Indoor Air Quality · Canada

Healthy air in tightly sealed homes

As Canadian houses are built more airtight to cut heating costs, mechanical ventilation decides how fresh the indoor air actually is. This reference explains heat- and energy-recovery ventilation, humidity control, and routine upkeep in plain language.

A residential heat-recovery ventilation unit mounted in a mechanical room
A wall-mounted heat-recovery ventilation (HRV) unit. Source: Wikimedia Commons.
Schematic showing how a heat exchanger transfers heat between exhaust and supply air
How a heat-recovery core warms incoming fresh air using outgoing stale air. Source: Wikimedia Commons.
Why ventilation matters here

Airtight construction changes the rules

Older houses leaked enough air through gaps and around windows to dilute moisture and indoor pollutants on their own. Modern Canadian building practice deliberately reduces that leakage to save heating energy, which means fresh air now has to be supplied on purpose.

Balanced mechanical ventilation with heat recovery is the common answer: it brings in outdoor air, removes stale indoor air, and recovers most of the heat that would otherwise be lost in winter.

A useful rule of thumb

If your windows fog up on cold mornings or the air feels stuffy by evening, ventilation and humidity — not the furnace — are usually the place to look first.

At a glance

HRV and ERV side by side

General characteristics. Always confirm specifications against the manufacturer's documentation for your unit.
AspectHRV (Heat Recovery)ERV (Energy Recovery)
Transfers heatYesYes
Transfers moistureNoPartially
Tends to suitCold, drier wintersHomes prone to very dry or very humid air
Winter effect indoorsCan lower indoor humidityHelps retain some indoor humidity
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