- When properly installed, window shades can be one of the most effective ways to save energy.
- Window shades help increase the impact of other energy efficient appliances and fixtures.
- Shading practices should change according to season to maximize benefits.
Making energy efficient improvements to your home can help increase comfort, while saving money and conserving natural resources in the process, but drafty windows can significantly reduce the effectiveness of these efforts. According to the U.S. Department of Energy (DOE), one can reduce home heating and cooling costs by as much as 30% through proper insulation and air sealing techniques. Tight-fitting, insulating window shades should be installed on windows that still feel drafty after weatherizing.
Proper Shade Installation
According to the DOE Energy Efficiency and Renewable Energy (EERE), when properly installed, window shades can be one of the simplest and most effective ways to save energy. To ensure that shades are functioning at the highest efficiency level, EERE recommends mounting shades as close to the glass as possible with the sides of the shade held close to the wall to establish a sealed air space. Shades with duel sides also offer greater efficiency. Shades with one light side and one dark side can be reversed as the seasons change, with the light side facing the warmer area, to reflect heat to the desired area; and shades with multiple layers and sealed edges also work to help regulate home temperature.
Weatherizing windows can help make windows more energy efficient by helping to keep in warm air during colder months, and by keeping cool air in during warmer months, but sometimes drafts can still occur. To test the effectiveness of current weatherization methods, on a windy day, hold a lit incense stick next to your windows. If the smoke stream travels horizontally, you have located an air leak, in spite of weatherization efforts.
- Caulk and weather-strip doors and windows that leak air.
- Look for dirty spots in insulation, which often indicate holes where air leaks into and out of your house. You can seal the holes by stapling sheets of plastic over the holes and caulking the edges of the plastic.
- Install storm windows over single-pane windows or replace them with double-pane windows. Storm windows as much as double the R-value of single-pane windows and they can help reduce drafts, water condensation, and frost formation. As a less costly and less permanent alternative, you can use a heavy-duty, clear plastic sheet on a frame or tape clear plastic film to the inside of your window frames during the cold winter months. Remember, the plastic must be sealed tightly to the frame to help reduce infiltration.
Maximizing Window Shade Utilization
While proper shade installation is essential, this energy-saving method must be coupled with proper usage to maximize savings. A study by the University of Missouri’s Department of Environmental Design found that the way in which shades are utilized can have a profound affect on energy savings. The university offers the following suggestions:
- South windows-Open window shades 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.
- East and west windows-Open window shades for the three best hours of sunshine. Solar heat is gained through east windows during morning hours and through west windows in late afternoon.
- North windows-Close shades, unless there is sun in morning or evening. North windows receive no direct sunlight and are always losing heat.
Window shades should be closed all hours the air conditioner is operating. If the air conditioner is not in use, close those windows and window treatments receiving direct sunlight. Use shaded windows for ventilation.
The insulation provided by window shades may seem insignificant, but small changes can affect the efficiency of other energy-saving appliances and fixtures. For example, your heating system is not just a furnace-it’s a heat-delivery system that starts at the furnace and delivers heat throughout your home using a network of ducts. You may have a top-of-the-line, energy-efficient furnace, but if the ducts leak and are uninsulated, and your walls, attic, windows, and doors are uninsulated, your energy bills will remain high. Taking a whole-house approach to saving energy ensures that dollars you invest in energy efficiency are wisely spent.