As winter finally arrived last week I spent hours blocking off the icy blast that creeps under my front door and around my windows. Having done that I went out Christmas shopping, only to find that the chain stores all keep their doors wedged open.

I looked about me into the dense fog shrouding my high street shops and rubbed my chin with frozen fingers. Something didn’t make sense. At Gap Kids, thinking I could do something to stop this madness, I shut the door behind me. But moments later a member of staff quietly wandered over to open it again.

Next stop Jigsaw. This time I shut the double doors with a deliberate air of well-meaning prudence — the smug expression Gordon Brown uses to present his budgets — whereupon a woman I took to be the manager nodded towards a security man, who walked to the doors and opened them again. I marched to the manager and asked what was going on. “It’s our policy,” she said. To freeze her customers and staff? “We would be in big trouble if we left the doors shut,” she said.

I went back to Gap Kids and asked for the manager there. When she appeared I gave her a brief overview of climate change and added that even if she didn’t believe carbon emissions will kill us she would anyway save money on utility bills, to the satisfaction of head office and shareholders, if she shut the doors.

She was sympathetic: I wasn’t the first person to tell her this. A woman had come in recently and talked hysterically about polar bears dying out. She said her staff got terribly cold but they couldn’t shut the glass doors in case somebody walked into them by mistake or even on purpose. “They might sue.”

I suggested that perhaps the glass could be frosted here and there, or covered in stickers, to prevent any such tragedy. Over the street at Waterstone’s it seems the doors are not transparent enough. They have heavy black frames and only the top half is glazed. Anecdotal evidence, the manager of Waterstone’s tells me, indicates customers think the shop is shut if the doors are closed and sales suffer as a result, so the doors must stay open.

I suggested the shop invest in a sign bearing the legend open/closed. Like others I spoke to, he said he was personally in favour of shutting the doors — “I’m pretty green myself” — but he had to follow company policy.

And yet the few remaining independent shops on the high street — the tea rooms, the health food shop, the pharmacy — all manage to keep their doors closed. As do those great corporate demons Starbucks and McDonald’s. I popped inside McDonald’s to ask how come it was so much more responsible than its neighbours? The startled manager explained that it would be wasteful to run the air-conditioning with the doors open. And the extractor fans wouldn’t work so well. How about that: McDonald’s has greater confidence in the intelligence of its customers than Waterstone’s does.

According to the Royal Commission on Environmental Pollution, retailers use 275 kilowatt hours (kWh) per square metre.

That’s vastly more than, say, local government offices (39kWh), factories (47kWh), warehouses (81kWh) and commercial offices (95kWh).

One explanation for the waste is lighting: many stores are lit to the same intensity as television studios. And now to heaters, the craziest of which must surely be the ones installed over the open front door, which typically have a rating of 500 kilowatts — roughly 17 times as powerful as a domestic fan heater.

Environmentalists say the best way for consumers to tackle retailers’ wasteful emissions would be to stop going to shops altogether and buy everything online. Department for Transport studies show that replacing shoppers in private cars with delivery vehicles would reduce traffic by 70%. And without customers to dazzle and roast in shops, retailers could become wholesalers and reduce utility bills on their premises.

As somebody who gets seasonal food delivered to my door I’ve already given up on supermarkets. And I can certainly live without ever again traipsing round clothes shops. But it does seem a little bleak to forgo every other kind of shop too. I’d much rather they changed their ways.

The worst sector, my own research suggests, is fashion. To be specific Accessorize, Hobbs, Kurt Geiger, LK Bennett, Molton Brown, Nicole Farhi, Nine West, Petit Bateau, Reiss and Whistles all had their doors open. Each one presumably justifies keeping them open on the grounds that rivals do the same. At any rate, that’s what Jigsaw’s press office told me: “We take this approach to stay competitive in a very difficult market and you will notice that most of our competitors have the same policy.”

Only doing it because everybody else does: an excuse used by naughty children at school. But better than arguing — with store managers and war criminals — that you’re only obeying orders.

Having done a certain amount of research, I probably shouldn’t have been surprised to find that the once ethical Body Shop likewise blasts hot air through open doors. But I was surprised. The apologetic manager, like so many others, advised me to contact head office.