Why doesnt my fridge make use of the winter weather?

February 19, 2008 8:55 AM

Why doesnt my fridge make use of the winter weather?

Is there a reason why fridges arent built with the coils outdoors or with a tube going outdoors (like a dryer or portable AC unit)? Shouldnt it be possible to push the waste heat outdoors or somehow make use of the fact its 4 degrees out today? Or maybe the cold air just passes through the fridge between the insulation and the thin plastic inside wall.

My heater seems to be fighting my fridge which only costs me energy dollars. Or does it all somehow balance out? I imagine the energy running the compressor is significant. The only reason I can think of is that its a pain/costly to cut a hole into your kitchen wall.

On preview: The fridge could have some logic to close the tube on warm days.

posted by damn dirty ape to technology (24 comments total)

Is there a reason why fridges arent built with the coils outdoors

Wouldn't that require more energy to push things over a greater distance?

somehow make use of the fact its 4 degrees out today

There probably is a way, but it's a question of how much would it cost I bet. And what do you do when it's warm out?

My heater seems to be fighting my fridge which only costs me energy dollars.

Huh? Are you saying if your heater was off, your frig was cool the room? If so, then that's like no frig I've ever seen.
posted by Brandon Blatcher at 9:00 AM on February 19, 2008

Your fridge removes heat from its interior and radiates it from coils on the back. It is, in effect (by a tiny margin) warming your house in cold weather. Why you'd want to put that heat outside is beyond me.
posted by Happy Dave at 9:03 AM on February 19, 2008

You would have far less control over where the fridge could be placed in the house, plus it would make it much harder to replace.

You could take advantage of the cold though, by placing some items outside yourself. However the last time I tried this with ice cream, squirrels absconded with two pints.
posted by drezdn at 9:04 AM on February 19, 2008 [3 favorites has favorites]

Well, yeah you could improve the efficiency of the fridge somewhat by using outdoor air in cold locations during winter, but it would be tricky. If you just pumped cold air to your fridge chamber you would have to have some clever regulating to keep it the right temp, to cold is as bad as to warm, for the fridge part anyhow. One solution would be to move the compressor out of the fridge and put it somewhere that you could expose to the outside. That would make the heat exchange much more efficient, the fridge quieter, and more room in the fridge to boot. Actually I have seen remote compressors that were installed for the quiet factor.

Ok so why not. Cause it would make the fridges more expensive. It would make the install more expensive. They could not be installed somewhere that did not have access to an outside wall. It wouldn't help with places that don't get cold. The insulation in modern fridges is pretty good so there is not much heat lost that way. And you would use some extra energy to run the fan or the coolant through pipes. The bigger issue, I would think, would be the fridge heating your house, fighting your cooling in the summer.
posted by d4nj450n at 9:11 AM on February 19, 2008

Well, it costs energy to move energy. What I meant is that teh compressor runs and pushes heat from the interior of the fridge back into the apartment at the same time my heater is heating the outside surface of the fridge. I see this as a waste of energy. Considering how much energy a compressor uses I'm curious as to why we cant use the winter weather to our advantage in the winter.

The idea is that if I bring in the natural cold from the outdoors I can run the compressor less often.

So a simple way to illustrate this is to cut a hole in the wall and run a tube into an insulated box. Put food in box. Why cant my fridge somehow take advantage of all those cold just on the other side of the wall?
posted by damn dirty ape at 9:14 AM on February 19, 2008

This doesn't really answer your question but it's relevant: Lifehacker linked to a DIY cold-weather outdoor refrigerator.
posted by brownpau at 9:14 AM on February 19, 2008

You fridge would need a heater to warm it up in winter when the temperature cooled below the temperature in the fridge. That's a whole lot more complexity.
posted by blue_beetle at 9:34 AM on February 19, 2008

You'd still need to use energy to regulate the temperature inside your fridge, though. I don't know if your 4-degree outside temperature is C or F; if it's F, that's much too cold for a fridge, and you'd actually need something to warm up the inside of the box. If it's C, that's riding the edge of the upper acceptable limit for cold food storage.

