How Do Windows Impact Energy Efficiency?
Glass is conductive and allows hot and cold air to transfer inside. Without focusing on energy savings, windows contribute to major temperature shifts, which require the heating and cooling system to work harder to maintain a consistent indoor temperature.
Today’s vinyl windows focus on thermal performance. Window features tackle the factors that influence heat transfer to create a stable temperature.
Solar Heat Gain Coefficient (SHGC)
SHGC measures a window’s ability to keep solar heat from passing through the glass. Solar heat transfer warms the interior of a home via the greenhouse effect. The lower the SHGC measure, the better a window rejects solar heat gain.
U-Factor measures a window’s resistance to heat transfer through the window. The measurement includes heat transfer in both directions. In other words, it measures the level of the window’s insulation. A lower number indicates a better insulation capability of the window.