A dehumidifier collects water vapor from the air, decreasing the humidity of the surrounding area. DOE defines dehumidifiers as self-contained, electrically operated, and mechanically refrigerated encased assemblies consisting of: (1) a refrigerated surface (evaporator) that condenses moisture from the atmosphere; (2) a refrigerating system, including an electric motor; (3) an air-circulating fan; and (4) a means for collecting and disposing of the condensate.
Efficiency standards for dehumidifiers were initially established in the Energy Policy Act of 2005. The law set standards in terms of liters of water condensed per kilowatt-hour (kWh) of energy consumed based on the unit's capacity (in pints/day), effective October 2007. For a 35-45 pint/day unit, the initial minimum standard was 1.3 liters/kWh. In spring 2007, appliance manfuacturers and efficiency advocates reached consensus on a revision to the standard that would set a performance level of 1.5 liters/kWh for equipment of 35-45 pint/day capacity. The consensus recommendations were incorporated into the Energy Independence and Security Act (EISA) of 2007. The current standards were updated in December 2007, when Congress enacted H.R. 6, requiring an increase in the efficiency of dehumidifiers manufactured on or after October 1, 2012 to between 1.35 and 2.5 liters/kWh, depending on product capacity. Dehumidifiers just meeting the current standards can consumer as much as 1000 kWh per year.
In May 2016, DOE updated the standards. DOE estimate that the 2016 dehumidifier standards will lower national energy usage by 30 billion kWh, save between $1.3 and $2.7 billion, and reduce CO2 emissions by 18.6 million metric tons over 30 years of sales. Consumers are expected to save $100-$140 on average over the life of the dehumidifier. New standards will take effect in 2019.
Technology options for improving dehumidifier efficiency include the use of more-efficient compressors and larger heat exchangers.