Back in the 1940s, when Robert Tamblyn was working at Toronto's Eaton Centre department store, he noticed that it had tapped the city's water main -- illegally -- to rig up a system that fanned the chilly water through a network of pipes to cool the women's evening-wear department.
It was years before the city's water commissioner wised up. And years more before Tamblyn had the idea of applying the same concept in a bigger way.
"Air conditioning was a whole new word up here in the 1940s," says Tamblyn, the engineer many credit with developing an alternative technology -- lake-source cooling -- in North America.
He has helped devise large-scale, energy-efficient cooling systems for the city of Toronto and Cornell University's Ithaca campus. The city system, the largest of its kind, began operating last summer.
The first successful citywide venture was set up in Stockholm in 1995, but its capacity is less than half of Toronto's.
Unlike the department store's jury-rigged setup, Toronto's taps directly into the icy waters at the bottom of Lake Ontario.
It works by drawing water from 272 feet below the surface, where temperatures hover around 40 degrees Fahrenheit year-round. The coldness of the lake water is transferred via heat exchangers to a separate, closed water supply that loops around downtown Toronto and to participating office towers. Thirty-five buildings have already signed on to the project, including the Hudson's Bay Co.'s 1 million-square-foot retail outlet and 32-story head office. The company predicts it will save $416,000 a year on energy with the system.
Next year, several legislative buildings will be connected to the network.
Launched by Enwave District Energy, a public-private partnership, the new system will be able to cool more than 20 million square feet when it reaches full capacity. Participating buildings can expect to reduce the amount of energy used for cooling by an average of 75 percent, officials say.
Dennis Fotinos, Enwave's president, said the system will ultimately eliminate 40,000 tons a year of carbon dioxide emissions that conventional air conditioning would produce, and free more than 59 megawatts of electricity from the Ontario power grid.
"The more demands you can take off an already overburdened power grid in the northeastern U.S. and Ontario through initiatives like this, the less likely you're going to have power surges that cause blackouts," Fotinos said. "It's cheaper to reduce demand than build new supply."
Conventional air conditioning systems in high-rise buildings use electrically powered chillers in the basement to cool circulating water before pumping it upward and fanning it out over each floor. As the water rises, it absorbs heat, much of which is dissipated into the air by cooling towers on the roof before the water is returned to the basement to repeat the cycle.
