Build an ultra efficient fridge

This is my instructable on taking a regular refrigerator, and making it very efficient, by making use of the cold winter air. I got this idea while working on projects in my basement. I got tired of going up and down the stairs, to get cold refreshing beverages. I really didn't want to put a mini fridge down stairs due to the cost of running it all year long, so I started wondering how I could cut down the expense. I live in Iowa, so I thought, why not use the cold outside air to cool down the fridge during the winter time! What about summer though... I knew I'd need to be able to switch it back to the internal compressor pump in the summer. This is done by routing the existing fridge thermostat to switch on external low current push pull fans. This changes the power consumption from 120v 5 amps to 12v 500 milliamps. This idea can easily be adapted to larger size fridges with the use of some additional items. I will cover that at the end.
This project also has the potential to save tons of carbon in the atmosphere per year if larger companies sold this type of technology in future fridge models or people adapt to this idea to existing fridges. I tried to give as much detail as possible, so most people (I hope) can do this on their own. Most people should be able to look at the pictures and get the idea.

Step 1

Get yourself a mini fridge. I bought mine on craigslist really cheap.
Get the supplies for the fridge transformation.
4" insulated duct tubing. (You can sometimes get this for really cheap at a used construction recycling center)
2, 4" computer fans. (I pulled these out of old burned out computer power supplies)
Silicone caulk. (local hardware or home improvement stores carry these)
End wire caps (local hardware or home improvement stores carry these)
Small piece of 4" metal duct tubing. (local hardware or home improvement store carry these)
House wiring 12 gauge. (I had some left over from other home projects, you can sometimes get this for really cheap at a used construction recycling center)
Piece of plywood. (I had this left over from other home projects, you can sometimes get this for really cheap at a used construction recycling center)
Dual outlet box.
One 3-way switch.
One home outlet.
One outlet cover.
One long piece of dual wire.
Window and door foam seal.
Old 12v 500mA adapter.
Tools you will need.
Small saw.
Wire cutters.
Screw drivers, both phillips and regular.
Nibblers or tin snips.

Comments

[Kent]

You might find that even the fan is not needed in the winter. Warm air will rise, cold air will sink. Anytime it is colder outside, air will flow.
But as someone commented, this project does not save energy. The "wasted" energy is heating your room. In the summer it would save energy to have the heat vented outside. With an EER of 8, it costs 240 Watts in your air conditioner to get rid of 600 Watts of power from the fridge. The same principle holds for light bulbs. You have to look at the whole system, the whole house.

[falcotheimpaler]

It saves "energy" in the form of electricity he doesn't have to pay for.

[Kent]

The energy being vented to the outside in the winter has to be replaced by other energy to keep the house at the desired temperature. He is saving refrigerator energy, and replacing it with heating system energy, so there is no savings. There is also some leakage of heat into the hoses, so overall, there is a net loss. Just put the whole thing outside.

[nitehawk86]

Possibly, but if your home is heated by geothermal or gas, it is probably far more efficient on energy than a big electric heat exchanger.

[NightLord]

It is also far mor efficient if you heat your house with biomass...

[falcotheimpaler]

Do this to a computer, and I'm sold.

[Blofish]

This is EXCELLENT !

[Skai]

this is really amazing. i think that i'm going to do solar panels, though, cuz solar panels can save all of my electricity bills for my entire house, instead of this just for my fridge. but maybe if i am not getting enough electricity from my solar panels, i can help myself be more efficient with my solar energy by doing this. awesome :)

[shardman1]

Great for saving cost on electricity. Wouldn't worry about the carbon emissions since manmade global warming does not actually exist.

[shooby]

Who cares whether it does or not? Using less resources is better, because suckers like us don't have to spend the time extracting, processing and transporting them.

[kokla]

oooh, someone's been drinking oil companies snake oil.

[Etitan]

http://www.nytimes.com/2009/04/24/science/earth/24deny.html?ref=science

[DallasDeckard]

http://online.wsj.com/article/SB10001424052748704342404574576683216723794.html

[Alaskan Big Bubba]

Come on now, it dosn't matter if your green or not, both sides have private interests and in reality the earth goes through temperature changes on it's own, did we not have an ice age and did man cause that? So what if the world is warming up, man can add to it, but not cause it. We still need to be concious and ideas like this are nifty, but be realistic.

[anotherone]

nice job!

[hitachi8]

 Nice  ! 

[leepinlarr]

I'm sure the btu's off a fridge, are not an issue

[cyberdove]

In the winter, cooling a refrigerator helps heat the house. So when bringing in cold air from outside, you are increasing your heating energy consumption.

[WilderLust]

very nice instructable; just make sure your air intake does not pickup any stinky air! if you are down wind from exhaust smell for example, you may have a certain strange flavor to you food... not smoked exactly but :-) i did something similar a while back with my big fridge and freezer but used electronics to control the switching depending on outside temperature.

[dark sponge]

I'm guessing this won't work in Texas.....

[_soapy_]

If you live anywhere that is cold at night, then it will work just fine for half the time. Deserts drop below freezing at night, and at those times it will actually be too cold for your fridge! This isn't going to be much use for me, but I have been considering trying to find a way to locate the compressor in the next room, where the heat is wanted, rather than right behind the fridge where it just heats up the fridge again! This idea has actually been used for thousands of years, already, just with a semi-outdoors larder or pantry with lots of stone to keep the temperature low. Using a couple of fans and temperature switches to update the design is genius.

