Open Doors

It was around 5° C (40° F) in London today, but shops and pubs and cafes had their doors open. They stay open all winter. There's a hot air blower above the doorframe. I don't know if I've written about this before. I was aghast when I first saw it.

One mate suggested that an open door is inviting to customers. Another suggested that, since air is such a great insulator, the downdraft makes for a blanket of air that's more efficient than a constantly opening-and-closing door. (I'm not sure if I believe that one.)