Thursday, January 28, 2010

Very dry air -- inside your home

One side effect from this arctic blast of air is the fact it holds very little moisture.  When we speak of humidity, it is relative to temperature.  It represents the percent volume of moisture in the air at that exact temperature.

For instance, a 100% humidity reading in the middle of winter feels a lot different than 100% in the middle of summer.  Warm air can hold a lot more moisture than cold air. 

When you take a very cold airmass, and then heat it up (as you do in your home), you are taking the minor amount of moisture available and throwing it into a warmer enviroment that can hold a lot more moisture.

So, if the air temp outside is 15° and the dew point is zero, if you bring that air inside and heat it to 70°, the humidity is 6%.

Our bodies feel comfortable when the humidity is roughly half of the air temperature indoors.  So, if you have your heat set at 70°, you want to humidity to be roughly 35%.  Humidifiers that work directly into the furnace work most effectively (room humidifiers run the risk of harboring mold, or creating mold on fabrics or carpets). 

Depending on conditions inside your home, you may want it closer to 30% or 40%.  If moisture forms on the walls, then the humdifier is set too high.  But, once the room is humidified well, you will get rid of the static electricity and dry skin/nasal passages/eyes.  Plus, with a higher humidity, the air will feel much warmer to your skin.