The BBC reports that the UK could cut its total electricity use by 1 per cent if the top five British supermarkets put doors on fridges, according to campaigners.
Aldi has pledged to put fridge doors in all of its new UK stores, saving 2,000 tonnes of carbon a year.
Other supermarkets say they will try to make open fridges more efficient.
But the Environmental Investigation Agency said supermarkets could cut their electricity bills by an average of 33 per cent by adding doors.
Each of Aldi’s 100 new stores will save 20 tonnes of carbon per year by having doors on fridges, the German chain said, adding it would reduce stores’ energy consumption by 20 per cent.
Glamorgan Cricketer and environmental campaigner Joe Cooke says all supermarkets operating in Wales should follow suit.
But Tesco, Sainsbury’s, Morrisons, Waitrose and M&S all said they would be using “air wall” technologies that force cold air towards the back of open displays to save energy.
Lidl said is uses curtains when its stores are closed and Asda said it would be trialling doors on chilled displays in 2022.
Ulla Lindberg, a refrigeration and consumer researcher from Swedish fridge maker Haglund Industry, said fridges with doors outperform even the most efficient open cabinet technology.
Supermarkets with fridge doors also saw less food waste and allowed supermarkets to cut their heating bills in winter because they need less heat in the chilled sections of their stores, Ms Lindberg said.
“Half of the energy in a supermarket is from the refrigeration so that means that you cut a lot [with doors],” she explained.