Viewing a single comment thread. View all comments

Beneficial-Car-3959 t1_iufatry wrote

Reply to comment by Klai8 in ELI5 Why are airport ceiling so high? by TrShry

I read that one giant supermarket in China has bigger electricity bill for cooling the building during winter than during summer because more people go to supermarket in winter. Humans are walking ovens.

64

TucsonTacos t1_iug631g wrote

The Mall of America in Burnsville, Minnesota (MSP basically) has no heating. Even during the height (low) of winter it is heated by the people inside.

56

SafetyMan35 t1_iuhevl9 wrote

From the MOA website: https://www.mallofamerica.com/about

MOA does not use a central heating system; instead, 70 degrees is maintained year-round with passive solar energy from 1.2 miles of skylights and heat generated from lighting, store fixtures + body heat

42

FriendoftheDork t1_iugou7g wrote

Must suck for the employees opening up though.

24

TucsonTacos t1_iugqfue wrote

I'm pretty sure most places turn off (down) the heat when they're closed so its probably about the same effect.

12

FriendoftheDork t1_iugsu91 wrote

I'm used to the heat being increased an hour or two before opening, and lowered significantly during the empty hours. But if there is no heating at all then they can't even get a little warm until you have a lot of human traffic.

10

TucsonTacos t1_iuioxp9 wrote

I mean that’s how the mall works. I’m not an engineer nor did I build it.

You’re just speculating that it ‘probably’ sucks because you ‘feel’ it must work like you think it does. I can’t explain why it does or doesn’t, but there’s no possible way when the mall opens it is -20 inside and they just pray enough people stay and shop in full winter gear until it warms up and they can take their coats off.

They’d never get enough people. Nobody would stay.

5

Curious_Opossum t1_iujfpdn wrote

I worked in MOA for almost a decade. It's very rarely cold in the morning. The place is massive and it doesn't have enough down time to get cold. The coolest it would get would be the morning after Christmas. Winter and empty for over 24 hours. Perfectly warm by noon. The amount of lights and electricity on top of body heat, ovens and grills from restaurants and the food courts, the heat from the rides, the sun coming through the skylights... It's more than enough to keep things warm for a long time.

4

[deleted] t1_iugjzc7 wrote

[deleted]

9

crossedstaves t1_iugunzx wrote

When you have a very large building you wind up having a reduced ratio of surface area to volume. The thermal energy inside the mall has a harder time finding a way out than it would in a smaller building because there's just less building surface in comparison. It takes time to get truly cold.

9

TucsonTacos t1_iugq882 wrote

I'm not an engineer nor had any part in designing the MoA. I have no idea how its heated or not heated at night.

2

ordinary_kittens t1_iugpnj5 wrote

It must be heated at night in the winter though, to keep pipes from freezing? Minnesota will routinely get to 10 degrees, even zero degrees, in the middle of January at night.

4

SafetyMan35 t1_iuheyvw wrote

From the mall website

MOA does not use a central heating system; instead, 70 degrees is maintained year-round with passive solar energy from 1.2 miles of skylights and heat generated from lighting, store fixtures + body heat

10

TucsonTacos t1_iugqdb4 wrote

I used to live there, and it gets even colder than that. If I had to guess I would say residual heat? Possibly something engineered with the hot water being next to the cold water pipes? I really have no idea but it was a comfortable temperature every time I went during winter.

4

The_Power_of_Ammonia t1_iuilb5i wrote

>Minnesota will routinely get to 10 degrees, even zero degrees, in the middle of January at night.

This made me laugh. As a lifelong Minnesotan, you're nearly 50 degrees too warm on that estimate!

1

ordinary_kittens t1_iuir330 wrote

I was trying to say the routine average cold temperature, not the coldest. I live in Canada, I assume during a cold snap you guys might get to -50F like we do, but surely it’s not routinely that cold every night?

2

CitizenSnipsJr t1_iuiube0 wrote

I've lived in MN my whole life and the coldest I remember was a few overnight lows of -30F during a polar vortex. I think some areas in greater MN might have hit -40F here and there but it's certainly not routine and doesn't stay that cold very long. Anything lower than say -10F is not common and usually only for a few days to a week or so.

3

ordinary_kittens t1_iuiuxlu wrote

Yeah, people in Canada tend to exaggerate by giving the windchill temperatures, but I think that’s cheating. Excluding windchill we don’t really get to -40F/-40C very often, maybe only once or twice every second winter, in the middle of the night during a cold snap, like you said.

1

The_Power_of_Ammonia t1_iuit1sp wrote

What part of Canada? I think we get and stay colder than most of the East and Great Lakes areas. We're further North than Toronto even.

Every year in Jan/Feb we'll get a week or two with nightly lows of -40 to -50 or so. Sometimes the daily high even stays below -30F for a week or two. Bright, sunny winter days are a special thing - too cold to snow!

