Energy Efficient Windows
The right kind for any climate
When plastic sheets, caulking and weather stripping just aren’t helping the home efficiency situation enough, replacing windows might be the only option. Single-pane windows, which are still in use in many U.S. homes, are pretty much the worst in terms of energy loss. Double-pane energy-efficient windows have special glass that can make a big difference.
The cost of installing new windows won’t be paid off for several years through energy savings, but it can have a big impact right away in terms of comfort and function. National Fenestration Council labels let you know the window is certified to perform as claimed, and Energy Star labels mean it offers a higher level of energy efficiency. Look for windows rated at less than 0.3 cubic feet per minute of air leakage.
Homes in the Sunbelt - Double-glazed windows with spectrally selective coatings can cut your need for home cooling by up to 15 percent by reducing the amount of heat that’s let into the home. They literally reflect some of the sunlight away. Other methods to keep the home cool include installing awnings on windows that face south or west, or covering windows with sun-reflecting film.
Homes in cold climates - Windows coated with low emissive (low-e) substances and filled with gas can prevent heat from escaping the home by reflecting it back into the room. Look for windows with a U-value below 0.35, which means they are better insulators.
Homes with both needs - These windows need to have both low U-values and low solar heat gain coefficient (SHGC) ratings, to get the best of both worlds. You might have to decide which is more important for your situation, free solar heating in the winter or keeping the hot sun out in the summer.
If you are building a new home or plan to upgrade your furnace within a few years, choosing the right windows can allow you to get a smaller, less costly HVAC system.
A somewhat cheaper solution, that’s more long-term than most weatherizing methods, is installing storm windows. Whether exterior or interior, they can reduce heat loss by 25 to 50 percent, even more if they are low-e coated.
Curtains and shades can still be effective for energy-efficient windows if used correctly. In warm months, keep south-facing windows covered during the day. In cool months, allow the sun to come in through south windows during the day but cover them at night.
