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.

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