How does make-up air affect my heating bill in a Toronto home during the winter?

Make-up air will increase your heating costs because you are bringing cold outdoor air into your home and heating it, but the increase is manageable with a properly tempered system and is the unavoidable cost of safely operating a high-CFM range hood in Toronto's winter climate. The real question is how much it adds and what you can do to minimize the impact.

The energy cost depends on three factors: how much air the system brings in (CFM), how cold it is outside, and how long the range hood runs. A 600 CFM range hood running for one hour on a -15 degree Celsius Toronto evening requires roughly 30,000 to 40,000 BTUs to temper that volume of outdoor air to room temperature. For context, a typical Toronto home furnace produces 60,000 to 100,000 BTUs per hour, so running the range hood at full blast for an extended period creates a meaningful heating load. If you use your range hood for 30 to 60 minutes per day during cooking, and your make-up air system uses an electric tempering coil, expect to see an increase of roughly $30 to $80 per month on your electricity bill during the coldest winter months (December through February). Gas-fired tempering units are somewhat cheaper to operate because natural gas costs less per BTU than electricity in Ontario, but they require a gas line run to the unit and TSSA-registered installation.

The energy impact is heavily influenced by your cooking habits. Most homeowners do not run their range hood at full speed continuously. If you typically cook for 30 minutes and run the hood on medium (perhaps 300 CFM instead of 600), the make-up air volume and heating cost are cut roughly in half. Multi-speed range hoods paired with make-up air systems that modulate their airflow based on the hood's speed setting are the most energy-efficient configuration. Some modern make-up air units include variable-speed fans and modulating tempering controls that match airflow to the hood's demand — these cost more upfront ($3,000 to $5,000 versus $2,000 to $3,500 for a basic unit) but reduce operating costs significantly over time.

There are several practical steps to minimize the heating cost impact. First, use your range hood at the lowest effective speed — most daily cooking does not require full blast. Second, ensure your make-up air duct is well-insulated (R-8 minimum) where it passes through unconditioned spaces, so you are not losing heat before the air reaches your home. Third, consider a make-up air unit with heat recovery capabilities, or pair your system with an ERV that recovers heat from exhausted air. Fourth, keep the run between the exterior wall penetration and the discharge point as short as possible to minimize heat loss through the duct itself.

One perspective that helps frame the cost: without make-up air, your home still draws in the same volume of cold outdoor air — it just comes in through uncontrolled leakage points around windows, doors, and penetrations, plus potentially through gas appliance flues (creating a carbon monoxide risk). A tempered make-up air system brings in the same air volume in a controlled, heated, filtered manner. You are not paying to heat extra air — you are paying to heat the same air safely and comfortably. For help sizing and installing an energy-efficient make-up air system, get matched with a local ductwork contractor through the Toronto Construction Network.