Results of Low Humidity
Extremes in low and high levels of humidity, the amount of water particles (moisture) in the air, can cause discomfort in our living and working environments. This time of year, one of low humidity, many people experience dry, chapped, itchy skin and scalp, increased static electricity, respiratory problems, and notice their woodwork is changing, which is exhibited by loose joints and cracking. Low humidity can also shrink window and door seals, which affects air leakage and energy costs.
A common misconception is the furnace running makes the air drier. It is rather the reduced ability of cold air to hold moisture that is the real troublemaker. Warmer air has the ability to hold more moisture. However, this time of year there is little to none for it to hold. There are three basic things that affect the humidity level in your home: weather conditions and temperature levels outside; how it is protected from dampness and leakage; and daily activities like bathing, cooking, washing and drying wet clothes.
Relative humidity is the percentage of moisture being held in the air at a certain temperature as compared to how much it could hold at a certain temperature According to an example given at blueflame.org, “When air at a certain temperature contains all the water vapor it can hold at that temperature, its relative humidity is 100 percent. If it contains only half the water vapor it is capable of holding at that temperature, the relative humidity is 50 percent. If the outside air temperature in winter is 0°F and the relative humidity is 75 percent, that same air inside your 70°F home will have a four percent relative humidity. That’s dry! The Sahara Desert has an average relative humidity of 25 percent.”
At a temperature of 20 degrees and above, the optimum relative humidity level is between 35%and 50% (personal preferences differ). A hygrometer, which measures relative humidity, can be purchased at many hardware or electronic stores. Digital hygrometers are the most accurate. For a quick test, in a room other than the kitchen or a recently used bathroom, drop three ice cubes in a glass, add water, then stir. If condensation does not form in three minutes, your air is too dry.
Adding a humidifier to your home can help remedy low humidity problems. There are three basic types: evaporating which puts moisture into the air from a pan of water through absorbent discs or an immersed heating unit as in a cool mist humidifier or vaporizer; portable or room which uses a small fan and wet pad or fine mist to discharge moisture, or a power humidifier which is connected to the ductwork and water supply dispersing moisture directly into the air stream. A humidistat is used on these systems, which works similar to a thermostat whereby a desired humidity level is set and the humidifier will operate as needed to maintain that level. Investing in a humidifier helps conserve energy in winter. According to Trane, people are more comfortable at a lower temperature setting when their air is not as dry.
Construction of your home, how tightly it is built, if it has the proper ventilation and vapor barriers also affect humidity levels. For more information and illustrations, go to How humidity dries out your house, Understanding Relative Humidity, and Indoor Humidity – How Much Is Needed?.