Energy Efficient Fridge Hack


We’ve already covered a pipe bomb mini-fridge this week, but inventor [Tom Chalko] provides us with today’s fridge hack. He noticed that chest-style (laying down, see above) freezers were more energy efficient when compared to normal stand up refrigerators at the same size, despite the colder temperatures involved. This is largely due to the fact that these chest-style freezers keep cold air in like water in a bowl, even if the lid is open. He has written a very thorough report on his findings (pdf), as well as a detailed walk through of the manageable task of converting a chest-style freezer into a chest-style fridge. In the end, his fridge only used 103 Wh of electricity on the first day to reach and maintain between 4° and 7° C (39° to 45° F), and he noted that 30% of that was just getting it up to temperature. After that, the fridge only turned on for roughly 90 seconds an hour, making it a very quiet fridge as well.

39 thoughts on “Energy Efficient Fridge Hack

  1. Unfortunately this doesn’t really scale well for those of us with families (or planning to store lots of leftovers).

    However, regarding the underlying idea–that you save energy costs when you minimize the outflow of cold air–how about compartmentalizing the full-size standup fridges?

    I mean, they are already more or less compartmentalized with regards to shelving and drawers, but if you make them airtight, then at least when you get a soda out of the bottom drawer it is only the bottom drawer which loses cooled air.

  2. @googfan

    I can’t find anything ironic (maybe you meant coincidental? Still can’t find nothing ’bout fridges) on your site.. but your site does make baby jesus cry. Animated titlebar?? Are we back in ’98 again or something?

  3. Yeah, a chest freezer with a thermostat works great as a fridge. I have been using one for about 7 years now to keep my homebrewed beer and yeast at 20C. The compressor barely ever turns on, but my ambient temp is a little higher than yours, 25C-30C in summer.

  4. It makes you wonder why there aren’t fridge/freezer combos that are side-by-side with horizontal doors instead.

    I used to monitor how much power my pc consumed idling, and actually managed to cut idle power about 50 watts by downclocking while not gaming.

    I live in arizona, and noticed that you can actually save quite a bit of money by closing a/c vents off to areas you don’t use often, like the bathroom or (in my case) livingroom.

    This guy rocks.

  5. @Insipid Melon

    Not sure what you mean? These chest freezers come in various sizes – the most common size have just as much if not more space than a typical fridge. You could EASILY fit everything you need in one.

    I mean people keep whole human bodies in them – before they are caught anyway!

  6. probably because its harder to find/organize things than with an upright unit. that’s why fridges and freezers in supermarkets (where efficiency is important because it means money) are upright; even though a chest is more energy efficient, organizational efficiency matters too. but that can be handled with a little creativity.

  7. @spacecoyote
    You are right, organizational efficiency matters too. I’m thinking of some sort of slideable shelving you could pull up when you open the door. I guess it could be somewhat heavy when some racks are full although it could be helped by pneumatics (think hatchback car style)

    Food for thought, sad pun free for all…

  8. The top-loading arrangement certainly helps, but so does (1.) not having a freezer compartment, (2.) having much thicker insulation than most conventional fridges, and (3.) not having an automatic defrost feature. As with most energy-saving schemes, there are trade-offs to be made with this approach.

  9. The organizational efficiency and convenience may indeed suck rocks, but if the energy efficiency is more important – and for many it is – then this is a very laudable solution.
    The average suburban soccer mom wouldn’t touch it with a ten foot pole, but for those of us with properties off-grid, generator-run, or power-limited, this makes perfect sense.

    I wonder if my propane-fired upright fridge (yes, they still make them) compressor would stand a move over to a chest-type chassis. Probably save a lot of fuel.

  10. If that compressor is only running 90 seconds an hour, wouldn’t it make sense to get a smaller compressor thats a tenth of the size? Thats cheaper then…

    (and even though a smaller compressor is probably not as efficient, I recon you’d save overall because there is a reasonably large start up cost with a fridge because you’ve got to pump enough coolant to get the pressures everywhere in the system to operating levels)

  11. @cantido
    Are you new to the internet? Don’t fall for those blog-ads all over comment sections, just get a freaking greasemonkey script to block people like that instead, and make sure you block the url they spam rather than actually going to it, who needs blogs of such losers.
    They annoy the hell out of me and I’d like to know who popularised making meaningless ‘comments’ in comment sections to spam your blogURL, and then once I know to get some tar and feathers and fix that person.

  12. For saving on power consumption you might look into a product called the e-cube, it’s essentially a device that attaches to your refrigeration unit be it freezer or refrigerator’s thermostat and contains a wax polymer so that the thermostat is measuring the actual temperature of the wax that’s been cooled by the refrigerator and not the ambient air of the refrigerator that changes with each opening.

