Site and Water Guidelines

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S.11 Heat Island Reduction

Reduce heat islands (thermal gradient differences between developed and undeveloped areas) to minimize impact on microclimate and human and wildlife habitat.

Recommended Performance Criteria

  1. Non-roof site surfaces:

    Provide at any combination of the following characteristics for 50% of the site hardscape:

    • Surface is light colored/high albedo (reflectance is .30 or greater.)
    • Surface composed of an open-grid pavement system (less than 50% impervious)
    • 50% of non-parking surfaces will be shaded within 5 years.
    • 50% of parking surfaces will be shaded within 10 years.
    • OR 100% of non-circulation parking surface will be shaded within 10 years.


    • Place a minimum of 50% of parking spaces underground or in a structured parking facility.
  2. Roof Surfaces:
    • Use ENERGY STAR Roof-compliant, high-reflectance AND high emissivity roofing (initial reflectance of at least 0.65 and three-year-aged reflectance of at least 0.5 when tested in accordance with ASTM #903 and emissivity of at least 0.9 when tested in accordance with ASTM 408) for a minimum of 75% of the roof surface.


    • Install a "green" (vegetated) roof for at least 50% of the roof area.


    • The two options can be combined by the following formula: (high albedo roof Area/.75) + (green roof area/.5) is greater than or equal to total roof area.

Related B3 Guidelines Documents

Supplemental Resources

  • Public Technology, Inc., U.S. Green Building Council, U.S. DOE, U.S EPA. Sustainable Building Technical Manual, Part 3 (Part 3 deals with Site issues, all issues under S.11), Chapters 5, 6,7 and 8. Available from
  • Green Roofs for Healthy Cities website:

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