Dehumidifier Testing and Capacity

Dehumidifier Performance and Testing

The U.S. Department of Energy (DOE) defines performance ratings for dehumidifiers and test methods for determining performance. For dehumidifiers, the two primary performance ratings are the capacity and the energy efficiency metric. Capacity is defined as the amount of water removed per day (24 hours) at test conditions (reported in pints/day) and identifies the relative amount of moisture a dehumidifier can remove. The energy efficiency metric identifies how many liters of water a dehumidifier can remove per kilowatt-hour of energy consumed.

DOE finalized new energy conservation standards for dehumidifiers that took effect in June 2019. These standards are based on a new energy efficiency metric, Integrated Energy Factor (IEF), which replaces the old metric, Energy Factor (EF). Unlike EF, IEF includes the energy the dehumidifier uses when it has cycled off. As of June 2019, all new dehumidifiers will be rated with an IEF value which is based on a new test procedure, also written by DOE, that more closely represents the expected annual energy consumption of dehumidifiers. The new test procedure specifies that portable dehumidifiers are tested at 65°F, rather than 80°F, to more accurately reflect expected performance in a basement setting. This 15°F reduction in testing temperature means that a dehumidifier tested to the new procedure will likely report a smaller capacity than when tested to the old procedure.

The DOE standards also establish separate minimum efficiencies for the two product categories, portable and whole-home dehumidifiers, as they are typically operated under different conditions in the home (e.g., temperatures, hours of operation per year, require ducting or not). If you are considering installing an ENERGY STAR certified whole-home dehumidifier, it is important that the unit is sized and installed correctly by a professional. See EPA's buying guidance page for more information on how to get the most value and best performance from your dehumidifiers.

If you want to learn more about the DOE test procedure and standards for dehumidifiers, contact appliancestandardsquestions@ee.doe.gov.

Capacity Changes in Portable and Whole-Home Dehumidifiers

Capacity ratings express how much moisture a dehumidifier can remove—larger, wetter rooms need higher capacity dehumidifiers. Starting in early 2020, you may see dehumidifiers that look comparable to previous models but have lower capacity ratings and different energy ratings. That’s because DOE changed the way dehumidifiers are tested, using cooler, more realistic conditions comparable to a basement setting. There’s less water to remove in cooler air, which is why the capacities have decreased.

If you are replacing an old dehumidifier with a new model, the smaller capacity may meet your dehumidification needs. The table below gives a rough correlation between the old capacity rating and the new capacity rating (as of 2020), though the actual change for specific models will vary, and individual manufacturers may be able to provide more reliable comparisons.