Also, if the temp in the morning is 35F, rises to 42F around 2pm, and drops to 20F or less at night, you're going to need something that keeps the temp inside the fridge steady, and I bet it would have to run more often than the compressor does now.

IANanelectrician, and I'm basing my knowledge on previous experience with ill-mannered fridges that couldn't quite keep a good temp, which required me to throw out a lot of food (both for being frozen when it shouldn't have been, and rotten because it got too warm).
posted by rtha at 9:38 AM on February 19, 2008

I read a thread on this exact subject very recently though I can't remember where, or find it now. The basic answer seemed to be 'because your tiny little fridge doesn't heat or cool anything enough to bother with the added expense and inconvenience needed for this especially given the complexities of summer vs. winter'. Industrial refrigeration systems are more likely to vent to the outside and make use to temperature differentials for part of the year. I'll see if I can dig that thread up, since my recollection of it doesn't include whether the information in it was anything more than speculation.
posted by jacquilynne at 9:39 AM on February 19, 2008

There was an episode of Invention Nation (Science Channel) that covered an outfit up in Vermont that was retrofitting commercial refrigerators with a thermostat-controlled duct system with intake/outtake fans. So, exactly what you're talking about. They discussed how it's more economically viable for cold-air, commercial applications due to the upfront cost of the thing, but it's being done.

So, there you go. By the way, the show is terrible, with hosts that have about as much personality as tree stumps. But it does at least cover some interesting subjects that I can go do some further research on.
posted by empyrean at 9:39 AM on February 19, 2008

The coldest part of winter is exactly when you don't want your fridge to vent to the outside. Look at it this way: suppose you didn't have a fridge at all; you'd have to run your heaters in the winter to keep your house warm. Then you buy a fridge. The fridge turns electric power into heat just the way your heaters do, and pumps the heat out into your rooms just the way your heaters do-- so you can turn your heaters down and shift that electric power to the fridge, and your electric power bill doesn't change. Your fridge runs essentially for free during the winter.

Summer is a different story-- your fridge should be vented to the outside then.
posted by jamjam at 10:27 AM on February 19, 2008 [2 favorites has favorites]

My heater seems to be fighting my fridge which only costs me energy dollars.

No, because heat from the refrigerator coils more than compensates for any cooling inside the refrigerator. If you attempted to air condition your home in the summer simply by opening the refrigerator door and letting it run, your home would become hotter, not cooler. In fact, one of the practical implications of the Second Law of Thermodynamics is that you can't cool an area with a unit that is entirely inside that area. A refrigerator has coils that are external to the chamber being cooled. An air conditioning unit or system has to be partly outside the building (room, whatever) being cooled. etc. Because they have to heat up something else more than they cool down whatever it is they're cooling. The reverse is not true of a heater; you can heat a room with a space heater located entirely within the room, for example.
posted by DevilsAdvocate at 10:46 AM on February 19, 2008

Is there a reason why fridges arent built with the coils outdoors or with a tube going outdoors (like a dryer or portable AC unit)?

Because then it wouldn't be expensive like a refrigerator, it would be expensive like a heat-pump. Like, five or ten times as much, easy.
posted by ROU_Xenophobe at 10:54 AM on February 19, 2008

jacquilynne, could you be thinking of this article on making an ambient air fridge, which was just featured in Lifehacker? It's not a change to a standard refrigerator, but rather an alternate form of refrigeration that allows the author to avoid using his fridge during the winter.
posted by cabingirl at 11:18 AM on February 19, 2008

"The only reason I can think of is that its a pain/costly to cut a hole into your kitchen wall. "

Yep, The unit itself would cost about twice as much and you need to supply the tubing run and electrical service outside. What you're talking about is called a remote condensing unit and it's common in commercial refrigeration.

