Preventing heat gain
If you want to stay comfortable in your home during Arizona's sizzling summers, you need to keep the hot air out and the cool air inside.
When heat enters your home, it's called heat gain. Heat gain makes your air conditioner work longer and harder, which translates into higher energy costs. So, how do you reduce heat gain, stay comfortable, and save on your summer bills?
Heat enters your home through walls, doors, and ceilings. Windows are the leading source of heat gain, accounting for nearly 50% of the heat that enters your home.
Replacing existing windows is expensive and can take years to receive a return on your investment. But there are still ways that you can make an impact on your energy savings and stay comfortable inside when summer heats up outside.
Follow these few easy steps to keep your home's heat gain under control:
- Inspect your windows for cracks or openings in the caulking. If needed, recaulk.
- Check all shade screens to ensure that there are no tears or rips in the material. If you don't have screens, consider installing them.
- Add shade trees or shrubs as an effective way to decrease heat gain. Consider deciduous trees that will block the sun during the summer yet shed their leaves during the winter.
- Install reflective window films with low ratings, which will block the sun. Look for a solar heat gain coefficient of 0.40 or less.
- Hang outdoor awnings over windows. This is also an effective way to reduce heat gain, provided that they keep your windows shaded during the hottest part of the day.
Get more tips on reducing household heat gain.
Selecting energy-efficient windows
If you are in the market to replace your windows or you're building a new home, installing energy-efficient windows will:
- Reduce your cooling and heating costs
- Lower your air conditioner maintenance costs
- Reduce damage to the fabrics and carpets inside your home
- Improve your comfort
Two agencies rate window energy efficiency: ENERGY STAR® and the National Fenestration Rating Council (NFRC).
ENERGY STAR: This program backed by the federal government helps consumers identify and select products that meet strict energy-efficiency guidelines set by the Environmental Protection Agency and the Department of Energy.
ENERGY STAR products can save families about 33% on their energy bill without sacrificing features, style, or comfort. In fact, if every home in the United States had ENERGY STAR-qualified windows, nearly $9 billion per year in energy costs would be saved. These savings are derived from using the newest technology in frame material, glass coatings, design, and gas fills. Visit the ENERGY STAR Web site to learn more about ENERGY STAR products for your home.
National Fenestration Rating Council: The National Fenestration Rating Council (NFRC) is a non-profit organization created by the window, door and skylight industry. The organization comprises manufacturers, suppliers, builders, architects and designers, specifiers, code officials, utilities, and government agencies.
The NFRC's primary goal is to provide accurate information to measure and compare the energy performance of window, door, and skylight products. The NFRC rating label appears on all Fenestration products that are part of the ENERGY STAR program. Visit the NFRC's Web site.
Efficiency and rating terms
- U-Factor determines the heat-flow of the window. The lower the U-factor, the greater a window's resistance to heat flow.
- Visible transmittance (VT) is an optical property that indicates the amount of visible light transmitted. VT is expressed as a number between 0 and 1. A lower value transmits less light. The higher the VT, the more light transmitted.
- Solar heat gain coefficient (SHGC) is the amount of solar radiation admitted through a window. The lower a window's SHGC, the less solar heat it conducts. SHGC is the most important factor to consider when purchasing a new ENERGY STAR window. Select windows with an SHGC of 0.40 or less.
- Air leakage (AL) is the occurrence of heat loss and gain through gaps in the window assembly. AL is expressed in cubic feet of air passing through a square foot of window area. The lower the AL, the less air is passing through the window, and the better your window is performing.