Energy Factor vs Energy Star: What Each Number Means

What is the Energy Factor?

The Energy Factor (EF) is an efficiency rating defined by the U.S. Department of Energy (DOE). It tells you how many liters of water a dehumidifier can remove per kilowatt-hour (kWh) of energy consumed. A higher EF means the unit removes more moisture for each unit of electricity, so it is generally more efficient.

In June 2019, the DOE replaced the old EF with a new metric called the Integrated Energy Factor (IEF). The IEF includes the energy the dehumidifier uses when it cycles off, not just when it is actively removing moisture. This makes the IEF a more complete picture of annual energy use. The DOE also changed the test temperature from 80°F to 65°F to better reflect basement conditions, which is why capacities on newer listings may look smaller than older ones.

When you read a dehumidifier listing, you may see the IEF expressed in liters per kilowatt-hour (L/kWh). This number is the most direct way to compare efficiency between models. The site's reviews of stated details always point you to the maker's page for the exact IEF value, because listings sometimes omit it or show only the Energy Star mark.

• EF: liters of water removed per kWh, measured at 80°F.
• IEF: liters of water removed per kWh, includes standby energy, measured at 65°F.
• Both are set by the DOE; the IEF is the current standard.

What is Energy Star certification?

Energy Star is a certification program run by the U.S. Environmental Protection Agency (EPA). A dehumidifier that earns the Energy Star label meets strict efficiency criteria set by the program. According to the ENERGY STAR website, certified models use more efficient refrigeration coils, compressors, and fans to remove the same amount of moisture as a similarly sized conventional unit, using about 20% less energy.

The Energy Star mark appears in a listing title or description when the maker has certified the model. It is a quick way to filter for efficient units, but it does not tell you the exact IEF value. For that, you need to read the maker's product page or the ENERGY STAR product finder.

On this site, the Energy Star mark is never stated for a title that does not name it. The reviews explain what the mark means and direct you to the ENERGY STAR pages for the certification criteria. The mark is a binary label, not a number, so two Energy Star models can have different IEF values.

Which spec should you prioritize?

For lower operating costs, the IEF is the number to look for, because it directly measures efficiency in liters per kWh. A higher IEF means the unit uses less energy to remove the same amount of moisture. Energy Star certification is a useful shortcut, but it is a binary label, not a number. Two Energy Star models can have different IEF values, so the one with the higher IEF will generally cost less to run.

When you read a listing, look for the IEF value in the specifications. If it is not stated, check the maker's page or the ENERGY STAR product finder. The site never converts efficiency figures into energy costs, because those depend on local electricity rates and usage patterns. Instead, the reviews help you compare IEF values as stated by the maker.

For a basement purchase, efficiency matters because the unit may run for many hours. If you are comparing models in the same capacity group, the IEF is the tie-breaker. The best basement dehumidifier with pump guide includes models that state their IEF, and the best Energy Star 50 to 99 pint dehumidifiers guide focuses on certified models.

How to read a listing for efficiency

Start by checking the title for the Energy Star mark. If it is there, the model meets the EPA's criteria. Then look for the IEF in the bullet list or specifications. The IEF is usually expressed in liters per kilowatt-hour (L/kWh). A higher number is better.

If the listing only shows the old EF, remember that the IEF is the current standard. The DOE's test procedure changed, so a unit rated under the old method may show a different capacity. Always compare like with like: use the IEF when available, and read the maker's page for the exact test conditions.

Some listings may not state any efficiency number. In that case, the review on this site will note that the detail is not stated by the seller. You can then visit the maker's page or the ENERGY STAR product finder to find the IEF. The best dehumidifier reviews page explains how the site handles missing details.

Common questions about efficiency ratings

Why do some listings show two capacity figures? The DOE changed the test procedure in 2020, so a model may have an old capacity rating and a new one. The ENERGY STAR page explains that the new test uses cooler, more realistic conditions, which is why capacities decreased.

Does a higher IEF always mean lower energy bills? In general, yes, because the unit uses less energy per liter of water removed. But actual energy use depends on how often the unit runs, which depends on the space and conditions. The site cannot promise specific savings.

Is Energy Star the same as the IEF? No. Energy Star is a certification mark; the IEF is a measured efficiency value. A model can be Energy Star certified and still have a range of IEF values.

For a small room, efficiency is still relevant, but the capacity is often lower. The best small room dehumidifier guide includes models that state their IEF, so you can compare efficiency even in a compact unit.

What to pick for your situation

Questions

What does the Energy Factor number mean on a dehumidifier listing?

The Energy Factor (EF) is a DOE rating that measures how many liters of water a dehumidifier removes per kilowatt-hour of energy. A higher EF means better efficiency. The newer Integrated Energy Factor (IEF) includes standby energy use and is the current standard.

Is Energy Star certification the same as having a high Energy Factor?

No. Energy Star is a certification mark from the EPA for models that meet strict efficiency criteria. The Energy Factor is a specific number. An Energy Star model will have a good EF or IEF, but the exact value can vary, so check the maker's page.

Which should I prioritize: Energy Star or the Energy Factor?

Prioritize the Integrated Energy Factor (IEF) if the maker states it, because it directly measures efficiency. Energy Star is a useful filter, but the IEF gives you a more precise comparison between models.

Why do some listings show two different capacity figures?

The DOE changed the test procedure in 2020, using cooler temperatures that better reflect basement conditions. This means newer models may show a lower capacity than older ones, even if they are similar. The ENERGY STAR page explains this change.