Sustainable Sites - Credit 7.1
Heat Island Effect - Nonroof (1 points)
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The intent of this credit is to reduce heat islands (thermal gradient differences between developed and undeveloped areas) to minimize impact on microclimate and human and wildlife habitat. Strategies include providing shade for at least 50% of hardscaped surfaces or providing hardscaped surfaces with solar reflectance index (SRI) of at least 29. The requirement for SRI can be met by using concrete rather than asphalt for 50% of all sidewalks, parking lots, drives and other impervious surfaces.
Solar reflectance is the ratio of the amount of solar radiation reflected from a material to the amount that shines on the material. Generally, light-colored surfaces have a high SRI. Where paved surfaces are required, using materials with higher SRI will reduce the heat island effect---consequently saving energy by reducing the demand for air conditioning--and improve air quality.
Concrete generally has an SRI of greater than 29. Concretes made with white cements or slag can have SRI greater than 78. As a comparison, new asphalt generally has an SRI of approximately 0, and asphalt five or more years old has an SRI of approximately 6. This credit is typically achieved when parking areas, walks and plazas are paved with concrete.
Another strategy to achieve this credit is to place a minimum of 50% of parking spaces under cover, including underground, under deck, under roof or under building. Concrete is typically the material of choice for parking structures. This credit is worth 1 point.