How much can a pool owner save?
The amount of saved resources between a covered and uncovered pool is a function of the evaporation rate and pool usage, while financial savings are determined by the pool owner’s cost to replace the lost resources.
Estimating evaporation rate and pool usage
For existing pools, the easiest way to determine the amount of water escaping the pool is to measure the water level difference over the period of one week. Multiply the pool’s surface area by the change in water level to determine the volume of balanced, heated water that will need to be replaced each week. Then, multiply this figure by the number of weeks in the swimming season to estimate seasonal water loss. Keep in mind, this amount will also include water loss from pool splash, backwashing and any leaks.
For new pool projects, potential evaporation rates have to be estimated. For the most comprehensive estimate, historical climate data can be used as a reference point to develop a picture of typical conditions for a particular area. These conditions consider the relationships between many variables to determine evaporation rates (e.g. air temperature, relative humidity, water temperature, uncovered pool surface area, wind speed and pool activity). The climate data also allows pool owners to estimate their pool usage in addition to how often the pool will be covered versus uncovered.
Energy savings
Energy efficiency is one of the most significant benefits of reducing evaporation with a pool cover. For a simple comparison, look at the estimated energy usage between mid-May and September for an outdoor, inground 60 m2 (646 sf) pool in Montreal, Toronto and Vancouver. The pool is used moderately for about nine hours during optimal days (defined for this scenario as a minimum of 18 C [64.4 F] on sunny days or 23 C [73.4 F] on cloudy days). The water temperature is set to a minimum 25 C (77 F).
In these three cities, the energy usage calculator estimates seasonal energy savings of 90 to 150 gigajoules (GJ) for a pool that is covered when it is not actively being used. With a cover, the pool heating system only needs to provide 30 to 35 per cent of the heat an uncovered pool requires, which represents a 65 to 70 per cent savings.
If the pool owner wishes to extend their swimming season, a cover becomes even more valuable in managing heat loss. While pool usage, number of optimal days and overall energy consumption might vary between pool owners, the energy savings from the pool cover ‘line of defense’ can translate into hundreds and even thousands of dollars each season.
Water, chemical and equipment savings
Water conservation and reduced chemical use are also benefits of a cover system. For example, during drought periods and water restrictions, the pool owner will require less make up water to return to proper operating levels. The cover acts as a vapour barrier to prevent treated water from evaporating; this can save time and excessive chemicals required to bring the water back to balance.
Furthermore, by curtailing unnecessary evaporation, wear and tear on the pool’s surface and equipment is also reduced. Over the life of the pool, these benefits can add up to significant savings.
