Dehumidifiers & Air Purifiers Why Buy an Energy-Efficient Dehumidifier or Air Purifier? Energy-efficient dehumidifiers and air purifiers reduce excess moisture, remove air contaminants, and combat mold and mildew. Excessive moisture can lead to decreased air quality, unpleasant odors, and damage to your home. Efficient dehumidifiers, like ENERGY STAR® certified models, remove the same amount of moisture as standard models but use nearly 15 percent less energy. Efficient air purifiers, like ENERGY STAR certified models, are almost 2 percent more energy efficient than standard models, saving consumers about $16 annually on utility bills.