Glossary · Heating, cooling & ventilation

HRV (heat recovery ventilator)

Also called: air exchanger · air-to-air exchanger · heat recovery ventilation

A ventilation system that swaps stale indoor air for fresh outdoor air while transferring heat from the outgoing air to the incoming air.

What it means

Two fans move equal amounts of air in and out through a heat-exchange core, so fresh air arrives pre-warmed in winter. It runs continuously or on a schedule at low speed, with high speed for showers or cooking. Filters and the core need regular cleaning, and airflows should be balanced by a trained installer.

Why it matters in an audit

As a house gets tighter from air sealing, an HRV keeps indoor air quality and humidity under control without throwing away most of the heat.

Typical numbers

Reference values with their sources. Your auditor’s report gives the figure for your own house.

What	Value	Source
Heat recovered (NRCan, 2018)	HRVs and ERVs recover 60%–90% of the heat in exhaust air	natural-resources.canada.ca ↗
Typical recovery (NRCan, Keeping the Heat In)	70%–80%	natural-resources.canada.ca ↗

Sources

Related terms

ERV (energy recovery ventilator) Like an HRV, but its core also transfers some moisture between the outgoing and incoming air, which helps manage humidity.
Indoor air quality (IAQ) How clean and healthy the air inside a home is, affected by ventilation, humidity, combustion gases, particles, chemicals and radon.
Relative humidity (RH) How much moisture the air holds compared with the most it could hold at that temperature, shown as a percentage.
Air sealing Blocking the hidden gaps where air leaks in and out of a house, which cuts drafts, heating and cooling costs, and moisture problems.
Radon mitigation (sub-slab depressurization) Fixing high radon, usually with a pipe through the basement floor and a fan that pulls soil gas from under the slab and vents it outside.
ECM (variable-speed) blower motor A high-efficiency, variable-speed fan motor for furnaces, air handlers and HRVs that uses far less electricity than older motors, especially at low speed.
Defrost cycle (heat pumps and HRVs) A short, automatic cycle that melts frost off a heat pump's outdoor coil or an HRV's core in freezing weather; it's a normal part of winter operation.

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