Windows are one way we dress up the exterior and interior of our homes, but without special attention, they can be huge energy drains. A home energy audit (check with your electric cooperative) can identify just how much conditioned air you may be losing to the outdoors through single-pane windows, windows with poor or no weatherstripping or caulking and windows without drapes or other coverings. It might be the equivalent of leaving the front door wide open!
According to the U.S. Department of Energy:
- In winter, about 30 percent of your home’s heating energy is lost through windows
- In summer, about 76 percent of the sunlight that falls on double-pane windows enters as heat.
The Missouri Department of Natural Resources offers these tips on cutting energy loss through windows:
Upgrade — Replace those single-pane windows with doubles. They may cost twice as much but will pay for themselves in much-reduced energy costs.
Add storm windows — Can’t afford new windows? Add plastic sheeting inside or outside. That’s the least expensive option. Glass storm windows with wood, metal or vinyl frames are another option. DNR estimates payback for storm windows ranges from several months to a year for plastic sheeting and five to 10 years for glass.
Dress up windows and save — Insulating shades, drapes, shutters, awnings and screens provide some insulation to windows. In summer, pull them tight to keep the sunlight out during the day. In winter, open the treatments up to let sunlight in during the day and close again at night. Tightly woven fabrics with separate or reflective linings are best for drapes.
Add reflective films — This treatment reflects sunlight away from windows and reflects heat back into the room.
Caulk and weatherstrip — These inexpensive methods stop air leaks around windows and can be applied by most homeowners themselves. In older houses and historic houses, replace window glazings that are cracked.
Plan window location — If you’re adding a room or even building a new house, orient windows to the south and use roof overhangs to shade windows on the east and west from the sun in summer. Overhangs are much less effective against the lower angles of the east and west sun, so reduce the size and number of east- and west-facing windows to reduce energy use.
Plant a tree — Strategically planting deciduous trees near south-, east- and west-facing windows will provide needed shade in the summer but let in the sun’s heat during winter.
Close up in summer — Close all window coverings during hours the air conditioner is operating. If the air conditioner is not in use, close those windows and window treatments receiving direct sunlight. If you’re aiming for cross ventilation, use only shaded windows.
Open and close in winter — In winter, there are about 16 hours a day when windows are enormous heat drains. To maximize efficiency, open the window treatment on south-facing windows for the six best hours of sunshine. These windows gain more heat during the day than they lose at night. Night insulation is very effective. On east windows, open the treatment for the three best morning hours and on the west, for the three best afternoon hours. On north windows, close them unless there is sun in the morning or afternoon.