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Re:India heatwave temperatures pass 50 Celsius by ajross on Sunday June 02, 2019 @11:07AM (#20075922)
A tub will work, sure, as long as it's pulled from a large body of water that hasn't warmed up with the air. Hopping in the local lake is an obvious choice.

But in a detached demographic sense: effectively everyone lives in a city in the modern world, and while their housing might not be air conditioned most of the major buildings are. In an emergency like this everyone would just crowd into office buildings and shopping malls.

That's not to say this wouldn't be horrifying, but it's not the kind of existential social crisis people tend to imagine. Cooling ourselves down in a heat wave, in the modern world, is a solved problem at least as far as keeping ourselves alive goes.

Re:India heatwave temperatures pass 50 Celsius by jogjayr on Sunday June 02, 2019 @01:06PM (#20076618)
> effectively everyone lives in a city in the modern world, and while their housing might not be air conditioned most of the major buildings are.

The states of Rajasthan, Madhya Pradesh, and Uttar Pradesh lag the rest of the nation in economic development. This statement is very much not true in those places, and even elsewhere in India. Air-conditioning is still a luxury outside of relatively well-off people's houses, corporate buildings, and malls.

> Cooling ourselves down in a heat wave, in the modern world, is a solved problem at least as far as keeping ourselves alive goes.

People there can't afford to not work. Sitting in an air-conditioned space for half the working day 4 months a year is not viable for them. A lot of the work is manual or farm labor that must necessarily be done outdoors.

Re:India heatwave temperatures pass 50 Celsius by machz on Sunday June 02, 2019 @10:57PM (#20080052)
These states are also not very humid. Temperatures in Rajasthan have exceeded 50 several times and people have traditional ways of dealing with it.

Not saying that #climatechange isn't an emergency; but people won't suddenly die.

Re:India heatwave temperatures pass 50 Celsius by wongarsu on Sunday June 02, 2019 @11:38AM (#20076096)
Every human is effectively a 100W space heater just from being alive. That means you need at least 30W of air conditioning capacity per human to keep the temperature constant (on top of what you need to counter heat from outside).

Unless these buildings are designed as emergency shelters for heat waves their air conditioning systems won't be able to cope with all the people.

Re:India heatwave temperatures pass 50 Celsius by bloopernova on Sunday June 02, 2019 @12:51PM (#20076540)
That's a deeply upsetting mental image. Thousands of people shelter in a building during a heatwave, the electrical grid is overloaded and the AC shuts down.

This makes me want to go live in a deep cave somewhere :(

Re:India heatwave temperatures pass 50 Celsius by newnewpdro on Sunday June 02, 2019 @01:15PM (#20076670)
I don't think it's that simple at all.

The principal human-appreciated effect of AC is the dehumidifying of the air when it's cooled.

The dry interior air allows human perspiration to regulate temperature effectively. The AC doesn't have to cool all the bodies, it just has to keep the air dry enough.

Re:India heatwave temperatures pass 50 Celsius by the8472 on Sunday June 02, 2019 @01:33PM (#20076805)
Don't ACs dehumidify by condensing the water? If so then it means they need to get rid of the heat of vaporization, the same amount of energy the humans shed by evaporative cooling.
Re:India heatwave temperatures pass 50 Celsius by newnewpdro on Sunday June 02, 2019 @04:22PM (#20077855)
In a closed system sure, but I'd expect a larger building to have significant fresh-air return systems.

In a scenario where you've filled the place with people, the interior humidity is going to exceed that of the exterior air and you'd just start dumping the moisture outside exchanging with the fresh, dryer air. It's a comfort regression sure, but not a everyone dies situation.

The survival of the people doesn't come down to the AC heat pump keeping up, it comes down to supplying them enough water to drink and disposing of the humidified air.

My point is just that it's the relative humidity that matters, and the AC system has some options there. I've lived through a desert summer in a small space without any AC at all. I'd just keep the windows closed as deep into the day as possible riding out the night's cooling until the air gets too humid indoors from sweat and respiration for the fan to have any cooling effect. At that point I'd open the windows for relief. The air coming in was usually much hotter than the interior air, since the space was well insulated and nights get cool, but it didn't matter because it's very dry air and perspiration resumes functioning. The situation is easily survived unless you run out of water for your person.

Of course if the outdoor air is something like 100% humidity there's only the heat pump option, but that simply doesn't happen in deserts when it's hot out. It's a desert, not the tropics.

In the desert the relative humidity shoots up when it cools down, the humid nights are the worst. But it's because they cooled down. Again, not a survival problem since it's not that hot, just uncomfortably muggy. One saving grace with deserts is they don't generally have any mosquitoes, so these humid nights can easily be spent outdoors without any annoyance.

Re:India heatwave temperatures pass 50 Celsius by wongarsu on Sunday June 02, 2019 @04:51PM (#20078089)
> In a scenario where you've filled the place with people, the interior humidity is going to exceed that of the exterior air and you'd just start dumping the moisture outside exchanging with the fresh, dryer air. It's a comfort regression sure, but not a everyone dies situation.

