Solar Heat Gain

Heat transfer always occurs from a higher temperature object to a cooler temperature object so on a sunny day heat from the sun travels from the outside of your house to the indoors. Solar Heat Gain (scientist call it a Solar Heat Gain Coefficient) measures heat transfer caused by radiation.


Energy is transferred through empty space.

Our Window’s Defense Against Radiation

Low - E glass coatings that reflects radiant heat back toward its source.
  • Our HP Max Glass has multi-layer defense against radiation:
    • First Barrier
    • Metal Oxide
    • Silver
    • Second Barrier
    • Metal Oxide
    • Silver
    • Metal Oxide
    • Third Barrier

Solar Heat Gain Numbers

The Solar Heat Gain number measures how much heat is transferred through your entire window from the sun. The lower the number the better in the summer. However, in northern climates, a higher number is better in the winter allowing the sun to help heat your home. Adding multiple layers of low-e coating will reduce the Solar Heat Gain. The number is a percentage. So a Solar Heat Gain of .28 means only 28% of the sun’s heat is entering your home. Beware of window companies that measure the center of the glass. These numbers will be lower but you are not buying just the center of the glass, you are buying an entire window. Our numbers represent the entire window.

Low-E Glass Helps in the Winter Too

Radiant heat is not only generated from the sun, it is also generated from your furnace. Low-E glass coatings will help trap that radiant heat inside your home in the winter. Low-E glass keeps your home cooler in the summer and warmer in the winter.