I am looking for some evidence of a definitive study into the effect of these damn things.

After remonstrating with a number of shops along the lines of 'Why have you got your heating/air conditioning on AND your doors open?' I got fed up with the usual range of reasons (see below) and took it up through the political route. This produced some rather worrying replies.

Remarkably the (un)informed view was that these are more efficient at keeping buildings warm than a door. Apparently it is believed they 'pressurise the building with warm air and stop it leaking out'.... and several other pages of complete nonsense along these lines.

Even the Energy Saving Trust stated that 'warm air curtains .. are an effective way of reducing heat loss' and that they are 'very effective at preventing the warm air inside the building escaping.' I was therefore wondering if anybody had any proof one way or the other?

Whilst I can accept that an air curtain can reduce convection of hot air through a doorway and can have an effect on preventing stratification of air flow in the doorway (i.e hot air leaking out over a stream of cold air flowing in) I doubt that the air curtain is as effective as an insulated door which was the point I was making.

I do find it difficult to believe that at least part of the heat being thrown down by the curtain is not going directly out the door. Has anybody done an independent study into this by checking temperatures around the outside of these doors?

If they are right we could stop putting up insulated houses and simply live under a canopy, put some fan heaters on poles and live in the balmy interior so created.... or maybe someone has the wrong end of the stick.

Glad of any pointers on work done so far.

Reasons for doors being open and heating/cooling systems attempting to heat/cool the rest of the planet:
> It is company policy to have the doors open
> It is so our customers know we are open. (Other than it being opening hours, the lights being on and there being people wandering about inside one assumes)
> Our customers like it
> So that disabled people can get in
> People find the doors hard to open
> The cold air from the shop helps with global warming (Give me strength!)

.... is it just me?

Methinks - as part of a Supply-Air system.............

Yes, if fresh air's got to be drawn in anyway somewhere, for ventilation, then why not depressurise the shop so none of the air curtain leaks outward, and all heat that would have otherwise been going out through even a closed door, is drawn back in. The heat that wd have been lost from the door area, is now instead lost in the exhaust air setup - unless some kind of heat recovery happens there (not air-to-air, as you no longer need fresh air input via ducts because it's now being supplied through the door).

Why do shops need to be heated anyway? When you go out, you dress according to the weather, so if it is cold you wear a coat. When you get in the shop, you are far too hot and have to carry your coat round with you. This makes no sense to me.

Hey, I'm not that tight Paul. I'd insist on provision of company issue thermals and stylish fleece caps and a wood burner in the staff room...

Seriously though, shops are too hot in the first place and certainly the bigger ones should have "air-lock" type porchs with two sets of doors. That is if we even need all these shops. If shopping wasn't the main recreational pursuit of most of the population of the developed world these buildings could be demolished or turned into something useful.

We call them moles! and we have heard that they live in Toronto too.

I agree Paul. I think the flaw in our economic system that you rightly point out might soon become too obvious for the politicians to keep covering up. We aren't going to keep growing the economy after Peak Oil, at least not when you allow for REAL rates of inflation. I'm certain they are cooking the books already in the USA and are actually in a recession and I'm starting to have my doubts about the UK statistics as well. Apparently inflation in the UK is running at 1.9% but that bears no resemblance to my household budget.

As for malls, I can see what what you mean if you didn't have to drive to them and they weren't full of useless tat that breaks or wears out as soon as you get it out of the bag. Lets just stop shopping for non-essential items and then we won't need to work as hard and we can enjoy life a bit more.