Energy Efficiency

How We Tested For Power Usage

To determine each dehumidifier’s energy efficiency we first made sure that the exact same conditions applied to each of our tests. First and foremost we made sure that the relative humidity of the ambient air remained consistent throughout all tests. We set the relative humidity to 50% for the majority of tests because it was easy to do and allowed us to maintain a consistent humidity level throughout the test procedure. It was much harder for us to test at a greater humidity level because the dehumidifier would dehumidify so quickly that it wouldn’t keep the room at a consistent humidity level throughout the duration of the test.

A consistent humidity level was important for the following reason – how much power any particular dehumidifier draws directly correlates with the ambient air’s relative humidity. In the simplest terms, think of the dehumidifier’s internals “working harder” at higher humidity levels. Thus the dehumidifier draws more power at 90% RH (or any other relative humidity percentage greater than 50%) than it does at 50% RH. The Danby DDR050BJPWDB, for example, would draw 760 watts of power at 90% RH and only 572 watts of power at 50% RH. It was therefore of utmost importance that we maintained a steady and consistent room humidity level while testing each dehumidifier for power usage.

Other than keeping the environment consistent throughout each test we also set each unit to high fan speed and waited until the compressor would cycle on prior to measuring power usage. Thus, each unit’s power usage was measured at 50% RH, on high fan speed, and with the compressor cycled on.

Initially, we also tested power usage on low fan speed but soon noticed that the difference between power draw on high and low fan speed was negligible (only a few watts). Thus, we didn’t feel like it was worth our time to test each individual unit for its power usage on the low fan speed setting. Note that we also performed some testing at 90% to 100% RH but had difficulty keeping consistent conditions (as described above) for the tests. In such tests we also saw very little variance in results.

Test Results

Below you’ll find the results of our testing on high fan speed at 50% RH. You can sort the tables below by clicking on the up/down arrows next to each column heading. Clicking on the down arrow will sort the dehumidifiers we tested from most energy efficient to least energy efficient. Clicking on the up arrow will reverse the list from least energy efficient (most energy usage) to most energy efficient (least energy usage).

Note that we’ve also included the manufacturer’s specification for each model’s power usage in the tables below. In earlier years it was always given in watts but more recently it has been specified in amps. Thus, the second column numbers in the first table below – specified in watts – are calculated based on third column numbers – those actually given by the manufacturer – at 115 V.

Current Models

Manufacturer and Model
Real World Wattage
Calculated Advertised Watts
Advertised Amps
Frigidaire FFAD5033W15708977.8
hOmeLabs HME020031N6107486.5
Black+Decker BDT50WTB
5548057
Honeywell TP70WKN5638057
Vremi VRM0101845708977.8
Danby DDR050BJPWDB5728977.8
Keystone KSTAD504D
5968977.8
Hisense DH7019K1G5978977.8
GE ADEL45LY5467136.2
Toshiba TDDP5012ES25788977.8
LG UD501KOG55867256.3
Frigidaire FFAD2233W1272403
3.5

Notes
1. All of the models above are 50 pint (70 pint 2012 DOE) dehumidifiers except for the 45 pint GE ADEL45LY and the 22 pint Frigidaire FFAD2233W1. Both units have a lower expected power draw than all the others due to the fact that they have a lower moisture removal capacity.

2. We’ve refined our testing methods over time so the above test results are not 100% comparable to those of the discontinued models below.

