The Role Energy Efficient Windows Play in the Sustainable Home 

According to the U.S. Department of Energy, old and inefficient window designs can be responsible for up to 25-30 percent of all heat loss and heat gain in your home. Old, single-pane windows that you found for a bargain are most likely causing your energy bills to go through the roof. 

In insulation terms, single pane glass that is only 1/4th of an inch thick will have an expected R-value of around .90. A double-pane window of similar thickness would have an expected R-value of at least 1.7 This means that you nearly double the insulation value of your windows through this upgrade. Some of the top-quality triple pane windows on the market today have an R-Value of 5, which would increase the energy performance of your windows five times over when upgrading from older, single-pane options. Even homes that undergo a complete low carbon retrofit would have a hard time achieving such drastic energy efficiency improvements. Replacing old windows, or at the very least installing window films over less energy-efficient options, is one of the best and most cost-effective strategies to improve the overall energy efficiency and thermal performance of your home. 

Energy-efficient windows can also significantly reduce the amount of energy we collectively use to light our home. Unless you live in Alaska where the sun hardly moves above the horizon during the winter months, almost all areas in North America receive enormous amounts of natural light throughout the year. According to the U.S. Energy Information Administration (EIA), “the U.S. residential sector and the commercial sector used about 232 billion kilowatt-hours (kWh) of electricity for lighting. It was about 8% of the total electricity consumed by both of these sectors and about 6% of total U.S. electricity consumption.” An average U.S. home with 45 light bulbs required to use many of these lights during the daytime hours due to a lack of natural lighting in the house, adds up to an enormous amount of energy usage over a year. Proper window placement can effectively eliminate the need for turning the lights on during the daytime, and thus save you money on your electric bill.