Marvin Windows Feature

What Makes a Window Energy-Efficient?

Energy-efficient windows can help make your home more comfortable as well as reduce your utility bills. Basically, energy-efficient windows reduce the amount of heat that enters or escapes through the windows. How do you know if a window is energy efficient? Certification programs such as the National Fenestration Rating Council (NFRC) or ENERGY STAR rank windows on key performance metrics for energy efficiency. Here are three of the more important ones you’ll want to know.

Jeremy Devol

Jeremy Devol
Window & Door Specialist

U-Factor – Simply put, U-factor measures how well a window keeps heat inside your home. It’s a measure of total heat flow through a window or door from room air to outside air. Lower numbers indicate greater insulating capabilities. It’s a particularly important measure for climates with colder winters.

Solar Heat Gain – Solar Heat Gain Coefficient (SHGC) measures how much radiant heat enters your home. All you really need to remember is this. The lower the number, the less heat a window lets in.

Visible Transmittance (VT) – Visible Transmittance is the amount of visible light transferred through a window. Low E coatings can reject solar heat gain without reducing visible light transfer. A high VT is desirable to maximize daylight.

Are Energy-Efficient Windows Worth It?

Over the long term, energy-efficient windows are definitely worth considering. Regardless of where you live, energy-efficient windows and doors can help you achieve long-term performance and energy cost savings in any climate. As an added bonus, you can receive hundreds of dollars in federal tax credits for energy-efficient windows provided they meet program criteria.