By upgrading the way these two buildings provide hot water, we can help save 46 tonnes eCO2 every year.

Since the release of Ontario’s Climate Change Action Plan, we’ve been hearing a lot about heat pumps and their potential to replace natural gas. TAF has a number of exciting projects underway related to electric heat pumps, and this week we started a demonstration project using another type – gas absorption heat pumps (GAHP). They too have promise to reduce large amounts of GHGs related to heating buildings. Onsite at our TowerWise Retrofit Project with Toronto Community Housing, we’re now installing two air source GAHPs that will provide domestic hot water to nearly 400 households.

Gas absorption heat pumps are very similar to electric heat pumps because they extract heat from the ambient, exterior air. Instead of using electricity, the GAHPs combust natural gas to drive the compression cycle and transfer heat from the exterior air into the buildings. Although GAHPs tend to have lower operating efficiencies compared to electric heat pumps, they keep operating costs low by avoiding a switch to a more expensive energy source.

How gas absorption heat pumps work:


Transitioning to this type of system can boost efficiencies beyond 100% and help the buildings meet their domestic hot water load much more effectively.  The two GAHP units in this project are intended to meet the base domestic hot water load, with condensing boilers connected as a backup heat source. With a relatively consistent demand for DHW throughout the year, the GAHP can take advantage of the high efficiencies during favorable outdoor conditions, particularly during the summer and fall.  By efficiently upgrading the way these two buildings provide hot water, we can help save 46 tonnes eCO2 every year.

Although GAHPs are not a brand new technology, there have been very few installations in colder climates, especially in multi-residential buildings. That’s why as part of this work we will be evaluating the performance of these units by monitoring things like water flow, temperature, and gas consumption.

By undertaking this demonstration project and collecting real world performance data we can make better informed decisions when implementing such technologies and ultimately accelerate their adoption.

Watch the video to learn more about the TowerWise Retrofit Project: