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A number of UHN sites have abandoned traditional air conditioning systems – one of the most energy-intense parts of a building – and replaced them with a renewable, sustainable cooling system that reduces energy consumption by 90%.

FM-PRO's Energy & Environment team has overseen the installation of Enwave's Deep Lake Water Cooling (DLWC) System – which uses cold water from Lake Ontario to provide air conditioning and cooling – at Toronto Rehab – University Centre (installed in 2010), Toronto General Hospital (installed in 2018) and, most recently, Princess Margaret Cancer Centre.

To connect UHN to the DLWC system, a new set of heat exchangers were installed at each site that connect to Enwave's "district cooling loop," which harnesses the renewable cold temperature of the water at the bottom of Lake Ontario to provide cooling to downtown Toronto buildings. Water doesn't get wasted either - after going through the district cooling loop, the treated lake water proceeds to Toronto's drinking water system to be used by homes and businesses around the city.

Connecting to this system allowed UHN to increase overall cooling capacity and to repurpose its electric chillers as backup systems to improve site resilience.

The DLWC system, which now cools Operating Rooms, MRI and CT equipment, clinics, patient rooms and offices, saves UHN $2 million in utility costs each year as well as 65 million litres of water – the equivalent of 27 Olympic-sized swimming pools.


Enwave's industry-leading Deep Lake Water Cooling system is the largest of its kind and not only cools downtown hospitals like Toronto General, but also commercial buildings like Royal Bank Plaza and Scotiabank Arena, data centres, educational campuses, government and residential buildings.

For more information on the Deep Lake Water Cooling System project across UHN, contact

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