A fun related anecdote: the French and English wikipedia pages for air conditioning have very different vibes. After explaining the history and technology behind air conditioning:
the English page first goes into impact, starting with positive impact on health: “The August 2003 France heatwave resulted in approximately 15,000 deaths, where 80% of the victims were over 75 years old. In response, the French government required all retirement homes to have at least one air-conditioned room at 25 °C (77 °F) per floor during heatwaves” and only then mentioning electricity consumption and various CFC issues.
the French page has an extensive “downsides” section, followed by a section on legislation. It mentions heat-waves only to explain how air conditioning makes things worse by increasing average (outside) temperature, and how one should not use AC to bring temperature below 26C during heat waves.
The WHO issued a statement (August 2024) that ~175k people die per year in Europe due to heat (between 2000-2019, statement with source, based off a 2021 study, for reference, they also estimate ~660k cold-related deaths per year).
For other studies, we have two from Nature (2023, summer 2022), which give estimates of ~50k and ~60k heat-related deaths (I assume most heat related deaths take place during the summer). The Lancet has a study (2024) that finds that between 1991 and 2020, there was a median of ~40k heat-related deaths (and ~360k cold-related deaths) per year.
For gun deaths, the CDC (via Pew) states ~45k gun-related deaths in the USA in 2023, so a comparable number, although slightly less.
Of course, Europe has about twice the population as the USA, so one should make per capita adjustments accordingly.
things worse by increasing average (outside) temperature
The effect of this clearly must be miniscule? Like, everything that uses N watts makes the outside hotter, but that heat dissipates almost immediately outside?
I thought the same thing. But looking at it, its still mostly wrong, but it is slightly less crazy than it first sounds.
I compared the watts per square meter coming down from sunlight (about 1000 at sea level according to the top google hit) and compared it to the watts of an air con system, 3000 acordong to some google hit (in the long run it will only heat the outside by its power consumption, although in the short term the heat from your house will add more), then we see the ac is like another 3 square meters of sun light.
So if you live somewhere where the density of dwellings is low, say a detached house with garden, then 3 extra square meters is nothing compared the square meter-age you already cover. But if you live in a 20 story appartment building in a city centre surroudned by similar buildings, and everyone runs ac, then maybe the ‘dwellings per square meter’ will be high enough that the ac will be adding energy that is non-negligable compared to the solar energy. (If we took +15% as our ‘non negligable’ threshold then the critical density is about 0.05 dwellings per square meter. Meaning in 100 square meters we have 5 dwellings adding 15 effective sunlight meters.) So maybe in Singapore this actually matters a little.
It still seems weird to single out ac though. The heat dissipated by driving a car through the city is surely much larger.
I tracked down the original source from the Wikipedia page. The average increase is much smaller than the headline number of “up to 2.5C” and is closer to 0.4C. I think the rough order of magnitude checks out (see Ben’s comment for more details) since an increase by 0.4C means a 0.005 increase in power (if Claude’s math is correct).
Hmm, I still don’t believe this. An AC is still ultimately hooked up to a single 240V outlet and so simply can’t consume that much power (usually maxxing out at 3000W, and almost always more like 1500W).
And ultimately the only thing that matters here is power consumption, which basically all gets converted into heat. I would be surprised if AC ends up more than 50% of power consumption, and 0.4C would still mean that electrical power consumption would be increasing ambient temperature by a full degree, which doesn’t seem realistic to me.
The cooled indoor air also makes its way outside after not very long though, so this should mostly cancel out over the course of a day, leaving just the power consumption of the AC.
And ultimately the only thing that matters here is power consumption,
Why? I think this is measuring exterior temperature, not the average of exterior and interior temperature. If cooling is set to a comfortable temperature and only run on heat wave days, then you should expect the heat wave days to also have a boost from the thermal mass of interior temperature, and there could be other indirect effects.
[Like, I would buy that power consumption dominates. But the only thing? Seems premature.]
I would be surprised if AC ends up more than 50% of power consumption
It does in Texas during heat waves (focusing only on peak demand, which seems fair). Texas is, of course, hotter than Europe (and places even hotter than Texas have even higher cooling costs).
This is what I was thinking. In a city in the summer there might be almost as much indoor space as outdoor space at ground level. The temporary change in outside temperature would then be almost as much as the reduction indoors, right?
I don’t really have a good sense nor am I doing the math for indoor versus outdoor space or how rapidly air moves through cities. I still suspect this concern is largely illusory and another justification for the cult of pain. But I do want to think about the physics correctly.
