Hawkins Windows LLC
Understanding Energy Ratings
.jpeg)
U-factor
U-Value, sometimes called window U-Factor, measures the rate of heat transfer it tells you how much heat is lost or gained through your window. According to Energy Star, the U-Value of a window can range from .25 to 1.25. The lower the U-Value, the more energy efficient your window is bound to be. If your windows see a lot of direct sunlight, you’ll want to find windows with lower u values.
Solar Heat Gain Coefficient
The Solar Heat Gain Coefficient measures the amount of solar radiation and heat that your windows allow inside the home. The lower the number, the less radiation. This measurement can range from 0 to 1. If your home sees a great deal of sunlight, look for windows with a lower SHGC measurement.
Visible Transmittance
Visible Transmittance tells you how much light is allowed to pass through a window. It’s measured on a scale from 0 to 1; the lower the number, the less light will be allowed in. Depending on where you live and the amount of sunlight your home gets, you may want windows with lower or higher visible transmittance.
Air Leakage
This measures the amount of air that a window allows to pass through. The lower the number, the more airtight the window. If you live somewhere windy, you might want a lower air leakage rating. Air leakage ratings typically range from 0.1 to 0.3.