I saw a documentary on The Mall of America, located in Minnesota, which claimed that it gets so many customers that it is heated only by body heat and sunlight, even in the dead of winter. Isn’t it freezing cold first thing in the morning for the first customers that arrive?
I’m guessing it probably retains most of its heat from the previous day overnight.
I know from theater experience that many bodies together genereate a great deal of heat. That The Mall of America doesn’t need a heating system doesn’t really surprise me much. It really depends on the insulation.
You’ve also got heat output from the lighting. There are a LOT of light bulbs in MoA.
Not to mention the fact that you’ve got a whole amusement park right in the middle that has to produce quite a bit of friction heat as the ride cars and ride motors do their thing.
There has to be more to this. It is Minnesota after all. Maybe it doesn’t have a traditional duct system but something else has to be going on. There would be heat fluctuations by area and overnight. What if the power went out for a while during a blizzard? That would subject all that merchandise to temperature fluctuations that aren’t good for some of them. If it is that easy to heat by skylights, lighting, and body heat, it must be hell during the summer unless the system is a lot more elaborate than they let on. I refuse to believe the whole mall relies on whatever passive heating comes all the time.
Source: Engineering Sights
Source: Mall of America - Wikipedia
From what I’ve read the entrance areas of the mall are heated. The rest of the mall is supposedly not heated, and is actually air conditioned year round to keep a comfortable temperature.
My only sources for this so far are Wikipedia and an article from the Seattle Times which actually quotes Wikipedia as its source for the information on the heating system. None of the sources in the Wikipedia article have actually had information about the heating system in them, either.
Ok, that makes more sense. They knew it would always produce more heat than needed so they have heavy duty air conditioners running most of the time. It is still a cool fact but it makes me want to slap another factoid writer.
Here is my version:
Everything in the Mall of America including lights, skylights, and people generate so much waste heat that a conventional heating system is unnecessary and instead, excess heat must be removed from the Mall even during the winter.
The way that it was presented in the things I looked up, it implied that the Mall is an almost perfect biosphere.
If you’re looking for an ecosystem the base of which consists of fast food hot dogs and plastic bags, maybe…
Large modern office buildings in general don’t have heating systems. (But they definitely do have AC.) The reason you’ll sometimes see a lot of lights on in the building at night is to heat the building. Only the outer layer of offices need to be kept lit since that’s where the heat loss is.
Hardly unique to MoA.
From ftg:
I thought the reason you see lights on at night in most office buildings (assuming they don’t have a night shift of course) was so janitorial staff could see to work.
I don’t think lighting alone in a largely empty office building at night would produce enough heat (That wouldn’t dissipate overnight before the workers came in in the morning) to outweigh the energy cost. I do not think large office buildings leave the lights on all night long just to generate heat. :dubious:
I would appreciate a cite for this, not for MoA but 'large modern office buildings", and am fully willing to stand corrected.
I kind of doubt this. Large modern office buildings tend to be lit with Fluorescent lights- either bars or new energy efficient lights. My house is lit with the latter and they give out very little heat. Maybe in the days of incandescent light that may have been true.
Similarly with The Mall- I suspect that lighting is a minor contributor. Cooling units for food and drinks produce a lot of heat, as does cooking in food outlets.
As a guide, a human body produces about 100 watts
http://www.mpimet.mpg.de/en/presse/faqs/ist-die-abwaerme-der-menschen-wichtig-fuer-das-klima.html
so each person in the mall produces as much heat as one bright incandescent light bulb, and about ten times that of a modern efficient light bulb.
Hmm I would almost think some kind of temperature regulated fans to vent higher temp air, maybe even just convection with vanes to close the ducts if temp drops below a certain level. That way you don’t have to actually force cool the place, just let some heat escape.
Also of note, I seem to remember that supermarkets learnt that fitting heat exhangers to transfer heat from chiller cabinets to other areas of the supermarket evened out temperatures throughout the store and cut down on heating costs. I am sure that technology would be used at the Mall both for that reason and also to move unwanted heat from one area to another.
Also, doesn’t the mall have large glass roof areas for borrowed light? The Eden Project in Cornwall maintains two ‘biomes’ - large glass houses - at about 70 degrees and ninety degrees all year round, and spends money on cooling, not heating! The vent windows are open on sunny days even when the outside temperature is below freezing.
The largest building in the world (in cubic feet) is the Boeing assembly plant in Everett, Washington and it is not heated. The office spaces inside the building do have AC. I worked in it for about 4½ years and it could get chilly inside on cold days. Most days all that was required to be comfortable was a t-shirt.
This isn’t unusual for large capacity buildings and such.
The office building I work in is always in cooling mode, even in the winter.
Sometimes an in-duct heater will kick in to cool a corner office, but largely the outside air (in the winter) or the AC rooftop units will be cooling the place.
Both of the large libraries I’ve worked in have that kind of system (the university library is actually mostly underground, which helps a lot). We hate it here; the designer was from Florida and we deeply suspect this is not quite appropriate for South Carolina usage. I’ve got a space heater and a blankie and a sweater wardrobe year round. I can’t imagine one of these dumb buildings anywhere farther north than here, but I guess it’s possible to make it work. (Doesn’t help that we have a lot of windows, which is something malls generally don’t bother with.)
The question is not the “efficiency” of mall- or office-based light bulbs, the question is what is the alternative means of heating available? If the alternative would be to heat the air via an electric heater, it’s just as efficient to just fill the place with light: any light that doesn’t escape the closed system* will be converted to heat, anyway.
OTOH, there are much more cost-efficient means of heating air than electricity, so in that sense it wouldn’t make too much sense to heat with light bulbs, and you have to factor in the wear on the bulbs (but would it cause more wear to turn them off and turn them on again in the morning?) but they are not measurably less efficient at converting electricity into heat than space heaters or other types of electric heaters.
*Or possibly get converted to biochemical potential in the form of mold or plants 
My comment about the ‘efficiency’ of the bulbs was to point out that a large office lit with incandescent bulbs would probably need about 20 bulbs at 100 watts or 2kW of light, much of which, agreed, would stay in the buliding. 20 modern bulbs would give 20 bulbs at 11 W for the same amount of light- 0.22kW. Quite a difference.
Another item about the MOA. It has almost no outside windows. The center amusement park does have a glass roof. There are a lot of doors. But not really many windows. Then think about the typical mall store arrangement. The front of the store is out into the interior hallways. The storage areas are toward the outside walls. So lots of insulation going on here.