Why do people use a swimming pool cover?
Swimming Pools lose energy in a variety of ways, but evaporation is by far the largest source of energy loss for swimming pools. When compared to evaporation, all other losses of swimming pool temperature are small. Since evaporation is the major source of swimming pool heat loss for all swimming pools, to minimize evaporation one must cover the pool. Covering the water with a swimming pool cover when it is not in use is the single most effective means of reducing swimming pool heating costs. Savings of 50-70% in pool water heating are possible.
Types of swimming pool covers
Technically, all you really need is a large sheet of plastic to cover your swimming pool. Plastic meets the requirement of being a vapor barrier. But a large sheet of plastic that you get from the lumber store is probably not your best choice to help swimming pool water heating. It will be very difficult to handle and store, it tears easily, and sunlight will deteriorate it rapidly. You can use it, but it will be very inconvenient and will only last 1 to 2 seasons at maximum. There are a number of swimming pool covers designed specifically for swimming pools. The swimming pool covers can be made of different materials, such as UV stabilized polyethylene, polypropylene, or vinyl. They can be transparent or opaque. They can be light colored swimming pool covers or dark colored swimming pool covers. One of the lowest cost swimming pool covers made specifically for swimming pools is the bubble cover (some call them solar covers). They are similar to bubble packing material except that they use a thicker grade of plastic and have UV inhibitors, etc. Vinyl swimming pool covers are a heavier material and have a longer life expectancy. You can also get insulated vinyl swimming pool covers with a thin layer of flexible insulation sandwiched between two layers of vinyl. Outdoor pools gain heat from the sun. The absorption of 75-85% of the solar energy striking the water's surface helps to provide a high swimming pool temperature. This is an important contribution to the swimming pool heating needs. When considering a swimming pool cover in order to provide a high swimming pool temperature, note that a swimming pool cover will also decrease the solar gain contribution to some extent, depending on the type of swimming pool cover used. A transparent bubble cover may reduce solar energy absorption by 5-15%, and a completely opaque cover by 20-40%.
Methods of using swimming pool covers
There are several ways of covering your swimming pool in order to reduce swimming pool heating costs. The simplest and lowest first cost method is to manually pull the swimming pool cover on and off, fold it, and place it somewhere out of the way. If you are paying someone to do this, you need to consider that cost in your economic evaluation. You can also purchase a swimming pool cover reel that can be used to manually roll the swimming pool cover up. The reel, usually on wheels, can then be rolled out of the way. Semi-automatic swimming pool covers use a motor driven reel system. They use electrical power to roll and unroll the swimming pool cover, but usually require someone to pull on the swimming pool cover when unrolling, or guide the swimming pool cover onto the reel when rolling the cover up. They can be built into the deck surrounding the swimming pool, or can use reels on carts. Automatic swimming pool covers have permanently mounted reels that automatically cover and uncover the swimming pool at the push of a button. They are also the most expensive first cost option. But you have to weigh the cost of labor for the manual and semi-automatic swimming pool covers to determine which route is best for your particular situation. Some swimming pool covers are fitted into tracks along the sides of the pool. This prevents anything or anybody from getting into the water. They even support the weight of several people. If liability is a concern, these are a good option to explore. They can be run manually, semi-automatically, or automatically.
When to use swimming pool covers
For pools which are open all day, a swimming pool cover should be placed over the water as soon as it closes, and taken off just before it opens for the day in order to get the maximum benefit considering swimming pool heating. For pools which are not in use during daylight hours, the effectiveness of a swimming pool cover to help provide a high swimming pool temperature will depend on whether the evaporation and other losses prevented by the swimming pool cover exceed the solar pool water temperature gain reduction caused by the pool cover. This balance is affected by, the type of swimming pool cover and the climate that you need to achieve a favorable swimming pool temperature in. In dry and/or windy conditions the evaporation rate increases, and it is generally beneficial to have a transparent or bubble cover on during daylight hours. In warm, humid conditions the evaporation rate decreases, and it may be more beneficial to leave the swimming pool cover off during the daytime to provide the pool water heating.
Other benefits of swimming pool covers
Swimming pool covers also provide many other benefits beside the tremendous energy savings in heating swimming pools. They conserve water by reducing the amount of make-up water needed by 30-50%. They can reduce chemical consumption by 35-60%. They also cut swimming pool cleaning time by keeping dirt and other debris out of the pool water. It is highly recommended that the first step to cutting energy loss be the evaluation of the economics of using a swimming pool cover in order to accomplish a high swimming pool temperature. (To clarify, we are not talking about swimming pool covers that you use to cover the pool in the off season or mesh safety covers. Those do not save energy. We are talking about plastic or vinyl swimming pool covers that you use during the swimming season when it is not in use.)
