How to measure humidity in your house

A hygrometer will show the relative humidity (RH) in your house. Although the RH will not be exactly the same throughout your home, one hygrometer per house is usually sufficient. You should place it where the humidity symptoms are most obvious, in the room that you are most concerned about, or where your family spends the most time. Because hygrometers are small, they can be moved around in your house from time to time.

Don’t place your hygrometer near a radiator, a heat register or a chimney, or in any other location where it could be affected by direct heat.

Remember that a hygrometer does not produce instant results. It may take up to two hours to provide a stable reading in a new location or to adjust to sudden changes in relative humidity.

What is relative humidity (RH)

Humidity is normally measured as relative humidity (RH). RH is a percentage that indicates the amount of moisture in the air relative to the maximum amount the air can hold at that temperature. For instance, when air at a given temperature contains all the water vapor it can hold at that temperature, it has a RH of 100 per cent. If the humidity exceeds 100 per cent, moisture will begin to condense from the air. If the air contains only half the water it can hold at that temperature, the RH is 50 per cent.

How does RH relate to how warm the air in your home feels?

Air with some moisture feels warmer.  Even if you set your thermostat at a lower temperature with the proper humidity level, the air will feel warmer without increasing the thermostat.  The optimal humidity level during winter months is between 30 and 40%.  If you keep your thermostate at 69F, with a humidity of 35%, the air will feel just as warm as if the thermostat was set at 72F.  TO maintain this humidity level, you will probably need a humidifier.