Dehumidifier Energy Efficiency: What Is IEF and Why It Matters

What Is the Integrated Energy Factor?

The Integrated Energy Factor, or IEF, is the official energy efficiency rating for dehumidifiers in the United States. It tells you how many liters of water the unit removes for each kilowatt-hour of electricity it consumes. The ENERGY STAR program explains that a higher IEF means a more efficient dehumidifier. In other words, a unit with a higher IEF will remove the same amount of moisture while using less electricity.

IEF is a direct replacement for the older Energy Factor (EF) metric. The U.S. Department of Energy (DOE) established the new metric and test procedure, which took effect in June 2019. Unlike EF, IEF accounts for the electricity the dehumidifier uses even when it has cycled off, such as for the fan, controls, and standby power. This makes IEF a more realistic measure of real-world energy use.

When you look at a dehumidifier's spec sheet or the yellow EnergyGuide label, the IEF value is usually expressed in liters per kilowatt-hour (L/kWh). You'll see values typically ranging from 1.5 to 4.0 or higher, depending on the size and type of unit. To compare models, simply look for the highest IEF you can find within the capacity range you need.

Why IEF Replaced the Older Energy Factor

The old Energy Factor (EF) only measured efficiency while the compressor was actively running. It ignored the power draw during off cycles, which can be significant because dehumidifiers frequently cycle on and off as they maintain a set humidity level. The DOE recognized that EF did not reflect annual energy consumption accurately, so it developed the IEF metric based on a new test procedure.

The new test procedure also changed the operating conditions. Portable dehumidifiers are now tested at 65°F instead of the previous 80°F. That 15°F drop more closely matches the actual basement environment where most portables spend their working life. Because cooler air holds less moisture, a dehumidifier tested at the lower temperature will report a smaller capacity (in pints per day) than it would under the old test. This is why you may see newer models with the same physical size but lower capacity ratings. The change affects how you read capacity numbers, but IEF remains the efficiency indicator.

For consumers, the shift to IEF means you can trust that the efficiency number reflects how the unit will behave in a typical home setting. When you compare two models with the same IEF, you know they should have similar energy consumption per liter of water removed, regardless of differences in cycle behavior.

How IEF Is Measured and What It Means for You

IEF is measured by running a dehumidifier in a controlled test chamber at 65°F and a specified relative humidity, then calculating how much water it removes over a set period while measuring the total energy consumed, including standby power. The DOE sets the exact procedure and also establishes minimum IEF levels that all dehumidifiers must meet. These standards were finalized in 2019 and apply to units manufactured after that date.

Understanding IEF helps you make better buying decisions. For example, a unit with an IEF of 2.5 L/kWh will remove 2.5 liters of water for every kilowatt-hour it uses. If you run a dehumidifier continuously in a damp basement, the difference between a 2.0 and a 3.0 IEF unit can add up to noticeable differences in your electricity bill over a season. While you shouldn't base your entire decision on IEF alone, it's a strong indicator of long-term operating cost.

Remember that capacity is a separate number. A large-capacity unit (say, 70 pints per day) will naturally use more electricity than a small 20-pint model, even if both have the same IEF, because it moves more air and runs more powerful components. So when comparing efficiency, only compare units that are similar in capacity, or look at IEF as a secondary factor after you've chosen the right size.

How ENERGY STAR Uses IEF

ENERGY STAR is a voluntary program run by the U.S. Environmental Protection Agency (EPA) and the Department of Energy. To earn the ENERGY STAR label, a dehumidifier must meet 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 but use 20% less energy.

ENERGY STAR certification is available for both portable and whole-home dehumidifiers. Portable room units are designed to dehumidify a single space and can be moved easily, while whole-home models are installed into your ductwork and often run continuously. To find a list of certified models, you can use the ENERGY STAR Product Finder, or look for the label on the product box.

