Peak Electrical Demand Impacts of Air-Source Heat Pumps in Canadian Residential Buildings

While heat pumps offer an efficient electrification of space heating, they can also increase house-level electrical demand, particularly when replacing the natural gas-based systems common in many Canadian regions. Understanding the magnitude of any potential increase in peak electrical demand is critical in order to support the widespread deployment of heat pump technologies. This paper uses a simulation-based approach to examine the peak demand implications of air-source heat pumps (ASHPs) in two Canadian cities (Toronto, Vancouver). First, a series of occupancy and non-HVAC load profiles are developed via a flexible, bottom-up approach in order to explore the range of peak demand increases possible with heat pumps under various occupancy scenarios. These models are then combined with detailed housing models and an enhanced, data-driven heat pump model to assess the peak demand implications of two market-available ASHP technologies: Variable capacity (VCHP), and cold climate (CCHP) heat pumps. Results show the impact that climate and heat pump selection can have on peak electrical demand. In colder climates (Toronto), the peak electrical demand may increase up to 4.1 kW (VCHP) and 2.9 kW (CCHP) vs. a natural gas furnace system for a typical tract-built single- family home. These peaks are closely associated with periods of colder weather when heat pump and auxiliary electric resistance heating is higher, and may occur with a greater degree of coincidence for systems in a given region. In milder climates (Vancouver), expected increases in the peak electrical demand are smaller, and may reach up to 1.4 kW (VCHP) and 1.6 kW (CCHP) for the same housing type. Peaks in Vancouver are more closely associated with a combination of heat pump and non-HVAC loads, and may occur with a lower degree of coincidence given they are more closely linked to occupancy.