Discontinued 50 Pint (70 pint 2012 DOE) Dehumidifiers

Manufacturer and Model
Real World Wattage
Advertised Wattage
Frigidaire FFAD7033R1632745
Keystone KSTAD70B590720
Danby DDR70A2GP590770
Honeywell DH70W642820
RCA RDH705571720
GE ADEL70LR632745
Haier DE65EM590690
Kenmore KM70590NA
Whirlpool AD70GUSB590746
Hisense DH-70KP1SLE610746
Friedrich D70BP620746
SPT SD-72PE600720
Haier HM70EP667750
Delonghi DD70PE655680

Discontinued 35 Pint (50 pint 2012 DOE) Dehumidifiers

Manufacturer and Model
Real World Wattage
Advertised Wattage
Frigidaire FFAD5033R1493530
Keystone KSTAD50B439520
Friedrich D50BP462533
Delonghi DD50PE439NA
SPT SD-52PE 450520

Discontinued 22 Pint (30 pint 2012 DOE) Dehumidifiers

Manufacturer and Model
Real World Wattage
Advertised Wattage
Frigidaire FFAD3033R1319320
Hisense DH-35K1SJE5352NA
GE ADEL30LR356405
Haier DM32M-L404465

The Primary Takeaway

It’s very important that you realize that even though smaller capacity units draw less power per unit time than large capacity units, they will be operating for a much longer time to remove the same amount of moisture.

Here’s what we mean. Let’s say you have a 1000 square foot space that you need to dehumidify. That space contains a set volume of air that is “holding” a set amount of moisture that needs to be removed from the air before the desired humidity level in the space is achieved. Let’s just say it’s “X” pints of moisture in the air. That X pints of moisture (that will eventually drip down into the dehumidifier’s condensate collection bucket) needs to be removed from the air by the dehumidifier. Let’s say, hypothetically, that it takes 24 hours for a 22 pint dehumidifier to remove this set amount (X pints) of moisture from the air within this imaginary 1000 sq ft space.

Our moisture removal tests showed that 50 pint units take about 1/3 (the exact number is 30%) as long as 22 pint units to dehumidify a 50 sq ft space from 90% down to 40% relative humidity. 35 pint units take about half as long as 22 pint units to dehumidify the same space “holding” the same amount of moisture from 90% down to 40% relative humidity.

Now let’s go back to our imaginary scenario of a 1000 square foot space “holding” X pints of moisture which takes a 22 pint dehumidifier 24 hours to dehumidify. By extrapolating our moisture removal test results we can now estimate that a 50 pint unit will take 7.2 hours (30% * 24) and a 35 pint unit will take 12 hours (50% * 24) to fully dehumidify our imaginary 1000 sq ft space.

Now let’s apply what we’ve learned to the real world where you’re going to have to pay a certain amount of money for the energy your dehumidifier uses to do its job and dehumidify the space you need to dehumidify.

Real World Costs Of Dehumidifier Ownership

Your monthly power usage is billed by your utility company by the KWH or kilowatt hour – “kilowatt” refers to power usage and “hour” refers to time. Thus, what matters is not just how much power the appliance draws, but for how long it draws that power.

Let’s apply our imaginary scenario to a real world power bill. We’ll use the national average price for electricity – 12 cents per KWH – in all of our calculations. We’ll use three different sized dehumidifiers to demonstrate our point. Instead of using specific models, we’ll apply average data (average power usage and moisture removal rate for given size class) to three “archetypes”. We’ll also convert watts to kilowatts (371 watts = 0.371 kilowatts, for example) for these calculations to work.

Note: The average values used below were obtained from 2014 data. Since then we’ve tested and reviewed many more dehumidifiers. Rest assured, the average data is still very similar. We just want to note here that the average power draw for dehumidifiers in the 50 pint size class is no longer exactly 612 watts. The average for the 35 pint size class is no longer exactly 454 watts, and so on and so forth.

Dehumidifier 1 >> 22 pint capacity

Power Draw >> 371 watts
Time Taken >> 24 hours

30pintenergycost

Dehumidifier 2 >> 35 pint capacity

Power Draw >> 454 watts
Time Taken >> 12 hours

50pintenergycost

Dehumidifier 3 >> 50 pint capacity

Power Draw >> 612 watts
Time Taken >> 7.2 hours

70pintenergycost

The calculations above speak for themselves. Yes, power draw is greater for larger capacity units. But larger capacity units draw that maximum power for a smaller amount of time. It should now be clear to you that 50 pint dehumidifiers are the most energy efficient. 35 pint dehumidifiers are slightly less efficient. And 22 pint units are the least energy efficient. Thus, we recommend that you stay within the 50 pint size class if energy efficiency is important to you.

