Ready to defenestrate yourself after seeing your sky-high energy bills?  The windows in your home play a crucial role in energy use and indoor comfort.  Luckily, efficient glazing and window frame options are becoming increasingly common and affordable. Not only will you stay cool in the summer and warm in the winter, you can earn tax credits worth up to $1,500 for installing new windows and doors.  Replacing single-pane windows with Energy Star windows throughout your home can save up to 4,545 pounds of carbon dioxide and $465 a year.  So pay close attention when upgrading your existing windows or building a new home.

Have you heard of the NFRC? The National Fenestration Rating Council is an independent, non-profit organization that administers a rating system for windows, doors, and skylights, aimed to provide a fair comparison of fenestration energy performance. To certify a product, manufacturers must adhere to the strict NFRC standards.  If you’re in the market for a window or slider, you can search through the entire selection of NFRC-certified products here.  And always look for the NFRC sticker on window products.

In the summer, an ideal window would let in visible light, but prevent heat from entering your home.  Unfortunately, under our current sun, the two often come together.  Reflective or tinted glass reduces heat gain and visible light, often resulting in higher costs for electrical lighting.  On the NFRC label, the amount of visible light that enters through the window is measured as visible transmittance. Visible transmittance ranges from 0 to 1, with 1 allowing the full range of visible light to enter through the glazing.  The solar heat gain coefficient (SHGC) declares the glass’ ability to resist heat from direct solar radiation.

In the winter, instead of preventing heat gain, it is more important to prevent heat loss.  A low thermal transmittance (U-factor) shows that a product prevents heat from escaping through conductivity.  The number is affected by conductivity of the frames, airflow around the window, and the emissivity of the glass.  Double glazing, two sheets of glass separated by a narrow air space, cuts the rate of heat loss dramatically.  Low-e (low emissivity) coatings, now available in dual pane and insulated glass windows, help to prevent unwanted energy from being absorbed and radiated into or out of the home.

Want to know which windows LivingHomes uses?  In the first LivingHome, we used aluminum Fleetwood windows and doors.  Fleetwood windows incorporate recycled aluminum and glass and are VOC-free.  In our most recent home, the Kohler LivingHome, we used Andersen Series 100 windows and doors.  Andersen window frames are made of Fibrex, a composite material with pre-consumer recycled content.  Andersen windows also contain reclaimed glass, qualify as SCS Indoor Advantage Gold, and are certified by Green Seal.  With U-factors between 0.29 and 0.46 and SHGC between 0.22 and 0.34, all these windows help maintain indoor comfort in your LivingHome and lower your energy usage and costs.

Sources:

• http://www.energystar.gov/index.cfm?c=windows_doors.pr_crit_windows
• http://www.andersenwindows.com/100-Series/index.html
• http://fleetwoodusa.com/