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Air-conditioners do great good, but at a high environmental cost (economist.com)
271 points by lazerpants 10 months ago | hide | past | web | favorite | 420 comments

I am very skeptical.

Air conditioning has enabled large amounts of people to move from cold climates to warm climates (places like Dallas and Hong Kong basically wouldn't exist like they do without it). And there is a lot more energy spent heating in the north than there is cooling in the south. So on average, I would assume there is a net benefit if you consider the tradeoffs.

I think there is a stigma people have that heating is essential for life, but A/C is optional. But we should really compare them against each other.

A/C was considered absolutely critical in making Singapore's economy flourish, at least according to Singapore's ex prime minister: http://www.digitalnpq.org/archive/2009_fall_2010_winter/16_y...

Lee | Air conditioning. 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.

Someone should tell that to US government. The first internship that i had in a (state) government office would do early dismissal when the inside temp was over 90 degrees for 2 hours. It was a miserable experience.

I'm 100% certain that this is not the norm. However, there is good precedent for being more conservative with the AC than most Americans are. In at least one major European country, that is actually the law: new office buildings cannot have traditional AC.

My guess is that new office buildings have alternatives built into the design.

It’s possible to build buildings that are reasonably comfortable in high heat. It just costs more than a generic box with AC.

I'm guessing this is not France, Spain, Greece, etc...

You can get away with no A/C a lot easier if you're almost in the Arctic circle. In reality I bet this rule has a fairly minimal impact on energy consumption because the buildings didn't need much air conditioning to start with.

What justification is offered for reducing people’s quality of life like this?

Air conditioning uses large amounts of energy. This use has costs. Using it less reduces these costs.

Airbags have cost too. And big, fancy jets.


Or possibly to fight the climate change that will cause millions or billions to need to move in the next century.

Climate change.

Probably because most European buildings don't heat up that much. In the US there seems to be a likeness for no-insulation and paperthin walls.

I'm not sure if the country mentioned above is Germany, but well in Germany I've been in many (small and large) corporate offices without AC. It just gets hot in summer.

I honestly find working to be harder in that environment. German summers are traditionally not that long, but still it's two months of lower productivity.

There is one benefit though, shorts and sandals is accepted as office clothing.

and people commonly take weeks or even a month off in summer.

That's naive. Modern building code in the US is pretty/very heavy on energy efficiency. And of course European buildings heat up.

All new buildings in EU now have to be A+ energy efficient meaning it’s nearly self sufficient - heats up from human heat and air-to-air heat pump.

So, basically the same legislation as what California had implemented a few years before the EU.

You do realize that wooden houses are much better insulated than brick houses? With brick you have to add an insulating layer (Styrofoam or other materials), with wood the walls themselves are the insulating material.

I live in a country that uses traditional brick and mortar construction and I can tell you that American homes are far easier to condition climatically.

FWIW this was quoted in the article itself.

Also the cover photo I think is taken in Singapore on the service road behind Boat Quay about here https://www.google.co.uk/maps/@1.2868298,103.8492369,3a,75y,...

(though I couldn't get it exactly right on streetview)

This topic is also the theme of a rather good collection of essays on Singapore's politics by Cherian George - there's some available online here https://www.airconditionednation.com/

Well, Most of the govt offices in India do not have A/C even today. The have fans all over. I guess, the A/C became essential partly because of how we construct buildings - which trap all the heat.

This is a good, related, read "How air conditioning changed the world":


Why does the conclusion have to be "A/C Good" or "A/C Bad"?

In some cases A/C literally makes normal functioning possible, and is thus a boon to society and opens the argument to what level of environmental costs are worth it.

In other cases, A/C allows someone to not have to change to lighter clothes to be comfortable, or they have poor insulation and thus have to use A/C far more than they otherwise would. In these cases there is much less argument that A/C is worth the environmental impacts.

Exploring the difference is valuable - instead of arguing "Good/Bad", we can start arguing "How can we make things better?". Reducing unneeded A/C is just a good idea, and admitting that A/C has environmental impacts does not mean we have to instantly ban it.

We shouldn't compare A/C against heating because there's no value in knowing if one is "better" - we need both. We should instead act to reduce unneeded A/C use _and_ unneeded heating use (and to keep, if improve, needed uses).

In Hong Kong in particular I noticed that every commercial building seems to have the AC perpetually on 18°C (65°F) even when it's 30°+ outside. I don't get it because it just makes you have to take a jacket with you. Why not put the AC on 23°C (73°F) in summer?

Building managers love that, but people do not because buildings don’t heat evenly and solar gains will make many people uncomfortable at 72-73.

I keep my house at 78 in the summer. Enough to feel comfortable compared to outside, especially with the humidity reduction. When I'm at home I wear shorts and a light T shirt. Commercial buildings at 70-72 are uncomfortably cool to me when the outside temp is 90, but I agree that 78 is probably too warm for typical professional work attire.

I know somebody that bought a space heater in Australia for their office in Singapore because the AC was perpetually too cold. For obvious reasons, you can't buy space heaters in Singapore.

can only guess it's one of those modern buildings with glass curtain walls and in these buildings those sitting under the vents are going to be hit by a massive blast of dry, freezing air, and those next to the windows are going to be absolutely cooking.

There are studies regarding the ideal temperature for productive office work, and while the exact numbers vary and don't tend to be anywhere near as low as 65, the general consensus seems to be well under 73.

This is a well known issue and it developed historically because of business wear (suits etc..)..

The reverse issue is also common -- you need to go from your house (comfortable) through the outdoors (freezing cold) into the mall. The mall is kept at a toasty temperature, which means you arrive wearing heavy cold-weather clothing and immediately overheat.

I don't see how this could have developed from business wear.

I always thought it was a way to hide bad smells and dry out the place.

> And there is a lot more energy spent heating in the north than there is cooling in the south.

Source for this?

Makes sense, you typically need to raise temperature more in the winter than you need to lower it in the summer.

And you need heating non-stop in winter, while in the summer half of the day is enough many times.

Also, most people have heating, but only some AC.

This is actually correct, here is a comparison between Miami and Minneapolis.


TLDR: Minneapolis uses 3.5x the energy of Miami for climate control.

But isn't electricity much more expensive per energy unit than natural gas? I don't have an ax to grind on this, but it seems like comparing apples to oranges if cost is a concern (which it may not be).

"Efficiencies of power plants for the energy used for cooling relative to heating" is included in the number above. The factor is 0.5 for heating.

I wasn't referring to efficiencies. I was referring to dollars per unit of energy, as paid by the end consumer. That "study" explicitly says it didn't take that into account. Electricity is expensive, as anyone who has ever lived in an apartment with electric radiators knows. Natural gas is cheap. My electric bill exceeds my natural gas bill every month of the year, and I live in Minneapolis with electric AC, a high-efficiency natural-gas-fired furnace and boiler (the latter for in-floor), and a modern well-insulated house. My anecdotal experience led me to question whether that study actually showed what it suggested it did. On careful reading, it turns out I was right. People with an ideological ax to grind are bad at research, and bad at analysis. Data should lead the way.

>People with an ideological ax to grind are bad at research, and bad at analysis.Data should lead the way.

So why speculate and not use data instead?

Look at your bills and use the price of kilowatt of electricity and the price of CCF or MCF of natural gas to calculate the cost of MBTU. The above study came to a conclusion that you will use 3.5 MBTUs in MN for each 1 MBTU spent in FL.

In my case 1 kWt cost ~10c, 1 MCF of natural gas costs ~$12. At these prices 15 SEER AC will require ~$6.67 for 1 MBTU of cooling 95% Efficient Nat gas furnace will require ~$12.63 for 1 MBTU of heating.

Can you do the rest of the math?

Someday, preferably soon, we need to cut GHG emissions by 80% or more. That future is not compatible with widespread natural gas heating.

That future is exactly compatible with nuclear power, which when done correctly (almost never is) is cheaper.

Agree. It is odd though that this thread doesn't address clothing. It's fairy straightforward to stay warm in a cold environment using clothing, but impossible to use clothing to stay cooler in a warm environment. People up north, technically, probably use more energy heating than they really need to. (i.e., everyone could wear sweaters and coats inside.) On the other hand, in the south, A/C is absolutely essential to be comfortable.

