Energy saving business idea.

This is something I've thought about a lot over the years. If a refrigerator could be located on an outside wall (or not with appropriate ducting) you could utilize cold outside air in the winter and duct the hot air from the condenser side (that normally just blows inside the house) to the outside in summer.

I've often thought about this too, and in fact commercial refrigeration equipment often appears to work this way – you can see the condensers located on the roofs of grocery stores. I imagine it's not quite as straightforward as it seems though, for one reason because as mknox points out, you'd have to locate your refrigerator on an outside wall (or otherwise plumb it to the exterior). For another, because most condensers – certainly the consumer grade ones – are designed for a specific operating temperature range. All this could still be overcome, of course, for example using adjustable venting.

jgs said:

All this could still be overcome, of course, for example using adjustable venting.

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Exactly. If you've ever seen those portable floor air conditioners that have hoses that go out a window, I was thinking something just like that. One to bring outside fresh air in, and the other to exhaust the hot air back outside in the summer. In the winter, close them off and keep the loop inside the house and capture the waste heat. It could probably be automated fairly simply with some sort of temperature sensor. I'm actually surprised this relatively simple system isn't already in place. Refrigerators run 24/7 and throw all their waste heat into the home only to have to pay more to have your air conditioner remove it.

Fritts said:

In the spirit of Tesla's commitment to improving society, I have an open source idea for any builders/businessmen out there: There's an old quip about a salesman being so good that he 'could sell ice cream to eskimos'. Oddly enough, that quote is 100% true. Every person who can afford a refrigerator/freezer owns one, even if they live someplace where it is sometimes/often/or almost always colder outside than they want it to be in the 'fridge/freezer. Solution: a vent with a fan and a temperature actuated switch from the refrigerator to the outside. Note - Refrigerators consume a great deal of electricity and run all day, every day, even when it's -30 F outside. I have a specific design in mind. Feel free to contact me for details.

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If you are going to open source it why not post the details here instead of asking people to PM you?

Similarly, I've envisioned a closed-loop heat exchanger between my attic and my clothes dryer so that in the summer I'm not buying natural gas to heat clothes at the same time I'm buying electricity to cool my house.

Rockster said:

Similarly, I've envisioned a closed-loop heat exchanger between my attic and my clothes dryer so that in the summer I'm not buying natural gas to heat clothes at the same time I'm buying electricity to cool my house.

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You need pretty intense heat for a dryer, though. Yeah, I know the typical attic gets pretty hot, but is it enough? Still, interesting idea.

We occasionally use an open loop system, an open loop of rope suspended in our back yard that is, with clothes suspended from it in the sun, but it's pretty labor-intensive.

mknox said:

Exactly. If you've ever seen those portable floor air conditioners that have hoses that go out a window, I was thinking something just like that. One to bring outside fresh air in, and the other to exhaust the hot air back outside in the summer. In the winter, close them off and keep the loop inside the house and capture the waste heat. It could probably be automated fairly simply with some sort of temperature sensor. I'm actually surprised this relatively simple system isn't already in place. Refrigerators run 24/7 and throw all their waste heat into the home only to have to pay more to have your air conditioner remove it.

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Actually, now that you mention it, this sounds like something you could retrofit during a kitchen remodel without hanging ugly ducts out the window. You'd probably need a small fan to keep exterior air moving through the duct, possibly activated by a temperature sensor as you say. Also, I'm not entirely sure you'd want to capture the waste heat in the winter. It's probably only a no-brainer if you heat with electrical resistive heating. Otherwise you might do better to cool the heat exchanger with exterior air. It depends on how the appliance's energy consumption varies with ambient air temperature, and of course the question I raised earlier about whether ambient temperature is within the appliance's operating range.

If I do get my long-contemplated kitchen remodel done, I'll have to discuss this with the builder.

jgs said:

You need pretty intense heat for a dryer, though. Yeah, I know the typical attic gets pretty hot, but is it enough? Still, interesting idea.

We occasionally use an open loop system, an open loop of rope suspended in our back yard that is, with clothes suspended from it in the sun, but it's pretty labor-intensive.

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I'd love to be able to do that, just like when I was a youth. Unfortunately, our homeowner's association (and many others, I suspect) prohibit clothes lines. I wonder how much energy HOA's have caused to be wasted in this manner, all in the name of promoting property values.

Rockster said:

I'd love to be able to do that, just like when I was a youth. Unfortunately, our homeowner's association (and many others, I suspect) prohibit clothes lines. I wonder how much energy HOA's have caused to be wasted in this manner, all in the name of promoting property values.

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My subdivision had such a by-law, but the Canadian province of Ontario invalidated those by-laws a few years ago in the name of energy conservation.

Rockster said:

Similarly, I've envisioned a closed-loop heat exchanger between my attic and my clothes dryer so that in the summer I'm not buying natural gas to heat clothes at the same time I'm buying electricity to cool my house.

