What is SHGC and Why is it Important?

Various standards and estimations are used to compare the insulating properties of different windows and doors. These estimations are essential for designers and building owners to make informed decisions that will directly affect their energy efficiency programs and, ultimately, their bottom line. One measure of energy transfer through a building component is significant and often drives decision-making in building design areas such as air conditioning and heating. This ultimate factor is the SHGC.



How do these values determine which door to install?

In warmer climates, designers tend to choose a door with a low SHGC (.06-31) to keep their buildings cool while reducing their energy costs. Colder climates lean toward a higher SHGC (.45-.57) to benefit from the free solar heat. The numbers vary depending on temperature, shading capabilities, and orientation.

In some geographic areas where there are drastic swings in the amount of sunlight a building sees between the warm summer months and the cold winter months, designers will use a hybrid shading model. This includes applying a Low-e coating to the glass to control the amount of solar radiation that is allowed to pass through the fenestration product and installing small visors above all of the glass to control the amount of sunlight that the fenestration product is exposed to (depending on the angle of the sun at that time of year).

This building is located at the Rochester Institute of Technology. It uses this hybrid model for shading and improving the building’s efficiency by controlling the incoming solar radiation so that it does not enter during the summer when the sun is high in the sky but is allowed to join in the winter when the sun is lower in the sky.

Find out how a thermal break can play a role in the energy efficiency of your doors.