To reduce heat islands to minimize effects on the microclimate and human and wildlife habitat.
Option 1. Nonroof measures
Use any combination of the following strategies for 50% of the nonroof site hardscape (including roads, sidewalks, courtyards, parking lots, parking structures, and driveways):
- Provide shade from open structures, such as those supporting solar photovoltaic panels, canopied walkways, and vine pergolas, all with a solar reflectance index (SRI) of at least 29.
- Use paving materials with an SRI of at least 29.
- Install an open-grid pavement system that is at least 50% pervious.
- Provide shade from tree canopy (within ten years of landscape installation).
Option 2. High-reflectance and vegetated roofs
Use roofing materials that have an SRI equal to or greater than the values in Table 1 for a minimum of 75% of the roof area of all new buildings within the project; or install a vegetated (“green”) roof for at least 50% of the roof area of all new buildings within the project. Combinations of SRI-compliant and vegetated roofs can be used provided they satisfy the equation in Option 3.
Table 1. Minimum solar reflectance index value, by roof slope
|Low (≤ 2:12)||78|
|Steep (> 2:12)||29|
Option 3. Mixed nonroof and roof measures
Use any of the strategies listed under Options 1 and 2 that in combination meet the following criterion:
Area of Nonroof Measures
Area of SRI Roof
Area of Vegetated Roof
|≥||Total Site Hardscape Area||+||Total Roof Area|
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