Morrisons has turned some of its supermarket freezers up by 3C.
The grocery chain says the move is part of a trial to cut carbon emissions, but has insisted the measure will not impact food safety.
It said the current industry standard of putting freezers at -18C was set almost 100 years ago and had not been updated since, despite improvements in refrigeration technology.
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Freezers in 10 stores across the country have been changed, taking into account the weather and supply routes, with plans to roll out the temperature change to other outlets.
According to the supermarket, an increase of 3C in freezer temperatures across the supply chain will “transform” the business by cutting carbon emissions, saving energy, and lowering costs.
It pointed to studies that showed the global adoption of the move had the capacity to realise savings equivalent to 8.6% of the UK’s energy consumption and reduce carbon emissions equivalent to taking 3.8 million cars off the road.
Morrisons is urging its suppliers to join the Move to -15C Coalition.
It said the carbon savings would be an important step towards its ambition to achieve net zero emissions from its own operations by 2035, while the associated long-term cost savings would enable it to cut, hold or promote prices across its 500 supermarkets and 1,600 convenience stores in the UK.
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Ruth McDonald, Morrisons group corporate services director, said: “Industry standards today are based on safety, science, or convenience.
“The standard temperature for the storage and transport of frozen food today looks like it is simply a convention from nearly 100 years ago.
“We now have vastly better freezers and modern technology and monitoring that gives us a precise picture of frozen food temperatures throughout the supply chain.”
Move to -15C Coalition chairman Thomas Eskesen said: “In order for us to be successful with making the change to -15C, it is essential that we have representatives and support from every stage of the frozen food supply chain, so to have a large UK retailer like Morrisons on board is an important step forward for us.
“By raising the temperature of its freezers in 10 of its stores across the UK, Morrisons is demonstrating that change is possible, and we know that this seemingly small change can lead to a significant, positive, environmental impact.”