Managing the humidity level in a home is a balancing act between maintaining the comfort of the occupants and protecting the structure. Excess moisture leads to many indoor air quality, structural and maintenance problems, and makes the home’s occupants feel "sticky." Too little moisture dries out skin, nasal passages, and throats, as well as wood in furniture and the house’s structure. Generally, a relative humidity level of about 40 to 60 percent is a good compromise. At this level, most condensation and mold growth is prevented, but people are comfortable.
One method of controlling household humidity is through exhaust ventilation of moisture-laden indoor air. However, when the outside air is warm and humid, ventilation will not solve the problem.
Mechanical air conditioning (cooling) of the air inside the home is effective in dehumidification, by condensing water vapor from the air. If the air conditioner is oversized, however, it may cool the home’s air quickly but not operate long enough to provide adequate dehumidification.
Mechanical dehumidifiers may be used in the home to control humidity in moisture-prone areas. A dehumidifier operates on the same principle as an air conditioner. While dehumidifiers can be effective in controlling moisture, they do require regular maintenance, and generate heat and noise. A dehumidifier needs to be sized to the space in which it will be operating.
