Window condensation tip of iceberg

Q: How can I get rid of condensation on the windows of my four-year-old home? We bought the place a year ago, and last winter we had wet windows and a frozen storm door until spring. There’s no humidifier on our furnace and we’ve been running a dehumidifier without much success. Any suggestions?

A: The problems you're having are very common in modern Canadian homes and it springs from inadequate building practices that need to be revised. The condensation you see is a direct result of insufficient ventilation, and it means more than just wet glass. The same process of condensation can also happen within wall cavities and attics that aren't sealed properly. And while it’s a problem in itself, window condensation is also an indicator of something else. It strongly suggests that the air quality in your home is lower than it should be, contaminated by various off-gassed pollutants that can't get out because your home is so tight. A dehumidifier might seem like a solution but it isn't. There are two reasons why. First, none are capable of lowering indoor humidity levels enough to prevent condensation. And second, dehumidifiers don't boost the quality of air in your home during winter, they just make the bad air somewhat drier. What you really need is a heat recovery ventilator (HRV). This is a permanently installed device that draws fresh outdoor air into your home while also pushing stale indoor air outside. And it does all this while retaining more than 80% of the energy you’ve invested warming air with your heating system. An HRV costs a couple of thousand dollars to have installed, and this is why the homebuilding industry has lobbied so hard to keep HRVs from being required by law. But politics aside, an HRV really is essential if you're going to enjoy the energy benefits of a tight home without the side effects of window condensation and low indoor air quality.