The other drawback is you couldn't change out your fridge without incurring the services of a professional.
posted by Mitheral at 11:22 AM on February 19, 2008

If you're really worried about the energy consumption, have you cleaned your coils? Dust-covered coils reduce your fridge's efficiency.
posted by boreddusty at 11:56 AM on February 19, 2008

Well, it costs energy to move energy.

Yes, but all the "waste" energy is heat. Listen to DevilsAdvicate and jamjam.

However, if you heat your house with gas or wood or something else cheaper than electricity, then it would make sense to design a system that would cool with the outside air somehow. The problem, as others have mentioned, is that it would be pretty expensive to do such a thing. The other problem is that while you would save energy when it is quite cold out, you would lose energy (versus having the coils inside) when the temperature was not as cold.
posted by ssg at 12:03 PM on February 19, 2008

In warehouses that are located in areas that have cold temperatures during most of the year, they can utilize this system. It is basically a computer controlled system that pulls in cold air. When it does this, the compressors of the cooler do not need to run. The energy cost savings, in my experience, on a 15,000 cf cooler that is 65% filled with product, has been about $1,000 a month. I don't believe that I have encountered these units for personal use though.
posted by zerobyproxy at 1:00 PM on February 19, 2008

Big (restaurant) fridges do have ductwork to exhaust the hot air outside. Walk-in fridges and larger commercial units are often built as "split systems" where (like most A/C units) the compressor and hot-side coils are outdoors and the evaporator/cold-side coils are inside.

As for why they don't draw cool air in from the outside, in non-split systems (like your domestic fridge), I guess that the manufacturers figure that the added complexity and cost wouldn't be attractive to consumers, even though overall it would be more energy efficient. As you note, there would have to be some logic and a mechanism for opening and closing the intake depending on the interior and exterior air temperature, and you'd also have to worry about whether having a duct full of cold air coming into your house would result in more of a heating bill increase than the fridge's electric bill would decrease by.

It's one of those things that's definitely not impossible, not by any means, but there's a complexity/efficiency curve, and domestic fridges lie in what the manufacturers think is the "sweet spot" with the emphasis on decreased complexity.

Really, if you wanted a very efficient household heating/cooling system, you could have one piece of refrigeration machinery -- a big heat pump -- outdoors or on the roof, and let it provide hot and cold (via an intermediate coolant running in pipes, say propylene glycol) for your heating, domestic hot water, and kitchen refrigeration needs. Then you'd benefit from an economy of scale, the same way some commercial buildings do. Add a big in-ground swimming pool and you can even do neat things like day/night heat storage; solar boosting isn't that hard either.

Nobody (that I'm aware of) does this for SFHs because the complexity and resulting capital expense would just be too high. Most consumers don't want anything that's different from what they've always had and know works.
posted by Kadin2048 at 1:15 PM on February 19, 2008

Cellars can be dug for less expense.
posted by breezeway at 1:37 PM on February 19, 2008

jacquilynne, could you be thinking of this article on making an ambient air fridge

Nope. I would have swore it was on Ask.Me, or maybe SDMB, but couldn't find it either place. It was very definitely a thread that went much like this one, though.
posted by jacquilynne at 1:49 PM on February 19, 2008

Jacquilynne, I believe you're thinking of the discussion of Canadian beer fridges on the blue.
posted by teg at 5:34 PM on February 19, 2008

Maybe you're thinking of this MeTa derail, jacquilynne. (Kadin2048 chimed in there, too, with some refrigeration science.)
posted by cgc373 at 7:29 PM on February 19, 2008

Saw Freeaire on BoingBoing today and thought of your question.

In colder climates, the Freeaire taps into the greatest source of refrigeration ever created: winter. The Freeaire can use cold outside air to cool the space, simply using what Nature has so kindly made available, to give the entire compressor system a winter vacation.

posted by littlegreenlights at 7:54 AM on April 9, 2008