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

Steve_79_P

I have the smart plugs but don't have the freezer packs!

I might be wrong on the energy thing, but my thinking is that any form of electric heating / cooling is not 100% efficient, so having to constantly change the temperature of an object by 20 degrees is going to use more energy than keeping it at a constant temp.

Steve_79_P

Plus opening the door of a fridge/freezer causes a spike in electrical draw

QrizB

Put me in the "it would be worth trying it bit you won't save much" camp.

Steve_79_P said:

Plus opening the door of a fridge/freezer causes a spike in electrical draw

Citation required, unless you're referring to the fridge light!

dunstonh

I have a smart American F/F and it uses between 16p and 22p a day.   And that assumes single rate.   We are on economy 7 but the app doesn't allow that.  So, in reality, it is less than those figures.      

Faffing about with a timer and freezer packs in an attempt to get a penny off the daily use doesn't seem worthwhile.  

victor2

BIt of quick arithmetic, with a few assumptions:

My fridge/freezer is rated at 431kWh/year.

Using an E7 rate of 43p/kWh peak and 14p/kWh offf-peak (rounded numbers from the EPG)

That is 1.18kWh per day.

If 2/3 of that is daytime use and 1/3 nighttime, the daily cost would be 33.9p plus 5.5p, or 39.4p in total per day.

If the usage could be reversed so that 2/3 is at the off-peak rate and 1/3 peak, the total daily cost would be 33.9p

So a potential saving of 5.5p per day, or £20 per year.

Edit: Total cost would be 27.9p, saving 11.4p/day or £42/year.

Big IFs in there though, not least the effective saving in peak usage.

Many fridge/freezers have an anti-frost feature, which involves a heating element. Our old American fridge/freezer (which used about 3kWh/day) had a heater rated at 800W, and it seemed to switch on once a day for about 20 minutes.You couldn't control when that happened, it was only by noticing a spike on my IHD and a process of elimination that I tracked it down - the warm glow in the back of the freezer helped that process too!

Steve_79_P

"Citation required, unless you're referring to the fridge light!"

Why do fridges and freezers bother with doors if opening them makes no difference? Tried out of interest and usage went up 150w on IHD

EssexHebridean

Something to bear in mind is that most freezer packs wouldn't even come close to defrosting fully in a fridge for a day - indeed the gel type ones that you get packaged with meat orders for example don't even defrost fully over 24 hours just in a standard insulated coldbox - so there would be less of a requirement to "refreeze" than is being assumed perhaps. My guess is that it comes down almost entirely to how much of a difference opening the doors an extra twice each would make.  

For me I think it would be a faff that wouldn't ever quite come to the point of being worthwhile as the potential saving would be a) incredibly small and b) incredibly difficult to measure. For others though in a situation where literally the tiniest saving could make a big difference to budgets, it could be worth knowing the answer to. 

[Deleted User]

Steve_79_P said:

"Citation required, unless you're referring to the fridge light!"

Why do fridges and freezers bother with doors if opening them makes no difference? Tried out of interest and usage went up 150w on IHD

To not let the cold out?

Section62

Deleted_User said:

Steve_79_P said:

"Citation required, unless you're referring to the fridge light!"

Why do fridges and freezers bother with doors if opening them makes no difference? Tried out of interest and usage went up 150w on IHD

To not let the cold out?

I thought it was to marginally discourage the OH from taking all the chocolate and/or icecream... the effort required to open the door is a (small) dissuading factor.  If the fridge/freezer were simply open shelves it would be much easier to grab a snack.

Alnat1

Years ago I had a big hairy looking magnetic spider on the fridge door which discouraged my then small kids from opening it. They used to ask me if they wanted anything. I remember we called him Boris