Because ENERGY STAR is tied to IEF, choosing an ENERGY STAR certified model is a simple way to ensure you're getting a highly efficient unit. However, not all efficient dehumidifiers are ENERGY STAR certified, so it's still worth checking the IEF number on any model you're considering. For a curated list of eco-friendly picks, see our best Energy Star dehumidifiers guide.

How to Compare Dehumidifiers Using IEF

Start by determining the capacity you need based on the square footage and dampness level of your space. The ENERGY STAR buying guidance provides a general chart: for a slightly to moderately damp small room (under 2,000 sq ft), you might need 20 to 30 pints per day; for a large room over 2,000 sq ft, 30 pints or more. For very damp spaces, the recommendation goes up to 50 to 90 pints. Use that as a starting point, then filter models within that capacity range and compare their IEF values.

When you have a shortlist, look at the IEF printed on the energy label. A difference of 0.5 L/kWh is significant. For example, a unit with IEF 2.5 versus 3.0 will use about 17% less energy for the same moisture removal. To get a more complete picture, also consider features like a built-in pump, auto-defrost, and humidity sensor, which affect convenience but not necessarily efficiency. For help with sizing, read our sizing dehumidifier by square footage article.

Finally, think about how you will use the unit. If it will run for long periods in a basement, efficiency matters a lot. If you only need occasional use in a bathroom, a smaller model with a slightly lower IEF might be acceptable. For larger spaces, a whole-home dehumidifier may be more efficient in the long run, but it requires professional installation. Our best commercial dehumidifiers guide covers high-capacity units that still carry respectable IEF ratings.

Other Efficiency and Moisture Control Factors

IEF is not the only factor that determines how much energy your dehumidifier will use. The way you operate the unit and the conditions in your home also play a role. The CDC recommends keeping indoor humidity below 50% all day long to prevent mold growth. Running a dehumidifier to maintain that level requires energy, but it's essential for a healthy home. If you keep humidity too high, mold can cause health issues, as the EPA explains in its mold guide.

A dehumidifier that is undersized will run almost continuously, wasting energy. Conversely, an oversized unit will cycle on and off frequently, which also reduces efficiency because it has to overcome standby losses. That's why proper sizing is the first step to efficiency. Our portable vs whole-house dehumidifiers article can help you decide which type suits your situation.

Also consider the environment where you place the unit. The ENERGY STAR page notes that if the space is below 65°F, frost can form on the coils, causing inefficient operation. Some dehumidifiers have an anti-frost sensor that shuts off the unit automatically. If your basement runs cool, look for a model with low-temperature operation. Finally, regular maintenance, such as cleaning the air filter and keeping the coils free of dust, helps maintain the rated IEF over time. For more on that, see our dehumidifier filter maintenance article.

What to pick for your use

Questions

What does IEF stand for?

IEF stands for Integrated Energy Factor. It measures how many liters of water a dehumidifier removes per kilowatt-hour of electricity it uses. A higher IEF means better energy efficiency.

How is IEF different from the old Energy Factor (EF)?

The old EF only measured efficiency while the compressor was running. IEF also includes the electricity used when the unit cycles off, such as for the fan and controls. IEF is based on a test at 65°F instead of 80°F, making it more realistic for typical basement use.

Do all dehumidifiers have an IEF rating?

Yes, as of June 2019, all new dehumidifiers manufactured for sale in the U.S. must be rated with an IEF value according to the Department of Energy's test procedure. Look for the IEF number on the EnergyGuide label or in the product specifications.

Does a higher IEF always mean a better dehumidifier?

Not necessarily. IEF tells you efficiency, but you also need to match capacity to your room size. A high-IEF unit that is too small will run constantly and may not adequately control humidity. Always choose the right capacity first, then compare IEF within that range.

How does ENERGY STAR certification relate to IEF?

ENERGY STAR certified dehumidifiers must meet strict efficiency criteria set by the EPA, which are based on IEF. Certified models use about 20% less energy than conventional units while removing the same amount of moisture. If you see the ENERGY STAR label, you can trust that the unit has a high IEF.