Why Humidy Increases Air Conditioning Costs

If you use an air conditioner to cool your home, you may recognize that summer electric bills are highest when the weather is hottest. But did you know that your electrical consumption is also higher when the humidity increases?

You air conditioner works hard to cool the air in your home. If you have central air conditioning, ducts carry warm house over the evaporator coil in cooling system. If you have a portable air conditioner, air flows through the grilles in the front panel.

In either case, refrigerant in the evaporator coil extracts heat from the moving air. But this cool coil surface also encourages condensation to take place, as moisture from the room air reaches its dew point. This process of condensation releases heat, which must be removed by the air conditioner. Higher humidity leads to more condensation, and more condensation produces more heat which the air conditioner has to remove. This increases your electrical costs.

If it seems odd that condensation releases heat, just think about getting out of the swimming pool and how the evaporation of water from your skin cools you off. Water condensation, on your evaporator coil or anywhere else, is just the opposite. Heat is released wherever water condenses.

You can reduce the cost of air conditioning by following these steps to reduce the humidity in your home:

Be sure your dryer is vented to the outdoors
Avoid drying clothes on an indoor clothes line
Cover pots when cooking
Use exhaust fans in your bathroom and kitchen
If you don't have exhaust fans in your bathroom and kitchen, have them installed
If you have a crawl space, be sure any bare dirt is covered with a plastic ground-moisture barrier

When you reduce the humidity in your home, you also reduce the possibility of having mold and mildew growth. There are a lot of a good reasons to control moisture in your home year round.

Source: John Krigger, co-author of Residential Energy - Cost Savings and Comfort for Existing Buildings (www.srmi.biz)