Solar Reflectance, Thermal Emittance and Solar Reflective Index (SRI)
To be considered “cool,” products must have a Solar Reflectance of at least 25%. Solar Reflectance is the fraction of the total solar energy that is reflected away from a surface.
Thermal Emittance is the measure of a panel’s ability to release heat that it has absorbed.
Solar Reflectance Index (SRI)
Put Solar Reflectance and Thermal Emittance together and you get the Solar Reflective Index (SRI). SRI is calculated by using the values of solar reflectance, thermal emittance and a medium wind coefficient. The higher the SRI value, the lower its surface temperature and consequently, the heat gain into the building. Cool metal roofs coated with the COOL-pigmented PVDF resin achieve an SRI of 25-88, depending on the color.
Conventional roof surfaces have low reflectance (0.05 to 0.25) and high thermal emittance (typically over 85%). Roof panels with both high reflectance and high emittance can reduce surface temperature by as much as 30-50% based on color and geographic location, which will result in a reduced heat gain to the building, therefore reducing energy demand.
Cool science isn’t just a meaningless marketing term. It’s a technology that is literally revolutionizing the building industry. Combating urban heat islands and high-energy consumption will require innovative products that meet or exceed even the most stringent industry requirements. Our SmartKote and SP-Cool coated panels are that type of product.
Just think, the more energy costs rise, the more money you save with SmartKote and SP-Cool.
For Solar Reflectance, Thermal Emittance, and the Solar Reflectance Index (SRI) ratings on American Buildings coatings, click here.