Take a chunk out of your electricity budget
Most freezers on the market today are energy efficient freezers compared to the models of even ten years ago, but you should still shop for the most efficient freezer you can find. Remember to consider the total cost of your freezer over twenty years, which is how long a typical freezer lasts. Total cost includes the purchase price plus all the electricity you’ll pay for over twenty years to run the freezer.
When looking at energy efficient freezers don’t just consider whether they have an ENERGY STAR rating. Look for the right size, the right configuration (upright or chest), and the best energy efficiency rating you can get.
Energy efficient freezer tips
Whether you’re planning to buy a new energy efficient freezer or just make your current unit a more energy efficient freezer, consider the following tips. Some of these tips are common across many energy efficiency guides and websites, while others I’ve come up with myself in my constant drive to cut energy use in my home. I’ve organized them into three categories: making your freezer operate more efficiently, making your use of your freezer more efficient, and choosing the best new freezer.
Energy efficient freezer operation
There are things you can do with even the oldest, most inefficient freezer to increase its efficiency. All of them can save you money and most of them won’t cost you much. And even if you’ve just bought, or are about to buy, a brand new energy efficient freezer, these tips can still help cut your energy bills. Even with an ENERGY STAR unit, you can do much better than the Energy Guide rating for the unit if you follow these energy efficient freezer tips.
Measure your freezer temperature at least every other month. For long-term storage (typically this means any chest freezer) it should be 0F or -18C. For shorter-term storage (typically, the freezer compartment of a refrigerator, or a chest freezer if you go through all its contents within a few months), you can set the temperature to 5F or -15C. To measure freezer temperature, your best bet is an electronic probe thermometer, which contains a digital read-out unit along with a probe at the end of a one to three yard long wire.
A probe thermometer allows you to read the freezer temperature several times over the course of a day, without having to open the freezer at all. Place the probe in the freezer between two bags of frozen food, or inside a jar half-filled with water. (If using a water jar, wait 24 hours for the water to freeze before you start measuring.) Take several readings of the freezer and calculate the average temperature. If you have the temperature set too high or too low, adjust the temperature dial accordingly and measure again after another 24 hours. Continue adjusting until you reach the desired level. While this adjustment won’t necessarily change a twenty-year-old clunker into an energy efficient freezer, there’s a good chance you’ll find your freezer is either too cold (thus wasting energy) or too warm (thus increasing the chance of spoiled food). Either way you’ll save money.
Even if you buy the most energy efficient freezer in the world, setting it too cold will waste a huge amount of energy. My 16-year-old freezer (which is no longer in use, but which when I bought it was one of the most energy efficient freezers on the market), could go all the way down to -29C, which was the recommended temperature to set it at when you were about to add a large amount of food to be frozen. I once set it all the way down before a big freezer-jam-making session, and forgot to turn it back to -18C for several weeks. That probably cost me close to a hundred kilowatts!
Much later on, I couldn’t figure out why my refrigerator compressor was running all the time until I took the temperature of the freezer compartment – a chilly -28C (-18F)! Because the freezer compartment was on the bottom, and because my kids kept reaching inside to look for popsicles, their arms had brushed against the temperature control dial in the top of the freezer. Whether by accident or on purpose, they had set the freezer to the lowest possible setting.
The moral is: measure often. Not only will this detect forgotten, accidental, or mischievous changes to your dial setting, but if the temperature changes markedly you may discover you have a faulty freezer thermostat or some external factor that is preventing the freezer from reaching its desired temperature.
Check your freezer door for a good seal. The gasket on your freezer door is there to ensure no airflow between the freezer and outside air. One clue that you may not have a good seal is excessive build-up of frost over a short period of time. To test your freezer door seal, place some paper (e.g. a dollar bill) between the freezer gasket and the body of the freezer, and close the door. There should not be any places where the bill moves without resistance.
Manually defrost your freezer whenever any significant frost builds up (more than 6 mm or a quarter of an inch). Frost of any thickness decreases the efficiency of the freezer. Avoid buying an automatic defrost freezer, which can decrease energy efficiency by up to 40%. And if your freezer suddenly starts to take on a lot more frost, or needs defrosting more than every couple of months, check the door again for a good seal.
