Selecting windows and doors: prices and climate strategies
January 10, 2012
Can the correct type of window or door really make a difference in your home's energy efficiency? The U.S. Department of Energy says it can--from 7-15 percent--if you use Energy Star-qualified products.
Installing the right windows on specific sides of your house or selecting the correct door materials based on your climate can also make a big difference. Understanding the performance ratings on the National Fenestration Ratings Council (NFRC) labels that display on all Energy Star products can help you make informed choices. And, never underestimate how important proper installation is. Even a premium product can be ineffective if it's not properly installed.
Managing heat gain to your advantage
Because heat goes in and out of your home through the windows and doors, you want to manage that heat gain to your advantage--you want the greatest gain in the winter to keep you warm and the smallest in the summer to keep you cool. Energy performance ratings most commonly used to rate windows and doors include these two:
- U-factor. Measures the rate of heat transfer. The lower the U-factor, the better the insulation.
- Solar Heat Gain Coefficient. The SHGC measures how well the product transmits or absorbs solar heat; the lower the number, the less solar heat is transmitted.
Climate strategies for windows and doors
The best cold climate strategy, according to Energy Star, is based on the following windows' orientation:
- South-facing: Allow solar heat in during the winter, but require shade in the summer. High SHGC; low U-Factor
- East- and west-facing: Low SHGC windows plus summer shade
- North-facing: Low U-factor to minimize winter heat loss
The best hot climate strategy is:
- South-, east- and west-facing windows: Low SHGC to minimize solar gain, low U-Factor to reduce cooling costs, shade south-facing windows
- North-facing: Low U-factor
Tinted or reflective windows and those with low-E, spectrally-selective coatings and gas between the panes can help make your sliding glass or French doors more energy-efficient based on your climate strategy. Steel or fiberglass-clad exterior doors with foam insulation are an excellent energy choice for severe climates.
Windows and doors: prices and savings
With costs running from $200 to thousands per door or window, you may be able to save by using the Climate Zone Finder on the Energy Star website to find specific requirements and optimum values for your area's windows and doors. Prices run higher for the most energy-efficient products, but you can save by strategically selecting different types of products based on orientation. You may also be eligible for up to $500 as a tax credit on your 2011 federal tax return and, of course, you can't discount what you'll save on heating and cooling bills.