It's hard to type with gloves on.

Clothing isn't the only option to stay cooler in a warm environment. Drinking water is quite effective. Just plain tap water is cool enough, but if you want to drink smaller amounts, there's always chilled water in the fridge or ice in the freezer.

I usually drink 4-6 litres of tap water while at work, and I have to use a personal heater at my desk to keep warm in winter (my co-workers complain if I set the thermostat higher). When it's summer, especially when it's 35+ degrees (95 F), I'm in heaven.

In fact, the coldest I've ever felt in my life (and I've lived in cold places like Moscow) was the one time as a silly freshman in college, when I drank just under a gallon of water (couldn't quite finish it) in under a minute on a dare. So very cold, and nothing could warm me up. Just had to wait it out.

You probably know already, but it's worth mentioning that drinking too much water can be deadly. There have been deaths in water drinking contests too.

Yes, the stunt I pulled in college was dangerous, but adding a gallon or even two to a healthy adult's water consumption throughout the course of a day is not. Especially considering the sodium content of modern diets. And those can be supplemented by snacking on crisps, pickles, or salted nuts, if needed.

Water drinking contests, along with overhydration during/after intense physical exertion (e.g. marathons, partying on MDMA), account for nearly all known cases of death from water intoxication.

Sure ... But I have always found it much less paintful to wear a jacket to stay warm than having only machine solutions for cooling off.

Dip shirt in liquid with boiling point lower than water. Re-wet as necessary.

Or weave sealed cells of a phase-change material with high thermal mass that melts at around 33 degC into your fabric, and freeze the garment before wearing it. This makes possible a thick, heavy jacket that you can wear to keep cool.

Are you suggesting that someone should wear a wet shirt so that they can stay warm? Or wear an ice cube to stay cool? I guess I'm missing the joke?

The intention, I imagine, was that the wet shirt keeps you cool by evaporative cooling.

Yes, exactly.

I suppose the vapor pressure could be lower than that for water, if there were effectively none in the air already. That would only be more effective than sweat on very humid days. You would be wetting your wet bulb with two different liquids.

The trick is to find one better than water that is also non-toxic, non-flammable, non-carcinogenic, and non-polluting. It would almost be easier to just remove all that water from the surrounding humid air, so that sweating works to cool you down again....

The phase-change material between liquid and solid would work better, but still requires a separate cooling technology to "recharge" it. And phase-change material still works better in building walls than in clothing. So you're right back to keeping your whole building cool, rather than a specific person.

You could also strap a personal radiator to your back, but no one wants to work on the tropical plantation in the first place, much less do it inside spacesuit-like apparel.

> Dip shirt in liquid with boiling point lower than water. Re-wet as necessary.

Can you recommend one suitable for regular use?

Ethyl alcohol is cheap, highly available; people are already familiar with its particular flammability and toxicity issues and are comfortable handling it.

You would not only get very drunk from that, you could damage your skin and/or catch fire, if there is a source of ignition.

There are a few liquids that would work. One example is the refrigerant HCFC-124. However, all of these liquids are chlorofluorocarbons, and cause much more damage to the atmosphere than any amount of A/C usage. Pretty much all volatile organic compounds fall into at least one of three categories: flammable, toxic, highly potent greenhouse gas.

Don't forget carcinogenic, teratogenic, corrosive, unbearably stinky, and insect pheromone.

For instance, you wouldn't want to smell like a ton of bananas all the time, or drive honeybees into a frenzy every time you pass by.

I'm comfortable pouring diluted alcohol in a glass and drinking it, not with soaking my clothes in it and covering large areas of my body in a continual bath of flammable liquid that also dries out my skin.

To heat, you just run the electricity through resistance. To cool down, you need to run a compressor, it's pretty energy-intensive. Anyway, each place has a different cold/warmth quota so you can't issue a universal rule.

Heat loss through a surface is proportional to the difference in temperatures from one side to the other.

So if you are cooling a house to 70 degrees in 90 degree weather, you are fighting a 20 degree difference.

If you are heating a house to 70 degrees in 30 degree weather, you are fighting a 40 degree difference.

In a severe heatwave, you might spend weeks with much of the day at 100 degrees; during a cold snap last winter, there was a span where I live where the temperature was usually around 0, and never higher than 10 degrees.

Meanwhile, a furnace works by directly converting energy to heat; for simplicity, let's assume a heater generates 1 unit of heat for 1 unit of energy (it's 100% efficient).

An air-conditioner, however, moves heat, moving heat from inside to outside. An air conditioner doesn't use 1 unit of energy to move 1 unit of heat; an air conditioner might move 3 units of heat using 1 unit of energy.

So putting the two together, it takes roughly 6 times as much energy to heat my house on the coldest days as it does to cool my house on the hottest days.

The full answer is a lot more complicated than that, because other things in houses are generating waste heat and you need to look at the deviations above and below your target temperature range over the full year and across many different places. Someone else has already posted a link to US energy usage showing that total energy spent on air conditioning is a fraction of that spent on heating, but from the above you should be able to get an intuitive feel for why that's so.

> an air conditioner might move 3 units of heat using 1 unit of energy.

So run that system backwards for heating, and you would at only use twice the energy for heating. That said, you can typically cut your heating bill in half using ASHP, with it losing efficiency as the outside temperature decreases. It rarely goes below a COP of 1, so it makes sense to use in place of resistance heating.

However that assumes that you must use electricity for heating. Using wood for heating, you are using a renewable resource that is cheaper for every unit of heat you get.

The downside of electric heat pumps is that they simply don't work when it gets too cold outside. They can't push the thermal gradient hard enough and end up switching to inefficient resistive heat. Go far enough north and even the resistive heat doesn't work very well and everybody uses gas.

When the correct gas is used, they are more efficient than resistive heating down to -20-30 C. Very few places in the world get that cold. That said, and as I mentioned, using wood or district heating, is far more common in those parts of the world. At least in Europe.

Very few places, like all of Canada, parts of the northern US, Alaska, most of Russia, etc...

Even then you have to be willing to keep the thermostat set at 55F/13C or the resistive heaters are going to kick in.

I'm unsure if you know how cold -20C actually is. At -20C outside you can still get an efficiency of 2.0. The majority of Canada does not reach that temperature outside of a few cold spells. Only two handful of cities in Canada have nights with less than -30C. In other words, the majority of time it will be more efficient than resistive heating. The north or interior of Alaska is typical mainland climate and very cold, and same goes for Russia. In both countries a non trivial part are not that cold. The majority of the world are simply not so cold that resistive heating is better than an ASHP system.

That is not to say gas isn't cheaper.

> An air-conditioner, however, moves heat, moving heat from inside to outside. An air conditioner doesn't use 1 unit of energy to move 1 unit of heat; an air conditioner might move 3 units of heat using 1 unit of energy.

Be careful, you're angering the thermo gods! If that was true, I would simply use an air-conditioner to heat my house. Cool, the outside and move the heat inside. In reality, you have the efficiencies backwards. Cooling is more energy intensive than heating.

> If that was true, I would simply use an air-conditioner to heat my house.

It's true, and people do. Install a heat pump, and save your traditional heat source for when it's sufficiently cold outside.

Heating using resistance is inefficient and gets you at most 1 unit of heat energy per unit of electrical energy. Heating and cooling using heat pumps can move more than one unit of heat energy per unit of electrical energy.

Heating via electrical resistance is 100% efficient. All energy goes into generating heat. There is no loss.

Gas heating is something like 90% efficient now.

People, stop. Downvoting doesn't change facts.

> Heating via electrical resistance is 100% efficient.

No, this is quite wrong. You're not taking into account generation and transmission losses. Gas heat is actually much more efficient than electrical resistance heating.

Plus, as others are saying, using energy to move heat from one place to another allows you to move more heat than you could generate just by converting the energy to heat.


Your pedantry only works in a closed loop where all externalities are accounted for.

There is no real world scenario in a place that has a beating season where the cost to the consumer is better with electricity versus gas or oil. Electric costs about 4x for whole house heating in my neck of the woods, and houses quote electric only heat sell at a discount.

My guess is that your evaluation of electric externalities doesn’t include the health impacts of burning coal, ecosystem damage due to hydroelectric or long term storage and other capital costs incurred by nuclear generation.

