The air conditioning trap: how cold air is heating the world | Hacker News Reader

The air conditioning trap: how cold air is heating the world

theguardian.com

47 pointsaxiomdata31638 comments

This is completely backwards. In the US air conditioning has facilitated people moving from colder to warmer areas, which decreases energy usage. Yes, you don't need AC in the Northeast but you need a lot of heat, so people moving to the Sunbelt reduces carbon emissions.

Outside the US, this ignores how much happier and more productive people are when they're not overheated. Traditionally cold areas have been much more productive than warm areas, but AC could change this.

Added note: I shave peak load for a living.

Yes, this article is pretty much misleading end to end, and not taking into account the cost of heating is the keystone.

Everyone who thinks about this issue should stop cherry-picking some particular consumption good you think should be curtailed.

One, it's anti-humanistic, you'll end up getting slammed for telling (poorer) people from hotter areas to suck it up, and contra the article, you'll deserve it.

Two, analytically it seems to confuse even people who should know better. You have to take the whole system into account.

Directly pricing the externalities of carbon emissions solves both of these.

Oh I was absolutely not happier or more productive while living in the US. Air conditioning there was driving me insane and it had bad effects on my health too.

It is unhealthy for sure: my flatmate coming back from jogging sweating and all... first thing he does, turn AC on.

It was also sad to see AC running day and night and reading news about climate change the same time.

Your final point misses the parent's point completely. Yes it uses energy, but cold areas use more. It might also be worth mentioning that the use of boilers may be dirtier than going through a centralised burner, as the economies of scale would favour efficiency improvements at large scale more than at small, building scale.

As for being unhealthy, that's an issue of dry, circulating air. This would be addressed better with radiative cooling and potentially humidity control. Some cleaning out of air filters may also be due.

edit: Oh and of course, building regulations (and enforcement thereof) and insulation shouldn't be forgotten, like I just did.

AC units (especially window units) can produce mold. It's a serious problem that is often overlooked. People should check the air they are breathing, especially while sleeping. Some molds are exceptionally toxic.

I run my AC almost 24x7. Air conditioning can be perfectly fine. Don't misconstrue a dumpy building with your dislike of cold air.

Contrast: https://www.vox.com/2015/3/23/8278085/singapore-lee-kuan-yew...

According to Singapore’s first prime minister:

> Air conditioning was a most important invention for us, perhaps one of the signal inventions of history. It changed the nature of civilization by making development possible in the tropics.

> Without air conditioning you can work only in the cool early-morning hours or at dusk. The first thing I did upon becoming prime minister was to install air conditioners in buildings where the civil service worked. This was key to public efficiency.

AC also uses significantly less electricity and fossil fuels than Heating during the winter.

Sounds interesting - do you have a source for that? I guess that would be country /location specific? Here in the UK most people use zero energy for aircon, and loads fo heating - but I'm sure in most of the world this would be inverse.

Here's a breakdown from 2007: https://www.npr.org/templates/story/story.php?storyId=139417...

More in-depth analysis: http://www.energysolutionscenter.org/assets/1/Page/GHP_Posit...

In general, it appears that it's slightly better for carbon emissions to live in a warmer area with regular AC than it is to live in a humid temperate area that requires both heat half the year and AC the other half, or a cold area that requires heat most of the year.

According to Figure 2 of the GHP paper that must be why Daytona would be preferable to Birmingham or Dallas if you wanted to minimize overall energy use by focusing on AC alone, using little or none during the warmer months.

A basic rule of thumb is that it takes enough natural gas to heat three homes in order to produce the electricity to heat only one home.

Also that it takes about 3kWh of electricity for an AC unit to cool off the heat produced by 1kWh of electrical appliances or other heat sources.

An air conditioner is just a heat pump running in reverse (basically). Heat pumps have efficiency >100%, while electric heating is 99.9% efficient and other forms (natural gas, wood, etc.) are significantly less efficient.

Logically, then, it is more efficient to cool a room each degree than it is to heat it.

