Alberta Toll Free 866-994-1950
Darrell cell 403-586-1950
Copyright Qualistat 2009-2012
HUMIDITY
Humidity is the measurement of moisture in the air in vapour form
There is Relative Humidity and Absolute Humidity
RELATIVE HUMIDITY
Warmer air holds more humidity (vapour) than cool air. This does not change the amount of vapour in the air (absolute humidity), warm air can hold more vapour so it is relative to the air temperature. If your Relative Humidity is too high, increase the temperature, which will allow the air to hold more humidity before it deposits it in the form of condensation.
ABSOLUTE HUMIDITY
The amount of vapour in the air does not change as the temperature changes. It is absolute, until you add more humidity by evaporation or other sources or we reduce the humidity by removing or diluting with dryer air.
DEW POINT
The maximum amount of vapour in the air at a given temperature before it cannot hold any more humidity and it turns to liquid.
If your home is at 20 degrees Celcius and 30% Relative humidity, the dew point is around 3-4 degrees celcius. In other words surfaces that are colder than 3 - 4 degrees will condense.
As you increase the temperature the relative humidity is reduced.
However here is the WARNING - if you reduce the temperature overnight to a cooler temperature, i.e. 15 degrees celcius, you will have more moisture on the windows in the morning because the air cannot hold that moisture and because the air is not keeping the glass warm.
Hygrometer
Alberta Toll Free 1-866-994-1950
Since 1986
Too Much Humidity?
At times a house can have too much humidity
When outdoor temperatures are cold you want to lower the humidity
For instance at -20 celcius the maximum Humidity level with Dual Glaze
windows is about 25% Dropping to -30 means a maximum humidity of 15%
To keep track, it is a good idea to have a hygrometer which tells you the humidity and temperature
To reduce the humidity you can increase the air temperature or you can
dilute it by adding dryer outdoor air.
Use the ventilation fan switch under the thermostat
This fan is designed to remove air, it turn on the furnace which brings dryer air in, and that air is mixed with the house air to reduce humidity.
Watch the humidity and run the fan when it gets too high. Buy a hygrometer ( left) to track relative humidity levels.
If your humidity does not reduce you may need to check the air volume of the ventilation system. At times these are undersized and are the cause of high humidity.
