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The recommended relative humidity for a home is between 30 and 50 percent. Moist, soupy air can breed mold and other potential hazards for indoor air quality and human health.

Photograph by S. T. Yiap/Photolibrary

By Brian Handwerk

for National Geographic

What to Look For

The recommended relative humidity for a home is between 30 and 50 percent. Moist, soupy air can breed mold and other potential hazards for indoor air quality and human health.

Dry air, on the other hand, cracks the skin and can necessitate a medicine cabinet full of moisturizing products, which may not all be eco-friendly. A lack of moisture in the air also dries out mucous membranes, which can increase your vulnerability to colds and irritate chronic conditions like asthma.

Eco-savvy shoppers can start simply by looking for an Energy Star label, bestowed by the U.S. Department of Energy (DOE) and the Environmental Protection Agency (EPA) to designate energy-efficient products.

Energy Star humidifiers and dehumidifiers work just as well as non-rated products at removing moisture from the air. But choosing an Energy Star-rated dehumidifier can save an estimated $20 per year, or $230 during the unit’s entire lifetime. Along with those savings comes a corresponding decrease in total energy use and greenhouse gas emissions—making these products 10 to 20 percent greener than their non-rated equivalents.

Humidifiers use more energy than you might think. Non-qualified models can burn as much juice as your home’s most environmentally costly appliances—like the refrigerator.

How to make a good choice:

  • Humidistat: Make sure the humidifier you choose has a built-in humidistat. This feature allows you to set your desired humidity level and programs the unit to turn on and off automatically to maintain that level, so it won’t run when it’s not needed.

  • Energy use: The more air you’re dehumidifying, the more the more energy you’re going to burn. So shoppers can score some major eco-benefits simply by taking the time to estimate their needs accurately, and not exceeding them.

    Energy Star has produced a calculator to help consumers estimate the size and capacity of the dehumidifier they’ll need, as well as the energy and money they can save.

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