Energy Efficient Cooling Systems

Fast Facts

  • Heating and cooling ("space conditioning") account for 50 to 70% of the energy used in the average American home.
  • In an average air-conditioned home, air conditioning consumes more than 2,000 kilowatt-hours of electricity per year, costing $1,350/year.
  • Switching to high-efficiency air conditioners and taking other actions to keep your home cool could reduce this energy use by 20% to 50%.
  • Air conditioners use about 5% of all the electricity produced in the United States, at a cost to homeowners of over $11 billion.
  • Roughly 100 million tons of carbon dioxide is released into the air each year from powering air conditioners--an average of about two tons for each home with an air conditioner.
  • The most efficient air conditioners on the market are up to 70% more efficient than the typical room air conditioners found in U.S. homes today.
  • A combination of proper insulation, energy-efficient windows and doors, day-lighting, shading, and natural ventilation will keep homes cool on most days without air conditioning.
  • Window fans or a whole-house fan provide effective means of exhausting the day's hot air during the night.
  • A central air conditioning system will cool your house more efficiently than room conditioners.
  • When using a central sir conditioner, each degree setting below 78F will increase your energy consumption and costs by approximately 8%.

What can I do to save energy in my home?

  • Over most of the cooling season, keep the house closed tightly during the day and ventilate at night either naturally or with fans.
  • If you only need to cool a small portion of your house (for instance, your bedroom), a room air conditioner may be the best choice.
  • Reduce the cooling load by effectively shading east and west windows and delaying heat-generating activities, such as dishwashing, until the evening on hot days.

Central Air Conditioners

Choose a central air conditioner with a high Seasonal Energy Efficiency Ratio (SEER). Look for the ENERGY STAR label. See their web site for central air conditioners with SEER ratings of 12 or greater.

You can lower your central air conditioners energy use by:

  • Setting the thermostat at 78F or higher.
  • Use bath and kitchen fans sparingly when the air conditioner is operating.
  • Inspect and clean both the indoor and outdoor coils. Dirt build-up on the indoor coil is the single most common cause of poor efficiency.
  • Check the refrigerant charge. If the system is overcharged or undercharged with refrigerant, it will not work properly.
  • Use the fan only switch for nighttime ventilation to substantially reduce air-conditioning costs.

Room Air Conditioners

Room air conditioners are labeled with their Energy Efficiency Ratio (EER). Look for units with an EER of 10.0 or above. Check the ENERGY STAR web site for a qualifying brand.

Proper sizing is very important for efficient air conditioning. An air conditioner generally needs 20 Btu for each square foot of living space. The ENERGY STAR web site also includes a calculator for sizing your room air conditioner.

You can lower your room air conditioners energy use by:

  • Installing the unit in a shaded spot on your home's north or east side. (Direct sunshine on the unit's outdoor heat exchanger decreases efficiency by as much as 10%.)
  • Set the fan speed on high, except on very humid days.
  • Consider using an interior fan in conjunction with your window air conditioner to spread the cooled air more effectively through your home without greatly increasing electricity use.
  • At the start of each cooling season, inspect the seal between the air conditioner and the window frame to ensure it makes contact with the unit's metal case.
  • Check your unit's air filter once a month and clean or replace filters as necessary. Keeping the filter clean can lower your air conditioner's energy consumption by 5% to 15%.

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