← Ontario Building Code FAQ
OBC DIVISION B · PART 6 — HEATING, VENTILATING AND AIR-CONDITIONING

Is an HRV required in new homes in Ontario?

New Ontario houses need a principal mechanical ventilation system under Section 9.32, and in practice nearly all SB-12 energy compliance packages require a heat recovery ventilator (HRV) with a specified minimum efficiency.

Code reference — verbatim
Section 9.32 requires a principal ventilation system with a normal operating exhaust capacity based on the number of bedrooms, and SB-12 compliance packages specify heat recovery ventilators with minimum sensible recovery efficiencies as part of the prescriptive energy efficiency options.
OBC Division B, Section 9.32 and Supplementary Standard SB-12
What this means in practice

Two code layers converge here. Section 9.32 requires every dwelling to have mechanical ventilation with a principal exhaust fan sized by bedroom count, plus supplemental exhaust (kitchen, bathrooms). Separately, SB-12 — Ontario's energy efficiency standard for housing — defines prescriptive compliance packages, and the packages achievable at current insulation levels include an HRV with a minimum sensible heat recovery efficiency (commonly 75%+). An HRV recovers heat from outgoing stale air to preheat incoming fresh air, so the ventilation requirement is met without a large energy penalty. In an airtight new home, disabling the HRV leads directly to condensation and air quality problems — it is the house's lungs.

Plain language

Yes, effectively. New homes are built airtight, so they need a machine that constantly swaps stale indoor air for fresh outdoor air while keeping the heat. That machine is the HRV, and the energy code all but mandates it.

Related questions

What are the ventilation requirements for buildings in Ontario?Where can exhaust ducts and vents discharge in Ontario?

Get answers like this for any code question

BUILDAiD Assist searches the building code and answers in plain English with exact citations — in seconds.

Try BUILDAiD Beta

This page is provided for general information. Building code requirements depend on your specific project, occupancy and municipality, and code editions change. Always verify requirements against the current Ontario Building Code and confirm with your local building department.