Can you imagine leaving your front door open during the current big freeze to welcome in your neighbours for a Christmas drink? That’s exactly what retailers and restaurants up and down the country are doing to entice customers.

But it’s all a waste of energy and time according to a study by Cambridge University. Not only are so-called ‘open door’ policies hugely wasteful in energy terms and contributors towards generating more carbon dioxide emissions, but also they have no discernible impact upon footfall and can create a working environment which causes discomfort for staff.

Two Cambridge stores took part in the University study: an independent toy shop and a branch of the national stationery chain, Ryman. In both cases, the heating was turned on at the start of business hours and was turned off once the set point temperature was reached. In the ‘Open Door’ tests, the fan heaters above the doors (known as air curtains) remained turned on throughout the whole day. In the ‘Closed Door’ test, the fan heaters remained off throughout the whole day. This methodology mirrored the way that the majority of stores and restaurants up and down the country operate: blasting hot air downwards over an open doorway to woo customers from the street with their warmth.

The energy and carbon savings made the Closed Door approach are nothing short of staggering: 30% in the example of the toy shop and 54% in the case of Ryman.

Kevin McCloud, the well-known TV presenter of Grand Designs, urged all shops to sign up to the Close the Door Campaign. He said: “Leaving the door open in winter to heat the street can double energy consumption and make a pretty job of just heating the planet. So just close the door, reduce carbon dioxide emissions, halve energy bills, and make customers and staff more comfortable into the bargain.”

His words were echoed this weekend by Chris Huhne, the energy secretary, who condemned retailers for their open door policies. He said: “This is irresponsible. Leaving doors wide open wastes energy.”

With major chains trying to be greener, surely closing their doors and switching off equipment would be an open and shut case for common sense energy efficiency. But perhaps what is really needed is a stick. Currently, there is no legislation which forces landlords, occupiers and tenants to regulate the way they operate their stores. They can be built to the highest environmental standards, yet all of that literally can go to waste through daft open door policies. If the government is really committed to reducing the nation’s carbon footprint, they could do no worse than making the high street more energy efficient.