A fun related anecdote: the French and English wikipedia pages for air conditioning have very different vibes. After explaining the history and technology behind air conditioning:
the English page first goes into impact, starting with positive impact on health: “The August 2003 France heatwave resulted in approximately 15,000 deaths, where 80% of the victims were over 75 years old. In response, the French government required all retirement homes to have at least one air-conditioned room at 25 °C (77 °F) per floor during heatwaves” and only then mentioning electricity consumption and various CFC issues.
the French page has an extensive “downsides” section, followed by a section on legislation. It mentions heat-waves only to explain how air conditioning makes things worse by increasing average (outside) temperature, and how one should not use AC to bring temperature below 26C during heat waves.
fun fact: more people die of heat in Europe per year than Americans who die of guns.
Actually I think the numbers are comparable.
The WHO issued a statement (August 2024) that ~175k people die per year in Europe due to heat (between 2000-2019, statement with source, based off a 2021 study, for reference, they also estimate ~660k cold-related deaths per year).
For other studies, we have two from Nature (2023, summer 2022), which give estimates of ~50k and ~60k heat-related deaths (I assume most heat related deaths take place during the summer). The Lancet has a study (2024) that finds that between 1991 and 2020, there was a median of ~40k heat-related deaths (and ~360k cold-related deaths) per year.
For gun deaths, the CDC (via Pew) states ~45k gun-related deaths in the USA in 2023, so a comparable number, although slightly less.
Of course, Europe has about twice the population as the USA, so one should make per capita adjustments accordingly.
The effect of this clearly must be miniscule? Like, everything that uses N watts makes the outside hotter, but that heat dissipates almost immediately outside?
I thought the same thing. But looking at it, its still mostly wrong, but it is slightly less crazy than it first sounds.
I compared the watts per square meter coming down from sunlight (about 1000 at sea level according to the top google hit) and compared it to the watts of an air con system, 3000 acordong to some google hit (in the long run it will only heat the outside by its power consumption, although in the short term the heat from your house will add more), then we see the ac is like another 3 square meters of sun light.
So if you live somewhere where the density of dwellings is low, say a detached house with garden, then 3 extra square meters is nothing compared the square meter-age you already cover. But if you live in a 20 story appartment building in a city centre surroudned by similar buildings, and everyone runs ac, then maybe the ‘dwellings per square meter’ will be high enough that the ac will be adding energy that is non-negligable compared to the solar energy. (If we took +15% as our ‘non negligable’ threshold then the critical density is about 0.05 dwellings per square meter. Meaning in 100 square meters we have 5 dwellings adding 15 effective sunlight meters.) So maybe in Singapore this actually matters a little.
It still seems weird to single out ac though. The heat dissipated by driving a car through the city is surely much larger.
I tracked down the original source from the Wikipedia page. The average increase is much smaller than the headline number of “up to 2.5C” and is closer to 0.4C. I think the rough order of magnitude checks out (see Ben’s comment for more details) since an increase by 0.4C means a 0.005 increase in power (if Claude’s math is correct).
Hmm, I still don’t believe this. An AC is still ultimately hooked up to a single 240V outlet and so simply can’t consume that much power (usually maxxing out at 3000W, and almost always more like 1500W).
And ultimately the only thing that matters here is power consumption, which basically all gets converted into heat. I would be surprised if AC ends up more than 50% of power consumption, and 0.4C would still mean that electrical power consumption would be increasing ambient temperature by a full degree, which doesn’t seem realistic to me.
No, AC actually moves 2-3x as much heat as it’s input power, so a 1500W AC will extract an additional 3000W from inside and dump 4500W outside
The cooled indoor air also makes its way outside after not very long though, so this should mostly cancel out over the course of a day, leaving just the power consumption of the AC.
Why? I think this is measuring exterior temperature, not the average of exterior and interior temperature. If cooling is set to a comfortable temperature and only run on heat wave days, then you should expect the heat wave days to also have a boost from the thermal mass of interior temperature, and there could be other indirect effects.
[Like, I would buy that power consumption dominates. But the only thing? Seems premature.]
It does in Texas during heat waves (focusing only on peak demand, which seems fair). Texas is, of course, hotter than Europe (and places even hotter than Texas have even higher cooling costs).
This is what I was thinking. In a city in the summer there might be almost as much indoor space as outdoor space at ground level. The temporary change in outside temperature would then be almost as much as the reduction indoors, right?
I don’t really have a good sense nor am I doing the math for indoor versus outdoor space or how rapidly air moves through cities. I still suspect this concern is largely illusory and another justification for the cult of pain. But I do want to think about the physics correctly.
Except 1000 nm lasers pointed at the sky, they dump around half of the energy they consume into the space.