The best hack I've seen for refrigerators is piping the outside air into it in winter. In Alaska and other cold places like that people can use refrigerators passively cooled by outside air for half a year and more, using almost zero electricity.
Except then you’re actively pumping cold air into your home, increasing the load on your heating system.
While a fridge works by extracting the heat from the stuff you put in your fridge and heating your home with it, decreasing the load on the rest of your heating system before even accounting for the compressor inefficiencies.
Kinda like when hotels put their ice machines in some tiny room on each floor: that room gets really hot because it’s tap water in and ice out.
You're pumping cold into the fridge, which is insulated as well as the piping, so I imagine it doesn't significantly affect the room temperature. You're right that fridge does heat up the room, but it's not that significant when it's -20^C (-4F) outside, you'll need to heat that house a lot more anyways.
The fridge is much more poorly insulated than the walls, with more surface area to boot. And any wind outside will suck out warm air or push in cold air with every opening.
Point being, that low-tech fridge (ice box connected to outside) is thermodynamically inefficient if you’re heating inside, while an electric fridge is an efficient heat pump.
In a cabin with poor insulation and “limitless” wood, go for it. But for a modern structure, it’s not fully thought out.
What would really make sense is a fridge that moves heat outside in hot climates.
You misunderstood how it's constructed (my explanation sucks I know), it's a heat exchanger pipe with one side out, and the other inside the freezer. The copper pipe is closed, so it's not literally pumping the air inside, as that would dry your food because air is extremely dry when temperatures are that low. The flow of the air inside the pipe is passive as it's almost vertical, so as the air cools down it will go down into the freezer, while heated air goes up the pipe outside the house. The same principal as geothermal heating/cooling, except that they use their extremely cold weather instead of the ground as the "infinite" heat sink. I'm sure that could be also improved with some electromagnetic valve to control the air movement and thus the temperature in the freezer...
That sounds better, but it still throws a lot of thermodynamic theory out the window.
When it's cold outside, and you want to heat inside, you want to use indoors as the heatsink. Even if it's -20 outside and +20C inside, you can still heat the inside by removing heat from something +10C and making it -20C.
If you put liquid water into your electric freezer, a fridge pumps heat OUT of the water to freeze it and exhausts it indoors. A net benefit.
While the heat tube system moves the heat from the water outside when you really want to move that enthalpy into the home. But it instead moves that heat outside. That's bad when you're trying to heat inside. It's just throwing away energy.
I'm curious how the real world numbers work out here. Assuming that you're using electric heat to heat the house, I get that a traditional fridge is better than venting heat outside.
But, if you have a ground source heat pump as your home's heat (sourcing from 45° ground temps) - wouldn't it be more efficient to use the outside air as a source for a fridge?
The ground source heat pump works exactly the same as the fridge does. And the fridge is extracting heat from an approx. 40F heat source. So not much of a difference. The ground source heat pump will be pretty efficient if it's hitting deep and wet soil to get a good heat exchange.
But if we're comparing to resistive heating, an air-source heat pump near/below freezing points, propane or even natural gas, the economics move in favour of the electric fridge.