That's equivalent to opening a window without the AC doing anything. If that would work we wouldn't be in a "crowd everyone into a shopping center" type situation, the people would be just fine outside in the shade.

> It's a desert, not the tropics.

While half of India is in the tropics, this part indeed isn't. But next month the monsoon will put humidity at approximately 100% [1].

1: https://en.climate-data.org/asia/india/delhi/new-delhi-30/

Re:India heatwave temperatures pass 50 Celsius by newnewpdro on Sunday June 02, 2019 @05:30PM (#20078376)
> That's equivalent to opening a window without the AC doing anything.

Even when the air temperature at your fresh air intake is cooler than the air at your condensor coil? Wouldn't we assume no system would draw its fresh air from near the condensor coil?

You still have a heat pump in the system, and there's a temperature difference between the air inlet and the pump outlet.

Re:India heatwave temperatures pass 50 Celsius by saeranv on Sunday June 02, 2019 @04:31PM (#20077922)
Yes, ACs are heat pumps, which means they're just moving heat from one area to another. So yes, the heat shed by human beings via evaporative cooling, is then dumped outside via heat of vaporization.

Specifically the ambient indoor air heat is absorbed by refrigerant which is transformed into a superheated vapor saturated with moisture. When this vapor either touches a cooler surface, or has cooler air blown past it, it will dehumidify and exhaust the heat it has absorbed indoors to the outside. The mechanical work done by the AC (fans, pumps) is also being released as heat. So the total energy being dumped outside is therefore the heat that's taken from the inside plus the energy used by the AC released as heat.

Re:India heatwave temperatures pass 50 Celsius by Scoundreller on Sunday June 02, 2019 @03:13PM (#20077373)
Right, but it does mean you just need to be in a somewhat sealed room to remove the humidity instead of constantly fighting the ever-warming walls/floors/ceiling. Of course you need to exchange CO2 and O2 to stay alive.
Re:India heatwave temperatures pass 50 Celsius by wongarsu on Sunday June 02, 2019 @03:44PM (#20077593)
But the people in the room will create more humidity that you have to constantly remove again.

Humans burning calories to stay alive creates heat, and thermodynamics that you spend energy to remove it or see the temperature rise. Whether that heat is hot air or bound as humidity shouldn't make a large difference.

Re:India heatwave temperatures pass 50 Celsius by saeranv on Sunday June 02, 2019 @04:41PM (#20078000)
It's more complicated then that. Take a look at this psychrometric chart showing the environmental bounds at which human comfort is guaranteed: http://comfort.cbe.berkeley.edu/

You can see there that even at extremely dry conditions, if the operative (ambient + radiant) temperature is hot enough, it will cause heat discomfort. Even if the human starts sweating, that'll only reduce the temperature a bit so dehumidification isn't the only role of air conditions, sensible cooling is also a factor.

Re:India heatwave temperatures pass 50 Celsius by saeranv on Sunday June 02, 2019 @04:42PM (#20078007)
How are you deriving the 30W of AC capacity here?
Re:India heatwave temperatures pass 50 Celsius by YeGoblynQueenne on Sunday June 02, 2019 @03:26PM (#20077458)
Air conditioning itself is a significant contributor to greenhouse gas emissions, via energy consumption:

https://www.rehva.eu/knowledge-base/rehva-journal/chapter/ai...

See the pie chart on page two: eletricity consumption from cooling systems is 17% of global consumption. The IPCC expects this usage to rise as temperatures rise.

I would also like to challenge the notion that human beings understand how to use air conditioning units. In pretty much every building I visited or vehicle I boarded with air conditioning, if the unit was on, the windows were also wide open at the same time. In Greece, where I'm from, in the summer, you can cool down just by walking past stores, with their doors thrown wide to signal they're open for business and their air conditioning blasting cool air onto the street. It may be 42°C in the shade, but in front of our shop, it's 15°! Come on in and buy our stuff! But put on your coat first.

Contemplate for a second the futility of this behaviour: air conditioning pumps heat out of a room, into the environment; leaving the windows open allows the heat to circulate back into the room. The unit typically has a thermostat, also typically set at an unrealistically low value, that would cause the user to turn on the heating in winter. The unit goes to work and pushes the warm air out trying to reach its target temperature. The warm air cycles back in from outside and tries to raise the temperature. The unit keeps working, and working, and working, wasting energy all the time. Eventually, this contributes to warming, which causes more people to buy and misuse air conditioning.

We might know how to survive a heat wave, by our clever use of technology, but we don't know how to use technology to avoid more and more severe heat waves.

Re:India heatwave temperatures pass 50 Celsius by ricardobeat on Sunday June 02, 2019 @03:36PM (#20077537)
Air curtains can be extremely efficient and allow doors to stay open. That sounds like an insane waste of money and energy if store owners are not using one - are you sure you're not just feeling the 10-20% lost cold air when walking past?
Re:India heatwave temperatures pass 50 Celsius by YeGoblynQueenne on Sunday June 02, 2019 @03:57PM (#20077689)
Yes, I'm sure.