> There is no real world scenario in a place that has a heating season where the cost to the consumer is better with electricity versus gas or oil. Electric costs about 4x for whole house heating...

I guess I live an unreal life. All of my heating and cooling is electric. My bills are lower than anyone I've compared with and in every case I'm heating and cooling more square feet. The magic? Ground source heat pump. Several people tried to talk me out of it and I'm glad I didn't listen.

That’s awesome — it tends to be a capital cost that people cannot afford to retrofit.

In my area, you need to drill deep wells for heat pumps to work. Our local branch library did it and it cost about $40k.

That's great — really, it is; if I ever get to build a custom house, I want to use a ground source heat pump — but we were specifically arguing over electric resistance heating.

I guess I missed that. Yes, electric resistance heating is horrible on the wallet.

I have electric resistance as a backup to my heat pump, only because they wouldn't install it without it. It would cost so much to run I have the breakers turned off just so it can't be shocked by my bill.

Yes, 100% is inefficient because you can get higher ratios if you use heat pumps. The loss is that you are using more energy compared to how much energy you would use if you had a heat pump instead.

That's not efficiency. That's an efficiency ratio, which is different.

Heat pumps have a higher EER, but also higher parasitic losses, which is the source of confusion on the whole thread.

It's like claiming that rockets are "more efficient" than cars because they move you faster.

The reason you are being downvoted is because your argument basically boils down to having an unreasonably narrow definition of what “efficient” means. In context, it’s obvious that “efficiency” here is the ratio between the amount of heat provided and the amount of energy spent. You might call it EER, I might call it COP, but it’s irrelevant because in context the word “efficient” is unambiguous.

Narrow interpretations of definitions to support a point don’t actually provide much useful insight to the topic being discussed, and are seen as distracting. So these non-useful comments are being downvoted to make them less visible. It is not an issue of whether they are technically correct.

You could probably make an interesting point about the electrical efficiency of heat pumps, or you could make a comment about terminology and explain that “technically” the correct term is X, but instead you chose to interpret a term in a way that contradicts the contextually obvious meaning and then base an argument on top of that.

My account is rate limited. Responding here, then going away.

"arrow interpretations of definitions to support a point don’t actually provide much useful insight to the topic being discussed, and are seen as distracting. So these non-useful comments are being downvoted to make them less visible. It is not an issue of whether they are technically correct."

Except, I'm not arguing for or against a "point", only that the terminology was wrong. But it does matter, because it leads to confusion, and if you stop to think about it for longer than it takes to jab at the downvote button, the reason why it matters is interesting.

It's not that people here are thinking about the subject carefully, they're just disagreeing reflexively.

If your goal was to argue that the terminology is wrong, then you’ve made some errors in formulating that argument—both logical errors and social errors. We all like a good pedant but you have to be upfront about it and explain why using the correct terminology is important. You failed to do either, instead, your arguments appeared to be arguments about conclusions rather than arguments about definitions:

> Heating via electrical resistance is 100% efficient. All energy goes into generating heat. There is no loss.

This sounds a bit coy, doesn’t it? It’s a bit suspicious that heat pumps are completely omitted from your comment, and it’s also a bit suspicious that explicit discussion about terminology is omitted, and instead the definitions are included as a presumption. Putting the main point of your argument into a presumption of the actual text of your argument is nothing short of poor form (i.e. rude) if done purposefully, and the rest of the argument built on top of these presuppositions is boring and uninformative.

If you can imagine a better approach, consider discussing the terminology and definitions directly, and then explaining why sloppy terminology can cause confusion. You have still not explained why the terminology is so important here. Instead, you’ve made the following statements:

> …if you stop to think about it for longer than it takes to jab at the downvote button, the reason why it matters is interesting.

> It's not that people here are thinking about the subject carefully, they're just disagreeing reflexively.

Consider whether these statements make claims about the internal thought processes of people who disagree with you, and whether making claims about how other people think will further whatever goals you have commenting on this site.

> Except, I'm not arguing for or against a "point", only that the terminology was wrong.

The problem is, the terminology is only wrong if you take an extremely narrow approach of "heating" being "generating heat". But it's quite obvious that we are discussing heating of an enclosed space. And it doesn't actually matter at all whether that heat being placed into the closed space was generated from raw energy within the enclosed space, or moved from externally into the enclosed space. And if there is no difference between these two options, you can achieve greater than 100% efficiency between energy-spent and heat-provided by moving the heat.

> It's not that people here are thinking about the subject carefully, they're just disagreeing reflexively.

Voting isn't specifically for correctness/incorrectness, but encompasses many things. In this specific case, I think the voting reasoning or on your comments can be likely be summarized as "is the comment contributing usefully to the discussion, or providing useful or insightful information in some other way". I think people aren't viewing your comments in this discussion as providing that, and some people may believe they are actually the opposite.

The only reason behind that difference is because it's not generating heat, but moving heat. The difference to users is unimportant. As long as BTUs are pumped into / out of their closed environment, their needs are being met.

And the bottom line is that for the same unit of energy used to generate 1 BTU from resistance heating, we can move several BTUs.

EDIT: I'd also like to note that heat pump systems which include resistance heating systems will typically mark them as "emergency heating". Because they are less efficient, unless it's so brutally cold outside that the heat pump has dropped below 1 EER or can't even operate properly.

EDIT2: I forgot that the units in SEER are not the same on both sides of the ratio. (That is, it's not actually a ratio, since those are supposed to be unitless.) So my original "13+ BTUs" was high. Changed it to a non-descript weasel-word instead.

This one I don't agree with. Heat pumps are typically a few multiples as efficient in terms of KW in to heat BTUs out. I'm not sure what useful point you are trying to make with this particular comment.

I often find that it surprised people to realize that a heat pump is effectively >100% efficient.

Ok, it might be better than heating via burning gas or coal. It's still less efficient than a good air conditioner.

I'm upvoting you, because it always irritates me when people refer to resistance heating as "inefficient". It is true in specific ways and its useful to understand those ways.

It is nice to know that the conversion from electricity to heat is effectively 100% efficient and we are really making a cost comparison instead.

This is backwards; while it's true that a resistor is less mechanically complicated than a compressor-expander-condenser heat pump like an air conditioner, the coefficient of performance for a resistor is limited to 1 (and is very nearly 1, say 0.9999), while the coefficient of performance for such heat pumps is 2–6. That is, for every joule of energy you burn up in the compressor, you transfer 2–6 joules out of your living space into the outdoors.

I know, that sounds crazy, and sometimes the CoP is given as an "efficiency", which makes it sound even crazier — a CoP of 2.0 is "200% efficient"! But it's not science fiction; it's a simple consequence of the Carnot cycle being reversible and the Carnot efficiency of heat engines at ordinary temperatures being quite low.

Actually, compressors use very little energy if you keep them running.

They use a lot of energy when they turn on initially, after that, its very little . Ive been working on smart thermostats that take advantage of this phenomenon to lower HVAC costs.

So you are saying that it's better to run a modern AC (inverter, all that) continuously on a low power than every hour or so? I'm thinking in context of cold leak (through windows, ...)

Actually, yes. The most high-efficiency central AC systems on the market use variable flow for exactly this reason. Below that are two-stage systems (low and high flow), then single-stage systems. Reliability and cost does play a part in all of this, though. [0]

AFAIK, the most efficient residential systems are ductless split systems, where you basically have a centralized compressor and distributed air handlers in individual rooms. This allows for variable flow and localized control, which reduces need.

[0] https://en.wikipedia.org/wiki/Seasonal_energy_efficiency_rat...

> But when either replacing equipment, or specifying new installations, a variety of SEERs are available. For most applications, the minimum or near-minimum SEER units are most cost effective, but the longer the cooling seasons, the higher the electricity costs, and the longer the purchasers will own the systems, the more that incrementally higher SEER units are justified.

Yes, exactly.

In most cases doesn't it take less energy to move head (aircon) and more to generate heat (resistive heating)?

That’s not how heat pumps work, heat pumps in air con can essily get 1:5 ratio the best radiative heating can do is 1:1.

Actually, heating with a heat pump is much more efficient than using a resistance.

