Page 104 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

LEED Sustainable Sites 85

Example SRI Values for Solar Infrared Temperature
Generic Material Reflectance Emittance Rise (°F) SRI
Gray EPDM 0.23 0.87 68 21
Gray asphalt shingle 0.22 0.91 67 22
Unpainted cement tile 0.25 0.90 65 25
White granular surface 0.26 0.92 63 28
bitumen
Red clay tile 0.33 0.90 58 36
Light gravel on built-up roof 0.34 0.90 57 37
Aluminum coating 0.61 0.25 48 50
White-coated gravel on 0.65 0.90 28 79
built-up roof
White coating on metal roof 0.67 0.85 28 82
White EPDM 0.69 0.87 25 84
White cement tile 0.73 0.90 21 90
White coating—1 coat, 8 mils 0.80 0.91 14 100
PVC white 0.83 0.92 11 104
White coating—2 coats,
0.85 0.91 9 107
20 mils
Source: LBNL Cool Roofing Materials Database (http://eetd,lbl.gov/CoolRoofs). These values are for
reference only and are not for use as substitutes for actual manufacturer data.
TABLE 2.7.3 Some Typical SRI Values for Roofing Materials

need well more than 100 squares of shingles to be covered. In addition, any roofed areas
that hold equipment, solar energy panels, skylights, or other appurtenances (EQR as
previously defined) are not included in the calculations. Using the site plan, the total
roof surface area of the project (TR) would equal the sum of the horizontal projections
of the roofs on the site plan (BF) less the sum of the roofed areas that hold equipment,
solar energy panels, or other appurtenances (EQR). That is,

TR = BF − EQR (2.7.3)

In addition, the following variables should be determined from the associated areas on
the site plan:
VR Sum of the vegetated roofed areas
RRL Sum of the low-slope roofed areas with an areal weighted average SRI greater than 78
RRS Sum of the steep-slope roofed areas with an areal weighted average SRI greater
than 29