Swimming pools use a fairly high amount of water and energy. So if you are thinking of installing a pool, you might consider joining a community pool instead. If you already have a pool, you can enjoy it and still claim bragging rights for a sustainable lifestyle, as well as earn points in the Cleaner Contra Costa Challenge if you:
- Use an energy-efficient, variable-speed pool pump
- Heat your pool efficiently or with renewable energy
- Use a pool cover
Implementing these measures will save water, energy, and money.
Pumping With Less, For Less
California uses 10% of its total energy on pumping, heating, and treating water. The energy used to power pool pumps is small by comparison. Still, inefficient pool pumps can use almost as much electric energy as you use to cool your house with an air conditioner or three times as much as is used to power your refrigerator. The newer variable speed pumps use less energy than the old single-speed pumps. The smaller, more efficient pumps also have less capacity than older models. But this is not a problem. "Our motto when talking about pool filtration is 'slower and longer is better,'" says Gary Fernstrom, a program manager for the Pacific Gas and Electric Company (PG&E) Pool Pump and Motor Rebate program. In the early 2,000s, Gary traveled the state in a specially outfitted truck that demonstrated the benefits of slower and more prolonged pumping. "When the speed of the pump motor is lowered to one-half of the original rpm, the power demands of that pump motor scales with the cube of the speed of the motor," says Gary. "Slowing the pump motor to half the original speed will require the operator to operate the pump twice as long to pump the same amount of water, but the motor is drawing only one-eighth the power. So one-eighth the power multiplied by twice the time, theoretically, yields one-quarter of the energy use for the same water turnover." In real life, the smaller, more efficient pumps use about one-third of the energy.
Due partly to the advocacy of people like Gary, you can no longer buy single-speed pumps. If you have one of these antiques, swapping it out for an efficient model today makes sense. Using an Energy Star pump can save you even more energy and money.
The Cover-Up
Covering your pool when not in use can save you half the costs of running your pool or more. Without a cover, you lose heat from the pool and water through radiation to the sky and evaporation. Every pound of 800F water you lose to evaporation wastes about 1,000 Btu of heat. A covered pool will use 30% to 50% less makeup water.
It is best to use a cover made specifically for pools and one that's easy to deploy, such as one spooled at one end, similar to tarps used on baseball fields when it rains. Various styles deploy either manually or automatically.
The material should be U.V. resistant. An opaque vinyl cover will decrease heat gain by 20% to 40%. A transparent bubble wrap cover will decrease heat gain by only 5% to 15%. And because the transparent cover (sometimes called a solar pool cover) allows the sunlight through to heat the pool, it can drastically reduce, or even eliminate, the need for water heaters. A basic pool cover can cost less than $200. A fully automatic cover will cost a whopping $5,000 to $15,000.
Cost for Heating Your Pool
The pool's temperature will determine the amount of money or energy you'll use. Most pool temperatures vary between 780F and 820F. For competitive swimming, it's kept on the cool side (780F). Kids and the elderly like it a little warmer (820F).
Heat pump pool heaters, while costing more initially, are far more efficient and affordable than either gas or electric-resistant heaters. The U.S. Department of Energy has calculated the cost of heating a typical pool with a heat pump based on a 1,000 square foot, outdoor pool with a pool cover heated with a heat pump with an average coefficient of performance (COP) of 5 at the cost of $.13/kWh. Heating your pool to a temperature of 780F during pool season will cost you $1,100 in San Francisco, $1,300 in Los Angeles, and $1,400 in Chicago. To heat to 820F, you'll shell out $1,500 in San Francisco, $2,000 in L.A., and $1,730 in the Windy City. Pool season goes from May to October in Chicago, May to November in Los Angeles, and May to September in San Francisco. That's a lot of money to spend to increase the comfort and speed of elite swimmers. The difference compared to gas heaters, however, can be as much as $300; for an electric resistance heater, the savings can be as high as $800.
A solar hot water system is an option, but you will still need a pool pump. The cost for a solar hot water system installed is comparable to that of a heat pump water heater, but the cost to run it depends on your solar availability and collector efficiency. The average price of an electric heat pump pool heater is, with installation, $4,000, a gas heater is around $1,500 to $6,000, and a standar electric heater will run you about $2,000.
A Great Way to Start a Green Wave
Pentair, a pool and spa products retailer, offers some great calculation tools to predict costs and savings based on the size of your pool and the kind of equipment you install. Once you've trimmed your energy use and plan for a more sustainable pool experience, join the Cleaner Contra Challenge. Go to the "Upgrade Pool Pump" section, and get valuable information about a $50 rebate and other ways to save money and energy and limit carbon emissions. Do this, and things will go swimmingly!
Photo by Chandra Oh on Unsplash.
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