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> i very much fear arriving at a summer house where the fridge has been unpowered for a couple of weeks. Another solution to this problem is to just empty the

> i very much fear arriving at a summer house where the fridge has been unpowered for a couple of weeks. Another solution to this problem is to just empty the fridge and turn it off while not in the summer house for a few weeks.

8fingerlouie 4y ago
We don't keep easily perishable goods in there like meat or vegetables, but some of them does require cooling to stay fresh. > just empty the fridge and turn it off while not in the summer house for a few weeks We tried that, but the fridge uses 6-8 hours to reach target temperature despite being brand new, and keeping food fresh without cooling for 10 hours is not easy. It actually uses less power being powered on continiously for 2 weeks (12 days from departure to arrival), than it does being powered off and working overtime for 6 hours trying to cool down. It's not much less power, but still less.
- wildmanx 4y ago
  > It actually uses less power being powered on continiously for 2 weeks (12 days from departure to arrival), than it does being powered off and working overtime for 6 hours trying to cool down. It's not much less power, but still less. I suppose you mean energy rather than power? (Cause the argument makes less sense with power.) That's an interesting phenomenon then since it goes counter to my (rather naive) understanding of physics. There could be some anomaly with the fridges efficiency curve that causes this. Maybe it's really inefficient cooling down the contents from room temperature while being really efficient maintaining the cool temp? After all, the latter is its main purpose..
  - 8fingerlouie 4y ago
    > Maybe it's really inefficient cooling down the contents from room temperature while being really efficient maintaining the cool temp? After all, the latter is its main purpose.. Normal power consumption of it (assuming 18C room temperature) is less than 0.4 kWh/day. That amounts to 4.8 kWh in a 12 day period. Cooling it down from 18C takes 5.6 kWh (measured). Temperature varies of course, and the lower the temperature the lower the power consumption, and the heat pump keeps a minimum temperature of 12C. During long summer days, the indoor temperature can easily reach 26C, which will require more power, and i have not measured every possible scenario. I'm not ruling out that actually cooling down the thing during winter will require less energy than keeping it running, but i'm fairly certain that doing the same from 26C will require more power than keeping it running.
    - mlyle 4y ago
      > Cooling it down from 18C takes 5.6 kWh This seems like a lot. It's 20 megajoules, so even at a COP of 1, it's enough energy to cool down 20 megajoules / (4182 J/kg/K) / 18 K = 265 kilos of water by 18 kelvin. And a refrigerator is supposed to attain a COP better than 1, and I suspect you have less thermal mass around than 265 kilos of water. Something is wrong-- either in measurement, or heat exchangers very badly occluded by dust, etc, or some other fault.
      - 8fingerlouie 4y ago
        It does sound like a lot, and I’ve only measured once. The fridge is in a cabinet, enclosed on 3 sides, so maybe it’s not letting enough hot air out ? I could be wrong, but I think it was stated as using 184 kWh / year (at room temp 22C, optimal conditions), which is just over 0.5 kWh/day, and considering that the summerhouse is usually cooler than that (12-16C) when unoccupied, I would assume it used even less power. As it is, for this entire week, the heat pump has (self) reported using 1.8 kWh/day, and according to my power company, my daily consumption has been 1.8 kWh/day. Considering that there are 5-7 IoT things plugged in, the fridge probably isn’t using much power.
        mlyle 4y ago
        > The fridge is in a cabinet, enclosed on 3 sides, so maybe it’s not letting enough hot air out ? Seems likely. Once it succeeds in warming its cabinet, a big share of that heat leaks back into the fridge. (And efficiency falls because of the bigger temperature difference).
  - lazide 4y ago
    Insulation can be really good now a days.
    - mlyle 4y ago
      You would always expect to be better off letting the refrigerator warm up, because: * Every bit of warming that finds its way into a powered-off refrigerator is heat the refrigerator would need to take out anyways. And the heat flowing in declines as the inside warms up. * There's standby power, etc. * A refrigerator is expected to be more efficient removing heat when the temperature difference between inside and outside is less.
      - wildmanx 4y ago
        As a counter argument, imagine an infinitely good insulation and 0 standby power (and a spherical cow inside, for illustration purposes). Then keeping it "running" is clearly better than letting the fridge warm up since power draw is 0 in the former case. Obviously the conditions are not as perfect, but with a very modern fridge, maybe you get sufficiently close that keeping running indeed is superior. I'm not arguing that that's the case here. I'm arguing that you don't "always" expect things to be worse off letting it run. There is a threshold, when approaching the mentioned fantasy conditions, beyond which letting it run may be better.
        mlyle 4y ago
        > imagine an infinitely good insulation Then it would never warm up, and at this limit the two cases are equivalent (powered and unpowered). > when approaching the mentioned fantasy conditions, beyond which letting it run may be better. Anywhere short of the limit, what I said holds. Anything better than infinite insulation, I don't know how to reason about.
        lazide 4y ago
        I think you're missing the point. Perfect insulation doesn't help if you open the door? If you're saying 'well with perfect insulation it doesn't matter if it has power' - well yeah. It doesn't matter if it has power. So you aren't wasting any either leaving it on.

