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The far-reaching effects of air conditioning

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Re: The far-reaching effects of air conditioning

#151

Post by closeparen »

yxhuvud wrote: post #104
blackguardx wrote: post #100

Earlier quoted context omitted.

In the US, centralized AC is the norm in the numerous suburban houses. Newer apartment buildings in cities have centralized AC and window units are usually only used in older buildings.

You are speaking centralized as in having one central unit for the building, are you not? I am speaking about having a big company, usually city-run, making the cool in a huge plant and then pump it out (in insulated pipes) to the rest of the city/town. The heat version of it is very common here in Sweden (for towns bigger than, say, 10k people) and it is a lot more efficient (and therefore, cheaper) than having heat…

Universities often have one or more chiller plants that cool multiple buildings on campus (also boiler plants).

Very large building-sized boiler and chiller plants served each half of my campus (probably less than a square mile in total). I'm not sure it would work at city scale.

Re: The far-reaching effects of air conditioning

#152

Post by arethuza »

QuarterReptile wrote: post #140
arethuza wrote: post #48

Earlier quoted context omitted.

I suspect it very much depends what you are used to - I probably think of 15C as "comfortable" and 25C inside would be sweltering. Having said that I'm in Scotland - the other day we had heavy rain and it was 8C which is weather we could get at any time of the year!

Maybe I'm being dense and saying the same thing as you, but it's more about the difference from outside to inside. In the mid Atlantic of the US, 22C can be pretty pleasant, but in the South turning it below 26C is a much more pleasant setting. Meanwhile, spend time in Southern China and you'll be laughed at for going below 30C, because it makes you nearly unable to go outside. If I feel like the humidity outside is…

I must admit that I don't know the difference in temperature from inside to outside - for half of the year (say May to October) we don't have heating on and we don't even have air conditioning (I don't know anyone who has air conditioning at home in Scotland).

The main difference I'd see between inside and outside is the lack of rain and wind in the former - temperature difference is secondary.

Re: The far-reaching effects of air conditioning

#153

Post by logfromblammo »

saint_fiasco wrote: post #130
NoGravitas wrote: post #107

Earlier quoted context omitted.

Here in the South, ceiling fans will let you keep your AC on 80F and still be comfortable. High ceilings help, too, but they're not as common as they used to be.

High ceilings probably mean keeping your AC on 80F doesn't save as much power as you expect, because it has to cool a larger volume of space.

You're not adding cool, but removing heat. And you're not doing it for the entire volume, but for the 2m layer nearest the floor.

Those high ceilings make it easier to remove heat from that bottom layer, especially with drop ceilings, plenum spaces, insulating spaces, and fans. You are cooling a larger volume of air, but it is not to a uniform 80 degF. The higher layers will be cooled to a lesser extent than the lower layers, so the AC burden is somewhat less overall than if the entire room volume were cooled to a uniformly low temperature.

Re: The far-reaching effects of air conditioning

#154

Post by Declanomous »

Lordarminius wrote: post #121
snarfy wrote: post #97

Earlier quoted context omitted.

I recall reading (no ref) that nazi experiments determined the optimal temperature for mental performance was 59F, which coincidentally is the average temperature of the earth.

Optimal for Caucasians maybe. In my office in the tropics, anything below 20C (68F) will generate howls of protest.

I went to school in Northern Wisconsin, and we had a bunch of people from the Caribbean living in my dorm freshman year. There was one thermostat that controlled steam delivery for each floor of the building, and then the radiators in each room did their own thing.

The people from the Caribbean would turn the heat up to 80 degrees all of the time. It got to the point where the thermostats were pulled off the wall in the middle of the night by to keep them from being turned up.

I think probably 3/4 of the building had their windows open all winter, even when it was -20 below outside, just to keep the temp livable. The thing is that it doesn't do much with steam heat, since those radiators can pump out more heat than you can possibly imagine.

The physical plant ended up putting the thermostat within a metal box that was grouted to the wall.

I can understand though. The first time it hits 40 degrees after the summer, I'm freezing, but if it hits 40 in January I'm walking around with shorts on. It was still kind of funny to listen to them describe what being really cold is like: "I'm on fire! Why do I feel like I'm on fire from being cold!"

I'm sure I sound equally hilarious when I'm somewhere hot though.

