Gaines Group Architects

Green term defined: solar reflectance index

harrisonburgWhen looking at cities on Google earth, we see a lot of dark surfaces. Most roofing is a dark color. Pavement is typically a dark color. It appears that even the majority of our cars are dark. This all contributes to something called “heat island impact.” To combat this a designer can use light colored materials for pavement, roofing, and reduce paved areas on a site.

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The solar reflectance index (SRI) is a measure of the constructed surface’s ability to stay cool in the sun by reflecting solar radiation and emitting thermal radiation. A standard black surface has a SRI of 0 and a standard white surface has a SRI of 100. In order to calculate the SRI of a material you use the solar reflectance and thermal emittance from the cool roof rating council standard. 263878_10150252705649932_76986384931_7060298_6065340_nYou can offset “heat island impact” by using white roofing, white concrete for paving, and vegetative roofs.