Windows add natural light and beauty to your home, but if there’s more to consider than just looks. Save money and energy by choosing windows that are energy-efficient.
Window Efficiency Ratings
The NFRC (National Fenestration Rating Council) provides accurate, independently verified, information to compare the energy performance of windows. Here are a few terms to know:
- U-factor – The rate at which the window conducts non-solar heat. The lower the number, the more efficient the window. The larger your heating bill is, the more important the u-factor becomes. Recommended U-factor for Kansas City is 0.25 or lower.
- Solar Heat Gain Coefficient (SHGC) – The amount of heat transmitted from the sun through the window. The lower the number, the more efficient the window. If you have high cooling bill is, the u-factor is even more important. Recommended SGHC for Kansas City is 0.25 or less.
- Air Leakage – The amount of air movement around the window edges. Measured in cubic feet per minute per square foot of frame area. A lower number means less air leakage.
- Visible Transmittance (VT) – The amount of visible light transmitted through the window.
- Light-to-Solar Gain (LSG) – LSG is the ratio between the SHGC and VT. The higher the number, the more light allowed through while blocking the heat.
Look for ENERGY STAR certified residential windows, which are rated for high energy performance and can lower your home’s energy bills.
Another factor that affects efficiency is the style and way in which the window opens, and how much air leakage it allows.
Fixed windows don’t open, so they have the least amount of air leakage. However, they’re not suitable in areas where you want to be able to open your windows for ventilation or safety, like a bedroom, kitchen or family room.
Awning, hopper and casement windows can open and close by tilting or swinging a single section outward. They also allow minimal air leakage.
Double-hung and double-sliding windows also open and close, but they have two sections that lift or tilt independently, resulting in higher rates of air leakage.
A glazing, or coating, on the window affects how much light and heat are let in. In rooms where you want more natural light, like bedrooms and kitchens, look for a high VT (Visual Transmittance) number with a high LSG (light-to-solar gain). If you are trying to reduce the glare coming in from the window, like in an office or TV room, choose a window with a lower VT number.
Improper installation can cause unnecessary energy loss even for the most efficient windows. That’s why it’s important to choose a professional installer once you’ve chosen the ideas windows for your home. In the Kansas City area, call Precision Windows and Doors at 816-524-8999 or 913-649-1199 for a free estimate.
About Precision Siding & Windows
Precision Siding & Windows offers premium replacement windows, siding, doors, garage doors, and installation. Our friendly, experienced staff arrives on time and works quickly to complete your home improvements or commercial construction including work on windows, doors, siding, guttering, and roofing.
With over 30 years of experience serving customers in Overland Park, Leawood, Parkville, Kansas City, Ottawa, Lee’s Summit, and even more areas within a 50-mile radius, we guarantee you’ll be satisfied with our high quality of work. Contact us for a free, no-pressure estimate to get started, and ask us about no-interest financing!