I happen to currently own 4 freezers of various sizes - two old uprights, and two quite new chest freezers. At this time of year, when it's hot, the freezers are working harder, and our power bills have increased as a result. So I've been thinking - how to use the freezers most efficiently? Would I be better to replace the two chest freezers with a bigger one? How can I save money?
I didn't set out to own 4 freezers! First we had an old upright we got from Trade Me for $40. It was all we could afford. It did the job - but it was ugly, and if it was opened frequently, which of course it WAS, since it was in the kitchen, and that's where the kids would find the ice-cream, it would ice up and have to be defrosted about every 6 weeks, or the door wouldn't shut.
So a few years ago, I bought two chest freezers, one small, one medium size. I researched and haggled, and got them at rock-bottom prices, on a 0% interest for 2 years payment plan, and paid them off. The small one replaced the ugly upright inside - and that's all the room I had there. The other went into a shed, in a space specially built for it. The ugly upright got put out in another shed, waiting for disposal. BUT, we home kill sheep, and get meat from hunting. When you process a few entire animals at a time, you don't want to add all that fresh meat to a freezer of frozen food - it tends to partially defrost what is already there, and the new things freeze in a bit of a lump and can be hard to separate afterwards. So the old upright got put into service, just to freeze newly butchered meat, which we could nicely lay out on the shelves, allowing good cold circulation, and then move it all to the chest freezers once frozen. Good plan, huh? BUT, I got so frustrated with the small chest freezer inside and how hard it was to find anything among all the small packages, and what a mess the kids would make searching for things in it....so I wanted another upright for in there. We ended up buying an old one off Trade Me - affordable, in better condition than Mr Ugly, but still, old. It works just fine. It has drawers instead of open shelves. BUT it gets opened a lot, so isn't efficient, and the kids are forever not shutting it properly (it's too old fashioned to beep in annoyance at this treatment, like our second hand but more modern fridge does). Result - in a hour of being left just slightly ajar, all the soft things will have melted, which leads to more ice build up. AND we have ended up having so much meat, veges, etc in the freezers that all four are currently in use.
Which brings me to today.
I didn't set out to own 4 freezers! First we had an old upright we got from Trade Me for $40. It was all we could afford. It did the job - but it was ugly, and if it was opened frequently, which of course it WAS, since it was in the kitchen, and that's where the kids would find the ice-cream, it would ice up and have to be defrosted about every 6 weeks, or the door wouldn't shut.
So a few years ago, I bought two chest freezers, one small, one medium size. I researched and haggled, and got them at rock-bottom prices, on a 0% interest for 2 years payment plan, and paid them off. The small one replaced the ugly upright inside - and that's all the room I had there. The other went into a shed, in a space specially built for it. The ugly upright got put out in another shed, waiting for disposal. BUT, we home kill sheep, and get meat from hunting. When you process a few entire animals at a time, you don't want to add all that fresh meat to a freezer of frozen food - it tends to partially defrost what is already there, and the new things freeze in a bit of a lump and can be hard to separate afterwards. So the old upright got put into service, just to freeze newly butchered meat, which we could nicely lay out on the shelves, allowing good cold circulation, and then move it all to the chest freezers once frozen. Good plan, huh? BUT, I got so frustrated with the small chest freezer inside and how hard it was to find anything among all the small packages, and what a mess the kids would make searching for things in it....so I wanted another upright for in there. We ended up buying an old one off Trade Me - affordable, in better condition than Mr Ugly, but still, old. It works just fine. It has drawers instead of open shelves. BUT it gets opened a lot, so isn't efficient, and the kids are forever not shutting it properly (it's too old fashioned to beep in annoyance at this treatment, like our second hand but more modern fridge does). Result - in a hour of being left just slightly ajar, all the soft things will have melted, which leads to more ice build up. AND we have ended up having so much meat, veges, etc in the freezers that all four are currently in use.
Which brings me to today.
Today I cleaned out and inventoried all four freezers, in preparation for my new menu planning process. I also rearranged the contents so now only three freezers are in use, and Mr Ugly is turned off again.
But, I got thinking about the math of it all - the efficiency or inefficiency and what it costs me. And what it would cost to make changes, and how long those changes would take to pay for themselves.
I'm always telling my children "Yes, you DO need to learn math, and yes you WILL use it in real life!" If you want to be a thrifty Kiwi, then some basic math skills are essential! Of course, if you don't have any, it's never too late to learn! There are plenty of free online math learning site - Khan Academy for example - but I digress....
But, I got thinking about the math of it all - the efficiency or inefficiency and what it costs me. And what it would cost to make changes, and how long those changes would take to pay for themselves.
