A $200-million complex under construction along the Halifax waterfront will use seawater for its heating and cooling system.

"So this building will be about 55 per cent more efficient than a building we would have designed 20 years ago," said Denis Morris, the president of M & R Engineering.

The Queen's Marque is being developed by The Armour Group. It includes a hotel, offices and residential space.

A heat pump system is being installed in the parking garage and it's connected to pipes that extend out into the harbour.

The Queen's Marque project on the Halifax waterfront will include a hotel, offices and residential space. It is expected to be completed in 2020. (CBC)

"We're 500 feet offshore and 45 feet underwater," said Morris, "so in the wintertime we extract heat and in the summertime we dump building heat back into it and put it back into the harbour."

Alderney Landing in Dartmouth uses seawater for air conditioning and the Emera building, also located along the Halifax waterfront, uses a heat pump system.

But Morris said the Queen's Marque system will be the largest in the city and will be expandable.

"The heat pump plant is modular and there's room to grow if other buildings in the downtown want to come online and share the technology," said Morris.

The Queen's Marque is expected to be completed in 2020.

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