8fingerlouie 4y ago

We don't keep easily perishable goods in there like meat or vegetables, but some of them does require cooling to stay fresh. > just empty the fridge and turn it off while not in the summer house for a few weeks We tried that, but the fridge uses 6-8 hours to reach target temperature despite being brand new, and keeping food fresh without cooling for 10 hours is not easy. It actually uses less power being powered on continiously for 2 weeks (12 days from departure to arrival), than it does being powered off and working overtime for 6 hours trying to cool down. It's not much less power, but still less.

wildmanx 4y ago
> It actually uses less power being powered on continiously for 2 weeks (12 days from departure to arrival), than it does being powered off and working overtime for 6 hours trying to cool down. It's not much less power, but still less. I suppose you mean energy rather than power? (Cause the argument makes less sense with power.) That's an interesting phenomenon then since it goes counter to my (rather naive) understanding of physics. There could be some anomaly with the fridges efficiency curve that causes this. Maybe it's really inefficient cooling down the contents from room temperature while being really efficient maintaining the cool temp? After all, the latter is its main purpose..
- 8fingerlouie 4y ago
  > Maybe it's really inefficient cooling down the contents from room temperature while being really efficient maintaining the cool temp? After all, the latter is its main purpose.. Normal power consumption of it (assuming 18C room temperature) is less than 0.4 kWh/day. That amounts to 4.8 kWh in a 12 day period. Cooling it down from 18C takes 5.6 kWh (measured). Temperature varies of course, and the lower the temperature the lower the power consumption, and the heat pump keeps a minimum temperature of 12C. During long summer days, the indoor temperature can easily reach 26C, which will require more power, and i have not measured every possible scenario. I'm not ruling out that actually cooling down the thing during winter will require less energy than keeping it running, but i'm fairly certain that doing the same from 26C will require more power than keeping it running.
  - mlyle 4y ago
    > Cooling it down from 18C takes 5.6 kWh This seems like a lot. It's 20 megajoules, so even at a COP of 1, it's enough energy to cool down 20 megajoules / (4182 J/kg/K) / 18 K = 265 kilos of water by 18 kelvin. And a refrigerator is supposed to attain a COP better than 1, and I suspect you have less thermal mass around than 265 kilos of water. Something is wrong-- either in measurement, or heat exchangers very badly occluded by dust, etc, or some other fault.
    - 8fingerlouie 4y ago
      It does sound like a lot, and I’ve only measured once. The fridge is in a cabinet, enclosed on 3 sides, so maybe it’s not letting enough hot air out ? I could be wrong, but I think it was stated as using 184 kWh / year (at room temp 22C, optimal conditions), which is just over 0.5 kWh/day, and considering that the summerhouse is usually cooler than that (12-16C) when unoccupied, I would assume it used even less power. As it is, for this entire week, the heat pump has (self) reported using 1.8 kWh/day, and according to my power company, my daily consumption has been 1.8 kWh/day. Considering that there are 5-7 IoT things plugged in, the fridge probably isn’t using much power.
      - mlyle 4y ago
        > The fridge is in a cabinet, enclosed on 3 sides, so maybe it’s not letting enough hot air out ? Seems likely. Once it succeeds in warming its cabinet, a big share of that heat leaks back into the fridge. (And efficiency falls because of the bigger temperature difference).
- lazide 4y ago
  Insulation can be really good now a days.
  - mlyle 4y ago
    You would always expect to be better off letting the refrigerator warm up, because: * Every bit of warming that finds its way into a powered-off refrigerator is heat the refrigerator would need to take out anyways. And the heat flowing in declines as the inside warms up. * There's standby power, etc. * A refrigerator is expected to be more efficient removing heat when the temperature difference between inside and outside is less.
    - wildmanx 4y ago
      As a counter argument, imagine an infinitely good insulation and 0 standby power (and a spherical cow inside, for illustration purposes). Then keeping it "running" is clearly better than letting the fridge warm up since power draw is 0 in the former case. Obviously the conditions are not as perfect, but with a very modern fridge, maybe you get sufficiently close that keeping running indeed is superior. I'm not arguing that that's the case here. I'm arguing that you don't "always" expect things to be worse off letting it run. There is a threshold, when approaching the mentioned fantasy conditions, beyond which letting it run may be better.
      - mlyle 4y ago
        > imagine an infinitely good insulation Then it would never warm up, and at this limit the two cases are equivalent (powered and unpowered). > when approaching the mentioned fantasy conditions, beyond which letting it run may be better. Anywhere short of the limit, what I said holds. Anything better than infinite insulation, I don't know how to reason about.
        lazide 4y ago
        I think you're missing the point. Perfect insulation doesn't help if you open the door? If you're saying 'well with perfect insulation it doesn't matter if it has power' - well yeah. It doesn't matter if it has power. So you aren't wasting any either leaving it on.