That's mostly true, but only if the temperature difference isn't too high. During the coldest days of winter -- or when boiling water, I'd imagine -- the COP can be as low as 1, ie the same as resistive heating.

For the same amount of heat moved, resistive heating is much more energy intensive than the A/C compressor. Heat pumps are about the same, though.

This supposition and guessing doesn't really qualify as a source.

Here is a source for US energy consumption percentages, 1993 vs. 2009: https://www.eia.gov/todayinenergy/detail.php?id=10271

But for heating you don't have to use electricity, you lose less energy burning propane for heat than if you burned propane to make electricity to deliver 100 miles away to turn back into heat. And there is always the option of wood burning which is common in northern areas and also renewable and cheap. Producing heat is 100% or more efficient, producing cold air is far less efficient.

Even really nice furnaces lose some energy up the flue, so they are less than 100% efficient. They hit ~95%, which is really good, but it's less than 100%.

Heat pumps can exceed 100% efficiency (as measured by heat moved into the building divided by energy input to the heat pump).

If we are being pedantic, they aren't furnaces with flues.

> And you need heating non-stop in winter

No you don't. I don't know anyone who leaves their heating on at night. In the winter I run my heating for a few hours a day maybe.

You must live in a warm place because if I turn off the heating when it is 0 degree celsius outside, then I wake up in the middle of the night because my face is numb.

You should invest in thermal insulation. When I turn off the heating for a weekend, and there is cold outside, the temperature inside only drops ~2-4°C during the whole weekend.

The house as insulated as it can be without costly work being done on it and trying to plug up every leak. It seems like you either have a small residence or state of the art design to only drop 3-4 degrees after an entire weekend, or that you also live in a warm place.

I live in Montreal and my house is well insulated. Even with a single A/C unit I can keep my house comfortable during a heatwave (one of which we had this summer that was devastating for the province). My summer electricity bill is about 1/4 of what it is in the winter time.

A big factor in this is how much it cools off at night. It’s easy to cope with heat and design buildings around cool nights, but when the overnight low is over 90, you need air conditioning.

Cooling in the north is not expected to be the same. ;-)

In my region of south eastern Canada the summers seem to be hotter and seem to be lasting longer. Today for example 27C and 80% humidity. Normally 15C to 20C and low humidity would be normal this time of year.

With the cost of fuel oil (common here) many people have installed supplemental heating in the form of heat pumps. The side benefit is they also have cooling capabilities.

My point, the local power company said in a news release power use during the summer took a big jump. But even with all the A/C units in use power use is still 20% lower than in winter, heating uses much more energy (and many people also supplement with wood).

That's because your winter is more extreme. In any modestly hot country, electricity consumption peaks in summer.

Also not every house in Canada has AC....but ALL have heating.

What about lighting?

In Calgary it's dark from 18:00 to 09:00 in December, but only from 23:00 to 05:30 in July.

If you have modern energy-efficient lighting, it uses very little power.

If you have traditional filament bulbs, it supplements the heating in winter!

The delta for AC cooling seems to be <10C, the delta for heating could be up to 50C. So it seems pretty sad that the energy consumption is only 20% lower.

Except your house is heated by literally anything that's doing anything inside it (like your own body, cooking, using a computer, taking a shower, ...), meaning it never reaches the outside temperature except if it's inhabited for a long period of time. Meaning cooling have to compensate for every bit of activity, whereas heating doesn't.

Heating in Canada will use ~kW, in the summer I'm not using any device in that order of magnitude, including humans (which are what, 100W?).

If I remember correctly, the energy use of heating/cooling is related to the square of the temperature difference, so if ACs with a low temperature delta use nearly as much energy as heating does in winter, with its higher delta, it indicates that there may be a lot of waste.

Plus people here have to learn that insulation is for hot or cold. Many people open their windows on hot days then complain it's hot in their houses.

It wouldn't take as much energy if people would close their windows.

And my dad leaves the AC on all day. I said just turn it on ten minutes before you go in the room it will probably do the same and be cheaper.

Also, over similar temperature differences, AC is more energy efficient than heating.

With AC you only move the heat, so spending 1 unit of energy you can move 2 or 3 units of heat. More, if the system is highly optimized.

With heating, you need to spend 1 unit of energy to create 1 unit of heat.

(Unless you heat with a heat pump. But even then, pumping heat for heating operates on less favourable temperature differences than pumping heat for AC.)

> Unless you heat with a heat pump. But even then, pumping heat for heating operates on less favourable temperature differences than pumping heat for AC

Modern split-system air conditioning units are just heat pumps, and often they are actually more efficient at heating than cooling. For example, Mitsubishi Electric units give out 4-5x the amount of heat vs amount of electricity put in. They will comfortably work at this efficiency down to around -15c (below that the efficiency reduces, but it's still higher than an electric radiator) so are suitable for most climates.


I'm rather surprised they are't more common here in Northern Europe, where a lot of residential heating is powered by electricity. Compared to alternatives like storage heaters, they aren't that much more expensive. And you can use them in the summer for the occasional heat wave :)

Here in England we heat by pumping fairly hot water through metal radiators, heated by gas or oil. A heat pump produces only lukewarm water at a slow but efficient rate. It is really hard extract the heat out of lukewarm water into a room, often the typical UK room loses heat faster than you can get it out of the water. (Hot water heats the room much more easily). As such the early adopters of heat pumps have expensive items that barely heat their houses and when they try to get more heat out of them in a hurry they become very inefficient.

There is almost no domestic air conditioning industry. On the rare occasions it gets too hot we open a window and thank the Gods. Thus there are very few cheap and reliable domestic suppliers of air conditioners for heating. And the air heating ones are tarnished by our experience with the unsuitable water heating ones.

So we burn oil/gas or electric storage heaters... Achieving a 300% efficiency and actually being able to heat a poorly insulated UK room just sounds too good to be true.

In northern Europe where ground source heat pumps are increasingly popular, houses built with those typically heat via coils installed in the floors. As you say, with only lukewarm water radiators by the windows (the traditional solution for oil/wood/etc. heating) aren't enough.

Again it sounds great but I know people whose underfloor coils started to leak at which point the system is written off... Retrofitting anything to an existing solid floor is a nightmare as well.

Sorry to be so negative. But that`s why so few of us have heat pumps... Its a shame, the air to air ones sound great on paper, much better than a £600 storage heater but I just can`t bring myself to trust them.

What? Can we start with an example such as: 1) Take a room starting at 20C, how much energy to get the room to 25C? 2) Conversely take a room at 25C, how much energy to get the room to 20C?

Intuitively heating should be cheaper, since loses are heat. Whereas with cooling you'll have inefficiency (e.g. in the pump) in the form of heat, therefore more energy to remove that additional heat.

Yes, look up the Coefficient of Performance: https://en.wikipedia.org/wiki/Heat_pump#Performance_consider...

A typical AC can take 1 kW of input power and remove ~3kW of heat energy from the room. The outdoor part of this system is heated by 4 kW, because you put the high-power stuff outside, where it's unimportant to performance. You can't thermondynamically make an AC work if it's purely in the room.

With resistive electric heating, you put in 1 kW of heat and the room temperature increases by 1 kW of heat energy.

With a heat pump in heating mode, you can put the inefficiency to use, using a 1 kW input to extract 3 kW of energy from, say, the ground, and putting 4 kW of energy into the room.

Two main problems with the argument: Cooling, as you say, is typically 30->25. Heating is often 0-25, requiring 5 times more energy (though we should be doing this in Kelvin...) Second, heating is super easy to do thermodynamically by just burning dirt-cheap natural gas. For a Michigan anecdote, I paid about $150/mo to keep my house cool in July, and it's typically $100 to keep my house warm in January.

> You can't thermondynamically make an AC work if it's purely in the room.

If you do keep it in the same room, it's called a dehumidifier. :)

(And yes, that's why air put out by a dehumidifier is warmer.)

> You can't thermondynamically make an AC work if it's purely in the room.

Could an AC that created matter from energy work?

> Cooling, as you say, is typically 30->25. Heating is often 0-25, requiring 5 times more energy

This argument seems flawed. You don't cut the heat off every night and let things cool back to ambient. You maintain a stable temperature.

The air outside right now where I am is 0.7 degrees, I have my heat pump set to 21 degrees.

