Tuesday, November 25, 2014

How much electricity does a fridge use?

Today I decided to determine how much electricity a fridge uses. Normally I'd use one of the power meters you can find on the Energy Cost Calculator, but this time I decided to actual electricity as determined by the electricity wholesaler United Energy.

Now you could ask how this could be done but it really is quite easy. I simply turned off every power switch in the house and so the only power being used was the refrigerator. In the past I've estimated the energy of the refrigerator at an average of 40 watts. Here is the graph from the energy wholesaler.


During the hours from 1 pm to 4 pm every power using device was switched off at the switch with only the refrigerator left running. The following is the power reported.

1 pm - 2pm  0.03 kWh
2 pm - 3 pm  0.08 kWh
3 pm - 4pm  0.03 kWh

Averaging the three value we get 0.047 kWh. This 47 watts per hour so my earlier estimate of energy of the refrigerator uses as 40 watts wasn't too far off the mark.

Performing the same test over a longer period may give a better estimate but the real limitation may be the value is reported to two decimal places. However that accuracy is good enough for us to understand the energy usage of the refrigerator.

For those interested in working out the electricity costs for a years, the Electricity Cost Calculator. Plug in your current electricity rate, 24 hours and the wattage which in this case would be 47 watts. The yearly cost estimate for our refrigerator is approximately $108.

Kelvin Eldridge
www.JustLocal.com.au
Helping you to reduce your electricity costs through knowledge.

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