While shopping for a new energy-efficient window, always look for the ENERGY STAR® label. Only replacement windows that have met strict performance standards can receive this certification from the government-run program. However, not all ENERGY STAR-certified windows are suitable for your home – each window is only certified for a particular area or climate zone, which is indicated on top of the label.
You also need to check the window’s National Fenestration Rating Council (NFRC) ratings, which are usually placed below the label.
The NFRC Ratings
- U-factor – The rating gives you an idea of a window’s insulative capabilities. The lower the window’s U-factor, the better it can prevent heat transfer.
- Solar Heat Gain Coefficient (SHGC) – The rating indicates the amount of heat from the sun that can pass through the window glass. The lower the SHGC rating, the less heat a window can let through into your home.
- Visible Transmittance (VT) – The VT rating gives you an idea of how much natural lighting a window can provide. The higher this rating, the better more sunlight a window can let inside.
- Air Leakage (AL) – A window’s AL rating indicates how much air can enter your home through a window. The lower this rating, the fewer drafts your windows will let in.
For homeowners living in temperate climates, we recommend installing windows with a low U-factor. The south side of your home receives the highest amount of sunlight so it’d be a good idea to install windows with a high SHGC. That way, you can take full advantage of the heat from the sun in winter. You can simply install shades over the windows in summer to keep your interior from becoming too hot.
Total Window Performance
It would also be a good idea to look for other features that can help optimize your window’s energy efficiency. If you’re considering installing vinyl replacement windows, for example, make sure the frames are insulated.
One more thing: make sure your new windows are installed by an experienced contractor. Otherwise, heat can leak through gaps between the wall and the window frame. WMGB Home Improvement, a contractor with more than three decades’ worth of experience, offers a wide range of premium windows, including egress window options. For inquiries, you can give us a call at (616) 328-6625, or fill out our form here. We serve homeowners in Kalamazoo and Grand Rapids, MI, as well as the surrounding communities.