No, an air conditioner is just a heat pump pumping heat from inside the house to outside. That doesn’t change the efficiency, it’s still greater than 1. The efficiency difference is because the required temperature differential typically is much bigger for heating than cooling.

Always remember that the Persians in Iran have had air conditioning for over 1000 years now, in a really hot place, completely sustainable. It might not make rooms freezing cold as it is possible today, but it works. It is called a "badgir". https://en.wikipedia.org/wiki/Windcatcher

I am sure we can learn from them and maybe develop that idea further.

"Completely sustainable" is a technically true but only for a fairly low (<20%) percentage of locations. It's just evaporative cooling, so it relies on a large water supply. It also increases local humidity significantly so it can make the outside environment even more uncomfortable much more quickly than normal air conditioning. It's also more expensive anywhere water isn't essentially free.

That said it's great in places like India and southeast Asia, where huge numbers of people live.

Those are sometimes called swamp coolers in slang, and are pretty common in the US where it's dry enough to be effective. But that pretty much excludes the entire east coast and Gulf areas.

And honestly, in many other regions: just accept that it sometimes gets hot. In Germany, where virtually no private home has AC, it can get really hot inside from June to September especially when houses are not that well isolated. But people just go on with it. In places like Texas or California, this is another story. But as you stated: probably it is hot enough for some kind of "persian style" cooling.

It's a neat idea, but doesn't help in humid regions, which I'd wager is where most AC is used(US Southeast, South East Asia, tropics, etc). An outdoor mall in Miami was built with a wind ribbon, which feels effectively useless sadly.

An interesting idea I read about recently was a guy claiming to lower his utility bills by effectively running an AC to remove humidity, then a swamp cooler inside. No idea if it's more or less effective, though.

We may be able to minimize air conditioning in most of North America (and other temperate regions) with some modification of buildings and green approaches.

The architectural approach is not a solution in the tropics and desert areas. Just ask Lee, Kwan Yew. It’s a necessity in a modern society in the tropics.

Yes, when it comes to the tradeoffs of global warming, the leadership of an oil economy that imports most of its goods is the best source of information.

I’d say that conservationist-environmentalists just want us south Asians to remain poor and backwards, denying as they do the importance of air conditioning, large-scale industrial agriculture, and GMOs. That might give them too much credit for having thought through things, however.

This article misses the important point of <i>moving</> air. We live in Washington, DC in a one hundred year old house, and our air conditioning doesn't get used much. What DOES get used a lot is the fan in our HVAC. We chose a very powerful system to MOVE that air around, and keep a constant breeze going through the house. This has kept it nice and comfortable without having to rely on the a/c. We also installed multiple, powerful fans in the attic that automatically turn on to exhaust air, pulling it up from the lower flowers so cooler air can sink. So all this to say, it's not just the a/c that keeps a home cooler.

13,400MW every second Clearly nobody checked this article.

But that’s against the average of 10GW, so that’s 3GW diff. Still a lot, but not what you’re listing.

A megawatt is a million joules per second. It’s a unit of power, not energy.

Mixing up watts and joules is like mixing up miles and miles per hour. It demonstrates a fundamental misunderstanding.

quick googling shows that NYC uses ~11,000 Megawatt-hours each day, that seems more reasonable.

But yeah, watts per second..

I'd suggest that "watts per second" might just amount to a colloquial way of saying "watt-seconds". I mean, you have a number of watts "during" or "over" a second, so that is kind of "per" second.

While yes, multiplying and dividing are opposites, and "per" generally means division, it seems to me there is a linguistic thing where polarities get switched or are just inferred from context.

AC is still a status signal, even outside the American south- when was the last time you were at a movie theater or a bank that wasn't colder than it needed to be, even uncomfortably so? It's traditional of places that try to impress luxury.

Honestly, while the power use is a problem, I don't think it's the most important AC-related problem. It's relatively small compared to all electricity, and is fixed with renewable power, unlike current heating solutions. Since AC just moves heat around, it causes significant localized heating in cities.