As one final nail in the 22 and 35 pint dehumidifiers’ proverbial coffins, consider the fact that the calculations above are only for one hypothetical 24 hour period. If you plan on using your dehumidifier for weeks, months, even years, multiply the above differences in cost by 7, 31, 365, etc. Think about this difference in energy cost when you’re evaluating the retail price differences between 50 pint and 35 pint units or between 50 pint and 22 pint units.

DOE and Energy Star Standards for Energy Efficiency

The findings above – that higher capacity units are a better option if energy efficiency is a priority – are further supported by the latest Department of Energy (DOE) and Energy Star standards for dehumidifiers manufactured since 2019.

The latest DOE standards look like this:

Pints/day (Capacity)
Integrated Energy Factor (IEF) - L/kWh
≤ 25.001.30
25.01-50.001.60
≥ 50.012.80
Source

Note how the IEF requirement is less for units with a capacity equal to or less than 25 pints/day.

The latest Energy Star requirements follow a similar pattern:

Pints/day (Capacity)
Integrated Energy Factor (IEF) - L/kWh
≤ 25.00≥ 1.57
25.01 to 50≥ 1.80
≥ 50≥ 3.30
Source

Note, again, how the IEF requirement is less for units with a capacity equal to or less than 25 pints/day.

The Energy Star requirements outlined here are 21% more stringent for low capacity units and only 13% more stringent for high capacity units compared to DOE requirements. This is due to the fact that new DOE requirements are already fairly stringent compared to previous requirements.

How We Determine Energy Efficiency Scores for Individual Models

In addition to raw power draw, moisture removal rate is also very important in assessing a particular dehumidifier’s overall energy efficiency compared to another model at the same capacity. Why? It’s actually quite simple: Just as a 50 pint dehumidifier can be more energy efficient than a 35 pint dehumidifier because it needs to run for less time than a 35 pint dehumidifier, so also a particular 50 pint dehumidifier can be more energy efficient than another 50 pint dehumidifier because it takes less time to dehumidify a particular space (it has a faster moisture removal rate). It’s really that simple.

We made the mistake in reviews from earlier years of making energy efficiency synonymous with power draw. Thus, 50 pint dehumidifiers (70 pint according to old standards) which tested for lower power draw received higher energy efficiency ratings (scored out of 5) while those dehumidifiers which we tested for higher power draw were rated lower. We didn’t take into account moisture removal rate in evaluating a particular dehumidifier’s energy efficiency.

Rest assured, this mistake was corrected for all ratings and reviews since. We now assess a particular dehumidifier’s moisture removal rate in addition to its power draw in rating its energy efficiency. We suggest that you do the same: evaluate each dehumidifier’s power draw in the tables above IN ADDITION TO each dehumidifier’s moisture removal rate in the tables we made available here.

The Most Energy Efficient Dehumidifiers

Considering everything we’ve discussed so far (tested power draw, tested moisture removal rate, the fact that higher capacity models are generally more energy efficient than lower capacity units, etc.), the three best most energy efficient dehumidifiers on the market are:

1. Frigidaire FFAD5033W1 (super high moisture removal rate in our testing and average power draw for its size)

2. Black+Decker BDT50WTB (second best moisture removal rate performance among high capacity units tested)

3. hOmeLabs HME020031N (above average moisture removal rate and a very good dehumidifier overall otherwise)

Comments

  1. J says

    Would it be possible to measure the amount of water condensed and compare it to the total power consumed to get a watthour/gallon measurement that should be independent of dehumidifier size and room size?

