jpg Fig41 Workers cleaning a curtain wall on a building in Beijing. (2009). Retrieved from http://www.chinadaily.com.cn/regional/2009-12/29/content_9328375.htm tt

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