When installed inside the average store refrigeration unit, the eCube is said to save up to 25 per cent of the energy normally used, saving retailers money and cutting carbon emissions.
The British invention works by controlling the refrigerator's thermostat to respond to the temperature of products inside, rather than the circulating air temperature, which means the refrigerator doesn't need to work as hard to cool itself down again when opened.
It s makers, who have already patented the product, say it could help slash the world's carbon emissions because it reduces the amount of energy needed to power refrigerators.
Spencer Freeman, UK sales and marketing director, said retailers with glass-fronted fridges in their stores could see a big difference in their energy bills if they installed an eCube.
He said: "Customers don't tend to choose what they want through the glass. They open the door, look for what they want and then, by the time they've shut the door, the warm air has gone in and the thermostat thinks: ' Hang on, it's got warm in here .'
"However, in the three minutes the door has been open, the drinks haven't changed in temperature, so there's no need for the thermostat to start or stop."
Freeman said shops would also become quieter if the eCube was installed because refrigeration units would not need such frequent power boosts.
An eCube costs £25 (£48.50 including installation and servicing). For more information call 0208 500 5033 or visit www.ecubedistribution.com.