What the parent comment neglected to mention is the working temperature of the gas / fluid in the heat pump.

R410a boils at -48.5 degrees[1]. So based on the size of the system and some maths I couldn’t explain so I’ll hand wave away, there’s your answer. Sorry, that’s the best I can do, you’d have to read some Wikipedia entries to get a better understanding.

Modern heat pumps / AC can be up to 1:4.5 thermal efficiency, but it depends on the the temperature difference, the size of the system, and what you’ve got it set to.

Other places I’ve lived it gets to 48 degrees outside and you set the AC to 17 degreee because Australians are really bad at insulating their homes, so a 31 degree temperature difference, so in that sense the parent comment is flawed.

1. https://en.m.wikipedia.org/wiki/R-410A

The rate of heat transfer through walls and windows also depends on the temperature differential.

Sure, but modern insulation is pretty darn good.

Also the sun will be adding some amount of heat during the day, which helps in the cold but makes the situation even worse in the heat.

> You can't thermondynamically make an AC work if it's purely in the room.

We have two AC units in our home that are entirely inside, there is just a hose connecting the unit to the window and the hot air is blown through the hose.

"Purely in the room" in this context means a closed system - in your house you are still dumping the excess heat outside your system

By "purely in the room" I imagine they meant within a closed system. By having a hose connecting your units to the outside world your room is no longer a closed system (ignoring things like drafts and imperfect insulation etc that already prevented it from being considered closed).

The way modern heat pumps work, I can't answer your question yet. What's the outside temperature? Let's say that taking your room from 15C to 20C takes 1.0 energy unit. If it's 15C outside, then I can use a heat pump to gain a bunch of efficiency, say only using 0.2 units of electricity to heat up the inside by one unit. If it's 25C outside, I can do the same in reverse, but I do have to also cool the A/C. We'll say taking the room from 25C to 20C when it's 25C outside takes 0.25 units.

The problem happens when there is a big difference in outside temperature. All of the gains of heat pumps disappear. So cooling from 25C inside to 20C inside when it's 30C outside might take 0.5 units of energy, which is a pretty common case. Heaters generally have to deal with much bigger swings, though. It's not uncommon to heat from 15C inside to 20C inside while the outside is at -10C, which takes (asymptotically approaching) 1.0 energy unit.

So the inefficiency of the A/C producing heat does matter, but not as much as the difference between the desired temperature and the outside temperature. The rate of heat transfer of the house also depends on the difference in temperature. Keeping a house 10C cooler than ambient takes less energy than keeping a house 20C hotter than ambient.

Considering that temperatures on Earth vary from about -90C to 50C, and humans like to keep indoor temps around 20C, cooling is generally more efficient than heating.

Heat pumps can move more than one unit of energy from A to B for every unit of energy they consume.

You can use heat pumps for heating as well.

So you move the heat and then... magic cold air comes instead? We assume the ambient temp. is "hot", not just the system to be cooled.

You move the heat and some air becomes colder (inside) and some air becomes hotter (outside). Any sufficiently advanced technology is indistinguishable from magic.

The key feature I've missed is that "moving heat" does not imply moving the hot air itself.

When you compress a gas, it releases energy as heat. When the gas expands, it absorbs energy by getting cold.

This gas is the refrigerant that the article refers to. Basically, what air conditioners, refrigerators, heat pumps, ect, do, is compress and expand the gas in a closed loop.

The whole theory behind a heat pump is that you get more heat, per unit of input energy, than if you used the input energy directly for heat. The consequence is that you end up blowing cold air outside.

plus there is still a lot of heating done with oil and even coal in some places. the temperature difference alone should point to heating being more expensive. (going from freezing to acceptable is a lot more energy than from hot to the same temperature).

throw in the added benefit of AC is humidity control and AC is just a win win tech.

There's also a lot of heating done with wood stoves, burning renewable locally sourced wood, too. Depends a lot on local context.

Also, there's a lot less efficiency loss burning oil directly for heat, compared to burning oil for steam for 40% electricity which then gets turned into AC with some further efficiency loss. I expect the AC cooling might still come out on top, but not be nearly as much as implied.

Humility makes this less true than you would think. AC’s drip water because they condescend it from the air which takes lots of energy.

I can't tell if this is a weird attempt at a pun, a funny typo, or some kind of koan.

It’s not the heat it’s the humility.

> I think there is a stigma people have that heating is essential for life, but A/C is optional.

I don’t know if it’s a stigma but it’s arguably a myth. Having lived both in areas where 40C is normal day after day in the summer and other areas where 0C (or below) is normal day after day in the winter, I can tell you which of heating and cooling is optional. In the extreme heat, as long as you drink enough water, you’re usually fine without air conditioning (but very uncomfortable). In extreme cold, blankets only go so far and you risk dying if the heat goes off. In my view one is definitely a luxury and the other is not.

Actually curious: is there anywhere on earth that the heat (by itself, assuming proper hydration) will kill you like the places on earth where the cold will kill you?

Temperatures over 105°F/40°C can be deadly for some people. Hydration is just one of several factors that affect how much heat the human body can handle. As far as I know, a reasonably healthy person with hydration and shelter wouldn't die from the heat alone anywhere on earth. But people often can and do die during heatwaves in many parts of the world.

In the near future, climate change will make wet-bulb temperatures higher than 35 C / 95 F possible. At that point, you are no longer able to sweat to cool your body. This can kill you in fairly short order.

In 2003 a heat wave was blamed for 70,000 deaths in Europe (mainly France)

On the other hand wi yet 2015 was blamed on 40,000 deaths in the UK alone

2003 was a wake up call. The heat wave this year was the second hottest since 2003 and there have been a lot fewer deaths (at least in France). People are better informed and the health professionals are better prepared.

I consider this stigma the other way around, though I live in a much colder country; an A/C is essential because cooling yourself off is hard.

On the other hand, you can forgoe heating by buying another thick blanket, keeping warm is relatively simple compared to keeping cool, notably because the human body naturally produces heat. All you need to do to keep warm is to prevent it from going away.

> places like Dallas

...and Houston which is further south and has a subtropical climate. It boomed in population after A/C became a standard thing.

> I think there is a stigma people have that heating is essential for life, but A/C is optional.

Yes, and A/C is a public health issue. In subtropical climates it keeps people indoors and away from disease carrying insects such as mosquitos.

But is there really a need for people to live in places like Houston? It's not like the US lacks places with a temperate climate.

Sharlin says> "But is there really a need for people to live in places like Houston?"

Houston _is_ a hellhole part of the year. But ports are necessary and, while they needn't be cities, they usually are.

Two things about that:

- Regardless of climate, cities are too often built in regions that are prime river-bottom farmland. It would have been better if such lands were left for farming (since they flood easily and harbor disease) and the cities located at higher elevation.

Houston was built literally in a swamp. Part of this is it's use as a port city, but it didn't have to be that way. Thanks to storms and flooding the city is slowly moving to whatever higher ground there is (honestly there isn't much).

But as long as the government provides flood insurance at bargain rates, developers will build new homes in flood-prone areas and sell the homes to suckers who don't know any better. The developers sell out and move on to new projects, the homeowner gets flooded and the government(taxpayer) pays for the stupidity and inefficiency of it all.

- Houston's humidity is high, so the usual pressurized A/C system is required. Dallas in contrast has low humidity so that evaporative A/C systems, which are much cheaper to build and to operate, can be used very effectively:


It seems like you could keep flood insurance and provide the right incentive for developers if as part of the permitting process for developers, they'd have to put up an insurance bond (or otherwise pay into a risk pool).

Is the net gain better than the net loss from flooding? For example, Houston doesn’t have to salt roads, plow snow or mitigate against earthquakes. You don’t have a wildfire risk, nor mudslides. So even if you have periodic floods, it would seem that the positives outweighs the negatives. You also rarely have airport closures or delays due to weather. It’s simplistic to cite flood risk as a reason not to build somewhere. If the cost of a flood is offset by the savings in many other areas, it could be a net positive. There is, however a hurricane risk, but even New York City and most of the Atlantic and Gulf Coast faces those risks. In the Midwest, you have tornado risk plus blizzards and snow, in California, you have fires, droughts and earthquakes.

