Over Christmas, I knocked together a couple of power monitors. The first check I wanted to make was our fridge energy consumption.
I hooked the power monitor up to our Fisher & Paykel family fridge/freezer, being one of the busier appliances in the house.
So how much do you think it costs to run a household fridge?
Measuring Fridge Energy Consumption
Our family fridge/freezer is an NZ made, 373 litre (250 litres for the fridge and 123 for the freezer) Fisher & Paykel model E372BLE purchased back in 2010.
It only has an Energy Star rating of 2-stars (out of 6), despite being pretty new.
I tucked the power monitor in behind the fridge and left it collecting data for a week. The week happened to be the hottest week of the year, so I imagine the fridge was working hard keeping the kid’s iceblocks chilly!
Fridge Energy Consumption Results
When it was working hard, power usage was just under 300W (bottom left figure on the photo).
After a week the fridge had used 10,870 Wh of power which equates to around 567 kWh (units of power) per annum and in dollar terms:
- 50c per day running costs
- $15 per month
- $175 per year.
I am actually pretty happy with $15 a month. It doesn’t seem over the top to me, given that most power is consumed for lighting, heating or cooling.
Saving Money on Fridge Running Costs
Our fridge is relatively new having only been manufactured in 2010. It runs well and is a good size for our family of four.
The options I use to assess whether the running costs of an appliance can be lowered are (a) modify our behavior (b) modify the appliance, and (c) replace the appliance.
Modify our Behaviour
The kitchen and fridge are at the centre of our busy household.
In theory, we could save some energy by making the fridge work less. That means less opening of the fridge and freezer, and not putting any warm items in that require cooling down.
In practice, I am not crazy enough to start policing fridge usage, so realistically there is not much behavioural change that could be applied to lower our power bill.
Modification our Fridge
The refrigeration cycle is a thermodynamic process used to move heat from one place to another, resulting in cooling.
For our fridge – this means moving heat from the inside of the fridge and depositing it on the outside of the fridge (at the rear, against the wall).
The main modification that might be possible to lower energy usage would be to move the fridge out of its current position in our fitted kitchen to allow for better airflow – and hence better efficiency.
Replace It!
Hypothetically, if we wanted to replace our fridge with a new one, the new equivalent would be the Fisher & Paykel E372BRE4 which can be picked up new for $1148 inc. GST.
(Update: I went to get a screenshot… and the sale had finished. What a crazy world of extreme (artificial?) discounting we live in).
This new fridge would have an energy star rating of 2.5-star and reportedly uses 455 kWh per annum. This is about 20% less than what I measured above, which would be a good reduction if we could achieve that.
On paper, this would save $35 per year in running costs. The payback period would, therefore, be $1148 ÷ $35 = 30 years.
As a cross check – the way the energy star system works is that each additional star represents an approximate 18% reduction in energy use. So – without digging into this too deeply – I guess that 1/2 a star would use say 10% less than 2-star.
This would put the payback period at above 30 years. Far too long.
Conclusions
While our fridge might not be quite as efficient as a newer model, with a 30 year payback period I think we’ll stick with it for now!
Side note : – The testing was during a very hot and humid summer week with peak daily temperatures between 26 – 32 ºC. I think I might re-test during the winter and see if there is a noticeable difference.
– TPG