  13. These things do in fact work great, and those that claim it’s not easy due to organization are simply luddites t hat are afraid of change. It’s easy to deal with as most freezers come with sliding shelves already. It’s very easy to organize without being creative.

    Plus you dont have the useless “crisper” drawer that is typically full of dead or wilted veggies that are long forgotten.

    The problem is that it’s door is a horizontal surface. Humans love putting things on those surfaces so you end up with crap on the fridge door. My buddy solved it by putting the whole thing on some industrial glides. when full it can easily slide out and in under the counter. Need milk, simply pull to slide out and open, then slide it back in without effort.

  14. @skibane: Even with a second unit set up as a freezer the author would _still_ be using a lot less energy than a single upright fridge would- and he would have a lot more storage. (Say twice the thermal differential- maybe 300whr/day + the original 100 is only 400whr- less than a normal fridge).

    @stunmonkey: I’m not sure “fired” is the right word. Propane powered fridges use the same cooling principle as an electric fridge- the expansion of a compressed gas absorbs heat. Only in the case of a propane fridge- the gas isn’t re-compressed- it’s simply burned off to get rid of it.

    Ideally- a wider, shallower, chest fridge is easier to organize- but takes up more room. Fridge drawers found in some higher end kitchens are awesome- but they still lose a LOT of cold air because the insulation is in the walls of the unit- not the drawer that pulls out.

  15. @Stunmonkey if your propane fridge is the typical gas absorbtion kind, orienting it at anything other than perpendicular to the earth will seriously impair it’s cooling function or damage it. The mechanical compressor kind should be OK though, it would depend on the model of propane engine used.

  16. and this is a HACK – who is surprised???
    A fridge has far better insulation => less energy loss. So it would be EVEN MORE EFFICIENT to have a fridge compressor in a freezer box and run it as a fridge. This due to the smaller compressor size and inherent internal bigger losses the less runtime you have on the compressor.
    Did you get that “Super Hacker”?….

  17. Got to admit I’m struggling to see the hack-ness in this. I normally dont mind vaguely related stuff but this really is just an efficiency report. Build a controller into it to do maximum cooling at cheap-rate in order to maintain freeze state while minimising compressor runs during expensive rate times, or get it to tweet pointlessly like all the other stupid tweeting white goods, but dont just write a report on its efficiency and post it as a hack!

  18. I believe I have seen actual “chest refrigerators” for sale on occasion. I converted a chest freezer (because I had one available) to a kegerator last fall. When replacing the thermostat something to beware of is short-cycling the compressor. I used a digital control that has a temperature spread and anti-short-cycle time period, so that even if the temp were to raise before the cycle was complete, the thermostat wont kick on.

  19. Derrrr…compartmentalized refrigerator=side by side, with water and ice thru door??? Freezer drawer on bottom–yes, it lets some cold air out when you open it, but when it is closed, guess how well the bottom of the fridge is insulated?

    We have had a Trio for years.

  20. Why not just lay your refrigerator on its back! Onc could put blocks under it to protect the coils. Or use a subzero which has the coils on the top facing the side. Door excessively heavy? That’s good since the inconvenience would cause you to open it very infrequently – thus adding to the energy savings!

  21. I have seen an upright fridge/freezer combo with a drawer style freezer on the bottom. It helps a bit. There is still huge airflow around the drawer and convection through the now empty cavity.

    As for changing the position of a fridge, anytime you tip a freon unit (fridge, freezer, AC) you need to let them sit and settle. This is because they work by changing the state of freon between liquid and gas. Due to the design, when tipped, liquid flows to areas where it can cause damage if turned on. The safe rule is to wait three hours for the liquid and gas to settle after putting the unit upright.

  22. I was wondering about utilizing a vacuum to keep food for extended periods of time without the need for electricity. Can anyone answer some questions I have? Like is a vacuum cold, would it prevent food spoilage (lack of oxygen), would it pull the food apart (bloating) or damage it? The vacuum could be provided mechanically (man-powered pump) without the need for electricity. Thoughts? BTW good work James!

  23. Anybody know if the motor in the chest freezer could be changed to 12v some how we use a chest freezer and generator for long periods of camping generator runs couple hours a day to keep everything chilled then we shut it off we use the chest fridge because of the insulation factor might try this idea but if I could get to 12v would beat runnin a noisy generator I run 2 large truck batteries in my ute ( seperate from crank battery) that run of a red arc ststem as well as to 80 watt solar pannels for lights and my evakool fridge any ideas

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