Here’s a trick question for a quiz: which uses the most electricity every year? An electric oven, hob, microwave or kettle?
The answer? The humble kettle, which eats up about 6% of all the electricity supplied to British homes.
An oven may use more power when it is on, but constantly filling a kettle – usually boiling far more water than we need – uses enough power annually that equals half the output of one of the world’s largest offshore wind farms, the London Array, off the Kent coast.
After we published an article on 19 January about the energy and financial savings to be gained from installing LED bulbs, we were contacted by Tom Baxter, visiting professor of chemical engineering at Strathclyde University.
Why, he asked, are we not all following the simplest – and completely free – way to cut electricity bills? Just by filling the kettle correctly he estimates the typical UK household would shave £19 off their annual £600 bill.
Almost every other sizeable way of cutting bills requires some sort of expense at the outset, says Baxter, such as buying new bulbs or paying for better insulation. But the use of kettles is the best way household bills can be reduced for free, he says.
Baxter examined recently published official figures on electricity generation in the UK. Government data shows we used 105.4 terawatt hours in 2017, with 16% of that going on kitchen appliances.
What’s remarkable is how much is used by kettles. Analysis by Cardiff University of 2012 consumption patterns – which may have changed marginally since then – found 34% of the electrical energy used for cooking went on kettles, 24% on kitchen hobs, 23% on ovens and 19% on microwaves. That cuppa is perhaps costing rather more than we thought.
Baxter says consumption for our kettles is 6 terawatt hours a year – “or about 6% of our electricity bill is from boiling kettles”.
He adds: “If Guardian readers are anything like me, I regularly overfill it for the task in hand, particularly for a cup of tea or coffee. Let’s say 80% of kettles are overfilled by treble the quantity of water needed. That means overfilling translates to 3.2% of our domestic electricity bill.”
So by using our kettles more effectively, we can potentially make decent savings.
“What’s more, it is free and, of course, we are doing our bit for the planet by improving our carbon footprint,” Baxter adds.
According to consumer organisation Which? the obvious thing to do is to fill to the minimum fill line indicated for the number of cups required.
Also, descale your kettle regularly, as if it is full of limescale you use more energy to boil the same amount of water. It also points out that “because gas is cheaper than electricity, it works out slightly cheaper to boil water on a gas hob than using an electric kettle, as long as you are boiling just the quantity you need and switch off the hob as soon as it has boiled.”
Consumers should also buy a more energy-efficient kettle when they replace their old one. But do your homework when it comes to pricey “smart” kettles. In 2016 the Guardian related how data expert Mark Rittman spent 11 hours attempting to get his new hi-tech kettle to boil some water.
