Thermal emittance

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The thermal emittance of a material refers to its ability to release absorbed heat. It is usually expressed as a number between 0 and 1. Determining the thermal emittance and solar reflectance of building materials, especially roofing materials can be very useful for reducing heating and cooling energy costs in buildings.

Roof tiles with a high thermal emittance will radiate heat gained from the sun back into the atmosphere more readily than one with a low thermal emittance. A radiant barrier system inside an attic with its low thermal emittance keeps the excessive heat of the attic away from living spaces.