Reducing Swimming Pool Heat Loss

Are you suffering from heat loss in your swimming pool?

Here are some of the major primary energy losses from swimming pools:

Evaporation is the primary mode of swimming pool heat loss, accounting for approximately 70% of the heat lost from both indoor and outdoor pools (Figure 1) . The remaining heat losses are generally from radiant heat for outdoor pools and ventilation for indoor pools. 

Evaporation dominates pool heat losses because each gallon of water that evaporates removes 8,300 Btus of heat from the pool, whereas heating the gallon of replacement water to the temperature of the pool requires only 8.3 Btus per degree Fahrenheit of temperature rise—or between 80 and 200 Btus per gallon for the typical heat gain required. Evaporation from indoor pools generates an additional energy penalty because the ambient air must be dehumidified or replaced with fresh air. 

The best way to reduce evaporation losses is to cover the pool when it is not in use. Pool covers block evaporation as well as radiant losses, and they can provide some insulation from convective losses. Achievable savings from pool covers depend on how long the pool is covered and on local conditions that affect how evaporation is taking place, with reported savings of 50% or more compared to the energy required for heating uncovered pools.

For outdoor pools, evaporation losses are driven by the ambient temperature, humidity and average wind speed. Windy and arid environments cause faster evaporation and greater energy losses. 


Additional Energy-Saving Ideas 


Pool owners are also encouraged to invest in other energy-saving measures to further reduce their pool operating bills. For additional energy savings, here are some ideas for more efficient heating and circulation systems:

• Air-source heat pumps cost more than gas heaters, but with a reported coefficient of performance of 4.3, they can pay for themselves in 1.5 to 2.5 years. 

 • Condensing gas boiler pool heaters offer efficiencies above 90% compared to their conventional counterparts, which have efficiencies in the mid 80s. 


• Solar thermal pool heaters are the most cost effective use of solar energy in most climates. 

• Variable-speed drive control allows pool circulation pumps to be ramped up and down with demand to achieve pumping energy savings of up to 50%.

Information provided by Madison Gas & Electric Company