What size ERV or HRV do I need for a Toronto home based on square footage?

Sizing an ERV or HRV for your Toronto home is based primarily on the number of bedrooms and bathrooms — not square footage alone — because the Ontario Building Code ties ventilation rates to occupancy capacity. That said, square footage is still a useful starting point for ballpark sizing, and most GTA homeowners want a quick answer before diving into the technical details.

As a practical guideline for GTA homes, here are typical sizing ranges. A home under 1,500 square feet with 2-3 bedrooms generally needs an HRV or ERV rated at 100-150 CFM. A mid-size home of 1,500-2,500 square feet with 3-4 bedrooms typically requires 150-200 CFM. Larger homes of 2,500-3,500 square feet with 4-5 bedrooms usually need 200-300 CFM. Homes above 3,500 square feet or with more than 5 bedrooms may need 300+ CFM or multiple units.

The proper way to size an HRV or ERV follows CSA F326, which is the Canadian standard for residential mechanical ventilation. This calculation considers the total number of rooms, the number of bedrooms (which determines assumed occupancy), and the required exhaust rates for bathrooms, kitchens, and laundry rooms. The total continuous ventilation rate equals the sum of the supply requirements for all habitable rooms plus the exhaust requirements for all service rooms. Your HVAC contractor should perform this calculation — it takes about 15 minutes and ensures the unit is neither undersized (inadequate ventilation) nor oversized (excessive energy consumption and potential indoor humidity problems in winter).

Oversizing is a real concern in Toronto's cold winters. An HRV that is too large for the home will exchange more air than necessary, pulling in excessive cold outdoor air that the heat exchanger core cannot fully temper. This leads to cold drafts at supply grilles, increased heating costs, and — counterintuitively — excessively dry indoor air in winter. Dry air below 30% relative humidity causes respiratory discomfort, static electricity, cracking hardwood floors, and damage to wood furniture and musical instruments. Properly sized, your HRV should maintain indoor humidity between 30-40% in winter while providing adequate fresh air.

The heat recovery efficiency rating matters as much as the CFM rating in a cold-climate city like Toronto. Look for units with a Sensible Recovery Efficiency (SRE) of 75% or higher at -25 degrees Celsius. High-end units achieve 80-85% heat recovery, meaning they capture most of the heat from the outgoing stale air and transfer it to the incoming fresh air. At Toronto winter temperatures of -15 to -20 degrees, a unit rated at 80% SRE will deliver incoming fresh air at roughly 15-18 degrees Celsius — cool but not cold. A unit rated at only 60% SRE will deliver air closer to 5-8 degrees, causing noticeable drafts and higher heating costs.

Budget $2,500-$5,000 for a properly sized HRV installation in a typical GTA home, or $3,000-$6,000 for an ERV. The unit itself accounts for roughly half the cost, with the remainder going to ductwork, electrical connections, controls, and exterior penetrations. Always get three quotes from qualified HVAC contractors, and confirm they will perform the CSA F326 sizing calculation before specifying equipment. Browse HVAC and ductwork contractors in your area through the Toronto Construction Network directory at torontoconstructionnetwork.com/directory?trade=hvac.