Keep Your Cool with Less Energy | Greentips
Greentips: May 2011
Nearly 90 percent of U.S. homes use air conditioning. These systems account for about 17 percent of total electricity consumption and up to 3,500 pounds of heat-trapping CO2 emissions per household each year. Upgrading to a more efficient model could help minimize your contribution to global warming—without having to break a sweat.
Size It Right
Room air conditioners (or window units) are less efficient than central air conditioning, but can be more cost-effective if you rarely use air conditioning or only need to cool one or two rooms. A central air system can also be very expensive to install ($10,000 or more) if your home doesn’t already have ductwork. Regardless of the system you choose, be sure to consider units sized to the square footage of the space to be cooled. A unit that is too small will run continuously while one that is too large will remove the heat but not all the humidity, leaving the air feeling clammy; oversized units are also prone to ice buildup that can affect operation.
Choose a model with a high energy efficiency ratio (EER), a measure of the amount of heat removed per hour per watt of electricity used. Energy Star certifies window units with EERs of 9.4 to10.8, and central air units with a seasonal energy efficiency ratio (SEER, which measures heat-removal efficiency over the cooling season) of 14 and above. Many governments and utilities offer rebates for these units, reducing the up-front cost.
For Additional Savings
- Keep the heat out. Reduce your need for air conditioning by minimizing the amount of heat transferred into your home. Insulate your exterior walls and attic, plug air leaks around doors and windows, close curtains during the day, and install energy-efficient windows. (An energy audit can help identify problem areas and prioritize improvements.) Also, shading your home’s southern and western sides with trees and shrubs can lower cooling costs by up to 30 percent.
- Keep your air conditioner cool. Place the unit away from direct sunlight and heat sources (e.g., appliances, lamps) that make it work harder, wasting energy.
- Raise the thermostat. Each degree higher can save 3 to 5 percent on cooling costs. Set your air conditioner’s timer or your thermostat to turn the unit down or off when you’re asleep or not at home.
- Become a fan of fans. Ceiling fans and whole-house fans can provide cooling for a fraction of the electricity used by air conditioners. A whole-house fan draws in outside air during the cooler evening hours while expelling hot inside air.
- Keep the air flowing. Maintain your air conditioner’s optimum efficiency by cleaning or replacing the air filter regularly, cleaning the blower fan blades, straightening bent coil fins, and, if you have central air, sealing and insulating your home’s ducts. These steps can boost the machine’s efficiency up to 30 percent. See the Related Resources for more maintenance tips.
