BEAT THE HEAT! Click here to book your AC or Heat Pump quote today.

What Seems Harmless Could Be Harmful — When Window Moisture Poses a Threat

What Seems Harmless Could Be Harmful -- When Window Moisture Poses a ThreatDry, cold arctic air, which can impact our climate here in Alberta year-round, creates some distinct challenges for our homes. One is window moisture. Aside from our often extremely cold winters, rapid drops in temperature can cause condensation to develop in any season.

How Condensation Occurs

All air holds some moisture. The air in our homes can contain an exaggerated amount, because water is introduced into the atmosphere by activities such as showering and cooking.

Moisture present in air condenses out when that air comes into contact with a cooler surface; the beads which form on the glass of a cold drink served in a warm, humid climate are a perfect example. When the air inside a home is warmer than that outside, window frames and glazing can provide that cooler surface.


There are several signs that your windows may be producing a potentially harmful amount of condensation. They include:

  • Frost on the inside of your window glazing
  • Ponding water on sills, or in the sealant around the glazing

Why Condensation Can Be Harmful

If excessive moisture is allowed to form, collect and stand for long periods, you run several risks as a homeowner:

  • The materials which comprise your windows can deteriorate, particularly if the frames or sills are made of wood
  • Ugly, malodorous colonies of mold and mildew are encouraged by dampness, especially in warm spaces (wet wood “rot” is simply the visible indication that a fungus is living in, and living off, wood)
  • If allowed to proliferate, the spores from mold and mildew can actively cause illness, or aggravate existing pulmonary conditions and asthma

Effective Measures

Timber decay, illness and unsightliness can all be avoided with a few simple do-it-yourself measures. Replace single-glazed windows with energy-efficient alternatives, or create a barrier with plastic sheeting. Run dehumidifiers; empty them regularly.

Here at Arpi’s Industries, we recommend the installation of a heat-recovery ventilator. These devices exchange stuffy, stale air with fresh outdoor ventilation, while retaining up to 80 percent of the heat stored in the indoor air. Contact us to learn more, or ask any questions related to window moisture.

Our goal is to help educate our customers in Calgary, Alberta about energy and home comfort issues (specific to HVAC systems). For more information about window moisture and other HVAC topics, downloadour free Home Comfort Resource guide. Credit/Copyright Attribution: “Stuart Miles/Shutterstock”