[dark sponge]

Using temperature switches is a good idea, or maybe some of these hooked up to a microcontroller and some relays.

http://www.allelectronics.com/make-a-store/item/LM34DZ/FAHRENHEIT-TEMPERATURE-SENSOR/-/1.html

You could have one sensor outside and one in the fridge, and one relay control the fan and the other one the compressor. If the sensors detect that it is cold enough outside, it will switch on the fan. If the sensors detect that it is not cold enough, it will turn the fan off. If the temperature sensor in the fridge detects that the fridge is not cold enough and the one outside detects that it is not cold enough to use outside air, it will turn on the compressor.

[Opcom]

Very good use of natural resources! Too bad I can't apply the reverse to my oven in Texas!! Even so, for a couple of months out of the year, it could be done, if not for the fridge proper, then for the beer fridge. It could save $100 or so in electricity, any resources saved are worth consideration.

[kokla]

the texan summer oven might be a solar slow cooker like what kids used to make in gradeschool science class. definately a couple panes of glass either side of a tire innertube could cook rice in a couple of hours

[kunalg]

The hot air outlet duct is facing downwards just above the cold air inlet. This can cause exhausted hot air to get sucked in along with the cold air. If the hot air outlet duct is turned so as to face upwards, the hot air will be able to escape up instead and will not mix with the cold air. This will increase the efficiency a wee bit more !

[kokla]

that's a good idea, perhaps if the inlet and outlet where facing 180 degrees opposite left to right. I imagine in it's summer and your vent faces upwards, a water and dust ingress is compromised.

[dexusno]

And will let rain fall into the hot air outlet...

[BJMN]

Yes - living in central Manitoba in Canada, we have a surplus of cold air for a lot of the year! I've thought for a long time about doing something like this. We already keep our chest freezers in an uninsulated building outside, so they don't run for a large portion of the year, but I hadn't gotten around to doing anything with the fridge yet. I especially like the idea in the comments about re-routing the hot coils to the outside. My current house doesn't have AC, so getting some hot air outside in the summer would be a great idea. As an engineer, I see tremendous potential in just changing how we see and use heat - a tremendous amount of our energy output simply goes into moving heat around, and anytime I see something that does this naturally appeals to me!

[votecoffee]

Good point about venting waste heat of compressor outside during summer to save on cooling bill. In winter, it can actually be beneficial to capture that heat. Changeable system would be good, with good insulation on ducting.

[neffk]

Very nice. This is a very elaborate project. Could it be made more simple by simply venting the coils to the outside during the winter? That would reduce the project to duct work. I would take on more readily than re-wiring my wife's major appliances :)

[votecoffee]

You could do the coil thing (build a box around coils and vent to outside), and it would increase the efficiency a good bit. Would not cut off compressor completely though. Use less power but not none, assuming the fan is done with solar and not house current. If fan is run 24/7 off house current, it may become questionable how much you're saving.

[proacguy]

The Idea is great!! The only thing I can caution anyone on is the bigger fridges have coils in the sides, back, and or top. So be careful when cutting the holes.

[teeps]

wicked project sir! Immediately reminded me of my own instructable on using this concept to cool a desktop computer:
http://www.instructables.com/id/Wisconsin-Cooled-Personal-Computer/

Excellent job and I certainly think that harnessing the weather like this is the way of the future (while certainly being a return to the past!)

[frank bailey]

great job , sounds like you know what you were doing , the instructions were good with a lot of detail , . you got my vote

[Tagarashi]

Great ible... What is sad though is even when you try and conserve energy. The energy companies just raise the rates.

[unbentcrayfish]

If you could make to tubes and stuff smaller and less noticeable it would have more applicators and I would love this even more

[gsl130]

Do you have problems with freezing, or getting things too cold? I mean, with outside air temps dropping well below 32 F, what keeps things from freezing? On a similar note, I bet we could come up with a sensor to switch between compressor and outside air as needed to keep food from getting to warm on those balmy winter days. Awesome instructable!

[nodyeliab]

Thanks! Nope no freezing, the existing thermostat turns the fans off or on, the switch in back determines if you want the thermostat to switch the compressor on and off or the fans . Yes, you can connect an external thermostat to switch between the fans and compressor, but due to the cost, I only mention using that option at the end of the instructable. I have thought of using a microcontroller to do that too, that would be another fun instructable!

[abarker]

Very nice.. thanks for the tut. I remember reading an article years ago about a guy who dismantled his frig to maximize efficiencies. He took the coils off and moved them (I think maybe he tried several versions here). He placed them in his hot water tank to preheat his water. He also tried a version with the coils outside to take advantage of the temp differences. With the coils and pumps moved away, he super-insulated the actual box. Always thought it would be a good idea to move that expressed heat under my front sidewalk to melt the ice in the winter.

[solis365]

I'm pretty sure there are houses built around this concept. You mount a fridge next to your wall anyway, so just have a duct going from the outdoors, through the wall, and into the fridge. If houses/kitchens were built this way it would save tons! nice job. there are lots of families that have an extra fridge or chest freezer in the basement to store bulk food - imagine if they did this for those large freezers. it would save tons!