Keep your freezer away from heat sources. Try not to locate any freezer or fridge near heat sources such as sunlight from a kitchen window, a stove range, a dishwasher, a clothes dryer (if you have a basement freezer), or a forced air heating register or duct. Freezer compressors use energy to extract heat from inside the freezer and spread it to the surrounding area. The hotter the surrounding area, the less heat is extracted from the freezer for a given amount of compressor work, and the less efficient the freezer will be.
Ideally you should keep a chest or other large capacity freezer in as cool a part of your house as possible, except that the temperature should never go down below 7C (45F) as temperatures below this will reduce the effectiveness of the refrigerant and may cause the freezer to malfunction or not cool adequately.
Maintain good airflow around the freezer. Keep some space on all sides of the outside of your freezer so that heat can escape from it. Ideally, when you first buy a freezer (or the next time you have a chance, if you already own one) plug it in and pull it away from the wall and any other furniture, appliances, or counters, and after it has been operating for a while, particularly during the time you hear the motor, feel the back, sides, and top for hot spots. Many modern freezers dissipate the heat they remove from the interior by running the warmed refrigerant through thin tubes along the outside of the unit, rather than having exposed coils on the back which tend to dust up. Knowing where these coils run can help you figure out what parts of your freezer should have good airflow around them. I measured my 16-year-old chest freezer a while back and found that the temperature on the front and sides ranged from 18C (the basement temperature) to as much as 28C depending on whether the compressor was running or not.
Also don’t keep the freezer in a small room with a closed door, as the heat expelled from the freezer will have nowhere to go, and will simply head back towards your frozen food! (No harm to the food – just more energy to keep it cool!)
Although you might think wrapping a freezer in insulation will make it more efficient, this is definitely not a good idea. The exception is that if you have determined that in certain areas no heat is dissipated during the cooling cycle, adding insulation there may be sensible. For example on my chest freezer I discovered that the door (on top) never heats up. So I glued an inch of pink Styrofoam insulation to the top only. But I can’t claim to have measured the effect this had on efficiency, and it was probably not that great, since heat rises, and so insulation on the top of the freezer is unlikely to be that effective.
Keep dust away from the coils and compressor. Clean the coils (if accessible) and the compressor area to remove any dust build-up, as anything that interferes with the heat dissipation decreases efficiency. If, like most modern energy efficient freezers, your freezer’s coils are hidden beneath the exterior casing, it may still help a little to keep the freezer free of heavy dust or grit.
Keep tabs on your freezer’s behavior. Listen for signs of an inefficiently operating freezer, including rapid on-off cycling of the compressor, or continuous operation over long periods. This can indicate either a freezer in need of repair or replacement, or some external factor such as a poor seal or outside heat source that is decreasing the freezer’s efficiency. Energy efficient freezers, when reasonably full and set to the appropriate temperature, should cycle every thirty minutes to three hours and most of that cycle the compressor should be off.
Measure your freezer’s energy consumption, with a Kill-A-Watt meter or other electrical consumption meter. In many areas you can borrow these from a public library, or you can buy them for as little as $20 from hardware or department stores. (If you’re really serious about making your whole home energy efficient, I recommend buying one for yourself. You can also lend it to friends later and help them become more energy efficient!)
Never assume that just because you bought an energy efficient freezer, it is operating at peak efficiency. Even if you adjust the temperature correctly, there can be other factors that cause it to use more energy than advertized.
To use the energy consumption meter, first plug the meter in where you can see it. If the electrical outlet is hidden behind the freezer, start by plugging an extension cord into the outlet, and plug the meter to the other end of the extension cord, placing it where you can read the meter display. Then plug the freezer plug into the meter. If the meter requires a reset to read kilowatt hours, reset it. Then let the freezer run for at least 2 days, preferably 3 or longer. Take periodic readings of the kilowatt hour consumption and time elapsed. (Some meters only read up to 99:59 hours, then wrap back to 00:00, so take this into account if you read for more than four days.) Divide the kilowatt hours consumed by the hours elapsed, then multiply by 24 to determine kilowatt hours per day.
Make sure your freezer is operating at the expected kilowatts per month level according to its Energy Guide label. If it is not, use other tips in this section to determine what might be contributing to its substandard performance. If you bought an energy efficient freezer you deserve to get the energy savings it claims to obtain!
Energy efficient freezer usage
Here are some tips for getting the same great benefits of freezer ownership without spending a fortune on electricity. You don’t have to buy a new energy efficient freezer to make the way you interact with your freezer more energy efficient!
