ENERGY STAR dehumidifiers
Understanding the rating system can help you save
You might expect that ENERGY STAR dehumidifiers are more efficient than those that don't carry the ENERGY STAR logo. But there are cases where you would be better off buying a non-ENERGY STAR certified dehumidifier, in terms of saving energy. It's important to understand how the ratings work before you buy.
People place their trust in the ENERGY STAR logo and will often simply buy a product that has this logo, without understanding whether it truly is the most energy efficient product they could purchase. ENERGY STAR dehumidifiers are those that have ranked above a certain efficiency factor within their capacity range, but the efficiency factor differs across ranges, so there are cases where dehumidifers in a range with a higher efficiency factor that do not qualify for ENERGY STAR may be more efficient than those with the ENERGY STAR logo in a range with a lower efficiency factor.
I experienced this myself just last week. Canadian Tire, my local big box store, had a sale of so-called Green products, and was offering ENERGY STAR dehumidifiers on sale for 25% off. I'm sure many people rushed out to buy one, but I did a little research first and discovered that this particular model, while cheap, wasn't the greatest investment. (I loaned my dehumidifier to a friend about ten years ago and keep forgetting to ask him for it back - I guess he has squatters' rights! But I do need a replacement as there are small patches of mold along the baseboards in my basement.)
The dehumidifier in question, a Whirlpool 25 pint dehumidifier, is ENERGY STAR certified and has an energy factor of 1.2 (more on energy factor below, but the key point is that the bigger the number, the better). But checking at the handy Office of Energy Efficiency website of the Canadian Government, where you can search on all models of dehumidifiers to find their energy factor, I discovered that there are actually 20 dehumidifiers in the OEE list (of a total of over 180) that are not ENERGY STAR dehumidifiers but that are substantially more efficient than what many Canadians went out and bought last week.
The reason for this is that ENERGY STAR dehumidifiers are broken into different capacity ranges - the amount of water they can take out of the air in an hour - and different capacity ranges have different minimum requirements for their energy factor. Smaller dehumidifiers can get away with using more energy to extract a pint of water out of the air than larger dehumidifiers, and still get ENERGY STAR certification. So the easiest way for a manufacturer or retailer to sell lots of dehumidifiers by relying on ENERGY STAR certification is to stick to selling dehumidifiers with a small capacity.
It's not the STAR, it's the FACTOR that matters
You're much better off to consider the ENERGY FACTOR of dehumidifiers than whether they are ENERGY STAR certified or not. What is the energy factor? It's the ratio of water extracted (in liters) to energy used (in kilowatt hours). So an energy factor of 1.0 means that 1 liter of water is extracted for each kilowatt hour of electricity used, while a higher energy factor (say, 2.0) means twice as much water (2 liters) is removed for the same one kilowatt hour.
(For those of you south of the border or metrically challenged, a liter is about the same as a quart - and for anyone who doesn't know what a kilowatt hour is, it's the amount of electricity you would use by running a 1,500 watt blow dryer for 40 minutes, or by leaving a 100 watt light bulb on for ten hours.)
The Whirlpool dehumidifier I was looking at has an energy factor of only 1.2, which means this dehumidifier can remove 1.2 liters of water per kilowatt hour. It can remove 11.8 liters per day, which means if you have a really humid basement and it has to run continually to dry it out, you'll use 11.8 x 1.2 kilowatt hours, or 14 kilowatt hours of electricity per day to run this unit.
Looking over the list of dehumidifiers the OEE provides, I find that about 175 dehumidifiers have at least the same capacity as the one I was looking at. Of those, 78 are not ENERGY STAR certified. Of the 78 dehumidifiers in the list that are not ENERGY STAR dehumidifiers and that have at least the capacity of the one sold at Canadian Tire, a full 65 of them are more energy efficient - have a higher energy factor - than the dehumidifier on sale. And 20 of them are at least 25% more energy efficient than the ENERGY STAR dehumidifier, because they are in higher capacity ranges that have much more stringent requirements for energy factor. By choosing a dehumidifier that is not one of the ENERGY STAR dehumidifiers but has a better energy factor, I could actually save up to 44% on the energy I use to run the dehumidifier.
Is this all too complicated?
It seems like a lot of work to go looking for the exact energy factor of each dehumidifier and choosing based on that - so I'll let you in on the easy solution. The energy factor required to have dehumidifiers certified as ENERGY STAR dehumidifiers goes up with capacity; here's the basic breakdown:
| Pints/day | Liters/day | Energy factor (L/kWh) |
| ≤25 | ≤12 | 1.2 |
| >25 to ≤35 | >12 to ≤17 | 1.4 |
| >35 to ≤45 | >17 to ≤21 | 1.5 |
| >45 to ≤54 | >21 to ≤26 | 1.6 |
The model I was thinking of buying had an energy factor of 1.2, and had the ENERGY STAR logo because the minimum energy factor for ENERGY STAR dehumidifiers with a 25 pint or 12 liter capacity is 1.2. But any model with a capacity of 35 or more pints (17 or more liters) has a minimum required energy factor of 1.5. So just look for the ENERGY STAR logo on a higher capacity dehumidifier - the higher the capacity, the more efficient the dehumidifiers must be to qualify as ENERGY STAR dehumidifiers. Of course, you'll pay more for a higher capacity dehumidifier, but a 33% energy savings adds up. For example, let's suppose you pay an extra $100 for the high-capacity, 1.6 energy factor dehumidifier, compared to the 1.2 energy factor ENERGY STAR dehumidifiers on sale at Canadian Tire. Let's assume the dehumidifier has to remove 3 liters of water per day. The 1.2 energy factor dehumidifier will use 2.5 kilowatt hours per day, while the 1.6 energy factor dehumidifier will use 1.875 kilowatt hours per day. That's a savings of 0.625 kilowatt hours per day, or about 2,300 kilowatt hours over a ten year period (the expected lifetime of a typical dehumidifier). 2,300 kilowatt hours, in my neck of the woods, costs about $230, so the investment in the higher capacity, much more efficient dehumidifier will save you $130 or thereabouts, compared to ENERGY STAR dehumidifiers that are at the bottom end of capacity.
Beyond looking at getting the best energy factor you can find for your dehumidifier, there are many ways in which you can cut down on home humidity so that your dehumidifier doesn't have to work as hard. See my main Energy efficient dehumidifiers article for more information.
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