Table 1: REFLECTANCE AND EMITTANCE EXAMPLES SOLAR ROOFING INITIAL SOLAR THERMAL TEMPERATURE REFLECTANCE TYPE REFLECTANCE EMITTANCE RISE-ROOF INDEX Smooth 0.06 0.86 83°F -1 Bitumen Black EPDM 0.06 0.86 83°F -1 White 0.26 0.92 63°F 28 Granular Surfaced Bitumen Light Gravel 0.34 0.9 57°F 37 on Bitumen New Bare 0.61 0.04 55°F 46 Galvanized (sloped roof) Aluminum 0.61 0.25 48°F 56 (sloped roof) Brand name 0.59-0.67 0.85 28-37°F 71-82 White-Metal (sloped) White-coated 0.65 0.9 28°F 79 Gravel on Bitumen White 0.65-0.85 0.89-0.91 9-28°F 79-107 Coatings White EPDM 0.69-0.76 0.87-0.9 25°F 84 Brand Name 0.75-0.83 0.90-0.92 11-19°F 93-104 White membranes (from Lawrence Berkeley National Laboratories) The US Building Council’s LEED rating system has set the following minimum criteria for at least 75% of any roof: Table 2: LEED credit for Sustainable Sites Credit 7.2- Heat island Effect: Roofs Roof Type Slope SRI (minimum) Low-sloped roof <2:12 78 Steep-sloped roof >2:12 29 B. SELECTION GUIDELINES FOR COOL ROOF PROJECTS
Table 1: REFLECTANCE AND EMITTANCE EXAMPLES ROOFING TYPE INITIAL SOLAR REFLECTANCE THERMAL EMITTANCE TEMPERATURE RISE-ROOF SOLAR REFLECTANCE INDEX Smooth Bitumen 0.06 0.86 83°F -1 Black EPDM 0.06 0.86 83°F -1 White Granular Surfaced Bitumen 0.26 0.92 63°F 28 Light Gravel on Bitumen 0.34 0.9 57°F 37 New Bare Galvanized (sloped roof) 0.61 0.04 55°F 46 Aluminum (sloped roof) 0.61 0.25 48°F 56 Brand name White-Metal (sloped) 0.59-0.67 0.85 28-37°F 71-82 White-coated Gravel on Bitumen 0.65 0.9 28°F 79 White Coatings 0.65-0.85 0.89-0.91 9-28°F 79-107 White EPDM 0.69-0.76 0.87-0.9 25°F 84 Brand Name White membranes 0.75-0.83 0.90-0.92 11-19°F 93-104 (from Lawrence Berkeley National Laboratories) The US Building Council’s LEED rating system has set the following minimum criteria for at least 75% of any roof: Table 2: LEED credit for Sustainable Sites Credit 7.2- Heat island Effect: Roofs Roof Type Slope SRI (minimum) Low-sloped roof <2:12 78 Steep-sloped roof >2:12 29 B. SELECTION GUIDELINES FOR COOL ROOF PROJECTS
09170101SustainableRoofingGuidelines.docx