Page 10 - U4SSC Case study: Energy efficiency in buildings, June 2020

Storage Tanks

Enwave Toronto recently signed an agreement with ‘The Well’, a mixed-use development in Toronto,
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where thermal storage tanks will be installed below the 7 level of underground parking, leveraging
existing cooling infrastructure to take advantage of off-peak cooling capacity. These thermal storage
tanks will be filled with chilled water from DLWC during the night, when cooling demand is lower
and electricity is greener and cheaper, to support peak capacity during the day. Enwave’s automated
dispatch system will be used to determine optimal timing to fill and dispatch the thermal storage tanks
given cost inputs, environmental metrics and load projections.

District Heat Recovery (DHR)

Many buildings connected to DLWC, such as data centres, require cooling year-round. These buildings
reject a substantial amount of heat into the DLWC system, which can be recovered in the winter and
upcycled through heat pumps to supply low-carbon heating to other buildings throughout downtown
Toronto. Heat pumps use the same technology as refrigerators: they move heat from a low-temperature
source (DLWC return pipe) to a high-temperature sink (the building to be heated). Heat pumps are
powered by electricity and typically offer efficiencies approximately four to five times that of high-
efficiency natural gas-fired boilers. Since electricity is currently substantially more expensive on a
blended rate basis than natural gas, heat pumps will need to be strategically deployed to minimize
electricity demand charges, in order to remain competitive in the market.

Table 1: Toronto’s Strategic Approach to District Energy

Strategy Partnership Approach
Description The operations teams for DLWC and the city’s potable water system work together in a close partnership to continually optimize operations.
Reason for DLWC operations are highly integrated with the city’s water operations. For example, city water flow rates affect the amount of cooling that can
Development be produced at any given time; therefore, the DLWC operations team communicates projected water volumes needed to meet cooling demand to
the city daily so that use of the city’s water reservoir can be optimized to match water flows with DLWC demand.
Impact on District Using a partnership approach rather than operating in silos based on contract parameters has been critical to optimising holistic benefits to the
Energy city. For example, the DLWC system includes backup power that also supplies the city’s potable water distribution pumps and gives those pumps
priority that adds resiliency to the potable water system, as well as the DLWC system.
Strategy Toronto Hydro Incentive
Description Toronto Hydro, the local electricity utility in Toronto, developed a tailored incentive, paid in $ per kW of reduced electricity demand, for buildings
to connect to DLWC.
Reason for Toronto Hydro recognized that connecting buildings to DLWC reduces its electricity demand and related costs Toronto Hydro incurs for upgrading
Development electricity infrastructure to support the ever-growing demand in downtown Toronto.
Impact on District The incentive provides buildings with a one-time payment when they connect to DLWC that can help support the business case for connection
Energy costs.

4 Case study: Energy efficiency in buildings, June 2020