Solar reflectance and thermal emittance measurements and Solar Reflectance Index (SRI) reporting in accordance with ASTM E1980
Surface Optics specializes in providing ASTM E903 compliant testing services to determine the solar reflectance and transmittance properties of materials. Our laboratory is equipped with advanced instrumentation and staffed by experienced professionals dedicated to delivering precise and reliable results for your solar energy, space and material science needs.
What is ASTM E1980?
ASTM E1980-11 (2019) is the standard practice for utilizing solar reflectance and thermal emittance measurements to calculate the Solar Reflectance Index (SRI) of horizontal and low-sloped opaque surfaces.
Solar reflectance and thermal emittance are crucial factors influencing surface and near-surface ambient air temperatures. Surfaces with low solar reflectance absorb a significant portion of incoming solar energy. Part of this absorbed energy is conducted into the ground and buildings, some is convected to the air (raising air temperatures), and some is radiated to the sky. Under similar conditions, lower emissivity surfaces have higher steady-state temperatures because they cannot effectively radiate heat to the sky, causing them to become hotter.
By determining solar reflectance and thermal emittance and calculating the relative temperature of surfaces compared to black and white reference temperatures (defined as the Solar Reflectance Index, SRI), designers and consumers can select materials that enhance the energy efficiency of buildings and communities. This method provides the SRI of surfaces based on measured solar reflectance and thermal emissivity.
Instrumentation
- ET100 Emissometer: Manufactured by Surface Optics Corporation, the ET100 measures directional reflectance at six bands in the thermal infrared spectral region at two incidence angles, 20° and 60°. Based on those values, directional and total hemispherical emissivity is calculated.
- SOC410-Solar Reflectometer: Manufactured by Surface Optics Corporation, the 410-Solar measures total reflectance at seven sub-bands in the 300-2500 nm spectral regions and calculates total solar reflectance.
Report
ASTM E1980 test reports include:
- The solar reflectance and the thermal emittance of the test surface.
- The calculated SRI for three convective coefficients corresponding to low, medium, and high-wind conditions.