Reading ENERGY STAR dehumidifier ratings: kWh, IEF and pints per day
An ENERGY STAR listing for a dehumidifier shows three numbers that matter for running cost. Each answers a different question, and mixing them up leads to bad comparisons.
Annual energy use (kWh per year)
This is the integrated annual energy consumption of the dehumidifier under typical conditions. EPA describes it as including the energy used in dehumidifying modes, fan modes and standby modes.
It is the number to use for cost: multiply it by your price per kWh. It is a standardized figure from a test, so it is good for comparing models and for a first estimate, but it is not a measurement of your basement. A very damp space or a long humid season means more running time.
Integrated energy factor, IEF (litres per kWh)
IEF measures how much water a dehumidifier removes for each kWh of electricity. Higher is more efficient. Unlike the older Energy Factor, IEF also counts the energy the unit uses when it has cycled off. ENERGY STAR notes that from June 2019 all new dehumidifiers are rated with IEF.
IEF is not power. A model with a good IEF can still use a lot of electricity if it is large and removes a lot of water. This is why we never turn IEF into watts.
Capacity (pints per day)
Capacity is the amount of water removed per day, 24 hours, at the test conditions. One US pint is about 0.47 litres, so 30 pints a day is about 14 litres.
Why old and new capacity numbers do not match
The test changed. ENERGY STAR explains that under the current DOE procedure portable dehumidifiers are tested at 65°F instead of 80°F, which gives lower capacity numbers for the same machine. ENERGY STAR gives this rough guide for portable units:
| Older rating | About the same under the new test |
|---|---|
| 30 pints/day | 20 pints/day |
| 50 pints/day | 30 pints/day |
| 90 pints/day | 55 pints/day |
The exact change varies by model. Practically: do not compare a capacity from an old box or an old review with a capacity in the current ENERGY STAR list. The data on this site follows the current list.
Portable and whole-home units
Whole-home dehumidifiers connect to ducting and are tested differently. They are listed separately here, and we do not rank them against portable units.
How to compare two models
- Pick the same type, portable with portable.
- Pick similar capacity. A larger unit will use more energy simply because it does more work.
- Among those, a lower annual kWh and a higher IEF are better.
- Use your own electricity rate to turn the kWh into dollars.
The comparison tool does steps 1 to 4 and flags the rows where the models differ. For how much a typical unit uses, see how much electricity a dehumidifier uses.