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EDIT: My goal with this question was to better understand the impact of cooling systems on local urban environments, but its been pointed out I am asking the incorrect questions for the answer's Im looking for. So this can be disregarded, but I'm not deleting as deleting questions seems to be frowned upon.

I am exploring some ideas regarding the impact of urbanization on the climate and our environment. My basic thought process is that the vast majority of homes and work places have some form of air conditioning(I understand many parts of the world dont, but from estimates I saw the global average is still quite high). And as I understand it air conditioning functions to displace heat(and slight heat generation from the energy usage). Like putting a brick in a bucket causes the water level to rise so too does the outside heat level rise when the heat from inside buildings is displaced.

What I am looking to find out is if there is a way to determine what percentage of the planet's land surface is covered by buildings occupied by humans to determine what percentage of the world is displacing heat from the inside of those buildings(and the area that space occupies) to outside(all the other area)

I understand not every building has air conditioning and will not being using that figure to make a determination(as my previous post had people suggesting). I am simply looking for a good place to start before adding control variables.

Does anyone have any resources to find out where one might come by these figures?

Additionally if someone has a possibly better method to find out the information I'm looking for I would love suggestions.

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    $\begingroup$ The only contribution of heat from air conditioning is related to their energy consumption. The rest is just redistribution of heat, that have no long term impact at all. If you want to estimate how much heat human housing adds to the Earth system, the best approach would be to calculate how much energy households consume worldwide. Because the vast majority of all the energy we use end up as heat sooner or later (the exception would be the small a mount of light that escape to space, mostly from public illumination in cities). $\endgroup$ – Camilo Rada Aug 15 '18 at 18:13
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    $\begingroup$ Using your analogy, air conditioning is like using your hands to push the water to one side of the bucket. As long as you keep moving your hands, the water level will be higher in one side of the bucket than the other (i.e. cooler inside and hotter outside). But as soon as you stop moving your hands, the level will go back to equilibrium. In the air conditioning case. As soon as the temperature outside goes down, and people turn off air conditioning. The inside will go back to thermal equilibrium with the outside. Erasing any effect on the heat redistribution (i.e. no long term effect) $\endgroup$ – Camilo Rada Aug 15 '18 at 20:23
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    $\begingroup$ Again, the largest effect by far is the amount of energy used by air conditioning to keep the thermal imbalance. If you just focus on energy consumption you will get a much better idea of the heat contribution of housing to the Earth system. That will also include the many places that are heated, and on the long run all that heat finally escapes to the outside of the buildings. $\endgroup$ – Camilo Rada Aug 15 '18 at 20:31
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    $\begingroup$ I agree mostly, but again what im concerned about is the level of heat, not the overall amount of heat in the atmosphere, I dont think a large field being 5 degrees hotter is a big deal, but if say, during the peak hours of heat it was 10 degrees hotter than it would be otherwise, isnt that worth measuring? Yes once things "equalize" it goes back to normal, but while its not equalized isnt the increased level something worth examining? $\endgroup$ – Dthorpe Aug 15 '18 at 20:36
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    $\begingroup$ Fair enough. If you are worried about local effects that makes sense. However, your request for global data suggested you were considering the global effect of pulling heat out of buildings. If you want to consider the local effects, you have to start by testing that hypothesis: Do air conditioning significantly increase the outside temperature? How much? How far? You will have to consider factors like wind and vertical mixing of the air. My guess is that the effect will be negligible, except within dense cities with many air conditioning, no wind and little vertical mixing $\endgroup$ – Camilo Rada Aug 15 '18 at 21:14
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I would dispute the idea that the "vast majority" of the world's buildings have air con; in fact, considering that a large proportion of the world's buildings are either (a) in hitherto cool places; or (b) in undeveloped places, I would imagine that it's probably a minority. But I don't have figures on this.

The main part of the question, though, is about the proportion of the earth's surface that is built on. That could be approached as a GIS exercise, and would be reasonably easy to do in places like the UK that have freely-available maps that show all buildings... and very much harder to do in parts of the world that don't.

This study made an estimate (from various data sources, including nighttime lighting) that about 3% of the Earth's land area is "urban". That certainly doesn't include all buildings, but it also includes urban spaces that are not buildings, so it may serve as a useful first approximation.

Depending on your objective, you might find it more useful to stop thinking specifically about air conditioning and instead ask about heat produced by buildings. All buildings produce heat, whether this is from heating, cooling, or other energy use. As a proxy for this net heat production you could simply look at the buildings' energy consumption.

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