There is a neat idea to solve that, though. Beam that heat right into space[1]! The principle is similar to the radiators that keep the ISS cool- since thermal radiation happens at a different wavelength from sunlight, you can make a material that is "white" (reflective) to sunlight but also "black" (radiative) to infrared radiation. Unfortunately thermodynamics puts a strong limit on this; for a given area you need to make the radiator hotter[2] to give off more radiation, but that makes the refrigeration cycle much less efficient. Buildings need to become much greener than they are already becoming.

[1]: https://phys.org/news/2018-10-energy-saving-radiative-coolin...

[2]: ie surround it in insulation that is transparent to infrared. That keeps the air from heating up but allows heat to escape to the sky. Trickier than it sounds, though- glass and some plastics are opaque to many kinds of infrared.

> when was the last time you were at a movie theater or a bank that wasn't colder than it needed to be, even uncomfortably so?

This is a problem of thermal mass that changes suddenly.

Every human is roughly 100W of heat. You need roughly 10KW of dissipation per hundred people. If you suddenly add a couple hundred people to a temperature controlled room, you need a bunch of extra AC overcapacity, and people are going to start to complain if you don't have enough overcapacity to prevent that temperature from rising within a couple of minutes.

Then you have the flip side--a couple hundred people leave the theatre. Your AC suddenly is overproducing cooling that it doesn't need, and your theatre may have a little bit of insulation to try to cut down on your AC costs. So, you undershoot the temperature and then the insulation keeps it there as you don't have 30-50KW of heat producing humans to bring it back up.

There's also the computers...

I used to work in a high-rise building that was closed up, and the climate control was not under our control (our department, our floor, etc.). So when everybody was in the office and the computers were running it would be stifling. When few people were around and the computers were sleeping, it would be much cooler and more tolerable.

"Then you have the flip side--a couple hundred people leave the theatre."

But those people don't leave a vacuum. They are replaced with air from outside, which is hotter than the cooled air inside. Sure, you need to set the thermostat to a lower temperature than desired before the movie starts. But, once everyone is has taken their seats, you can set it to 25C or whatever. When the people leave and the hot air from outside replaces them, the AC will turn off and there won't be anything to force the temperature down below 25C. Am I wrong?

> They are replaced with air from outside, which is hotter than the cooled air inside.

That would actually make the response worse, not better.

Let's assume the AC is at steady state. It is pumping 30KW of heat energy out in order to maintain constant temperature. If everybody leaves and hot air comes in, the temperature rises and the AC system thinks "Temperature went up, I need to pump even more energy out."

The temperature needs to fall before the AC system starts backing off. However, by the time the temperature actually falls, the "velocity" of the temperature movement will cause the system to undershoot the target temperature.

This is a control systems problem. You can avoid over/undershoot (which a few people will complain about), but then you give up response time (which lots of people will complain about).

I've resisted installing an AC in my apartment for the last few years, even though temperatures have been over 30° very often during the summer.

Sadly, I work from home, and using a computer makes the heat worse, and working with a scalding object in a very hot environment lowers productivity terribly, and it doesn't seem like computers are getting cooler.

Have you tried with a fan or some cold showers? I also work remotely and often in tropical climates.

I did the math once, it takes about 3 watts of energy to remove one watt of energy (heat) from an average house in Texas when it's over 95F (35C) outside using a typical air conditioner.

That would be a COP of 1/3, or a EER of about 1. I'm going to assert that you probably messed up your math somewhere, seeing as an EER of around 11 at 95°F is pretty common. (And also represents roughly the minimum required efficiency of an A/C sold in Texas since 2006.)

Second- 1/3 is about what you'd expect for a Peltier module at a similar temperature difference.

It's the other way around. One unit of energy to remove three units of heat.

The best starting point is the government mandated minimum SEER of 13. The Wiki article on SEER works this out. The money quote is:

   A SEER of 13 is approximately equivalent to
   an EER of 11, and a COP of 3.2, which means
   that 3.2 units of heat are removed from
   indoors per unit of energy used to run the
   air conditioner.

That's the minimum. Anything higher than SEER 13 is proportionally more efficient.

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

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