    • J says

      Ah, i just noticed the energy star reqs are L/kwh. That would be better, and really should be required on all dehumidifiers.

  2. Roger Butler says

    Question: At what relative humidity (and temperature) are these units rated? If I have a 70 P/day unit and I want to maintain 40% RH at 68°F, will it still remove 70 P/day? I have this requirement and the dehumidifiers are not keeping up.

    Thanks
    Roger

    • Admin says

      If you have a 70 pints/day unit it was rated at 80°F and 60% RH. At 68°F and closer to 40% RH it will remove much less than 70 pints per day.

  3. Adam S says

    Great analysis! Can you comment on the efficiency of dessicant based units? I have an older whirlpool AD40USR-1 on my sailboat but it is super heavy to move on and off. I was thinking about replacing it with an Eva Dry EDV-4000, which is much lighter, but I have no way to assess the moisture removal rate per amp of the two units. Any suggestions would be appreciated!

  4. EJ says

    Hi,
    If running a dehumidifier continuously (with hose), isn’t a smaller unit more energy efficient and cheaper to run than a larger unit? Your energy calculations seem to not apply to continuous drainage mode. Please let me know. Thanks

    • Admin says

      Even running on continuous drainage mode the unit will automatically shut off when the desired humidity level is reached. Larger capacity units reach the desired humidity level much faster and will therefore be at full power draw for a much lower period of time.

  5. Sharon Lipsky says

    Can you please comment on the Frigidaire FAD704DWD energy star?
    Is it equivalent to the FFAD7033R1?
    If so, why is the energy star rated model less expensive on Amazon?

    Thanks

  6. Kay says

    I have an Evadry 2200, and running continuously, it pulls out maybe 1/2 gallon per week. I could toss it in the front yard, and it would work just as well. If I remember correctly, it was nearly $100. I have calculated that I could run even a 30 pint dehumidifier for 48 hours and see an improvement over what I’ve seen in the entire past year. Don’t waste money in the retail stores on dehumidifiers. They are useless. I am extremely glad this site exists. Thank you for the in-depth research. Without the knowledge, I would continue believing what I have is good enough because I just didn’t know any better.

    • Anonymous says

      Thank you for your information. How much extra a month and electricity do you think the dehumidifier produces?

      • anon says

        It depends on the unit, how much humidity you’re removing, and your local energy prices.

        If your dehumidifier runs at 600 watts (50 pint/4000sqft unit) for 8 hours a day and it costs 10 cents per kwh in your area, you’re looking at $15 a month. That’s about 2-3 gallons of water per day.

  7. Thea Clair says

    For the model payment equations, are the hours of use based on how long the de-humidifyer is actively running, or how long it is powered on and cycling on and off to control humidity? We have our de-humidifyer powered on most hours of the day to control humidity, but it isn’t running constantly. We recently bought one (a 70 pint from Hisense that you haven’t reviewed yet) and I’m trying to get a feel for how much it will cost us in the long run.
    Thanks!

  8. JOE D says

    BUT the real truth about the electricity cost is not accurate here nor easily seen on your electric bill.
    Ex. I am presently /831/18 looking at my PSE&G Long Island residential bill. it shows the power (electricity) supply charges at $.1025 /kwh which seems reasonable. But right above that it lists Delivery&System charges which lists another $.08/kwh so my total kwh charge is really closer to .18-.19 cents per kwh.

  9. Debbie says

    What would you recommend for a 700 sf apartment for a college student. I definitely want it to be energy efficient.

  10. George West says

    Purchased two GE ADEL50 units last Sept.2017. One unit has stopped working, amusing a hose drain …. angle is appropriate, no kinks, distance 3′ to drain. “empty” light continues to flash ? there’s nothing to empty ! I’ve removed the drain hose and found no apparent obstruction(s) but still empty light continues to flash.
    (Help) …..

  11. frank bollman says

    My GE dehumidifier heats the air to remove moisture. In the winter the electricity cost is partially absorbed by heating. In the summer the electricity cost to run the unit is potentially doubled.

