I am more interested in the effect on the environment. What is the break even point for replacing an inefficient fridge with a new one in terms of damage to the environment considering things like the production process, transport and the eventual power consumption?
One site suggests that a refrigerator has 5900 megajoules of energy embodied in it. That's accurate enough for napkin math, so we'll run with it. 1 kWh = 3.6 megajoules, so 1638 kWh per refrigerator.
Two hops upthread, the commenter says "280kWh/year" for their 1938 fridge. No clue what kind of power they use, but we can calculate the recoup cost of a replacement without knowing it.
It looks like modern refrigerators are considered about 3x as efficient as pre-70s refrigerators, so let's say that a straight swap of a size-equivalent refrigerator of average efficiency will cost 100kWh/year.
Spending 1638 kWh on a new refrigerator will save 160kWh/year, so the break even point in carbon terms occurs after 10 years have passed.
This is all very bad napkin math done in crayon. If you want better figures, you'll need to know your own refrigerator runtime figures, which means measuring your fridge's power usage for a standard week of use (if you maintain a very stable indoor temperature through heating/cooling) or for a year (if you do not), and you'll need to know the energy saved per year of your current fridge, and etc.
ps. Apparently they have a fridge from 90 years ago that's still running. If you replace one modern fridge with another and only save 20 kWh/year, it will take you 90 years to recoup that cost. The 10 year figure is only possible because their 1938 fridge is so inefficient.
pps. Owner of said 1938 fridge, I intend no disrespect. This DOE paper talks in detail about the changes that improved efficiency – inventing high-efficiency compressors, changing the shape of the drain pipe (1% efficiency gain!), and replacing the refrigerant and insulation materials with more efficient ones. https://www.nrel.gov/docs/legosti/old/7281.pdf
It looks like modern refrigerators are considered about 3x as efficient as pre-70s refrigerators, so let's say that a straight swap of a size-equivalent refrigerator of average efficiency will cost 100kWh/year.
...and that's where you're wrong. These are the most efficient as of 2020:
The top of that list is a 5.1cft model that uses 186kWh/year. The next one is also roughly the same size and uses 202kWh/year, followed by an 8.8cft that uses 294kWh/year. 100kWh/year is, frankly speaking, impossible. Mine has 9cft.
That "calculator" is being very deceptive by grouping everything "before 1980" together. The 60s and 70s models are certainly far more power-hungry because they made them bigger and with thinner insulation (more interior space) and things like defrost heaters, but the ones before that are not.
This DOE paper talks in detail about the changes that improved efficiency
...and none of the energy usage figures they quote are anywhere near the 300kWh/year range. A look at the real numbers shows just how efficient these early models are.
In EU you can buy a A+++ fridge, that used less than 100kWh/year. Granted, I have not put a meter on mine, so I'd have to take the 2010/30/EC specification at face value.
75kWh/year is for the "cooler" only, which doesn't go below freezing. Ice takes a huge amount of energy to make, so that isn't surprising. I'm not sure I can even set my vintage fridge to not freeze, but it would probably consume in that ballpark too if I never let the evaporator go below 4C or so. The above link shows the companion freezer, which does, uses a 237kWh/year --- pretty good, but then the two together use a far more realistic 312kWh/year.
If you have both, I suspect that they have significantly more storage than your vintage fridge?
In any case, if you buy a A+++ freezer they "only" use around 200kWh/year. This is mostly due to better insulation, and is in general an environmental and economical benefit to buy if your freezer is old.
Okay :) It sounds like you have sufficient information to make an informed decision.
The only takeaway for me is that a fridge upgrade has to be at least 50 kWh/year more efficient, or it's more likely than not a complete waste of carbon.
