Information, References

The simulated models of the facade were made using Google SketchUp 8. (Available: http://www.sketchup.com/intl/en/product/gsu.html)

The Cira Center model was taken from SketchUp's 3D Warehouse, made by HershP on May 24, 2007.




One particularly effective solution is to use a double skin façade when designing a building. Double skin facades usually are made up of an inner layer of double or triple pane glass usually filled with air, krypton, or argon gas in order to provide insulatory value. The outer skin of the façade usually around 800 mm out from the inner skin is also made of glass. This double skin design causes a volume of air to be trapped inside the cavity of the double skin. As the solar radiation penetrates the façade the air in the cavity heats up and begins to rise forcing cooler air near the ground to be forced into the cavity and the hot air out of a vent at the top of the building, similar to a chimney. An example of this can be seen in the figure below.

In warmer conditions the air exiting the vent at the top has no practical use and is just expelled into the air however in colder winter conditions the hot air collected in the façade can be used to feed the air handling unit of the heating system. The double skin also acts as a sound insulator as well. Filtering outside noise from the building.


In many cases facades are also paired with a series of light shelves in order to further increase the effectiveness of the façade. The shelves can be as simple as a set of venetian blinds or they be a more complicated structure incorporated in to the façade. In either case the light shelf’s basic design is to reflect light and solar radiation deeper into a build or in some cases to act as a blind and block solar radiation. An example of a light shelf can be seen below.







These designs are often paired with light-colored walls and ceilings so that light reflected into the building will then continue further. In many cases deep penetration of sunlight will not only cut down on lighting cost be can actually improve human productivity and effectiveness, especially in an office building environment. This is due to many different factors, such as a preference for natural lighting over artificial lighting, as well as the spectral distribution of light. Daylight is often less harsh than artificial lighting and also changes as the day goes by, which human eyes have adapted to over time. Keeping at least part of this natural rhythm can keep workers more comfortable and decrease eye strain. Also, by reflecting light indirectly into the building workers gain these benefits while avoiding glares, which are very common in unshaded windows.


In some cases, such as the Al Bahar Towers, which serves as the Abu Dhabi Investment Council Headquarters in Dubai, the facades on buildings are designed to be transformable. In this building, the facade’s pieces change shape individually depending on the amount of light detected by a set of sensors. These pieces then can either open or close more in order to block light or allow it into the building, as shown in the figure below. This building’s cylindrical shape allows it to have a very large volume and views in all directions, but it also allows in quite a bit of solar radiation, which is a problem for this hot and dry climate. Designers estimated that this facade could “effectively reducing heat gain and glare by 50%,” though this could obviously be overly optimistic. They also claimed that this change could lead to less lighting and cooling costs and decrease the carbon dioxide emissions of the building by 1750 tons a year. These designs are becoming more widespread as the technology is explored.






A link to the original project proposal, much of which has been altered, can be found here.
A graded first draft of the final report can be accessed here.
The group's presentation can be found here.
The group's final paper can be found here.
The SketchUp file with the facade displayed on the Cira Center can be found in the 3d Warehouse and is accessible here.



References:


H. Poirazis. "Double Skin Façades for Office Buildings: Literature Review." Lund Institute of Technology. Lund, Sweden. Report EBD-R--04/3, 2004.

J.Vaglio. “Double-Skin Facade.” Internet: http://www.jeffvaglio.com/research/double-skin-facade. 2012 [May 10, 2013].

J. Hensen, Ph.D., M. Bartak, F. Drkal, Ph.D. "Modeling and Simulation of a Double-Skin Façade System." ASHRAE Transactions, Vol 108, Part 2, pp 1251-1259. 2002.

O. A. Abdou. "Effects of Luminous Environment on Worker Productivity in Building Spaces." Journal of Architectural Engineering, Vol. 3, pp. 124-132, Sep 1197

R.P. Leslie. "Review: Capturing the daylight dividend in buildings: why and how?" Building and Environment, vol. 38, pp. 381 – 385, 2003.

D. Libeskind. “Aedas: Al Bahar Towers.” Internet: http://www.designboom.com/architecture/aedas-al-bahar-towers. Sep 19, 2012. [May 8, 2013].