Dehumidifier Energy Factor: EER vs IEF Ratings Explained

What Is an Energy Factor Rating?

When you shop for a dehumidifier, you'll see an efficiency rating that tells you how much water the unit removes per unit of electricity. The official metric is expressed in liters per kilowatt-hour (L/kWh). A higher number means the unit uses less energy to remove the same amount of moisture.

You might hear this called the Energy Factor (EF) or sometimes Energy Efficiency Ratio (EER). For dehumidifiers, the correct term is Energy Factor, and it has been replaced by a newer metric called Integrated Energy Factor (IEF). Both measure the same thing, but IEF gives a more realistic picture of annual energy use.

The reason this matters goes beyond your electricity bill. Dehumidifiers are often run for many hours each day, especially in damp basements or during humid seasons. A small difference in efficiency can translate into noticeable differences in energy consumption over a year. Understanding how to read these ratings helps you make a more informed purchase and avoid paying more to operate a less efficient machine.

From Energy Factor to Integrated Energy Factor

In 2019, the U.S. Department of Energy introduced new energy conservation standards based on Integrated Energy Factor (IEF). IEF replaces the older Energy Factor (EF) and includes the energy the dehumidifier uses when it cycles off, not just while it is actively removing moisture. This matters because dehumidifiers cycle on and off throughout the day.

The test procedure also changed. Portable dehumidifiers are now tested at 65°F instead of 80°F, which more closely matches typical basement conditions. Because cooler air holds less moisture, the new test produces lower capacity numbers than the old method. This is why a unit that was rated at 30 pints under the old procedure may be rated at only 20 pints under the new one.

Including off-cycle power is a significant improvement. Older EF ratings only considered the energy drawn while the compressor was running, ignoring the power used by fans, sensors, and timers when the unit was idle. A dehumidifier that cycles frequently, as many do in spaces with high humidity, can consume a meaningful amount of energy even when it is not actively removing water. IEF captures that, so a model with a high IEF is genuinely more efficient in real-world use.

Why Capacity Ratings Changed in 2020

The switch to IEF and the cooler test temperature caused capacity ratings to drop for models made after 2019. If you are replacing an older unit, the new numbers might look smaller, but the actual moisture removal performance is similar. The table below shows the approximate mapping between old and new capacity ratings for portable and whole-home dehumidifiers.

When sizing a replacement, use the new capacity values rather than the old ones. A unit rated at 30 pints under the old system will still handle the same space as a new unit rated at 20 pints. See our sizing guide for help matching capacity to room size.

How to Compare Efficiency Between Models

To compare the running costs of two dehumidifiers, look at their IEF ratings. The higher the IEF, the less electricity it takes to remove a liter of water. ENERGY STAR certified dehumidifiers use more efficient coils, compressors, and fans, and they remove the same amount of moisture as a similar conventional unit while using 20% less energy.

When comparing models, use the IEF as a relative indicator. A unit with a higher IEF will always be more efficient than a lower-rated unit of similar capacity and features, assuming identical operating conditions. For more background on the ENERGY STAR program, see our explainer.

It is also worth noting that the IEF is measured under standardized conditions, so your actual results may vary depending on room temperature, humidity level, and how often the unit cycles. Nevertheless, the IEF is the best single number the industry provides for comparing efficiency across different brands and models.

What to Look for When Buying

When shopping for a dehumidifier, check the product spec sheet for the IEF rating. Look for the ENERGY STAR label, which indicates the unit meets strict efficiency criteria. Also pay attention to the capacity rating, since the numbers have changed since 2020. Use the new capacity values to size your unit correctly for your space.

• Check the IEF (L/kWh) and prefer higher values.
• Choose ENERGY STAR certified models for guaranteed efficiency.
• Use the new capacity ratings to select a unit for your room size. 50-99 pint, 100-149 pint, and 150 pint and larger options are available.
• Consider operating temperature: if your space stays below 65°F, look for a model designed for low temperatures.
• If you plan to run a dehumidifier continuously, efficiency becomes even more important, so prioritize a high IEF over a lower-priced but less efficient alternative.

How IEF Affects Running Costs

The IEF directly influences how much you spend on electricity. A more efficient dehumidifier will use less energy to remove the same amount of moisture, which lowers your utility bill over time. If you plan to run the unit frequently, as recommended for keeping indoor humidity below 50% (per CDC guidance), the IEF becomes especially important.

To get a complete picture of energy use, also consider the unit's wattage and how long it runs each day. Efficient models often have better insulation, advanced sensors, and optimized compressors, all of which contribute to a higher IEF. For more on electricity consumption, see our article on dehumidifier electricity usage.

Running a dehumidifier is a key step in preventing mold growth. The EPA notes that controlling moisture is the best way to prevent mold, and the CDC recommends keeping indoor humidity no higher than 50%. A more efficient dehumidifier makes it easier to maintain that level without worrying about excessive energy costs. By choosing a model with a high IEF, you can protect your home and your budget at the same time.

What to pick for your use

Questions

What is the difference between EER and IEF?

EER is commonly used for air conditioners. For dehumidifiers, the official efficiency metric is Energy Factor (EF), now replaced by Integrated Energy Factor (IEF). IEF includes the energy used during cycling and is measured at a cooler baseline temperature.

Why did my dehumidifier's capacity rating change?

Because of the new IEF test procedure, portable dehumidifiers are tested at 65°F instead of 80°F. Cooler air contains less moisture, so the reported capacity is lower even though the unit's actual ability to remove moisture is similar.

What is a good IEF value?

There is no universal threshold, but higher IEF values indicate better efficiency. ENERGY STAR certified models must meet specific IEF criteria, so they are a safe choice for efficiency.

How do I calculate running costs from IEF?

You can compare IEF values to gauge relative energy use. A higher IEF means less electricity consumed per liter of water removed. For exact costs, multiply your electricity rate by the unit's wattage and estimated runtime.

Does IEF affect how much water a dehumidifier removes?

No. IEF measures efficiency, not capacity. Capacity is expressed in pints per day and depends on the unit's size and test conditions. IEF tells you how efficiently it uses energy while doing that work.

Should I replace an older dehumidifier to get a better IEF?

If your current unit is more than a few years old, upgrading to an ENERGY STAR certified model with a higher IEF may reduce your energy bills. Check the IEF on the new unit and compare it with your existing one. A significant improvement in efficiency can pay off over time.