Toss out the old. Periodically go through your freezer and discard any food that has been in there more than six months, or food you know you’re never going to eat. The more unwanted food you keep in your freezer the sooner the freezer will just be keeping your garbage cold. And you may discover good things in your freezer you forgot you had. How will all this save energy? First, you’ll be able to find the things you really want in there faster, if you don’t have to sort through old food that is destined for the dustbin. That means less time with the freezer door open, letting in heat. Second, you may eventually get to the point where you can shut down the freezer for at least part of the year….
Shut it down if you can. When your chest or upright freezer is running low on content, see if it’s possible to consolidate its contents with what’s in your refrigerator freezer compartment. You can then disconnect the freezer until the next preserving season starts up. You may even discover, after disconnecting it, that you don’t need to reconnect it. Rule number one in energy conservation: not using the energy-consuming device is the best way to save energy! I did this with my chest freezer in 2006: emptied it out, threw out the stuff I knew I would never use, crammed most of the rest into the half-empty freezer compartment in my fridge, and had to cook or eat the rest over the next several days. And I haven’t plugged the freezer back in yet. Saves me about 350 kWh per year!
None like it hot. When storing foods in your freezer, allow them to cool to room temperature, or better yet, place them outside in cold weather for a while, before placing in the freezer. Never place hot foods in the freezer (and never place hot foods in a plastic freezer container – let them cool first). The hotter the food is when you put it into the freezer, the harder the freezer has to work to bring it down to 0F or -18C.
Keep track of what you froze and what you use. This tip may only work for those who are well-organized, but there’s no harm in trying if you’re not! Keep an inventory of your freezer contents, carefully label all items in your freezer, and compartmentalize the freezer as much as possible to make it easy to determine, before you open the freezer, what foods are in what part of the freezer. For example, a chest freezer often comes with hanging baskets; use one for frozen fruits, another for desserts like ice cream, another for meats, and so on. Don’t just toss new foods into whatever area is free. The faster you can find what you’re looking for, the less time the freezer stays open and the less work the compressor has to do to extract the heat introduced when you opened the freezer. Also, the less food is wasted because it’s lost to freezer burn.
Use appropriate containers and check for breakage. Make sure your foods are stored in freezer-safe bags or containers. Periodically check for any rips in bags or cracks or breaks in plastic containers. Check glass jars for breaks as well (and remember, when freezing liquids or jams in glass jars, to always leave an inch of space at the top of the jar, as the water in the food will expand and may crack or burst the jar). The idea here is to avoid any exposure of foods to the air of the freezer. Not only will such exposure ruin or spoil the flavor of the food, but any evaporation of water from the exposed food increases the workload on the freezer.
Buy ice insurance. Keep a couple of ice blocks triple-bagged in your chest freezer. If you have lots of free space, add extra ice blocks to fill the space. Not only will this cut the amount of air space (which as described above reduces the amount of cold air that escapes when the freezer is open) but it will help keep your freezer contents cold longer in the event of a power failure.
Keep extra foam insulation sheets handy if you live in a remote area where power failures are frequent and long. When a power failure occurs, surround the freezer with as much insulation as possible. This will slow down the warming process and may make the difference between spoiled food and food that’s still good to eat. Just remember to remove the insulation the minute the power comes back on.
My parents keep several sheets of foam handy for their cottage freezer because tree falls and snowstorms knock out power frequently, sometimes for several days at a time. Between ice packs and insulation, they usually manage to salvage food that otherwise would have spoiled. Plus they save energy when the power comes back on, because it takes less energy to bring the freezer back down to operating temperature if it hasn’t warmed up as much.
Use the buddy system. If you and a neighbor or friend are both into freezing seasonal foods for later use, buddy up with them to share a freezer. It makes no sense for each of you to have a half-full chest freezer, if you both have a freezer compartment in your refrigerator that can store the amount of frozen produce you’ll need for the next few weeks. Put most of the food in one chest freezer in one of your houses, and what you’ll need for a few weeks into your refrigerator freezer compartment. When one of you depletes what’s in the smaller fridge freezer, you pay your buddy a visit (or he or she pays you a visit) and stocks up from the chest freezer. Energy efficient freezers can be a powerful social tool!
