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Why your windows fog up

Why your windows fog up

Why your windows fog up

Are you worried about the formation of condensation on your windows and wondering what is causing it to happen?  This is what is happening.

The appearance of fog on your windows inside the house is linked to an excess of humidity in the house compared to the temperature outside.

The colder it is outside, the lower the humidity inside should be. The following is a table from the Canada Mortgage and Housing Corporation (CMHC) that suggests humidity levels based on outside temperatures:

Outside air temperature

Recommended maximum indoor relative humidity (temperature below 21° C / 70° F)

-29° C / -20° F

20 %

-24° C / -10° F

25 %

-18° C / 0° F

30 %

-12° C / 10° F

35 %

-7° C / 20° F

40 %


What influences the humidity inside your house

Different elements cause an increase in humidity levels in a house: taking a shower, washing dishes and clothes, cleaning floors, cooking, etc.

Similarly, a very humid basement or malfunctioning ventilation devices can also be the cause.

It is also recommended not to lower the temperature too much when you leave because window panes will become cold and the excess water vapor will quickly turn into liquid.

How to limit the appearance of condensation on windows

  • Remove mosquito nets in the fall
  • Open the curtains during the day
  • Keep room doors open
  • Use the range hood
  • Turn on the bathroom fan before each shower
  • Avoid overwatering plants
  • Avoid air drying clothes
  • Use an air exchanger or, at the very least, a dehumidifier

Jackie Beaudoin, Leclerc Insurance and Financial Services
Source :  Protégez-Vous