Step 1: Look for Energy Star Label & Rating
When it comes to purchasing energy-efficient products, you should go for products with an Energy Star label. Nonetheless, selecting Energy Star qualified windows for your home is not as easy as it sounds. Energy Star window efficiency is determined by two performance ratings: U-factor and Solar Heat Gain Coefficient (SHGC). To learn what window performance criteria would work better for your home, it is important to understand these two rating systems.
- U-Factor: A rating that shows how much non-solar heat can escape from your home through the window. The lower the U-factor rating, the more energy-efficient the window is.
- SHGC: This determines how much solar heat can pass through the window. The lower the SHGC, the better the window is at blocking unwanted solar heat gain.
According to Energy Star, energy-efficient windows are like winter coats; you should pick them based on your climate. Here are some performance measurement recommendations for different U.S. climate zones.
Step 2: Frame Your Windows Right
Most homeowners overlook the importance of window frames when selecting windows. In fact, the material of window frames does affect the energy efficiency of windows. Window frames can be made by a variety of materials, such as aluminum, wood, vinyl and composite. Each type has different rates of heat transfer. It’s hard to conclude which material is the best in terms of energy saving because all of them have advantages and disadvantages. Oftentimes, it’s up to where you live and what style you like. For instance, although wood, vinyl and fiberglass frames are mostly recommended by window experts, as they are much more resistant to heat transfer than aluminum, aluminum frames are still a practical option in humid climates. Also, even if vinyl frames are good at reducing air leakage, their limitation in colors options may hinder homeowners.
Step 3: Understand Different Types of Window Glazing
Window glasses are not all the same. According to Department of Energy, there is an increase in sophistication of glazing technology. Homeowners should choose the right kind of glazing based on their climate and home’s design to efficiently lower heating costs. The most common types of glazing are gas fills, heat-absorbing tints, low-e coatings and reflective coatings.
- Gas Fills: Filling the space between glass panes with inert gasses, such as argon or krypton, can result in a lower U-factor. This type of glazing is widely used in colder areas of the U.S.
- Heat-Absorbing Tints: There are different colors of window tints. The most common ones are gray- and bronzed-tinted windows that help reduce heat and glare of the sun. In contrast, blue and green tints allow more penetration of daylight and slightly reduced heat transfer. Black should be avoided in hot climates, as it absorbs more light than heat. See what it will cost in your area with our window tinting cost estimator.
- Low-E Coatings: Although these coatings cost 10% to 15% more than regular windows, they reduce energy loss by 30% to 50%. During hot days, you should put the low-e coating on the outside of the glass and move them to the inside of the glass in the winter.
- Reflective Coatings: Reflective window glazing can greatly cut out 40%-70% of the solar heat and reduce a window’s SHGC. Therefore, it’s been commonly used in hot climate zones.
Step 4: Choose Window Styles Based on How It Operates
Window design is more than aesthetics. Some window styles are better at improving your home’s energy efficiency than others.
- Hinged windows, such as casement or awning, generally reduce the amount of air leakage than sliding windows because the sash closes by pressing against the frame. Therefore, hinged windows are very ubiquitous in windy climates.
- Sliding windows, including single or double hung and slider, have more potential for air leaks near the center of the glass. As a result, they must be weather-stripped well. The national average weather stripping cost is $272.