Check for blockages when closing. Always check, when you close a freezer, especially a full one, that none of the foods inside are blocking the door from closing. An ice cream carton sticking out just a touch too much on a vertical door freezer can make the difference between a perfect seal and a freezer door open half an inch or more. Some chest freezers have a flat underside to the door, except where a freezer light compartment protrudes downwards a couple of inches; keep that area free of overloaded freezer baskets or the light compartment could keep the door ajar. Running an energy efficient freezer when the door is open even an inch is about as energy efficient as driving a Hummer.
Energy efficient freezers – what to look for when buying a new one
If you are planning to buy a new energy efficient freezer, here are some things to look at as you start to shop. The key points are: buy the most energy efficient freezer you can afford (and remember to factor in the total cost of ownership); buy the right type of freezer (chest freezers are best; manual defrost is best); buy the right size; and don’t buy one if you don’t need one!
Chest freezers are better. Go for a chest freezer rather than an upright. Because hot air rises, it follows that cold air falls. When you open a chest freezer, the cold air won’t rise up out of the freezer and the warmer air in the room won’t fall down into the freezer. So less heat enters the freezer when you open it. With a vertical freezer, when you open the door, all that cold air comes tumbling out and is replaced by warm room air, so more energy is lost. Especially for an upright freezer, it’s a good idea to keep it as full as possible – even with empty plastic bottles if you aren’t keeping much in one area – so that when the door does open, there is less empty space within the freezer for cold air to fall out of.
The same difference between chest and upright freezers applies to the effect of a bad door seal. If the door gasket on a chest freezer is not completely sealed, the freezer will still not take on much heat because hot air tends to rise rather than fall. But an upright freezer with a bad door seal will leak out cold air from the bottom and draw in warm air above.
Buy the most energy efficient freezer possible. Buy an ENERGY STAR certified unit, which will use at least 15% less energy than the minimum standard required by US law for currently sold freezers, and will save up to 40% over models from as recently as 2001. If your refrigerator is more than 10 years old, you should almost certainly upgrade, as there have been marked improvements to the energy efficiency of freezers over the past ten years. A 20-year-old freezer can use more than twice what today’s best models use.
But don’t just stop at the ENERGY STAR label. Try to buy the freezer of the right size that has the best energy efficiency rating among those with an ENERGY STAR label. There is a wide variation between the lowest and highest scorers on ENERGY STAR labels, and you might as well go with the one that will save you the most energy.
Note that the ENERGY STAR criteria for freezers changed in April 2008 to become more stringent. As a result, an appliance store floor-model energy efficient freezer or a freezer that has been kept in inventory a long time may still have its original ENERGY STAR label even though it may no longer qualify to be ENERGY STAR qualified. It’s always a good idea to check the ENERGY STAR website once you’ve selected a freezer, to ensure it really is the most energy efficient freezer currently available.
Don’t supersize your freezer. Buy the right-sized energy efficient freezer. Just because a 16-cubic foot freezer is only 20% more expensive than a 10-cubic foot freezer doesn’t make the bigger one better for your needs. Unless you’re doing a ton of freezing of home-grown or seasonal produce (or storing whole sides of beef or venison) you probably don’t need more than a 10-cubic foot model for a family of four. And remember that a full freezer is a more energy efficient freezer than a half-full one, so a smaller freezer makes it more likely you’ll achieve this goal.
Not only that, but to qualify for the ENERGY STAR label, compact freezers (under 7.75 cubic feet) must be at least 20% more energy efficient freezers than the minimum federal standard, as opposed to only 10% for larger freezers (but it is often hard to find a stand-alone freezer for sale that is under 10 cubic feet).
Avoid anti-sweat heaters. Make sure you don’t buy a freezer with an anti-sweat heater, as this uses heat to prevent moisture build-up, and adding heat to a freezer is the perfect way to make it less efficient. Anti-sweat heaters can decrease efficiency by 5-15% on average. An energy efficient freezer may still obtain ENERGY STAR status with an anti-sweat heater, but this feature, while it looks good on the promo literature and gives the salesperson something to talk about, is going to cost you money. The freezer would be more energy efficient without it.
Most energy efficient freezers
You can check the ENERGY STAR website for up-to-date information on the most energy efficient freezers: ENERGY STAR Certified Residential Freezers. ENERGY STAR is the energy efficiency certification used in both the USA and Canada.