ASTM E1918-16

5.1 Solar reflectance is an important factor affecting surface and near-surface ambient air temperature. Surfaces with low solar reflectance (typically 30 % or lower), absorb a high fraction of the incoming solar energy which is either conducted into buildings or convected to air (leading to higher air temperatures). Use of materials with high solar reflectance may result in lower air-conditioning energy use and cooler cities and communities. The test method described here measures the solar reflectance of surfaces in the field.

1.1 This test method covers the measurement of solar reflectance of various horizontal and low-sloped surfaces and materials in the field, using a pyranometer. The test method is intended for use when the sun angle to the normal from a surface is less than 45°.