4 Metrics to Use for Evaluating Whole-Window Performance

While modern replacement windows are designed with energy performance in mind, not all of them perform the same way. You’ll need to make careful choices if you want to pick the best ones out of the bunch. Fortunately, assessing the energy performance of a given window is made easier by the National Fenestration Rating Council (NFRC), which assesses whole-window performance through set metrics. 

You’ll find all these details included in the black-and-white NFRC label placed visibly on the window. But what exactly are these metrics? Renewal by Andersen® of Montana offers a quick overview of them here:

1. U-Factor – This rates the amount of heat that escapes your home through the window. The lower the U-factor, the less heat is lost via the unit. If you live somewhere with a predominantly cold climate, you’ll find that choosing replacement windows with a low U-factor is especially beneficial as they can help reduce your heating bills.

2. Solar Heat Gain Coefficient (SHGC) – This determines the amount of solar heat being transferred into your home via the windows. Those who live in areas with a warm climate will appreciate windows with a lower SHGC rating, and here’s why: they absorb and transmit less solar heat, helping keep the home cooler for longer periods without needing to crank up the air conditioner.

3. Visible Transmittance (VT) – This measures the amount of sunlight your window is letting into your home. The higher the VT, the more natural light that’s being streamed into your living space. Buying windows with high visible transmittance ensures your home will be illuminated naturally during the daytime. This, in turn, allows you to save a fair bit on artificial lighting costs.

4. Air Leakage – This optional rating determines the volume of air that leaks into your home from the outside. You’ll want to choose a window with a lower air leakage rating to eliminate the possibility of drafts.

Request a Window Quote Now

You’ll find the best-performing replacement windows in one place – Renewal by Andersen of Montana. All of our windows are designed to deliver superior durability and energy-saving performance, making them a worthwhile investment for every discerning homeowner. Schedule your window consultation by calling (406) 259-3944 today or filling out this contact form. We proudly serve homeowners in Billings, MT, and other areas in Yellowstone County.