21 August 2017

Re-fridging

One too many rounds of frozen fruit at the back of the fridge and I decided it was time to replace our refrigerator.

The old fridge had served us for eleven years. It was secondhand, so had a couple of years life already before that. On average, your fridge makes up about 16% of a household's electricity use; it seems our old one accounted for between 25% and 40% of ours.

Tyson did the research and sourced us a brand new fridge that was the most efficient model we could afford. Although almost 50% bigger (inside - strangely, not 50% bigger outside) it was rated as using only about 60% as much electricity.


Note that the star ratings compare 'like products' (similar size and configuration) so are not directly comparable; also star ratings are reassessed every few years, so an old 4-star and a new 4-star are not equivalent. The important information is the red 'kWh per year' estimate - that IS directly comparable.


Initial Time: Approx 5hrs (including research, visiting the store, arranging trailer, doing pick-up and swap over)

Initial Cost: $720    

Ongoing time or cost commitment: zero time; cost saving

Impact:

On the ratings alone we would anticipate saving 269kWh per year ($71 on current prices)

However, Tyson hooked up a nifty device to check how much electricity the fridges REALLY use.


We measured the old fridge for two days before unplugging it and found it used 4.8kWh in 40.5hrs - which works out at 1,038kWh per year - considerably worse than it is rated. Given that we measured in the middle of winter, it is likely that the actual number is higher than that, as the old beast would use more electricity in summer.

The new fridge, in comparison, has used 14.4kwH so far over 24 days, which is 219kWh per year - far FAR better than it is rated.

Comparing these real measured figures, we are saving 819kWh of electricity per year with the new fridge: $217 (at current prices); 672kg of CO2 (on data from 2014)

On these figures, the fridge pays for itself in 3yrs 4months. However, as I imagine the difference between the two would be greater in summer, it is likely to be even less.

But what of the embodied energy used to manufacture, transport, sell and ultimately dispose of the fridge? This academic paper by Jenessa Doherty (York University Faculty of Environmental Science, Toronto, c.2015) calculates everything from raw material extraction to the fridge reaching a customer, comparing a fridge that is approximately three times more efficient than the one being replaced, which saves 935kWh a year. She determines that the embodied energy in a new fridge equates to equates to between 2.3 and 2.9 years of electricity savings (depending on what portion of fridge is made from recycled materials, and whether there is a computer in the fridge - high in trace metals). Other websites, which were mostly much more vague, also threw around an approximate three-year figure.

This doesn't allow for disposal. However, it looks like from around November 2020, electricity savings on the new fridge will have paid off both its embodied energy and its purchase price, and it will be all savings from there on.

And that is without calculating how much less food we are now wasting as the fridge is doing its job properly at last.



(The gpo power meter cost $49 for a pack of three. We are now measuring electricity use of the computer system, washing machine and fridge. I will let you know if anything exciting results)

Links:

http://www.academia.edu/22753163/Efficient_Refrigerators_The_Embedded_Energy_Footprint_in_Modern_Technology  - Jenessa Doherty paper

www.energyrating.gov.au - Australian government website where you can compare energy ratings for specific models of a whole range of products, if you no longer have the ratings sticker that your appliance came with.


2 comments:

  1. This is a great post. I like this topic.This site has lots of advantage.I found many interesting things from this site. It helps me in many ways.Thanks for posting this again. view site…

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  2. It just so happens I've just started measuring things at our house again, and popped by here to see if I'd missed any posts. Our 520L fridge measured at about 240kWh per year.

    ReplyDelete