The City of Ottawa has approved its first-ever pilot project to utilize thermal energy from wastewater for low-carbon heating and cooling of two new high-rise residential buildings.
For the net zero carbon development pilot, Ottawa has entered into an agreement with the development’s partners to connect to the City’s sanitary sewer and Combined Sewage Storage Tunnel, which both run beneath the planned 1.1-hectare Dream LeBreton affordable housing site.
Theia Partners and Envari Holdings will design, build, and operate the Wastewater Energy Transfer (WET) system so that Ottawa sewage can be filtered and pumped through a heat exchanger to draw energy for the 608 high-rise rental units. The heat exchange process combined with a pumping loop for sewage can capture and use heat found within wastewater systems and could reduce carbon dioxide equivalent emissions by some 1,100 tonnes.
In a statement, the City’s Environment and Climate Change Committee announced that the city would “set a fee for a WET system design review, and an annual energy transfer fee based on the rate of flow needed to meet anticipated energy demands for Dream LeBreton. Staff would report back on results of the pilot no later than 18 months after it is implemented.”
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On average, 545 million litres of wastewater is treated each day at the Robert O. Pickard Environmental Centre, before it is returned to the Ottawa River, the committee stated.
The committee says in-person site visits of operational wastewater energy transfer systems were conducted in Washington, D.C., last September. It describes the WET process as utilizing the relatively high heat capacity of sewage and water. It means that a lot of thermal heat can be extracted per degree of temperature change in the wastewater and provide a more consistent source temperature and higher heat capacity than ambient air provides for an air source heat pump.
SHARC Energy Systems is a Canadian company based in Vancouver. Its wastewater energy transfer technology is being considered for the Ottawa project. The other technology being considered is manufactured by Huber Technology Inc.
Michael Cooper, founder of the Dream Group of Companies, and Dream LeBreton, said in a statement that he looks forward to “providing desperately needed affordable housing, contributing to a healthier planet by building a zero-carbon community.”
The Dream Lebreton project is also expected to utilize solar power-generating systems.
According to the Canada Green Building Council, the Dream LeBreton project will be the country’s largest residential zero-carbon development.
The proposed development is targeting the Canadian Green Building Council’s Zero Carbon Standard for Design and Performance, as well as LEED Gold for both New Construction and Neighbourhood Development.
The buildings, which neighbour the carbon-neutral Zibi project, are estimated to be ready for occupancy by early 2026.