By Mitch Smith
Much has been said in recent years about the need to reduce the reliance on fossil fuels—not to mention household energy bills. In the pool industry, these conversations often focus on pool heating, which can be considered a luxury, on top of the amenity of having a pool.
However, heated pools tend to be used more which helps pool owners maximize their investment. Adding a week or two to the season, or being able to swim comfortably early in the morning or late in the evening, can dramatically improve pool owner satisfaction. The ability to increase satisfaction in the most economical and environmentally friendly way possible is a great outcome.
As consumers become more savvy about conserving energy—whether their motivation is to save money, protect natural resources, or both—energy-efficient heating options become more attractive. Pool owners do not want to spend as much money heating a pool as it costs to buy and install it in the first place.
An article posted online earlier this year asked: “Is it possible to live a green lifestyle and own a backyard pool?1” It essentially goes on to say, yes, and the first item on the list of ways pools can be eco-friendly is to use solar heat.
Solar heating devices offer an excellent way for pool owners to cut the energy consumption associated with pools and use free natural heat sources.
Harnessing the sun
Solar heating methods for above-ground pools fall into two categories: products on the water’s surface, and external devices. Using these methods together enhances the performance of each.
One factor often giving customers the idea solar heating is cumbersome, or not the right option for them, is the perception a large area attracting the sun (e.g. a roof pitched at just the right angle) is required for collectors. This may be true if solar energy is being used to heat a large pool or house, but the amount of solar energy required to make a noticeable difference in a medium-sized above-ground swimming pool, can easily be collected in a relatively small space. Some products do it using only the pool’s surface.
A basic form of solar pool heating is the solar blanket. This is a sheet of bubble plastic cut to the same shape as the pool that lays on the water’s surface when the pool is not in use. During the day, energy from the sun passes through the blanket and warms the water. Day or night, the blanket prevents heat from evaporating out of the water, so whatever heat is collected (or generated by more active heating technologies, e.g. gas, heat pump or solar heater) remains in the water.
Some solar blankets come in sections held together by magnets or other mechanisms. Some pool owners find these products easier to handle and store when not in use. Whether the blanket is one large sheet or in sections, the concept is the same—passive solar energy collection has no monetary cost after the initial purchase, so the heat is essentially free.
Over the years, products have been developed allowing this solar blanket behaviour to occur while the pool is in use. Often designed to look like floating pool toys, these devices dispense isopropyl alcohol (C3H8O) into the water, which quickly finds the surface and forms a film that acts like a solar blanket, by keeping heat in the water.
Swimmers temporarily disrupt the isopropyl alcohol, but surface tension properties cause it to form the invisible blanket-like film again and again. Unlike solar blankets, there is a recurring replacement cost with the isopropyl alcohol dispensers, but it is far lower than the cost of a traditional solar blanket or operating a fossil-fuelled heater.