We could argue, under the same logic of not building in Houston, that the Netherlands ought not be developed given their elevation.

> It’s simplistic to cite flood risk as a reason not to build somewhere.

I didn't say people shouldn't build in Houston. I proposed a framework under which the economic incentives would presumably provide improved signals about whether building/living in Houston was a better idea than doing so elsewhere: require developments built in areas that can make federal flood insurance claims to pay something into the risk pool. Developers and potential residents can decide if the rest is worth it.

Costs like plowing snow or risks like earthquakes and wildfire risks seem to be covered by local taxes and/or private insurance. If the savings Houston achieves from having no need for them really do outweigh the problems of flood risk -- as your comment seems to suggest -- then presumably Houston would remain an economically appealing place to live even after my proposed change.

Presumably the same thing happens with the Netherlands and the Dutch bear the economic costs knowing it's worth it.

FWIW Houston does salt roads infrequently in the wintertime. So they had to invest the capital and gain the skills to do so. They simply use less salt than Detroit each year.

Under current incentives, the positives of living in Houston certainly outweigh the negatives. Otherwise people would not live there. But were the externalities exposed and the costs shifted away from the taxpayers, then the population map would undoubtedly shift Northward.

Part of the problem is that most of Houston is near sea-level and flooding occurs where there is heavy rainfall, a random process. This problem exists for adjacent areas, out to San Antonio and Austin. Typical political response to flooding is to build a dam or holding reservoir, whereupon the next heavy rainfall occurs in an area above, below or away from the dam...build another dam/reservoir...rain falls somewhere else.... You get the idea.

Then there are hurricanes, their associated storm surge and flooding which simply overwhelm any dams/reservoirs.

The idiocy/malfunction of society vis-a-vis housing development and flood-prone regions is only one example of many such economic externalities:


What appeared to be a good idea intended to help a relatively small group of suffering people turns out to have been sponsored by a much smaller group of extremely greedy people (here, developers and insurance companies), all to the detriment of taxpayers (who weren't/aren't paying enough attention). Adam Smith's "invisible hand" once again spanks humanity's butt:

“People of the same trade seldom meet together, even for merriment and diversion, but the conversation ends in a conspiracy against the public, or in some contrivance to raise prices.”

- Adam Smith.

My mantra is "Flooding is Nature's way of telling you to move." regardless of whether you're speaking of storm surge in Houston or flash flooding in Utah. I see no reason to live in a region encircled/protected by a dam or seawall

And once you start attempting to dam off the sea, taxpayers never cease paying for it. There's a proper myth and a term for that - Sisyphean - although the phrase "spitting into the wind" (and variants) comes to mind also. BTW did you know that Galveston was once the largest port city in Texas? It was wiped out by the 1900 hurricane (6,000-12,000 dead) although people continue to live there today:



Or basically anywhere not the west coast, within a few miles of the water? In Chicago you have heating in the winter and AC in the summer. Same with NYC. In the California central valley, your AC will be running a lot of the time. Wyoming, some serious heating, Etc.

>> But is there really a need for people to live in places like Houston?

No, if we can all live without food. Plants love the hot parts of the world. The prairies bake in the summer.

I'm reminded of President Bush visiting the John Deere factory. He asked a worker about the most important innovation for combination harvesters. Without hesitation: "Enclosed cabs with air conditioning".

I’m pretty sure though that a large majority of people nowadays living there are neither farmers nor work in jobs directly supporting said farmers.

Where exactly would you draw the line? Should farmers live alone in bunkhouses like loggers do? Farming and farmers are tied to land for years, decades. They need innumerable support services, from pilots and engineers to kindergartens and dentists for their kids. I'm hard pressed to point to any job in Iowa that doesn't in some degree support farmers and farming.

Then add all those involved in resource extraction, mining/oil. Their jobs are location dependent too. They also need services.

I type this while at work (military) with two doors open to outside. There is a pleasant breeze passing through the office. This weather holds for more than half the year. But if one more person moves here, driving up my rent again, I'll start running the AC just to speed up climate change.

Can you have it both ways? You could also say "is there really a need for people to live in places like Africa? India? Indonesia?"

But the GP’s argument was that AC is good because it made populating places like Texas possible. But was it worth it to populate those places in retrospect if it depended on a technology with known negative externalities?

Similarly, the personal automobile made urban sprawl possible. But is sprawl and ensuing car-dependency a good thing all things considered? Many would say no.

It's market forces at work with little regulation, especially in places like Houston. Real estate prices are much more appealing in places with extreme temperatures. We all couldn't afford to live in temperate climates like the bay area without some extreme zoning density regulations.

You could even extend that argument to include "is there a need for people to live in a place where they can't grow enough food to sustain their population".

I wouldn't pull too hard on that thread here, though.

It's a good port city in land (swamp) that is otherwise undesirable, so yes.

(I'm posting from Houston.)

There's a popular Houston real-estate blog called... Swamp Lot. Can't make this stuff up.


What? Where? Your only option is the West Coast and literally the coast. If you go 50+ miles inland you'll burn up in the summer.

I think the difference is A/C is more of a modern comfort that allows us to live in hot places. People could live in cold places without any modern technology or utility service. Fire and a pile of wood was all it took. Both are essential in either extreme, but we've had one solved for much longer.

I'm from the Midwest and I now live in New York. My heating costs are significantly less than my A/C costs. My energy bills increase dramatically in the summer. Is my usage not typical? Or are there "hidden" costs I'm not considering?

Second: isn't the shift you describe also a significant contributor to sprawl, which also increases energy waste?

I grew up in central Florida in the 1960s. Our house and many of our school rooms didn't have air conditioning until the mid 1970s. It's doable: brick school rooms are a decent insulator. Jalousie windows in every house.

I had bad luck arguing this a couple of weeks ago.


I personally consider air conditioning one of the pillars of civilization.

The article points out the issue with AC isn't energy/CO2, it's refrigerants.

>Second, air-conditioners use so-called “F gases” (such as hydrofluorocarbons, or HFCs) as refrigerants. When—as is common—the machines leak in use or on disposal, these gases escape, doing vast damage. HFCs trap between 1,000 and 9,000 times as much heat as the same amount of CO2, meaning they are much more potent causes of global warming. On this basis, Paul Hawken of Project Drawdown, a think-tank, calculates that improving air-conditioners could do more than anything else to reduce greenhouse gases.

And yet "spray duster cans" are refrigerants sold to be purposely vented.

A while ago (back when Google worked) I stumbled upon a refrigerant hacking page that detailed DIY retrofitting of refrigeration equipment to use propane as the refrigerant instead. Obviously the flammability is a problem, but as standard refrigerants seem to be pressing towards the flammable-with-harmful-combustion-products direction, I wonder why the industry isn't reconsidering. It seems nicer to have a plain fireball rather than one which creates hydrofluoric acid.

Refrigerating and air conditioning equipment can use plain hydrocarbon refrigerants such as propane and isobutane. US approval is fairly recent -- less than 10 years ago -- as you can see in this EPA table:


I believe that products using these low-GWP, zero-ODP refrigerants are marketed using the term "Greenfreeze."


Here in Europe (and I believe in many other parts of the world as well) propane and butane have been the standard refrigerant in domestic appliances for a couple of decades. I think the industry went straight to these when CFC's were banned.

Considering that your average refrigerator contains a quite modest amount of refrigerant, compared to all the other flammable stuff in your average apartment, it's not really any significant fire risk.

Wow I was in HVAC for 15 years and NEVER heard about 'greenfreeze' WOW.

Thanks for links!

> I wonder why the industry isn't reconsidering

For some depressing reading, see https://theintercept.com/2018/08/25/chemours-epa-coolant-ref...

Ive heard of people using propane as a refrigerant over 30 years ago and it probably goes much farther back. Back in the day it was considered much less efficient, but of course those super effective old refrigerants it was compared to aren't sold anymore so it might not be far off.

> The article points out the issue with AC isn't energy/CO2, it's refrigerants.

Well, it's both.

