U-Value (Heat Transfer Co-efficient) The U-value, also known as the overall heat transfer coefficient, represents the rate of heat transfer through a material or assembly. It measures how well a material or construction component insulates against heat loss or gain. A lower U-value indicates better insulation properties, meaning less heat is transmitted through the material. SHGC (Solar Heat Gain Co-efficient) SHGC stands for Solar Heat Gain Coefficient. It is a measure of ho