Fridge/freezer on Economy 7 possible energy-cost-saving trick?

devondiver

Apologies if this has been covered before but - 

The top freezer tray of our fridge/freezer is always over half filled by various 'freezer packs' - waiting to be used for trips to the supermarket or for accelerated cooling when stocking our campervan fridge. I'm quite happy to keep them in the freezer and don't miss the space they take up, plus I'm mindful of the principle that a freezer 'works better' the fuller it is.

But - as the fridge/freezer is often quoted as being one of the major power users in the home it recently occurred to me that a small but perhaps significant power saving might be achieved if I were to transfer the freezer packs, or perhaps the complete tray, from the freezer to (the top of) the fridge in the morning and then back into the freezer overnight - when the packs would be re-frozen using cheaper night-time E7 electricity.

During the day the freezer packs would absorb heat in the fridge and reduce the 'day-rate' power consumption here, but there would be none of the risks associated with switching anything off - as has been suggested in other discussions of this subject. I am aware that one would need to keep in mind the possible temperature rise in the freezer from any 'shock-loading' but I think this can be taken into account and perhaps mitigated by using the 'fast freeze' button. And to make maximum savings I would need to stay up late (or get up!) in order to time the fridge to freezer transfer close to the start of the cheap overnight rate.

Maybe if all households employed this or similar fridge/freezer tricks - possibly using purpose-designed appliances built around this principle (perhaps employing modern phase-change material technology) - then daytime/peak household grid power consumption might be significantly reduced - in addition to significant domestic power cost savings being made.

I'm afraid I haven't attempted to 'do the math' on this, not being nearly as conversant with the relevant factors as some seasoned posters, but welcome any serious input.

Cheers all, and thanks for reading. Paul.

Steve_79_P

Would imagine that keeping everything in a freezer at say -18deg and not opening the door would use less energy than unnecessarily opening and closing the freezer to add items at say 2deg every day, then having to cool them to -18 again. But couldn't be sure on this. Either way, can't see it making a huge difference as these two machines are usually on 24/7

[Deleted User]

Well it certainly wouldn't save any energy - but I think you really meant saving money by shifting demand.

Whilst nothing really jumps out at me as being incorrect in your logic, I also don't get the feeling that the differential would be very much.  Maybe I'm wrong about that though.

devondiver

[Deleted User] said:

Well it certainly wouldn't save any energy - but I think you really meant saving money by shifting demand.

What I really meant was 'energy-COST-saving' - as in my title.  To me cost = money.

[Deleted User]

devondiver said:

[Deleted User] said:

Well it certainly wouldn't save any energy - but I think you really meant saving money by shifting demand.

What I really meant was 'energy-COST-saving' - as in my title.  To me cost = money.

I read that as "energy or cost saving" rather than "cost of energy saving".  My mistake.

devondiver

Steve_79_P said:

Would imagine that keeping everything in a freezer at say -18deg and not opening the door would use less energy than unnecessarily opening and closing the freezer -

Our freezer normally gets opened and closed at least several times a day. So I don't believe a further twice would negate potential savings.

Steve_79_P said:

- these two machines are usually on 24/7

Not entirely true. They switch on periodically depending on cooling requirement. 

Steve_79_P

Me too. It's quite possible it will use more energy whilst saving you money, but I don't think it would be significant.

[Deleted User]

Someone with smart plugs could do an experiment.  I wonder if it would be different using the two compartments of a fridge/freezer when compared to a separate fridge and freezer.

devondiver

Steve_79_P said:

It's quite possible it will use more energy

Sorry but I don't see how it could use (significantly) more energy. And the objective would be, as I said, to reduce daytime/peak grid load, whilst also making domestic cost savings by transferring (some of) the load to cheap night-rate.

devondiver

[Deleted User] said:

Someone with smart plugs could do an experiment.

Good idea. Not something I have I'm afraid. Any volunteers?

MWT

devondiver said:

But - as the fridge/freezer is often quoted as being one of the major power users in the home...

Our large fridge/freezer in the kitchen is using less than 1kWh a day, it really doesn't seem like there is enough of a possible saving to make it worth the effort...