Key aspects of RFP

UNDERSTANDING HEATED SWIMMING POOLS AND THEIR ENERGY USE

Swimming pools and pool facilities consume large amounts of energy. You can reduce a good fraction of that energy with best practices in energy management and the use of applicable energy technologies. There are numerous other things you can do to reduce O&M costs.

A comprehensive information set that treats these topics clearly and in concise detail is found in a series of fact sheets assembled by the Energy Efficiency and Renewable Energy office of the U.S. Dept. of Energy. Visit their Swimming Pool Heating page as well as the pages dedicated to Indoor pools and Outdoor pools.

Energy balance of a heated pool

For both indoor and outdoor pools, the evaporation of water from the pool surface is by far the greatest mechanism for energy loss, accounting for 70% of losses. This is due to the enormous quantity of energy taken up (in the form of heat) when water in the pool is changed from the liquid to the vapor phase as it evaporates.

For outdoor pools, evaporation is greatly increased by wind blowing over the pool. For example, a 7 mph wind at the surface of the pool can triple the rate, thereby tripling the energy required to make up for the heat loss. Radiation to the night sky ranks second behind evaporation as the mechanism for heat-loss from an outdoor pool and on average can account for 20% of losses. On the energy-input side, however, outdoor pools gain significant energy from the sun.

For indoor pools: the energy required to operate the building's ventilation system is the second largest energy load (behind evaporation). It accounts for 27% of losses. Because most indoor pools are used year-around and have no opportunity to gain solar heat, they often have much higher energy costs than outdoor pools.

Reducing energy loses for pools and pool facilities

Best management practices and a number of cost-effective technologies can be applied to reduce these and to reduce several other losses that will be mentioned here as well.

Consider and evaluate (in the order provided) the following energy-saving options:

• Install a swimming pool cover and ensure the pool is covered whenever it is not in use. You can use this website’s Solar Calculator to see how very quickly this investment will pay for itself.

• If the number of pools and pool facilities warrants it, undertake a full energy audit of the swimming pool facility. This will identify (& quantify) energy losses that can be reduced and just as importantly, uncover energy sources you can exploit at your swimming pool facilities to lower costs.

• For outdoor pools, install a wind break. It should be high enough and close enough to the pool that it does not create turbulence over the pool and increase evaporation. Also of importance is that the break not block the sun from shining on the pool.

• Install a solar hot water system for the pool. Unglazed (as opposed to glazed) collectors are recommended given their lower cost and their suitability to this low-temperature application. The Solar Calculator will tell you what you can expect to gain with this investment.

• To obtain other energy-saving ideas, review the online articles at related website previously mentioned (Swimming Pool Heating).