Moisture on my Windows

Why does the air in my home feel so dry yet there is moisture collecting on my windows? Most of us will not feel comfortable living in a space where the air is below 30% relative humidity. Even on the coldest days, indoor air will hold a small amount of moisture that can and will condense when it meets a cold surface such as your windows. Humidity levels in our Winnipeg homes will change from one season to the next simply because of the extreme temperature range that we see locally. Colder air by nature will hold less moisture than warmer air. Fortunately, there are solutions available to overcome humidity problems. It becomes essential to first discover and understand the mechanics of your home to properly assess and apply the most effective or appropriate fix. In other words, how is your lifestyle affecting your home?

What may be adding humidity to your home?

  • How many occupants? People and pets will add humidity.

  • How many showers, baths or hot tubs in a day?

  • How much cooking and laundry on an average day?

  • Watered plants and aquariums add humidity.

  • Water seepage causes damp basements.

  • A power humidifier may be adding humidity– is it working properly?

What may be reducing the humidity in your home?

  • Electric furnaces or baseboard resistance heaters.

  • Electronic equipment, televisions, computers etc.

  • Air conditioning removes moisture (only when it runs)

  • Over-ventilating will dry out your home

When we use exhaust fans or HRV units to exchange air on cold winter days, we most often will be dehumidifying or lowering the humidity level in our homes. On warm or hot and humid Winnipeg days, air exchange works the opposite and adds moisture and raises the humidity level indoors. This of course only adds to the work that a Central Air Conditioner needs to do as it dehumidifies while cooling your home.

So the big question is ……What to do with my wet Windows when it’s already too dry?

  • Window coverings will isolate the window from the warmer room air making them the coldest and most likely target for moisture to collect. Try leaving them at least partially open and you will see the difference. Louvered window shades are a great option for this especially when privacy is needed.

  • Make sure that any heating vents nearby are fully open and able to provide some air movement across the surface of the window. Adding an air vent or directing a fan to move more air may not be practical but would certainly help with removing any moisture on your windows. Ever wonder why the moisture only collects on the bottom of your windows? The laws of convection states: Warm air rises and Cooler air drops. So even though there may only be one- or two-degrees temperature difference from floor to ceiling, your windows will tend to be colder at the bottom and collect moisture there.

Here at Tradesman Mechanical we strongly recommend that you invest in an inexpensive hygrometer as a starting point to determine the actual humidity level in your home. You can find these at your local hardware store or from Tradesman for less than $50.00.


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