Dry air is good air

desert

“Put an end to desert like air in your home” says the flyer containing an ad from a well known maker of heating and ventilating products. Reading further, “The average humidity in the Sahara Desert is 25 percent. In wintertime the average humidity inside some homes can be even lower….”

Yes it can, does that mean you should rush out and buy a humidifier? Not necessarily. Some of The biggest problems in homes are the result of excess humidity. CMHC recommends that humidity levels in a home in very cold weather (ie Edmonton) never exceed 30%, pretty close to that desert like air. Desert air is not only healthy, but it also preserves things, like the building materials in your home.

Excess indoor humidity results in condensation, and condensation results in, mold growth, wet insulation, wet wood, and the destruction of all building materials that need to be kept dry.

Excessively dry air on the other hand, can shrink warp or crack  solid wood furniture or flooring, dry out paper, and some textiles, make you feel colder, dry your skin,  or even create health problems for some people.

Health experts and those who sell or install hardwood flooring will recommend humidity levels of between 35 and 60%, but those levels are too high for homes in the extremely cold winters we have in Edmonton.

To understand why the ideal of 50% relative humidity is not so ideal for cold winter homes, the dew point for air containing 50% relative humidity at 20 degrees C is 10 C. Dew point is when water vapor becomes condensation.  In other words if you keep your home at the usual indoor temperature of 20 C, and your indoor humidity at 50%, condensation will form on anything that has a temperature of 10 C or less.  Like the surface of your double glazed or double pane windows when the temperature outdoors is around -18 C.  If you see condensation or frost inside your house the humidity is too high.

Next;  Keeping it dry