1

ordinary_kittens t1_iuitwg2 wrote

I don’t like to give my location but I live near Edmonton, so very dry and cold.

I don’t know Fahrenheit very well but a cold night here will maybe be -30C, with maybe only a week where the temperatures dip below -40C. I mean without windchill (since we are talking about pipes freezing indoors).

I checked the average low temperature for January for Minnesota before posting, and it said the average low was around 4F, so I figured I was fairly close to around what the average low temperature was.

Yes, lots of bright sunny winter days here, too. But, I can tell you guys aren’t much warmer than us despite being so much further south…those midwestern winters are brutal!

1

The_Power_of_Ammonia t1_iuiv7mz wrote

I like those temps for a lot of reasons, one of them that the C/F distinction more or less goes away down there haha.

All good mate, talking about the winter's cold can quickly turn into a Salty Spitoon contest of who's toughest! I'm happy to give it to you up in Edmonton though - you know the senses involved with a clear January day for sure!

Right around the corner now, good sauna weather! I was just noting to a friend too how we're a third of the way down from summer: 50⁰ off from the top of July, 100⁰ still to go down to the bottom of January. . . Bring it on!

1

CitizenSnipsJr t1_iuiukwm wrote

Do you live in international falls or something? -30F is extremely rare for the metro area, and -40 to -50 is basically unheard of.

1

The_Power_of_Ammonia t1_iuiwdbq wrote

It hits those lows every single year. I'm in the west metro, lived here my whole life.

2014/15 (I think it was) we had highs of -55F, plus windchill. That was exceptional, but we get a week or two at least every year of lows around -40.

1

CitizenSnipsJr t1_iuiz1n1 wrote

WC temps are made up BS and don't really mean anything. It's only touched overnight lows of -30F a handful of times over many seasons in the metro and only for a couple days max. I only remember two days where the daytime temp was below -20F and that was during a polar vortex.

1

Enchelion t1_iuiq3le wrote

They might use heat tape on the pipes themselves (or at least any at risk) or heat the utility rooms but not centrally heat the rest of the building.

1

Bolson32 t1_iugearz wrote

I was coming to ask this exact question lol... What about in the winter? That's wild!

1

HarryHacker42 t1_iuiguuz wrote

And then the power went out, the people left, the building froze, the pipes burst and all hell broke loose :)

1

Murazama t1_iuhwlsk wrote

We have a Walmart I work at on occasion. High ceilings, only thing HVAC pushes around is the air for the coolers (I assume) because during Winter it's like a fucking icebox in there, during summer is great, but no heating what so ever, and no amount of bodies in there seems to warm it up. I was in there yesterday, 51°f outside with overcast skies/rain showers and it felt 40ish inside the building. Might be the huge coolers that are wide open and cranked just to above freezing for beer/produce they use but holy hell it's cold in there.

0

DTux5249 t1_iufp766 wrote

This is why cold blooded creatures are superior life forms; We waste so much energy mindlessly, while a reptile has an excuse to sit back and back bask for hours on end

17

rechlin t1_iufy7na wrote

So what you are saying is that we should welcome the lizard people as our new overlords?

13

urzu_seven t1_iugbcel wrote

Considering we have driven the lizard people underground I'd say us warm blooded mammals are doing pretty good!

2

mingus-dew t1_iuhy8s4 wrote

Conversely, an endothermic animal can remain active in a variety of temperatures and also use thermoregulation to fight infection.

But yeah we have very high energy demands and so can't chill as much as ectotherms.

1

Dirty_Hertz t1_iufz3fy wrote

I believe I read once that the Mall of America in Minneapolis where it gets to -40 degrees sometimes doesn't have a heating source, and as an HVAC designer I believe it.

13

WayneConrad t1_iug83ok wrote

If I recall, an average adult at rest gives off something like 100 W of heat. So around 15 humans is a space heater on full blast. 150 people waiting to board a plane makes a lot of heat

5

KingZarkon t1_iugn6d8 wrote

That's at rest. If they are active, say walking around in an airport while carrying luggage, that goes way up.

6

thewaynegibbons t1_iufqznc wrote

Source? Genuine question, not doubting you.

2

bulksalty t1_iufzxoz wrote

Basically all the calories you take in are burned as heat (you get a small amount of work, but the vast majority are heat lost). If you're eating 2000 calories/day and not adding to your fat reserves, you're almost certainly releasing at least 1960 calories/day as heat.

2

[deleted] t1_iug7v7m wrote

[deleted]

4

skepdoc t1_iugkft4 wrote

I have it on good authority that the human body generates more bioelectricity than a 120-volt battery and over 25,000 BTUs of body heat.

5

Coompa t1_iuhb5zv wrote

Im dimmer than that I think.

3

urzu_seven t1_iugbghj wrote

Dang it, now I want to walk around with a lightbulb that is powered by me all day...

1