There is great potential in so-called "natural refrigerants", primarily CO2, ammonia, propane, butane. They can be ~as efficient as the various F gases, without leaving nasty chemicals in the environment, and have pretty low GWP's (CO2 equivalent).

places like Dallas and Hong Kong basically wouldn't exist like they do without it

I have visited both Texas and HK at peak heat as a tourist - I'm from the UK. Yes it does get a bit warm in both Dallas and say Kowloon but you learn to adjust. You slow down and bimble. You notice shade and instinctively go through it. You keep yourself hydrated and lots of other tiny strategies. This is how people have done it for centuries. I did live in the Middle East for a few years, so that gave me a few pointers.

A/C is nice but not necessary (for a real value of necessary)

As someone whos AC at work died during the summer in Dallas my productivity after the AC went out was a quarter to a fifth of my output before. The cost to my employer for that reduction is well worth the cost of AC.

Sod your employer, we are talking about the cost to the commons (planet)

> there is a stigma people have that heating is essential for life, but A/C is optional.

It's not a stigma, but a reality. Humans survive in a certain temperature range. On large parts of the earth for large parts of the year, the outside temperature is below the safe range. On only a few small parts of the earth - often where there are no other resources - is the temperature above the safe range. Humanity survived 200,000 years without A/C; I'm guessing heat was a necessity pretty early on, at least to inhabit most of the planet.

And anyway the question is irrelevant. We need to reduce energy consumption; is this some sort of competition between the heating and a/c industries?

It's not just about surviving though. Sure, AC is not absolutely required for life in many cases, but it allows one to be comfortable and productive, such that life without it wouldn't be very pleasant or practical.

The world doesn't need any more people. Fewer would be an improvement.

My problem with AC is how ubiguitous it is, and how people use it without thought of the environmental cost. It's ridiculous in many cases: people who sleep with their windows open and AC on (this exists), AC bus travel, where one needs a jacket, jeans and warm socks as the bus will be cold after a few hours. Air conditioning shows how far some people have become distanced from nature, and the environment in which they live. People who live in warm climates should expect to feel warm, maybe (at times) uncomfortably so. But good building design, suitable clothing, an open window, and a fan when temperatures get unbearable can go a long way. In the summer, I sleep (comfortably) with a window open, listing to the sound of my neighbours' AC units kicking in. It's depressing.

That's not to say that AC doesn't have valid uses, but that in many cases a more balanced, environmentally-friendly approach can be taken.

Some things which could be avoided: open doors in cooled buildings to entice people to go in (for example 7/11 or general retail in tropical or hot places). Refrigerated aisles in supermarkets which don’t have doors to keep cool air mingling with warmer air in the aisle., etc. Offices which keep so cool, people wesr jackets in the office when not winter. Those are wasteful examples.

Many store fronts have large sliding glass walls that open up the entire structure to open air - and they blast AC at 16 degrees inside, while the entire store is open to 30+ degree air outside.

The idea is so that the AC would leak out the doors and entice people to want to walk into the store. But that means that all the AC is wasted.

This kind of irresponsible use of AC is everywhere in hot climates in large shoppping streets, pretty much everywhere - North America, Asia (in asia it's insane how much AC is wasted), and I don't see it as much in Europe but probably some stores do it.

That's just a waste and is really sad.

You say it is a waste, but to the store, it is an advertising expense.

Would you rather they buy Facebook ads and use hydroelectric (assuming ad server's power source)?

It's both a waste as well as an advertising expense. It's an expense that has a much higher cost and externality than the benefit of the advertising.

> North America, Asia (in asia it's insane how much AC is wasted), and I don't see it as much in Europe but probably some stores do it

+ Brasil. It's infuriating.

I have one "problem" with airconditioning: it's a "cure" for cooling down a building after it heats up too much, but the more cost-effective, sustainable solution is prevention.

If we prioritize battling the urban heat island effect first, the remaining temperature problems can be tackled at a much lower energy cost with with airco.

[0] https://en.wikipedia.org/wiki/Urban_heat_island

[1] http://www.lowtechmagazine.com/2012/03/solar-oriented-cities...

[2] http://www.lowtechmagazine.com/2012/03/solar-oriented-cities...

[3] http://www.lowtechmagazine.com/2012/03/solar-oriented-cities...

Isn't the "urban heat island" effect a fundamental property of the way we've designed and built our cities?

To fix it, wouldn't we need to redesign buildings to have things like green roofs and use construction materials that reflect heat. And we'd have to tear up much of our paving and roads and replace them with trees, water, and green space. That all sounds nice, and it's a good principle to consider when designing new urban areas.

But it's extremely expensive and disruptive to go rebuilding existing cities, and all the construction itself would have an environmental cost. Surely air conditioning is cheaper?

I like the idea of moving towards Caves of Steel, but with parks on top and atrium areas where streets currently are.

It might also be possible to use a heat-stack effect to draw the air out of the city as a whole.

If we could adopt a combination of subways, dreaded e-scooters, bikes and golf cards for elderly and people with disabilities we could make this happen. Some European cities have huge pedestrian zones and it works.

> But it's extremely expensive and disruptive to go rebuilding existing cities, and all the construction itself would have an environmental cost. Surely air conditioning is cheaper?

It's at best a cheaper up-front investment. And while it is one thing to think about the limits of retrofitting old buildings, that is no excuse to not do better with newly constructed ones.

First thing to do is stop making the problem worse.

Last I checked we are still building our cities. Mine is in the process of knocking down all the one story commercial space and replacing it with six story mixed use buildings.

Increasing density in urban areas by building up is the right thing to do, compared to expanding urban areas which would require more paving, more roads, and more inefficient use of land.

It's the way we design those new buildings that's important.

Increased density means fewer low density buildings and paved surfaces elsewhere. Urbanization is a massive net positive for the environment.

It's a lot easier to insulate multi story buildings. Volume grows faster than surface area.

You're just trading off energy spent cooling denser cities vs. increased transportation in less dense cities.

Why is that bad? people complain about the enormous costs of accommodation, to which the main solution is simply to build more.

Your proposed alternative is to increase urban sprawl?

What? No. My point is that each new building is a chance to do better. Claiming it’s too late because we have built up areas is helplessness.

If you double the size of a town and build the new half well you solve more than half of the problem.

You're right!

With that said, it might be worth considering that it will often be easier to pitch "add air conditioning" to people than "tear down, reorganize, and rebuild the whole metroplex at once". Greatly disrupting the lives of millions of people at once is not something to be taken on lightly, easily, or quickly.

The dream is amazing, beautiful, and without question what's best for the planet and for us. There might be something to be learned from nuance in terms of how to get there is all.

I completely agree with you on this, but changing entire megapolis's is not going to be an easy task. Here in Southern California we have a huge heat island effect, due to the non stop city going from South Orange County to Ventura county (close to 100 miles) and from the ocean to at least 50 miles inland. I've read it can cause rain storms to completely bypass this area.

Wow, there's some fantastic mapping of this effect from a few years ago: https://calepa.ca.gov/2015/09/16/urbanheat/. Links to a study and lots of data produced from it.

Southern California: "urban heat archipelago".

From the linked page:

"largest effect is in southern California, where the urban heat islands blur together to form an “urban heat archipelago” with average temperatures up to 19° F higher in the Riverside-San Bernardino region at the eastern end of the basin."

If it is really 19° F higher in Riverside due to urbanization(hard to believe that really), I can see why correcting historical temps for urban heat island effects is so necessary. How to do that accurately must be fiendishly difficult.

Houston would still be unbearable even without urban heat island effect. But yes, it would be slightly cheaper. But the cost to reengineer the entire city would far outweigh the marginal increase in energy costs to cool certain areas of buildings.

> Without drastic improvements in air-conditioners’ efficiency, the IEA reckons, they will be burning up 6,000 TWhs by 2050.

I feel like future improvements in the efficiency and greenness of energy production have the potential to offset increasing energy demands. We could solve much of this faster if we'd just properly utilize nuclear, but politics get in the way of using efficient designs and public perception is unfairly negative despite it being the safest of all energy production methods[1]. If electric vehicles gain more traction then the emissions from the transport of materials for nuclear etc. also stop being a factor.

Side note, I hate this font they use that makes a 1 look like a seriffed I. Unnecessarily hard to read.

1: https://ourworldindata.org/what-is-the-safest-form-of-energy

The problem with energy efficiency is that it paradoxically tends to increase consumption.

