Does an HRV help with condensation on windows in a Toronto home during winter?

Yes, a properly operating HRV is one of the most effective solutions for winter window condensation in Toronto homes — and in many cases, it is the only real fix. Window condensation happens when warm, humid indoor air contacts cold glass surfaces, and the moisture in the air condenses into water droplets. During Toronto winters, with outdoor temperatures regularly dropping below -10 degrees Celsius, even double-pane windows can become cold enough to trigger condensation when indoor humidity is too high.

The root cause of winter window condensation is excess indoor humidity trapped inside a well-sealed home. Every Toronto home generates significant moisture from daily activities — cooking produces 2-3 litres of moisture per day, a 10-minute shower produces about half a litre, each person exhales about 1 litre per day, and houseplants, laundry, and even gas fireplaces add more. In an older, leaky home, much of this moisture escapes through air leaks around windows, doors, and the building envelope. But in newer GTA homes built after 2000 — or older homes that have been renovated with new windows, insulation, and air sealing — that moisture has nowhere to go. It builds up inside the home until it finds the coldest surface available, which is always the windows.

An HRV solves this by exhausting the humid indoor air and replacing it with dry outdoor air. Toronto winter air is extremely dry — at -15 degrees Celsius, outdoor air at 70% relative humidity contains very little actual moisture. When this cold, dry air enters your home through the HRV and warms up to 20-21 degrees, its relative humidity drops to roughly 15-20%. This dry incoming air mixes with your humid indoor air, lowering the overall indoor humidity to the 30-40% range where condensation stops forming on most window types.

The target indoor humidity level depends on your window quality and outdoor temperature. With standard double-pane windows common in GTA homes, you want indoor humidity around 30-35% when outdoor temperatures drop below -10 degrees. With triple-pane windows, you can maintain 35-40% humidity without condensation. If you see condensation between the panes of a sealed window unit, that indicates a failed seal in the insulated glass — the HRV will not fix that, and the glass unit needs replacement.

If you already have an HRV and still see condensation, several issues could be at play. The most common is that the HRV is not running or is running on too low a speed. Check that the unit is powered on and set to at least low continuous operation. Second, check the filters — clogged filters reduce airflow dramatically, and a filter that has not been cleaned in six months is barely moving air. Third, check the exterior intake and exhaust hoods for ice blockage, which is common after Toronto ice storms and freezing rain events. A blocked hood shuts down effective ventilation entirely. Finally, if your home has been recently air-sealed or renovated (new windows, added insulation, spray foam), your existing HRV may now be undersized for the tighter building envelope. A home that used to leak air freely now retains much more moisture, and the HRV may need to run at higher speed or be upgraded to a larger unit.

For homes without an HRV, installing one is the best long-term solution for chronic winter condensation. Budget $2,500-$5,000 for installation in a typical Toronto home. In the meantime, running bathroom exhaust fans for 20-30 minutes after showers and using a kitchen range hood while cooking helps reduce moisture levels.