Asphalt Shingles

The Cool Roofing Materials Database was created in 1998 and may not be current.

General Description

Asphalt shingles are a very economic roofing choice, which have a large share of the market, including most houses with sloping roofs. From a reflectance point of view, they are very similar to rolled asphalt roofing, which is often used as the top layer of low slope roofing. These materials are composed of asphalt saturated mats made from organic felts or fiberglass. The asphalt is protected from the sun's uv light by roofing granules pressed into the shingle while it is hot (and soft). The roofing granules are 1 millimeter-sized stones (e.g., of crushed granite), which are coated with an inorganic silicate material. The coating contains microscopic pigment particles, similar to those used in paint, to provide color.

Graph charting the solar reflectance of seven different asphalt shingles.

The solar reflectance of all commercial asphalt shingles is rather low (see table). Premium white shingles are only about 30% reflective, and other colors reflect less. (Incidentally, white roofing materials usually contain additive to inhibit biological growth, to avoid roof discoloration.) The low solar reflectance can be attributed to several factors. First, there is a limited amount of pigment in the granule coating. Also, the roughness of the shingle contributes to multiple scattering of light and thus to increased absorption. Finally, the black asphalt substrate is not 100% covered, and reflects only about 5% of the light which strikes it. ISP Minerals of Hagerstown, MD has developed a whiter white roofing granule which can be fabricated into shingles with reflectance exceeding 50%. It is hoped that this granule will become available commercially.

Table 1. Solar Reflectance and Thermal Performance of Asphalt Shingles
Product Solar Reflectance Infrared Emittance Temperature Rise Solar Reflectance Index Reference
White 0.21 0.91 68F 21 LBNL 1
ISPK-711 White 0.36 0.91 55F 40 LBNL 2
ISPK-711 White 0.31 0.91 59F 34 FSEC 1
Shasta White 0.26 0.91 64F 27 FSEC 1
Generic White 0.25 0.91 64F 26 FSEC 1
Generic Grey 0.22 0.91 67F 22 FSEC 1
Antique Silver 0.20 0.91 69F 19 LBNL 1
Aspen Gray 0.18 0.91 71F 17 FSEC 1
Ocean Gray 0.12 0.91 76F 9 FSEC 1
Gray 0.08 0.91 79F 4 LBNL 1
Beachwood Sand 0.20 0.91 69F 19 FSEC 1
Light Brown 0.19 0.91 70F 18 LBNL 1
Medium Lt. Brown 0.10 0.91 77F 7 LBNL 1
Medium Brown 0.12 0.91 76F 9 LBNL 1
Autumn Brown 0.10 0.91 77F 7 FSEC 1
Dark Brown 0.08 0.91 79F 4 LBNL 1
Green 0.19 0.91 70F 18 LBNL 1
Surf Green 0.16 0.91 72F 14 FSEC 1
Onyx Black 0.03 0.91 83 F -2 FSEC 1
Island Brown 0.09 0.91 78 F 6 FSEC 1
Weathered Wood 0.08 0.91 79 F 4 FSEC 1
Coral 0.16 0.91 72 F 14 LBNL 1
Saddle Tan 0.16 0.91 72 F 14 LBNL 1
Desert Tan 0.12 0.91 76 F 9 FSEC 1
Generic Black 0.05 0.91 82 F 1 FSEC 1
Black 0.05 0.91 82 F 1 LBNL 1

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