Impact of a demand-side management strategy in operating a hybrid geo-district energy system for a high-rise mixed-use residential building in Toronto, Canada

Abstract

In Ontario, Canada, the building thermal energy market is largely driven by the low cost of natural gas as a heating fuel source, with natural gas rates being approximately five times less per unit energy than electricity. The hybridization of geo-exchange with conventional building energy systems is a well-established means of optimizing the economics of geo-exchange and accelerating the adoption of this technology as a standard building thermal energy system. Demand-side management (DSM) is a mechanism which can be utilized in Ontario's electricity market (or others with similar demand charge structures) to manipulate a user's overall electricity cost. This case study presents the results of a project currently under development in Ontario for a hybrid geo-exchange system, comprised of an in-house Ground-Source Heat-Pump (GSHP) supplemented by a hot/chilled water district energy system. Utilizing the GSHP as a flexible load, the heat-pump is deactivated during the electrical grid's peak periods, shifting the building's demand to the district system. Transferring the load to the district results in a reduction in the high-rise building's contribution to the electrical grid's peak power demand, and consequently a reduction in the building's blended annual electricity rate. This case study illustrates the potential to reduce a high-rise building's blended annual electricity rate by up to 52%, impacting both the building's plug load and geo-exchange operating costs, proportionally. The simulated results indicate a potential geo-heating and geo-cooling operational cost savings of 14% and 67%, respectively.