The U.S. Department of Energy says about 25 percent of the average household energy bill goes to lost heat or cold through windows. The government says installing windows certified by the Energy Star program (energystar.gov) can reduce energy costs by around 15 percent. So what exactly makes an Energy Star certified window?
There are five qualifications: Glass Coating
Energy Star windows are coated with a low-emittance (Low-E) film. Low-E coating works to keep heat inside during the winter and heat outside during the summer. Low-E coating allows about 95 percent of natural light to pass through.
Multiple Panes
Double pane windows reduce the amount of energy transferred from outside to inside. This cuts down on heat loss or use of air conditioning. Double pane windows are also tougher than single pane.
Gas Fill
Double pane windows have a thin layer of gas inserted between the panes. This gas, either argon or krypton, is odorless and non-toxic. The idea behind the gas is to provide better installation and reduce outside noise pollution.
Warm Edge Spacers
A spacer keeps the panes the correct distance apart. Warm edge spacers -- made from steel, foam or fiberglass -- reduce energy loss that occurred with traditional aluminum spacers.
Weather Stripping
Weather stripping has come along way over the last 20 years. Today's plastic stripping is more durable, lasts longer and reduces the flow of energy.
