April 2005
Save Energy Using A Pool Cover

Maintaining a pool is expensive. And if your pool's heated, the costs are even greater. But there are ways to manage the heating costs.

Some of the energy you buy for heating your pool gets lost. Outdoor heated pools lose heat from radiation to the sky, to the ground and other reasons. Indoor pools lose heat due to ventilation and other sources.

Evaporation claims 70 percent of all heat loss for both types. Evaporation should be your biggest concern over other heat loss matters because it wastes more energy.

How does evaporating water consume energy? A report from the U.S. Department of Energy (DOE) states that over 8,500 BTUs are lost for every gallon of water that evaporates out of a pool. (See Energy Glossary below)

Also, a typical pool loses one to 5.5 inches of water a week. If you have a 1,000 square foot pool, one inch of water would equal 625 gallons. At 8,500 BTUs per gallon lost, you lose over five million BTUs of natural gas, or more than 50 therms, per week. Using the March price per therm, $0.899, 50 therms total almost $45 in heat loss due to evaporation.

Minimize heat loss from your pool by solving heat loss problems such as evaporation. Start by using a pool cover when the pool is not in use. The DOE classifies a pool cover as the single most effective means of reducing pool heating costs, with possible savings of 50 to 70 percent.

The DOE released cost comparisons of heating pools with and without the use of a pool cover. For Atlanta during the months of April through October, these are estimated gas heating costs:

Temperature With Cover Without Cover Savings With Cover
78°F $400 $2130 $1730
80°F $530 $2810 $2280
82°F $740 $3600 $2860

*Figures are based on a 1,000 square-foot, outdoor pool with an 80 percent efficient natural gas heater at $1 per therm. Heating costs vary depending on the price per therm.

Several types of pool covers are available from pool manufacturers. The type of pool cover you need differs from the heavy-duty, out-of-season covers. The cover should be easily accessible to remove when the pool is in use, but also easy to install when the pool is no longer in use. Although vinyl, insulated vinyl or bubble/solar covers slightly decrease the amount of solar heat, they reduce evaporation.

As the pool owner, you have control over the temperature settings. Determine a temperature that's comfortable for you and your family. Usually, pool temperatures range between 78 and 82 degrees.

Constantly changing the thermostat may result in increased energy costs. Set the thermostat and leave it, unless you're away from home for several days. In this case, lower the thermostat to save energy while you're away.

The cost of heating your pool also depends on the efficiency of the natural gas pool heater. The efficiency of the heater indicates how much energy the unit consumes as well as the amount of energy wasted. An 85 percent efficient heater means 15 percent of the energy consumed is wasted.

Look for gas heaters with high efficiencies to ensure you're getting the most for your money. Verify the efficiency of your current pool heater; the efficiency should be on the nameplate of the heater.

As the heater ages it loses its efficiency. According to the DOE, five to 10-year-old heaters range in efficiency between 70 and 75 percent. And ten to 20-year-old heaters range between 60 and 65 percent.

Now you know how a pool heater can affect your energy bill. Try reducing energy loss due to evaporation by using a pool cover and see results in your heating costs.

Energy Glossary
BTU: British Thermal Units
The energy produced by natural gas is measured in BTU. It's the amount of heat required to raise the temperature of one pound of pure water one degree Fahrenheit.
You buy your natural gas in therms. 100,000 BTUs equals one therm.
CCF: Hundred Cubic Feet
One CCF is nearly equivalent to one therm.