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Alternatives:
(1) (a) Have more than enough clothes to last you between laundry days
(b) Hang your cool, damp clothes on racks to dry
My parents (in the UK) have never owned a clothes dryer.
(2) LG DLHX4072W electric heat pump dryer.
Advantage of a heat pump dryer is that it doesn't need to be vented, which is good for eliminating a hole in the wall.

.. or some may actually poke holes in your design and you may get an opportunity to refine it.

Fritts said:

I haven't posted the details because if no one capable of producing such a thing is interested in the idea, I'm not going to go into minute detail for people just to look at and say "neat idea".

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So if someone you didn't know PM'd you and said they had all the qualifications needed you'd share your idea?

Fritts said:

@ JGS The tricky part is a 'door' that opens and closes because you want to turn the air exchange on and off. That way temperature control is maintained. I envision two small circular fans inside round duct, just outside the refrigerator. One for intake, one for outtake. They would become two sides of a square entry to the 'fridge with a 'door' pivoting in the middle. With the fans off, the door would be shut in it's passive position. The fans pulling and pushing the opposite sides of the door would force it open during air exchange. Inside the refrigerator and outside the home, the ducts go up and down the wall so that air comes in the bottom and is drawn out from the top, (heat rises). The fans would be turned on and off by a logic circuit similar to the one already in the refrigerator. If the temp in the refrigerator is above the threshold and the temperature outside is below the threshold, the fans turn on. I also envision an insulation plug that could be inserted/removed from inside the refrigerator because many places wouldn't have cold outside temps for much of the year.

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It sounds as though you're thinking in terms of exchanging ambient air directly into the fridge. That probably works when exterior temperatures are near or below freezing, although I wouldn't be shocked if there were non-obvious drawbacks to the approach. I seem to recall seeing detailed designs for such a thing when I was idly looking into it 5 to 10 years ago; you might try googling for it a bit. The tangent I was on was to exchange ambient air not directly into the interior of the fridge, but to cool the condenser coils on a conventional fridge. That has the advantage of improving your home's energy utilization in the summer as well, since you're venting the heated air outdoors instead of into your house. It also lets you use any appliance you want. Anyway, both the devices you're talking about – a door that opens and closes, and a fan – are fairly common components and in fact I have examples of both of them within 20 feet of me. Regarding the "door", the exhaust for my home's boiler has a simple damper that's opened when the boiler's burning and closed when it isn't. It's just a round door pre-mounted into a piece of duct and a small DC motor to rotate it open or closed. I presume this is a commonplace for gas burning appliances. And I have some thermostatically controlled fans mounted in my server cabinet. Those came from Newegg or someplace like that. I'm not sure how widely variable the thermostat's setpoint is, but it might well be good enough. Given that you're imagining using a fan for air transfer, I'm not sure how important it is to stack your ducts for convective circulation – convection is pretty weak compared to forcing the air with a fan – although it wouldn't hurt. I also don't imagine you need two fans, one ought to suffice. I suppose having two might help keep the airflow the way you want it when the "refrigerator" door is open, so you aren't unintentionally exchanging cold air into the house instead of the fridge compartment, but then again you're almost certainly better off having your damper automatically close and fan automatically cut off when the refrigerator door is open.

I've thought about this also.

There are air to air heat exchangers... where the outside air transfers its temperature to the inside air, but the two air bodies don't actually mix. Also, remote chillers would kind of work this way. In other words, if the chilling loop was not part of the food storage cabinet, but instead was located in some other part of the house, it could work more efficiently some of the time. The key, of course, is making it cost effective in comparison to the energy savings. If you look at the total amount of electricity used by a refrigerator or freezer, you'd have to come up with something that costs less than that over the lifetime of the add-on/change. You still have to have a compressor for the times when the passive system won't work.

I was really thinking that, if square footage was not a problem (ie. not a small house), that some room could be designed to be switchable in terms of inside or outside temperature. In a newly designed house, this room optionally participates in the thermal management of the rest of the house and is insulated from the rest of the house. So you can choose to for it to be "outside" temp or "inside" temp. It's really only cost effective and convenient if the house was designed for this from the start.

techmaven said:

some room could be designed to be switchable in terms of inside or outside temperature.

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Larder - Wikipedia, the free encyclopedia

In a newly designed house, this room optionally participates in the thermal management of the rest of the house

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Under what circumstances would you want to heat or cool the room instead of having it be at ambient temperature? I guess you might need to do this if it was exceptionally cold outside and you didn't want the food to freeze, but otherwise holding it at ambient seems best in almost every circumstance. Modulo my earlier fretting about the operating temperature range for consumer appliances, that is. (If you Google "garage fridge" or similar, you'll see there are frequently problems reported, although at least one comment I read suggested these problems don't occur unless you have a combined fridge-freezer unit.)

I think your point about cost-effectiveness of any of these schemes is very well taken though. Looking at energy.gov, they give about seventy-five dollars as a swag for the annual operating cost of a refrigerator-freezer. At best you are only going to reduce that, not zero it. Let's be generous and suppose you can reduce the annual operating costs by 50%. You're looking at a return of less than forty dollars a year.