Condensation is a natural occurrence on all surfaces in the home caused by excess humidity in the air.
Windows are acting as a barrier to prevent the moisture from escaping the home.
Condensation on windows occurs when the surface temperature of the glass (glazing), sash or frame is lower than that of the humid air around it. The moisture vapour in the air changes into liquid water or ice on contact with these cold surfaces.
**Condensation will often occur at the edge of the glazing because this is where cold air is more likely to seep through.
You may experience condensation for couple of reasons:
- It is typical to experience condensation at the start of the heating season. After a few weeks your home should dry out.
- Interior window accessories such as curtains, blinds must not prevent air from moving around the surface of the window. Any restriction of air movement will increase condensation on the window.
- A family of four adds a half pint of water to the air in the home each hour. Cooking can add 4-5 pint of water per day, and steamy showers add another pint.
- Indoor plants increase humidity.
- Sometimes homeowners will see more condensation on recently-replaced energy efficient windows than on their old windows. That’s because the old window were probably drafty and the moisture was escaping through the small air gaps. Once you have energy efficient windows the humidity is locked in the house and doesn’t escape through the cracks. The energy-efficient windows are far better for the home and energy bills than leaky windows.
Why do other windows don’t have moisture build up?
- Windows that have heat sources located below them are less susceptible to condensation than other windows.
- The air movement in each room is different, that might cause difference in humidity levels.
Wind chill factors are not included in traditional temperature readings. When an indoor temperature reaches 20 C and the outside air temperature reaches -12 C, a relative recommendation of humidity is 30%.
However, when an outside air temperature reaches -12 C with a 20 kilometer per hour wind, the outdoor wind chill temperature is -26 C, the humidity levels in a household should be brought down to 20% to reduce any condensation build up.
Condensation Chart: Maximum Humidity Before Window Condensation Occurs | |
Outside Air Temperature | Indoor Relative Humdity |
-28 C (-18 F) or below | Not over 15 % |
-28 C (-18 F) to -23 C (19 F) | Not over 20 % |
-22 C (18 F) to -17 C (-2 F) | Not over 25 % |
-16 C (-8 F) to -12 C (10 F) | Not over 30 % |
-11 C (11 F) to -6 C (21 F) | Not over 35 % |
-5 C (22 F) to 4 C (40 F) | Not over 40 % |
Humidity Reduction Tips:
You need to take steps to reduce condensation in your home!
- Adjust humidifier setting lower for colder weather, or Disconnect humidifiers that are either fixed to your heating system or are portable.
- Use kitchen fans that vent to the outside when cooking.
- Make sure all sources of ventilation to the outside are functional.
- If there are signs of excessive humidity in your house, you should increase ventilation.
- You can add a dehumidifier to reduce excess moisture.
* Additional steps that can be taken *
Combustion gas appliances produce moisture.
Keep bathroom doors shut with exhaust fans on to eliminate moisture while showering.
When coming in from the rain or snow, wipe up any water or melted snow before it evaporates
Mopping floors can add large amounts of moisture to the air. Be sure to run exhaust fans (bathroom and kitchens) while floors are wet and try to avoid mopping floors on extremely cold days.
Hanging wet clothes to dry inside your home is a high source of moisture. Dryer machines should be vented to the outside.
All rooms should be at a minimum 10 C (50 F) even in unoccupied rooms as condensation will still occur.
During the day drapes and blinds should be left open. To allow air flow against glass be sure to raise blinds in the evening at least 100mm (4") up.
Solve the moisture problem in the home and you’ll help reduce condensation!
For Energy Efficient Replacement Windows and Doors Installation Call:
Winnipeg 204.272.5750
Calgary 403.668.1447
Edmonton 780.628.2915
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