Sorry to ruin summer, but swimming pools are terrible for the environm

Pools are massive energy hogs. Heating them up, and keeping them warm, is a costly expense, especially for cities operating large public pools. But these pools are also clamored for by communities. So when cities set out to appease their citizens, they often make a trade-off—providing a beloved public amenity and coughing up for the energy it consumes.

[Image: Perkins&Will]

A new community center design suggests that trade-off may no longer be necessary. The North East Scarborough Community and Childcare Centre, now under construction in Toronto, will be Ontario’s first net zero energy-consuming community recreation facility with swimming pools when it opens in 2024. Located on the lower level, a six-lane lap pool and adjacent leisure pool have been designed to function as efficiently as possible, with all their energy use provided by on-site heat and electricity generation.

[Image: Perkins&Will]

There are more than 300,000 public swimming pools and more than 10 million residential pools in the United States, and in 2020 alone an estimated 96,000 additional residential pools were constructed. All this adds up to a significant amount of energy usage. One study suggests U.S. pools consume between 9 and 14 billion kilowatt hours (kWh) of electricity, or about the electricity demand of 11 states. A study of public pools in San Antonio, Texas, found that the average annual energy costs of conventional pool heating was more than $12,000. In colder Toronto, those figures would likely be even higher.

Places like Toronto are reconsidering how these huge energy users are powered. The new community center offers what the city hopes to be a model. The four-story community center features a gym, running track, childcare facility and indoor cricket field, surrounded by a public park. An all-electric building with considerable on-site renewable energy generation, it’s expected to produce as much energy as it uses—and produce net zero emissions.

Designed by the architecture firm Perkins&Will, the project is a pilot for the city of Toronto, which is hoping to make all its community centers and other city-built projects equally energy efficient. Addressing the pool energy issue was a primary goal. “This was a pilot project for the city as well as ourselves,” says Zeina Elali, senior sustainability advisor at Perkins&Will. “It’s something that’s been a challenge in the industry.”

Pools represent a major energy challenge for architects like Elali, who is tasked with helping clients get the projects they want while also reducing their environmental impact. That takes more than just swapping in LED lights or slapping on a few photovoltaic (PV) panels. “I think a lot of the private sector and public sector have already reached for the low hanging fruit,” says Elali. “It was about time to tackle the larger carbon contributors.”

[Image: Perkins&Will]

The pools in the new community center will have a reduced energy load due to a few unique design solutions. One is that they are both buried half underground, thermally insulating them from the often freezing temperatures Toronto sees in its winters, and reducing the amount of artificial heat they require. The pools also use electric air-source heat pumps, which transfer heat to or from outside air to quickly generate heat for the pool. For the same amount of energy, these highly efficient heat pumps can produce three times the heat of a conventional fossil fuel-based heating system.

Even with this more efficient heating, the pools still require energy. “You’re never going to bring down the usage to zero, so you’re bringing it down as much as you can through mechanical efficiencies,” says Christina Grimes, an associate at Perkins&Will.

The rest of the energy demand is being offset by the project’s expansive and inventive PV panel arrays. The roof of the building is covered with solar panels, as is a large parking lot that will double as space for a weekly farmers market. A walkway connecting a nearby housing development has a narrow PV canopy overhead, and the building itself has PV panels integrated into its facade. “We’ve got every kind of PV system you can imagine on this project,” says Grimes.

[Image: Perkins&Will]

To help the project achieve its net zero emissions goal, the designers worked every angle, focusing on reducing the building’s operating emissions as well as the emissions created during construction, known as its embodied carbon. Opting for a lower-emission mix of concrete brought the total embodied emissions down by 24%.

These energy efficiency efforts aren’t cheap, but the architects argue that the upfront capital costs will be more than offset over time. “Your utility bill should be zero,” says Grimes. “A 30-year timeline is the way you have to think of the return on your investment.”

More communities are seeing the wisdom in making these investments. Perkins&Will has designed two other net zero community centers for other cities in Ontario, and construction on both is expected to begin later this year. Each will have a pool.