Window Tips

Windows

Windows can be one of your home's most attractive features. Windows provide views, daylighting, ventilation, and heat from the sun in the winter. Unfortunately, they can also account for 10% to 25% of your heating bill by letting heat out.

During the summer, your air conditioner must work harder to cool hot air from sunny windows. Install ENERGY STAR®-qualified windows and use curtains and shade to give your air conditioner and energy bill a break.

If your home has single-pane windows, consider replacing them with double-pane windows with high-performance glass—low-e or spectrally selective coatings. In colder climates, select gas-filled windows with low-e coatings to reduce heat loss. In warmer climates, select windows with spectrally selective coatings to reduce heat gain.

If you decide not to replace your windows, consider following these tips to improve their performance.

Window Cold Weather Tips:

　　Use a heavy-duty, clear plastic sheet on a frame or tape clear plastic film to the inside of your window frames to reduce drafts.

Install tight-fitting, insulating window shades on windows that feel drafty after weatherizing.

Close your curtains and shades at night to protect against cold drafts; open them during the day to let in warming sunlight.

Install exterior or interior storm windows, which can reduce heat loss through the windows by 25% to 50%.

They should have weatherstripping at all movable joints; be made of strong, durable materials; and have interlocking or overlapping joints.

Repair and weatherize your current storm windows, if necessary

Warm Weather Window Tips:

Install white window shades, drapes, or blinds to reflect heat away from the house.

Close curtains on south- and west-facing windows during the day.

Install awnings on south- and west-facing windows.

Apply sun-control or other reflective films on south-facing windows to reduce solar heat gain.

Long-Term Savings Tip

Installing high-performance windows will improve your home's energy performance. While it may take many years for new windows to pay off in energy savings, the benefits of added comfort, improved aesthetics, and functionality can offset the cost.

Shopping Tips for Windows

Look for the ENERGY STAR® label.

Check with local utilities to see what rebates or other incentives are available for window replacement.

Choose high-performance windows that have at least two panes of glass and a low-e coating.

Choose a low U-factor for better insulation in colder climates; the U-factor is the rate at which a window, door, or skylight conducts non-solar heat flow.

Look for a low solar heat gain coefficient (SHGC)—this is a measure of solar radiation admitted through a window, door, or skylight. Low SHGCs reduce heat gain in warm climates.

Select windows with both low U-factors and low SHGCs to maximize energy savings in temperate climates with both cold and hot seasons.

Look for whole-unit U-factors and SHGCs, rather than center-of-glass (COG) U-factors and SHGCs. Whole-unit numbers more accurately reflect the energy performance of the entire product.

Have your windows installed by trained professionals according to manufacturer's instructions; otherwise, your warranty may be void.

Consider windows with impact-resistant glass if you live along a coast or in areas with flying debris from storms.

Energy Efficient Windows

Windows provide our homes with light, warmth, and ventilation, but they can also negatively impact a home's energy efficiency. You can reduce energy costs by installing energy-efficient windows in your home. If your budget is tight, energy efficiency improvements to existing windows can also help.

Improving the Energy Efficiency of Existing Windows

You can improve the energy efficiency of existing windows by adding storm windows, caulking and weatherstripping, and using window treatments or coverings.

Adding storm windows can reduce air leakage and improve comfort. Caulking and weatherstripping can reduce air leakage around windows. Use caulk for stationary cracks, gaps, or joints less than one-quarter-inch wide, and weatherstripping for building components that move, such as doors and operable windows. Window treatments or coverings can reduce heat loss in the winter and heat gain in the summer. Most window treatments, however, aren't effective at reducing air leakage or infiltration.

Selecting New Energy-Efficient Windows

If your home has very old and/or inefficient windows, it might be more cost-effective to replace them than to try to improve their energy efficiency. New, energy-efficient windows eventually pay for themselves through lower heating and cooling costs, and sometimes even lighting costs.

When properly selected and installed, energy-efficient windows can help minimize your heating, cooling, and lighting costs. Improving window performance in your home involves design, selection, and installation.