Edit: because obviousy I also go into shops to buy stuff and I've never seen an air door used. If air doors are used, they are very, very rare.

Re:India heatwave temperatures pass 50 Celsius by saeranv on Sunday June 02, 2019 @04:46PM (#20078032)
Also the AC dumps heat outside, which in urban areas contributes to local heat increase (i.e Urban Heat Island effect), which in turn requires even more AC too fight.
Re:India heatwave temperatures pass 50 Celsius by TheCoelacanth on Sunday June 02, 2019 @11:28AM (#20076053)
Offices and shopping malls are upper-middle class things in India. They would not come close to holding the entire population. There would be millions of people dying if temperatures got that high.
Re:India heatwave temperatures pass 50 Celsius by ajross on Sunday June 02, 2019 @11:35AM (#20076084)
I'd want to see cites for that, honestly. Obviously India's commerce centers can't come close to handling a billion shoppers, but there's enough floor space in the urban core of Bangalore to house the at-risk population for a 72 hour heat wave.

The point is emergency management here. And I'd bet anything that somewhere there's a workable plan drawn up for exactly this kind of occurrence.

Re:India heatwave temperatures pass 50 Celsius by TheCoelacanth on Sunday June 02, 2019 @11:50AM (#20076167)
India's total retail space is 2 sq ft/person[1]. That's not enough space for someone to sleep in, even assuming that 100% of the retail space there is air conditioned (it's not) and assuming that the AC systems can keep up with that much body heat in temperatures that high (they can't).

[1] https://en.wikipedia.org/wiki/Retailing_in_India#The_Indian_...

Re:India heatwave temperatures pass 50 Celsius by lotsofpulp on Sunday June 02, 2019 @12:13PM (#20076317)
>The point is emergency management here. And I'd bet anything that somewhere there's a workable plan drawn up for exactly this kind of occurrence.

Aside from ACs having a limit on cooling far below “everyone packed in a building”, if you’ve ever done business in India, I don’t see how one could assume there would be a plan drawn up for this grand of a scenario, much less many smaller scale scenarios.

Re:India heatwave temperatures pass 50 Celsius by Arun2009 on Sunday June 02, 2019 @01:10PM (#20076643)
> there's enough floor space in the urban core of Bangalore

There's vastly more to India than a few metro cities. A quick google search reveals that around 65+ % of Indian population lives in rural areas.

India is in for some very dark times if the climate situation gets worse. The positive lining in the cloud is that we have some measure of political stability for the next 5 years.

Re:India heatwave temperatures pass 50 Celsius by dragonwriter on Sunday June 02, 2019 @02:26PM (#20077102)
> effectively everyone lives in a city in the modern world, and while their housing might not be air conditioned most of the major buildings are. In an emergency like this everyone would just crowd into office buildings and shopping malls.

Heat waves spur increases in violent crime, limited in some degree by the fact that people stay in their own homes in really hot (but not uninhabitably so) heat waves.

Heat waves that go further to where the only survivable solution is pulling people out of their homes into large communal shelters (whether they otherwise serve as offices or shopping malls or whatever) is...going to be very ugly.

And that's even before considering whether the facilities or supporting infrastructure (plumbing, electrical systems, etc.) are adequate to support these places being used as shelters. Almost certainly they won't be until it's happened and failed a few times, and even after that the places that most need it will be the least able to finance the necessary upgrades.

Re:India heatwave temperatures pass 50 Celsius by blensor on Sunday June 02, 2019 @12:48PM (#20076520)
Is this really a long term solution. An A/C does not "produce" cold air it just reduces the temperature at one spot by increasing the temperature in another place making the temperature around those buildings even warmer. At some point A/C units will be battling for that little temperature difference that allows them to perform their function with increasingly higher energy demand.
Re:India heatwave temperatures pass 50 Celsius by TaylorAlexander on Sunday June 02, 2019 @01:18PM (#20076697)
Yeah and how much CO2 emissions will that A/C emit?
Re:India heatwave temperatures pass 50 Celsius by bufferoverflow on Sunday June 02, 2019 @02:37PM (#20077166)
Zero if it runs off solar.
Re:India heatwave temperatures pass 50 Celsius by blensor on Sunday June 02, 2019 @02:50PM (#20077227)
I'm not sure if it's an actual issue but solar panels are quite dark and get really hot. I could imagine that a huge solar array does measurably heat the immediate surrounding area.
Re:India heatwave temperatures pass 50 Celsius by bufferoverflow on Sunday June 02, 2019 @08:26PM (#20079408)
Even if it were true, it doesn't produce extra CO2.
Re:India heatwave temperatures pass 50 Celsius by TaylorAlexander on Sunday June 02, 2019 @10:58PM (#20080056)
Sure, but a solar powered A/C system is well out of the price range of a few billion people on earth.