[bzxcvbn]

Air conditioning consumes a ton of energy. About 10% of all electricity consumed worldwide. https://www.iea.org/reports/the-future-of-cooling It emits about 4% of greenhouse gases https://www.sciencedirect.com/science/article/abs/pii/S25424... But the volume itself is not meaningful - the gases used by AC units are extremely powerful - up to 750 times the greenhouse effect of CO2. And of course, the AC unit itself heats the city - which is why they get much hotter than the countryside during heat waves, further exacerbating the demand for AC and making the problem even worse. It's a vicious circle.

> if europe was hotter

How do you suggest achieving that? Other than global warming?

[outworlder]

> the gases used by AC units are extremely powerful - up to 750 times the greenhouse effect of CO2.

They are sealed systems. They only emit gasses when breached. Or when not properly disposed of.

> And of course, the AC unit itself heats the city

A few watts - whatever power it requires to operate. Say it uses 1.5kw. That's the max it will heat up the city. It will of course move 4x this amount of heat(maybe more!), being a heat pump. But the 'new' heat is only what's imported by the power grid. The rest of the heat was already in the city.

It's also worth noting that it's often quite sunny when it's hot. If you power AC units with sunlight, you are actually not introducing any more heat to the system at all. That sunlight would already hit your city and be converted into heat, if you use some of it to move heat around, you are not increasing the overall heat level.

[bzxcvbn]

> They are sealed systems. They only emit gasses when breached. Or when not properly disposed of.

And mechanical devices having leaks is a folklore tale told to scare children?

> A few watts - whatever power it requires to operate. Say it uses 1.5kw. That's the max it will heat up the city.

Yeah. 1500W. Times the number of AC units in the city. That's what adds up to the temperature difference between the city and the countryside.

> If you power AC units with sunlight...

...with a solar panel above your own home, with no inefficiency in the electrical grid, the solar panel, or the AC unit itself. Please, this isn't a high school physics exam, you can't assume that there is no friction or that the AC unit is spherical. This is real life.

[brnt]

Take a look at heating if you want to see staggering energy consumption numbers. In a majority of places, people don't use heat pumps with a COP of say 4-5, but convert chemical energy with a cop of 0.5-0.9.

[dragonwriter]

> That's what adds up to the temperature difference between the city and the countryside.

No, most of the difference is albedo difference meaning urban areas capture more radiant solar energy.

[orra]

> They are sealed systems. They only emit gasses when breached.

Aircons in cars tend to need regassed every one or two years. (I'm not sure why car aircons need regassed more often than domestic aircons.)

[plonk]

> It emits about 4% of greenhouse gases [...] But the volume itself is not meaningful - the gases used by AC units are extremely powerful - up to 750 times the greenhouse effect of CO2.

Do AC units emit these gases? Aren't you mixing up CO2 from electricity production and gases that stay internal to the unit?

[bzxcvbn]

They have two types of emissions: CO2 emissions from electricity production, and refrigerant gases that are supposed to stay inside the unit. But of course, units have leaks.

[RL_Quine]

Many refrigerants have a greenhouse effect of literally zero. It’s safe and legal for me to vent my refrigerator because it’s filed with isobutane.

[bzxcvbn]

Good for you, but at least in the US, R600a (isobutane) is not used in AC units.

Besides, in the early XXth century, it was okay to vent CFC into the atmosphere. We didn't know that it destroyed the ozone layer. What makes you think that we won't discover something similar about isobutane in a few decades, besides wishful thinking?

[RL_Quine]

We study the greenhouse potential of gasses and have found r600a to have a potential of zero, in that it can not be ozone depleting.