Re: The far-reaching effects of air conditioning

#156

Post by Ajedi32 »

VLM wrote: post #114
yxhuvud wrote: post #92

Earlier quoted context omitted.

I wonder why central cooling hasn't taken off like central heating has. It seems to me that the economy of scale would work really well with cold just as it does with heat.

Compressed liquid refrigerant is very expensive compared to cheap water for heating. Long pipes full of liquid would be very expensive to initially fill not to mention after leaks. And there would be leaks... Historically most refrigerants have had "issues" when leaked either environmental or being toxic or otherwise it minimizes danger to keep as little as possible. Even if we could afford to use 1000x as much refri…

Why would you need to use the refrigerant itself for heat transfer from end users? Couldn't you just use water for that; like they do for central heating? (E.g. Chill water using centralized AC, then pump the cold water through pipes to cool homes and businesses?)

Re: The far-reaching effects of air conditioning

#157

Post by pinot »

VLM wrote: post #114
yxhuvud wrote: post #92

Earlier quoted context omitted.

I wonder why central cooling hasn't taken off like central heating has. It seems to me that the economy of scale would work really well with cold just as it does with heat.

Compressed liquid refrigerant is very expensive compared to cheap water for heating. Long pipes full of liquid would be very expensive to initially fill not to mention after leaks. And there would be leaks... Historically most refrigerants have had "issues" when leaked either environmental or being toxic or otherwise it minimizes danger to keep as little as possible. Even if we could afford to use 1000x as much refri…

You do not have to distribute the compressor gasses- you just pump cold water/glycol around. Every factory everywhere does it this way for distributed cooling, as well as hospitals/colleges/corp campuses with central plants.

For a long while, Stanford had an underground reservoir of ice for even better cooling (freeze ice at night when electrical prices are low, melt off during the day) http://web.stanford.edu/dept/news/news/1999/april21/iceplant...

Re: The far-reaching effects of air conditioning

#158

Post by pinot »

closeparen wrote: post #151
yxhuvud wrote: post #104

Earlier quoted context omitted.

You are speaking centralized as in having one central unit for the building, are you not? I am speaking about having a big company, usually city-run, making the cool in a huge plant and then pump it out (in insulated pipes) to the rest of the city/town. The heat version of it is very common here in Sweden (for towns bigger than, say, 10k people) and it is a lot more efficient (and therefore, cheaper) than having heat…

Universities often have one or more chiller plants that cool multiple buildings on campus (also boiler plants). Very large building-sized boiler and chiller plants served each half of my campus (probably less than a square mile in total). I'm not sure it would work at city scale.

It's called District Cooling

https://en.wikipedia.org/wiki/District_cooling

Re: The far-reaching effects of air conditioning

#159

Post by dalbasal »

Declanomous wrote: post #149
pavlov wrote: post #56

Earlier quoted context omitted.

Japan is further ahead, as they have optimized this with a decade-old policy called "Cool Biz". To save energy and money by reducing AC, office workers are allowed to wear more casual clothing in the summer: https://qz.com/465327/ditch-the-tie-and-reduce-the-ac-japans...

I wish we had that rule. My last 3 jobs have been in historical buildings. One didn't have AC, and the other two have barely had functional AC. My desk reaches about 80 degrees once the weather is over 65, and it won't drop below that until the fall. In order to make our AC more efficient they "weather sealed" the windows, which mostly involved gluing them shut. So now I can't open the window when it's cooler outside…

You shouldn't have left Ireland.

Re: The far-reaching effects of air conditioning

#160

Post by iamthepieman »

From the OP

"Historically, a cool building in a hot climate implied thick walls, high ceilings, balconies, courtyards and windows facing away from the sun."

New Orleans is one of the clearest examples of this hot and humid specific architecture[0]. In that picture the second floor balcony represents roughly the height of the 1st floor ceiling. The many doors like porticos, can be opened on the shaded side of the building allowing for air flow. You see this style all over the city.

Apart from reflective coatings on glass in high rises and office buildings and the occasional Leed certified building trying to save on energy usage, you don't see much architectural consideration for the climate.

This is especially true in office buildings (in the U.S. anyways) built 1900-1950 or so with blocky brick buildings in which the central rooms have little natural ventilation[1]

[0]https://www.google.com/maps/@29.9459548,-90.0658908,3a,75y,2...

[1] http://forgotten-ny.com/wp-content/uploads/2005/01/e149stbus...

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