Revolving Doors

[cdd]

YOu know what I'm talkin about, those stupid partitoned rotating chambers that you turn as you walk through to enter. Pervasive in shopping malls, hotels, and crazy universities.

Who agrees that these things should be consigned to the Room 101 of Inventions? They take ages to go through, whether electric (bad) or non-electric (very bad), and if lots of people ned to enterit leads to unbelievable bottlenecking.

PRoponents claim they insulate and reduce airflow. I fail to see how: every time someone uses it, several sizeable pockets of warm air are exchanged for cold air, and for electronic ones that rotate continuously, the effect is even greater. Surely sideways-sliding doors are the best for this?

</Fury>

[Philip Cobbold]

It was even more stupid when supermarkets used to fit them as standard - trying to navigate them with a trolley was interesting, and would mean only one person could fit in each section. Luckily they're pretty much a thing of the past now in those sort of situtations.

[nwtv2003]

It was even more stupid when supermarkets used to fit them as standard - trying to navigate them with a trolley was interesting, and would mean only one person could fit in each section. Luckily they're pretty much a thing of the past now in those sort of situtations.

Our local Morrisons still have them and they're a pain in the arse indeed, it's not the fact they go slow, its when people walk into them or whack trollies into them, and they go into a sudden halt for a couple of seconds. Although we have an option of a door placed in the middle of the two revolving doors.

[cdd]

when people walk into them or whack trollies into them, and they go into a sudden halt for a couple of seconds. Although we have an option of a door placed in the middle of the two revolving doors.

Well that's easy, it's because the designers of the electric ones are terrified about people getting crushed to death by lingering in the gap between the edge of the compartment and the wall and getting sued. Despite the fact you would have to be extremely stupid to do such a thing, we all must pay the price...

Since I know someone (probably Sput) going to challenge me about my assertion that the "insulation" theory is a load of old tosh, I present my working:

1. Average size of compartment = 1.5m^3
2. Average rate of revolution = 0.25/sec
3. Average compartment divison = 1/4

Assuming the electric ones rotate continuously (and most do from what I've seen most do), that's (1.5*4)*0.25m^3 (1.5m^3) of warm air that is being ACTIVELY convected out per second, and exchanged for cold air. I would say there's very little inefficiency there. And I don't buy the idea of the revolving door "chamber" being isolated from the rest of the air, I think the slants do a good job of drawing in plenty of cold air from outside (for the outside half) and plenty of warm air too (from the inside half). I agree it might be a bit less than 1.5m^3, but you can't deny it's quite near to there.

Compare this with a sliding door, where natural or human-induced wind is the only factor convecting air - and the amount of heat lost is substantially less.

[Gavin Scott]

Holy smokes. I'd give you a point for showing your workings, but I can't help but think you could apply this raw intelligence better elsewhere.

I would say that based on the footprint they occupy (an important consideration in a retail space) they *must* be the most effective entrance insulators - over and above any other type available, based on the high number of them in operation around the world.

Despite the fact you would have to be extremely stupid to do such a thing, we all must pay the price...

Well no, one just needs to be human. We all lose concentration when we're out and about.

[Nick Harvey]

It was even more stupid when supermarkets used to fit them as standard - trying to navigate them with a trolley was interesting, and would mean only one person could fit in each section. Luckily they're pretty much a thing of the past now in those sort of situtations.

Except at the main entrance to Royal United Hospital in Bath.

The compartments are specially designed to be big enough for a wheelchair.

Okay if you're well enough to drive it yourself, but useless if not, as there's not enough room in the compartment for anyone to push the thing.

[cdd]

No better place than Wikipedia for copious amounts of information about rubbish!
http://en.wikipedia.org/wiki/Revolving_door

BOOKS have been writing on the subject. Anyway, one interesting reason why it is said to be important is because "the sudden volume of rushing air [with normal doors] can be so great as to blow out windows". Sounds like a load of old rubbish to me, I've done them the courtesy of adding {{uncited}}.

Anyway, I have found more ammunition for my anti-revolving door brigade: people attempting to exit from both sides of a revolving door in a fire in a nightclub in America caused it to jam and contributed to over 500 deaths.

I would say that based on the footprint they occupy (an important consideration in a retail space) they *must* be the most effective entrance insulators - over and above any other type available, based on the high number of them in operation around the world.

I guess so - the revolging door movement, after all, is sideways and I guess with clever design the seprators could be aerodynamic to reduce air resistance (and, thus, the drawing in of air from the inside). For this to work, the separators would need to bend away from the direction of movement toward the end of the separator, and very few I've seen are designed like that - instead being completely straight.

I don't deny there's something I've missed and that they are in fact very insulating... I just find it kinda hard to believe, especialy since for one person to enter several of those compartment pockest have to around (one half revolution).



By the way, on a semi-related note: How many doors that claim "THIS DOOR IS ALARMED" actually are? I have always assumed quite a small percentage, but I've never really had the guts to start calling the bluff of alarmed doors.

[Gavin Scott]

I guess so - the revolging door movement, after all, is sideways and I guess with clever design the seprators could be aerodynamic to reduce air resistance (and, thus, the drawing in of air from the inside). For this to work, the separators would need to bend away from the direction of movement toward the end of the separator, and very few I've seen are designed like that - instead being completely straight.

I don't deny there's something I've missed and that they are in fact very insulating... I just find it kinda hard to believe, especialy since for one person to enter several of those compartment pockest have to around (one half revolution).

I've seen them with different internal partitions. I suppose different manufacturers will tweak around with it.

Traditionally, sliding doors have fan heaters above, forcing a curtain of warm air downwards constantly. These are furiously expensive to run all day.

Despite the large size of these new revolving doors, if they are properly balanced and on friction reducing bearings, they require a surprisingly small amount of energy to make them move - and they don't require fan heating.

Efficient and effective, then - but yes, they can be a pain in the arse when some kid attempts to dodge the door at the last second causing an emergency stop, and making all the occupants groan and grumble.

Well me, anyway.

[marksi]

Traditionally, sliding doors have fan heaters above, forcing a curtain of warm air downwards constantly. These are furiously expensive to run all day.

Tesco Knocknagoney has a "hot air curtain" the full width of the opening to their Knocknagoney store, about 5 metres wide, which has no doors. It is completely open to the elements on an elevated piece of land overlooking Belfast Lough.

[cdd]

Tesco Knocknagoney has a "hot air curtain" the full width of the opening to their Knocknagoney store, about 5 metres wide, which has no doors.

Speaking of Tesco stores without doors, has anyone noticed how quite few Tesco stores have been including sort of porticos that surround the front entrance?

A diagram (and, simultaneously, an opportunity to show off my fantastic drawing skills):

entrance comaprinsn.jpg

I suspect this is something to do with stopping the heat problem you speak of, although it seems more likely it's purpose is to prevent ram-raiding et cet.

[Pete]

now interestingly, tesco extra on the kingsway in dundee had one of these. it was useless and all the air escaped. the service and fags desks all had big horrible bar heaters above them washing yet more power.

Last week, they moved all the trolleys into the car park and built a very simple porch with a glass front and gaps on the side. the shop is now roasting upon entry and the heaters over the desks are not on any longer.

I was rather impressed.