  12. ann says

    I would like to better understand the independence of what seems like a very useful service. Can you tell me what the parent organization is for this website and/or who provides its funding?

    • Admin says

      All units are purchased in-store out of pocket just like a regular consumer would purchase them. Please see the footer of this page in addition to our privacy policy for additional disclaimers.

  13. James K McMahon says

    I am planning to replace my ancient “Westinghouse 20″ dehumidifier due to the new more energy efficient models that are now being sold and reviewed as you have done. (Yes, my old one still runs and has an automatic shutoff so it will not run constantly.) I found this Report fascinating and it reinforces my intention to purchase a 70 pint dehumidifier based on it running much less time to dehumidify my 754 SF condominium basement in the summer here in Maine. I am considering purchasing a new dehumidifier with a built in pump to propel the condensation up vertically and out a basement window – since I do not have a drain in my basement and am getting too old to lug the pail upstairs. In reading your Report, I assume that one of these new models will draw more electricity than a non built in pump model and that one with continuous drainage will draw even more. Any comment on a regular dehumidifier v. one with a built in pump that pumps up vertically. I am in my “due diligence” stage right now and am still trying to check the claims being made of a verticle lift of as high as 16′ (New GE Model APEL70LW). Any advice for this old man? JKM.

    • Admin says

      Our current recommendation for consumers looking for built-in pump functionality is to purchase the top rated Frigidaire FFAD7033R1 which does not include a built-in pump and instead buy an external condensate pump separately.

      • James K McMahon says

        Thanks for your recommendation. Two followup questions. Does the term continuous drainage mean the fan runs continuously and the compressor turns on and off based on the desired humidity level setting and approximately how much more energy will be used with an external condensate pump? My only concern about the model you recommend is the small bucket and how often I will have to lug it upstairs should I purchase the unit without the external condensate pump. Any way to estimate how quickly the bucket is likely to fill up with a setting at 60% humidity in my 754 SF basement? JKM.

        • Admin says

          The fan will shut off shortly after the compressor shuts off when the desired humidity level is reached. We have yet to test how much energy is used when using an external condensate pump. My guess is that it would be negligible.

          Regarding estimating how long it would take for the bucket to fill up – if the unit is run at full capacity in an environment that’s highly humid you could end up needing to empty the bucket up to about 5 times per 24 hour period. If the space is only mildly humid it could be as little as once or twice per day. This is unfortunately the type of thing that you won’t know for sure until you actually use the dehumidifier in the exact space that you plan on using it.

          • Anonymous says

            My guess is that this is too late to help Mr McMahon in his due diligence phase, but I can confirm that the fan-only power consumption is negligible – maybe 40-50 watts. I own the unit and have been interested in energy efficiency and the cost of running all the junk I have. I definitely agree, due to my experience, that a larger unit that operates the condenser for less time is cheaper. The only reason I get away with a 50 pint unit is that it doesn’t need to work all that hard for 50%. If I could go back, I would buy the 70.

  14. Dan says

    If properly sized, how often should a dehumidifier be cycling/running? I have a 50pint unit in my basement, and it is almost always running. The basement does not have any standing water or dampness, just a little bit of moistness during the summer months (upstate NY).

    Would getting a second dehumidifier in the space allow them to cycle a bit more and not run 100% of the time?

    • Admin says

      If the dehumidifier is constantly running and never turning off then it is very likely undersized for the space you need to dehumidify. A second dehumidifier will definitely help but before you consider buying one, check that the current unit isn’t set to continuous mode. If it’s set to this mode it will constantly run no matter the humidity level in the space.

    • John says

      You might want to invest in a temperature and humidity gauge. Your space may be adequately dry but the humidistat on the unit may not be accurate or working. You may be perfectly fine at 60% while your unit is trying to get it down to 40/25/ or 0%!

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