Since calculating the saving of turning out lights, I’ve become obsessive with calculating the cost of running appliances in our house. It is surprising how much certain appliances cost to run.
Who knew that boiling the kettle could be such an energy suck?
Knowing how much electricity that you’re using each day and what appliances cost the most is the first step to reducing your electricity bill.
The easiest way to calculate the energy usage of each appliance is to use a plug-in power metre. This allows you to see how much electricity each appliance is using. Some states loan these metres out, so check with your local library or council and see if you can borrow one.
If you don’t have access to a free metre and you don’t want to buy one, there are other options for measuring your energy usage manually. Find out how below.
Calculate Your Daily Electricity Usage
Start by reading your metre every day (or more or less depending on how keen you are) and keep a record to chart your electricity usage, keeping in mind what appliances you use during the day. You will see usage spikes on the days that you run the washing machine or use the air conditioner, for example.
Reading the metre and tracking electricity usage day by day means that you can immediately observe the effects of the changes that you make to reduce the amount of electricity that you use, without having to wait for the next bill.
Make reading the metre and reducing consumption a competition with the family to get everyone involved. For instructions on how to read your electricity metre, see the article on the Down to Earth Blog.
Calculate the Electricity Usage for Specific Appliance
Reading your metre only gives an indication of your electricity consumption overall. To work out how much electricity each appliance consumes and how much each appliance costs you, you need to calculate the kilowatt usage for each. There are several methods for doing this.
Using The Energy Rating Sticker
Firstly, many appliances give you an indication of how many kilowatts per year the appliance uses. You will find this information on the energy rating sticker. The appliance for the sticker below uses 505 kilowatts a year. According to our electricity bill we pay $0.17130 per kilowatt hour, so this appliance would cost us $86 per year or $0.23 per day to run.
Hourly Running Costs By Wattage
Apart from the energy rating sticker, most appliances have their wattage printed on them so you can work out how much they cost to run. A simple equation to work out how much running appliance costs you:
Wattage x hours used per day / 1000 = daily kilowatt usage
(1 kilowatt hour = 1,000 watts)
As an example, our kettle takes 2,200 watts to run. Assuming that I boiled it (full) for a total of 1/2 an hour per day it would use 1.1 kilowatts per day.
To work out the cost, multiply the kilowatts per day by the cost per kilowatt-hour as per your electricity bill.
According to our latest electricity bill, our electricity costs $0.2325 per kilowatt hour (QLD, May 2017). So at 1/2 hour per day, it costs us 26c each day to boil the kettle.
To calculate the usage per year, multiply the daily kilowatt usage by the number of days the appliance is used per year.
For the kettle, over a 365 day year that is 401.5 kilowatts (365 x 1.1 kilowatts)
To calculate the cost per year, multiply the yearly kilowatt usage by the cost per kilowatt-hour as per your electricity bill.
In total, $93.35 per year to boil the kettle (401.5 x $0.2325)
If your appliance only has the amps printed on it, multiply the number of amps by the voltage (240 volts in Australia, 120 volts in the US) to get the wattage, ie 6 amps x 240 volts = 1,440 watts.
Alternatively, if you don’t have the wattage, you could get an estimate of the wattage online for that appliance.
Calculating the cost of using appliances isn’t an exact science but it gives you an idea of which appliances cost the most.
The first step in reducing electricity consumption is knowing your consumption habits. Are you boiling the kettle too often? Is Saturday are your biggest energy day because the kids are home? Knowledge = less power in this case!
Once you are aware of your current consumption habits, it becomes easier to choose which habits to change and which ones that will have the biggest impact on your electricity bill.
Disclosure: Links to merchants within this post may be affiliate links.