Many people have experienced troublesome windows at one point or another. Mold and condensation are unsightly and unhealthy. Years of weathering can make windows difficult to open or close. And drafts can make your favorite room uncomfortable. Installing new windows will not only fix these problems, they can also improve your energy efficiency if you choose models that take advantage of new materials and manufacturing processes.
Brian Ng, communications manager of the Energy Star Residential Branch, says the new windows use "a combination of glazings, tintings and reflective glass that helps keep solar heat out of the house. ... Some also use better frame materials that have foam insulation built inside of them that helps increase what is called the U-value of the windows, which is a measure of how well the window itself insulates. And some windows are filled with inert gasses like argon that keep solar heat out of house and that also slightly increases the U-value."
Kerry Haglund, owner and founder of Haglund Design Inc. and one of Glass Magazine's 2012 Most Influential Individuals Impacting the Glass and Metal Industry, says, "The coating in the glazing surface has probably the most impact, but it is these technologies used in combination that have greatly affected the thermal performance of the whole window."
Unfortunately, those technologies are measured using many technical terms that can be difficult for consumers to understand. U-value is measured on a scale of 0.25 to 1.25, and the lower the U-value, the better the insulation. Visible transmittance is the measure of how much light passes through the window, and it is measured on a scale of zero to one. The higher the number the more light that passes through.
Solar heat gain coefficient measures how much solar heat passes through the window, on a scale of zero to one. Ng and Haglund say climates that are cold year-round should look for windows with a higher SHCG, while year-round hot climates should look for lower SHGC. Finally, condensation resistance is measured on a scale of zero to 100. The higher the rating the less condensation that will build up.
But climate is not the only factor that should determine which windows to buy for your house. A crucial factor to consider is the orientation of your home. Ng says, "You will want to install south-facing windows with one SHGC, while north-facing windows will have another."
Ng points out that consumers can visit the Energy Star website to look for windows based on climate and orientation. Haglund echoes this, saying: "Make sure the windows meet the local energy code and are Energy Star qualified. Look for the efficient properties on the National Fenestration Rating Council (NFRC) label. The NFRC label displays whole-window energy properties, and it is the only reliable way to compare products. Choose products that are right for your home. Use tools found at efficientwindows.org to help educate yourself about the products."
A third factor is installation. "Installation is key," Ng says. He recommends consumers "ask contractors if they have any certifications from manufacturers. Typically window manufacturers have their own certification programs for installation. There is also a body called the American Window and Door Institute, which certifies window installers." Finally, he notes that if your house was built before 1978, it may have lead paint on it, so homeowners should consult a lead professional before installing new windows.
Energy-efficient windows will reduce a homeowner's heating and cooling costs. Ng says, "You're going to see improvements in energy efficiency, but the payback period is so long that it's usually not cost-efficient to install new windows if you're just looking for energy efficiency gains." Nevertheless, Ng pointed out that there are federal tax credits that go through 2013. The credit is capped at $200 per window. Ng added, "Homeowners can visit dsire.org, and they can search by state for any state or local energy efficiency (tax) incentives."
If you are installing new windows, with a little research you can find the right energy-efficient windows for your climate and your home's orientation. And with the right installation, it will make your home more comfortable and reduce energy usage. Those troublesome windows need not bother you any longer.