I'm always telling my children "Yes, you DO need to learn math, and yes you WILL use it in real life!" If you want to be a thrifty Kiwi, then some basic math skills are essential! Of course, if you don't have any, it's never too late to learn! There are plenty of free online math learning site - Khan Academy for example - but I digress....
Each freezer has an energy efficiency rating sticker on the front - if it's sold in NZ new or second hand through a dealer, it must do so by law. All but my old Mr Ugly have stickers on them, though some of them are getting hard to read, so I'm glad I'm doing this now and have written it all down! That sticker tells you approximately the number of units of energy, listed in kWh (which means kilo-watt hours) per year under normal usage conditions that your freezer will use. Of course, your conditions might not be "normal" but it's a good place to start to do some math. Conveniently, power companies bills are based on kWh too. I've just looked at my power bill, and for everything but the controlled water heating, I am paying 26.509 cents per kWh plus 0.160 cents electricity authority levy - so my power costs me 26.669 cents per kWh, or $0.26669 per kWh
Taking a look at each of my freezers, let's work out approximately what they're costing per year to run:
Yearly Running Costs of Four Freezers
| Small chest freezer Rating: 276 kWh/year 276 x 0.26669 = $73.61 per year, in theory Not quite-so-old upright freezer Rating: 760 kWh/year 760 x 0.26669 = $202.68 per year | Medium sized chest freezer Rating: 425 kWh/year 425 x 0.26669 = $113.34 per year Ancient and ugly upright freezer Rating: unknown, but I'm going to go with it being more than the not-so-old upright. Let's call it 900 kWh/year 900 x 0.26669 = $240.02 per year |
So if I add these all together, in theory my four freezers cost $629.65 per year to run, or $52.47 per month. Frankly, I think it might actually be a bit more than that - would be interesting to get one of those gizmos you put onto a plug that tells you exactly how much power an appliance is using over a determined period. However, let's roll with this for now. So, just by turning off Mr Ugly today, I'm saving approximately $20 per month.
As you can tell from the above figures, upright freezers are considerably less efficient that chest ones. The disparity is exacerbated here by the fact that the uprights are old, and the chests are new-ish. All fridges and freezers over 10 years old are far less efficient than modern ones, as technology and industry standards have changed. Uprights are less efficient because every time you open them, all the cold air literally falls out, since cold air sinks, and they have to work hard to chill again when you shut the door. With a chest freezer, when you open the lid, there is minimal loss of cold air. On the other hand, for frequently accessed items, an upright freezer is a lot more convenient than a chest freezer.
Running Costs per Litre of Volume
Now, the other thing to consider is, what is the running price per volume of space - when you get that break down, you can see whether one size of freezer is more efficient than another - as you can do a more direct comparison. For example, I could then compare the cost of what running a bigger freezer vs the two chest freezers I have now would be.
All freezers (and refrigerators) are measured by the volume of space in them. If you imagined filling a freezer with water, how many litres of water would it take to fill it? That is it's volume capacity. Let's look at the volume vs running cost of each of my four.
| Small chest freezer Volume 140 litres Cost per year: $73.61 = $0.5258 per litre per year (52.58 cents per litre per year) (to get this figure, divide cost by volume - $73.61 divided by 140 = 0.5258) Not-so-old upright freezer Volume 305 litres Cost per year $202.68 = $0.6645 per litre per year | Medium chest freezer Volume 320 litres Cost per year: $113.34 = $0.3542 per litre per year Ancient upright freezer Volume 272 litres* Cost per year $240.02 = $0.8824 per litre per year |
* Most freezers will have their volume written on a label on the back of them. If you can't find or access it, you can also calculate the volume by measuring the internal dimensions and multiplying height x width x depth in METRES, then use an online conversion calculator to convert cubic metres to cubic litres.
The Relative Thriftiness of Buying a New Freezer
So, now I know the cost of running each freezer, I can decide, would it be economical to replace the smaller freezers with a larger one? Of course, one does have to take into consideration whether one would keep a large freezer full most of the time. One of the advantages of having several smaller freezers is that as we use up meat from our sheep, I can consolidate the contents of other freezers, and turn one or more off. A half-empty freezer runs more inefficiently than a full one, though there are ways to help this along, such as filling the empty space with bottles of frozen water. (Remember to leave head space in the bottles and have the lids loose until they are frozen, then you can tighten lids and lay them down. Otherwise the expansion during freezing will split the bottles). That aside for a moment, would it be cheaper to run one larger freezer in place of my two chest freezers?
