By Dan Vivian and Cecile Wilson
CO2 at Mauna Loa, 12 November 2023: 419.55 ppm
Air conditioners should be banned in Ontario. Yes, we’re being deliberately provocative, but now that we have your attention, hear this out.
Heat pumps are air conditioners that also heat more efficiently than electric resistance heating or natural gas or other fossil fuels. They can run in reverse to extract warm air from the outside and bring it inside. In mild temperatures, they can be 300- to 400-per-cent more efficient than traditional forms of heating. Even though electricity is more expensive than natural gas, by using heat pumps for heating in the milder temperatures of the winter (down to about -2 degrees), the utility bills and even lifetime costs are less expensive than with natural gas.
Ontario’s electric grid currently has very low greenhouse gas emissions. By using a heat pump to heat down to about -2, the greenhouse gas emissions (GHGs) are reduced by about 60 per cent. Different heat pump models have different efficiencies, but these numbers are approximately true for most cold-climate heat pumps.
If we run a heat pump to even lower temperatures (down to about -8), the lifetime costs are about the same as natural gas, and we reduce the greenhouse gases by about 70 per cent. Because a heat pump’s efficiency declines as the temperature drops, most heat pumps require a backup heat source below about -25. Luckily, the total number of hours we heat our houses at these extreme low temperatures is minimal. If we run our heat pumps in colder temperatures and use electricity as our backup source of heat, we reduce our GHG emissions by over 90 per cent but only pay a small financial premium above the lifetime costs of natural gas heating.
When to install a heat pump
So, if heat pumps are better, when should you buy them? Using up the life of a product makes sense for both financial and lower carbon reasons. There is an embedded carbon penalty in the use of heat pumps. That is, the manufacture and distribution of heat pumps require energy that typically comes from fossil fuels that emit GHGs. If you retire an AC unit too early, you will cause additional GHGs emissions from the manufacture and delivery of the replacement heat pump.
When you install a heat pump, your HVAC contractor will remove your air conditioner. Most HVAC contractors advise that an AC unit will last about 20 years. It makes sense to replace an AC unit with a heat pump after about 15 years to avoid significant embedded carbon emissions or financial loss. Once your heat pump is installed, you can use it in addition to your current heating system. If your furnace is also 15 years old, you may like to replace both appliances at the same time.
Take advantage of financial supports
Although heat pumps can save you money, they do require an initial outlay of cash. Thankfully, there are several programs that provide grants and loans to help you make the transition to cleaner energy. To qualify for any of these supports, the homeowner must complete a home energy audit by a Registered Energy Advisor before any work is done.
Currently, heat pumps are being subsidized by Natural Resources Canada (NRCAN) with a $6,500 grant if you already have natural gas heating or a $5,000 grant if you have other heat sources. These grants (that’s right, they don’t have to be paid back!) are administered by Enbridge. In addition, you also are eligible for a $600 rebate, which essentially covers the cost of the audit.
NRCAN will provide up to $40,000 of no-interest loans for qualifying homeowners for upgrades like heat pumps, high performance windows, insulation and solar panels. The City of Ottawa will add up to 10 per cent of the value of your home in additional low-interest loans for these upgrades. For City loans, you must show some air-sealing improvements if air sealing is recommended in your energy audit. The City loans are paid back via a surcharge on your tax bill.
We are hearing that the program may end in March so now is the time to go ahead with the energy audit and suggested retrofits. This would be a good Christmas or holiday present for a climate-conscious family and the environment, too!
For more information on grants and loans available, search on the internet for:
Natural Resources Canada: Greener Homes Loan
Better Homes Ottawa (City of Ottawa programs)
Enbridge Home Efficiency Rebate Plus
Dan Vivian is principal of Building Science Trust and a Registered Energy Advisor. Cecile Wilson is a resident of the Glebe and (hopefully) soon-to-be owner of a cold-climate heat pump.