Refrigerators eat up energy, unless you choose wisely.
BACK in 2004, Dr Tom Chalko had just built an off-grid eco-house at Mount Best, in South Gippsland. But during the summer, while he waited for his solar panels to arrive, he was short on electricity.
“I needed refrigeration, but I didn’t have enough energy for it,” he recalls. “My small vertical fridge was consuming more energy than my wind turbine was able to produce.”
So the retired physics academic set about solving his problem. Suspecting that chest freezers were more efficient, he began tinkering with one to suit his needs.
After just a few days, he gave his old vertical fridge away.
When it comes to retaining cold air, conventional fridges have a bafflingly straightforward design flaw: every time you open the door, cold air escapes. That doesn’t happen with a chest freezer.
“When you open the horizontal door, no warm air gets in – because cool air is heavier, it stays in the fridge,” Dr Chalko says.
He devised a thermostat that kept a chest freezer at fridge temperatures and, for even better efficiency, cut off standby power while the compressor wasn’t running.
His converted chest fridge now runs for only about two minutes every hour, and consumes an average of about 0.1 kilowatt-hours per day. That’s about ten times less than the best vertical fridges, and up to fifty times less than the worst energy guzzlers.
There’s been another, unexpected benefit too: reduced food spoilage. “My motivation was efficiency, but the best thing is the food preserving performance,” he says.
“I still can’t get over it. Because of the reduced temperature fluctuations, food-spoiling microorganisms don’t breed. I can go shopping once a month and I always pull fresh produce from the fridge.”
If you want to make your own one, Dr Chalko has published instructions (including a lengthy list of parts) on his website. He also makes and sells the thermostats himself ($150).
He argues that in Victoria, because of the inefficiency of brown coal power plants, and further losses that occur in electricity transmission, any energy waste at the household level is amplified many times.
“Earth is a system of limited resources and I started considering my house and property that way too,” he says. “My question is always, ‘How can I make the most of what I’ve got?’”
For many Australian households, the first step is to switch off the second fridge that’s whirring away in the garage.
“If you buy a new fridge and keep the old one running, you’ve actually taken a big step backwards,” says building efficiency expert Peter Reefman. “It’s important to take your old fridge to a good recycling centre.”
When he tested the energy consumption of his refrigerator, he found it was the biggest energy user in the house, by a long way. Now, his new, more efficient one saves him about $200 a year.
You can compare different makes and models on the government’s Energy Rating website. But, as Mr Reefman says, always bear in mind that “the stars lie”.
The ratings compare like with like, so a huge double-door fridge can score more stars than a small unit. To understand what it will cost to run, look at the energy consumption figure on the sticker.
“Buy the smallest fridge possible, and try to get one that consumes 1 kilowatt-hour per day, or less,” he says.