Toronto, ON — Residents of a townhouse complex in Toronto are beyond thrilled with their new cold climate air-source heat pump, which replaced the buildings old heating system. In fact, 64 per cent of residents shared that their heat pump was significantly better.
This finding comes from a recent case study by the Atmospheric Fund (TAF). The project involved a 1987 townhouse complex at 66 Walpole Ave in Toronto.
Conducted in 2019, the project was done to reduce site-wide energy consumption by 20 per cent. The previous system consisted of electric baseboard radiators, a hot water tank, and 7.6 LPF toilets.
The new cooling system installed consisted of LG multi-split cold climate air source heat pumps, Rheem air source domestic hot water heat pumps, and a low-flow toilet retrofit.
The LG mini-split unit was installed in each suite, with one indoor head in the main living space and an additional indoor head per bedroom. Five units piloted Rheem heat pumps, and all toilets in the complex were upgraded from standard toilets to three LPF low-flow toilets.
The new system resulted in a 56 per cent reduction in domestic hot water heating energy, a 52.5 per cent increase in winter thermal comfort, a 33 per cent reduction in water consumption with low-flow toilets, and a 29 per cent reduction in heating energy.
Efficient but oversized
While the introduction of the LG cold climate heat pumps saw thermal comfort improve significantly in the summer months, the heat pumps only achieved 43 per cent of their targeted savings. The report highlighted that oversizing was the reason for this.
The outdoor units in the project were slightly oversized, which resulted in shorter run cycles in shoulder seasons. TAF states that the oversizing was necessary because the ASHPs carried the full heating load in the winter without relying on backup heating.
In addition, the outdoor unit needed enough capacity to match the combined output of all indoor heat. At the time of installation, the smallest indoor heads available had capacities of 8,100 BTU/h, much greater than the heating load of the individual bedrooms, according to the report.
Another limitation highlighted in the report was the thermostat logic for the LG units. With the thermostats available for this product at the time, it was possible to set an upper and lower temperature limit, which is important for curbing the rebound effect.
However, the control logic available only allows for one upper and lower setpoint for all modes rather than individual setpoints for each mode (particularly heating and cooling). This results in the need to set a relatively large temperature band and reduces potential energy savings. TAF highlighted that the current market provides more thermostat options.
DHW heat pump
As mentioned previously, the findings from the Rheem DHW heat pumps showed a 56 per cent reduction in electricity consumption. This accounted for 53 per cent of the target savings for this measure.
The report did highlight that one of the challenges with this heat pump was how it draws heat from the surrounding air, which required ample room for airflow. Additionally, this system requires access to a drain, which may not always be present in a retrofit scenario.
As mentioned, only five units featured these heat pumps, as they were the only ones that met the necessary conditions for installing the system.
TAF also reported that one of the significant challenges during the time of installation was that most of the heat pump products on the market involved indoor heads with a larger capacity than the project needed. Due to this, cycling occurred more frequently than expected, reducing performance.
The report does acknowledge that there are currently more options available on the market for smaller units.
Through survey results, 70 per cent of residents found it to be too hot in their suites in the summer, particularly in the living room and kitchen which are typically located at the ground level. However, post-retrofit, 97 per cent of residents expressed satisfaction with their summer temperatures.
In the colder seasons, 50 per cent of residents surveyed pre-retrofit felt too cold in their suites in winter. However, post-retrofit saw an increase in thermal comfort, with 80 per cent of residents feeling satisfied with their winter temperatures.
In total, 80 per cent of residents found their heat pump easy to use and control. Even with some challenges, 60 per cent of residents gave their overall retrofit experience a rating of eight and above out of 10.