Reflective Shading

In the summer of 2005, an innovative reflective shading device was evaluated at the Canadian Centre for Housing Technology (CCHT) twin-house facility. The shades were built from materials readily available at the hardware store: foil covered polyethylene bubble (two layers of polyethylene bubble sandwiched between two layers of aluminium foil), and screen frames. The shades were installed on the interior of the south and west facing windows of the CCHT Test House, leaving a small gap (~3 cm, 1") between the window surface and the shade.

Foil shades installed in the CCHT Test House

Past evaluations of shading systems at the CCHT had revealed that opaque exterior shading was more effective than interior Venetian blinds at reducing cooling energy consumption. The reflective shading experiment was led by CMHC, hoping to identify an inexpensive interior shading option that could be used in locations where exterior shading was not a possibility, or as a temporary measure during the hottest portion of the cooling season. During the experiment, two different shading strategies were evaluated: shading 24 hours per day, and shading from 9 a.m. to 5 p.m.

Although energy savings were achieved, the reflective shades caused window surface temperatures to approach the operating limits. These high temperatures lead to thermal stresses that could potentially damage the glazing unit. 

Report:

Assessment of Reflective Interior Shades at the Canadian Centre for Housing Technology
Manning, M.M. Swinton, M.C. Ruest, K.
pp. 38. 2007-02-09
[Full citation / Référence complète]

Research Highlights:

The Effects of Reflective Interior Shades on Cooling Energy Consumption at the CCHT Research Facility