Total volume of two chest freezers: 140 + 320 L = 460L - I'd need a freezer at least that big to replace them both. A quick look at a couple of appliance store websites, and I can buy an F&P 511 litre chest freezer new for $1499, with 30 months interest free. Of course, I might not buy new, and I would definitely shop around and then haggle for the best price, but let's use that as an example. This model has a 586 kWh/year rating, so it's cost to run:
Total volume of two chest freezers: 140 + 320 L = 460L - I'd need a freezer at least that big to replace them both. A quick look at a couple of appliance store websites, and I can buy an F&P 511 litre chest freezer new for $1499, with 30 months interest free. Of course, I might not buy new, and I would definitely shop around and then haggle for the best price, but let's use that as an example. This model has a 586 kWh/year rating, so it's cost to run:
- 586 x $0.26669 = $156.28 per year, and costs $0.3058 per litre per year
- It would be replacing two chest freezers which cost $73.61 and $113.34 = $186.95
- This would be a theoretical saving of $30.67 per year.
So, if I purchased the freezer for $1499, saving $30.67 per year, it would take the new freezer almost 49 years to pay for itself. If I was paying any interest on the purchase, the interest cost would be more than the savings in power!
However, if I could buy a second hand 500 Litre chest freezer with an energy rating of 586 or better, and sell the existing freezers for the same amount or more than I buy the new one for (effectively costing me nothing), then a replacement could be a money saver. But, as always, I must do the math on each possible scenario before parting with money!
However, if I could buy a second hand 500 Litre chest freezer with an energy rating of 586 or better, and sell the existing freezers for the same amount or more than I buy the new one for (effectively costing me nothing), then a replacement could be a money saver. But, as always, I must do the math on each possible scenario before parting with money!
Now, let's consider another scenario - replacing my upright freezer with a more modern model.
A 304 litre new vertical freezer is $1997 (verticals are more expensive than chest freezers), with an energy rating of 559. Let's do the math:
559 x 0.26669 = $149.08 per year to run
or $0.4904 per litre
It would replace my not-so-old chest freezer, which costs $202.68 per year to run, saving $53.60 per year. However, reality is it would actually replace my ancient freezer, as I would get rid of that one, and keep the not-so-old for occasional running to freeze fresh meat. So really it would be saving me $90.94 per year. But even at that rate, the new freezer would take 22 years to pay for itself. Since my existing upright freezers have almost no value - I might get $100 for the newer one - I couldn't sell them to buy a newer second hand one.
Having said that, I really think my freezer is costing me more per year to run, not just in power but in lost stock when it gets left open a little from time to time.
Based on this math, I won't be rushing out to buy an new freezer any time soon. But I will keep my eyes open for really good deals on modern second hand ones, and be ready to run the figures. Who knows, one day I might find a worthwhile swap out!
Meanwhile, now I've done the math, I know what each freezer costs to run, in ideal conditions. This motivates me to be more aware, and more efficient about how I use the freezer space, so I can minimise the number of appliances that need to be running, and therefore the monthly costs. It would also be worthwhile to consider having less meat etc stored in summer, so I can cut right down on freezers, when they have to work harder to keep cool, and then stocking up more as we come into winter. So this might affect my choices about when to have animals butchered etc.
Have you done the math on YOUR freezer?
559 x 0.26669 = $149.08 per year to run
or $0.4904 per litre
It would replace my not-so-old chest freezer, which costs $202.68 per year to run, saving $53.60 per year. However, reality is it would actually replace my ancient freezer, as I would get rid of that one, and keep the not-so-old for occasional running to freeze fresh meat. So really it would be saving me $90.94 per year. But even at that rate, the new freezer would take 22 years to pay for itself. Since my existing upright freezers have almost no value - I might get $100 for the newer one - I couldn't sell them to buy a newer second hand one.
Having said that, I really think my freezer is costing me more per year to run, not just in power but in lost stock when it gets left open a little from time to time.
Based on this math, I won't be rushing out to buy an new freezer any time soon. But I will keep my eyes open for really good deals on modern second hand ones, and be ready to run the figures. Who knows, one day I might find a worthwhile swap out!
Meanwhile, now I've done the math, I know what each freezer costs to run, in ideal conditions. This motivates me to be more aware, and more efficient about how I use the freezer space, so I can minimise the number of appliances that need to be running, and therefore the monthly costs. It would also be worthwhile to consider having less meat etc stored in summer, so I can cut right down on freezers, when they have to work harder to keep cool, and then stocking up more as we come into winter. So this might affect my choices about when to have animals butchered etc.
Have you done the math on YOUR freezer?
RSS Feed
