How to Know If You’re Purchasing an Energy Efficient Window

In the past few months, you noticed a steady rise in your energy cost. You should find the culprit before your energy costs skyrocket. Have you checked your windows? Keep in mind that if you have a drafty window, your furnace is required to work overtime to compensate.

Instead of wasting your energy and money, you should think about investing in energy efficient home window replacement but how do you know if you are purchasing an energy efficient window? You have to look into energy efficiency rating system for windows.

Understanding the NFRC (National Fenestration Rating Council) rating system

You must know that only NFRC administers uniform rating and labeling system for the energy performance of doors, windows, skylights, and other attachment products. At the very least, when you buy windows, you should check the NFRC label. In the label, you will see the following:

  • U-factor: U-factor gauges how the window effectively prevents the heat from escaping. Keep in mind that the U-factor falls between 0.20 and 1.20. When looking at the U-factor, remember that the lower the value, the greater the window’s resistance to the flow of heat. In the end, this simply means it has better insulating value.
  • SHGC (Solar Heat Gain Coefficient): the SHGC gauges how well the window blocks the heat caused by the sun. It is expressed in numbers – typically between 0 and 1. Remember that the lower a window’s SHGC, the less solar heat it diffuses.
  • VT (Visible Transmittance): VT, on the other hand, gauges the amount of light that comes through the window. It is also expressed in numbers – typically between O and 1. Remember that the higher the VT, the more light is diffused.
  • AL (Air Leakage): this refers to the passing of air through a square foot of a window area. This is an important aspect because heat gain and loss happen due to cracks in the window assembly. Remember that the lower the AL, the less air can infiltrate through the cracks.
  • CR (Condensation Resistance): this refers to the ability of the window to repel condensation on its interior surface. Remember that the higher the CR, the better the window is at repelling the formation of condensation.

You must know though that the AL and the CR are optional. This means that the manufacturer can opt not to include it in the standard label. Even with the U-factor, SHGC, and VT, you still have an idea what window to consider.

Understanding Energy Star certified products

You can also look for windows with the Energy Star label. The Energy Star is introduced by EPA (Environmental Protection Agency). It is a labeling program that is designed to promote energy-efficient products. The sole purpose of this labeling program is to reduce greenhouse gas emissions. Through the partnerships of Energy Star, it provides the technical information and tools that you need to choose an energy efficient solution.