There’s a basic economic aspect we mustn’t forget - supply and demand. When energy prices drop, consumers often buy more if it.

I’m on mobile so I don’t have a link at hand, but I recall reading that people drove a lot less when gas prices were higher. When they went back down, people went back to driving more.

If you really want to lower energy consumption- just raise the price.

Lowering energy consumption isn't the end goal, lowering harmful emissions is. If in the future, energy is produced entirely by solar, hydro, and nuclear, vehicles/machinery use little or no fossil fuels, and air conditioners have continued to be improved wrt use of coolant/leakage, then there's no need to reduce consumption because consumption is harmless.

In the meantime, pricing poor people out of electric is not a good solution.

At some point waste heat itself will warm the planet enough to matter. With exponential growth one can get there pretty quickly. A few hundred years. At some point we should add a heat tax to compliment the carbon tax (that we should already have in place).

True, but very low priority compared to getting CO2 under control. From "Sustainable Energy – without the hot air" by David MacKay, pages 170 to 171:

"the average solar power absorbed by atmosphere, land, and oceans is 238 W/m^2; doubling the atmospheric CO2 concentration would effectively increase the net heating by 4 W/m^2. This 1.7% increase in heating is believed to be bad news for climate. Variations in solar power during the 11-year solar cycle have a range of 0.25 W/m^2. So now let’s assume that in 100 years or so, the world population is 10 billion, and everyone is living at a European standard of living, using 125 kWh per day derived from fossil sources, from nuclear power, or from mined geothermal power. The area of the earth per person would be 51 000 m^2. Dividing the power per person by the area per person, we find that the extra power contributed by human energy use would be 0.1 W/m^2. That’s one fortieth of the 4 W/m^2 that we’re currently fretting about, and a little smaller than the 0.25 W/m^2 effect of solar variations. So yes, under these assumptions, human power production would /just/ show up as a contributor to global climate change."


It seems to me the assumption that energy consumption per person has peaked at the current European level and not increase in 100 years wildly false. Compelling new uses for energy will be found and other cultures are less likely, I think, to restrict personal energy consumption as much as Europe does currently.

That might be true, but remember that MacKay's numbers assume 100% non-renewable energy. In reality, solar panel prices are dropping fast, and they'll likely make up a substantial portion of the energy supply. Solar energy captured with photovoltaic panels is solar energy that's not heating the earth directly, so the waste heat problem is much smaller. The same is true for all renewable sources, e.g. winds and tides heat the earth uselessly if we don't capture them.

I agree. Keep power production on Earth to like 50% solar (wind, sunlight, tidal, etc) and there will be no problem with this heat issue. Bezos has specifically stated that he hopes to put industrial production off earth to avoid the industrial heat production problem in the far future.

> The problem with energy efficiency is that it paradoxically tends to increase consumption.

There's a practical limit to the increase in indulgence, after which the efficiency gain is all win.

We're not seeing a very dramatic effect or problem from inexpensive energy driving massively increased consumption in the US as one example. Efficiency is winning.

For example, US energy prices are 1/3 that of Australia, while per capita energy consumption is about 30% higher. US per capita energy consumption is comparable to Sweden, despite their energy prices being ~50% higher.

Natural gas is very cheap in the US, about 1/2 the cost in most regions. That doesn't mean I'm going to turn the temp in my house up to 87f this Winter.

The average fuel efficiency for vehicles has gone up by about 100% over ~45 years, while miles driven per capita in the US has increased by closer to 40-45%. Electric cars that get 90mpg equivalent, aren't going to cause people to drive 3x more than they do today.

US household energy consumption hasn't changed much in 20 years. Fridges got a lot more efficient over time on electricity, people still typically only own one of them per household. The same with furnaces and water heaters.

Smartphones sip electricity, especially compared to laptops and desktops - people aren't buying 20 of them to compensate for the dramatic difference in electricity consumption that results in using a smartphone instead of a desktop.

Most of the things we buy that consume energy have practical limitations on them, when it comes to how many of them we own or how much energy we'll consume with a given thing. As you reach those practical limits, efficiency starts to have a very positive effect.

Industrial level uses are much more sensitive to price. Get 1 cent/kwh electricity and your aluminum production is going to increase quite a bit, etc.

You'll still be constrained by the cost of the ore and the demand for the final product.

"The problem with energy efficiency is that it paradoxically tends to increase consumption."

Where's the evidence for that? Electricity consumption in most developed countries has been declining since around the mid-2000s.

Here in the UK, total electricity demand peaked in 2005 and has declined every year since, in spite of population growth (and more air conditioners!). Demand in 2017 was around 15% lower than in 2005, with about a 10% higher population.

Jevons paradox only applies when the cost of energy is the dominating factor. If I replace my fridge with a newer more efficient fridge, I'm not going to buy more fridges: I don't have the space!

>If you really want to lower energy consumption- just raise the price.

Energy prices have a direct effect on all the getting stuff done that economies are based around. "Just increase the price" "Just shoot yourself in the foot" but pitched it in a way that doesn't sound miserable.

As other commenters have mentioned and provided citations for, lower energy prices correlate with increased consumption but at a diminishing rate.

The gains in efficiency for AC can be made via more efficient or retrofit building design.

Radiant heat barriers, deep-pack wall insulation, even growing vines on sun-exposed walls would all reduce cooling needs.

Or, a big shade tree, covering the house.

Nuclear costs are high and probably rising, renewables falling. I think renewables are the future on the whole, especially if storage tech keeps improving https://www.nirs.org/1011-old-reactors-vs-new-renewables/

Something I've long wondered about: Do restaurants, malls and movie theaters need to be that damn cold? Does it really increase sales that much?

It's a major pet peeve of mine. Office buildings are often much cooler than they need to be too. I think most places, including homes, could reduce A/C significantly.

Part of the problem is humidity removal. There are many times when I'll lower the thermostat even though the temperature is already at 76F, but I need to get the humidity lower in order to make the room/house comfortable.

It's especially the case at night where, if the humidity were lower, I'd just turn off A/C and open the windows.

Living in Florida, we keep our AC at 78 - which is what a representative of our local energy company suggested. For two humans, and two dogs, it's comfortable. When we have company, we kick it down to 76 - or 74 if someone is cooking.

When I got my first job the excuse I heard for the office being so cold is that it is chilled for men in suits (with jackets on). Which is definitely not how most employees are dressed in the summer!

Does anyone really care about the environment? It's in front of our eyes every day. Supermarkets have superfluous packaging. They have fridges without any doors on pumping out cold air constantly. We have advertisements sucking energy constantly. Bitcoin uses a significant chunk of the world electricity? It's "innovative"! Massive commutes to completely pointless jobs where companies compete to deliver the pointless service before employees travel 90 minutes back to their inadequately insulated home.

If someone came down from space to visit us and we said we are trying to fix the environment they'd laugh.

We are in this mess because our system inexorably leads to it. We've been in this mess since we adopted this system. We have to ditch it.

A/C consumes less energy than heating.

A/C is effectively a closed system when operating. A fireplace or furnace is not.

A/C is needed most in places and times where solar panels work the best. Heating is the opposite.

Objectively living in Maine has a significantly higher environmental cost than living in Arizona.

Especially once you consider that in some places (New England) you have people living in both extremes. So they're using heat in the winter AND air conditioning in the summer.

New England winters are on average colder than some places near the arctic circle (Iceland for example) and summers get hotter than many places in the US as well.

I live in New England, and the situation is definitely a little complex. Some factors where I live:

- Firewood is really cheap. My house uses oil for its primary heating, but we supplement with a wood stove because aesthetics and cheap heat.

- A lot of the summer it's not the heat that gets you, more the humidity. We run A/C a lot, but often we could get by with just better dehumidifiers whose waste-heat stayed outside the house.

- Only relatively new houses have central A/C and/or dehumidifiers. Older houses tend to use window-mounted A/C's, which are less efficient and less appealing. Unfortunately retrofitting a house with central A/C can be outside many people's budgets.

- At my latitude, we get enough sunlight to make roof-mounted solar panels worthwhile for many people. But the financial break-even time can be pretty long, and there don't always seem to be government-subsidized low-interest loans to help.

Ah firewood is nice.

I live in a dense urban area and we wouldn't really have the option. We're on an electric heat pump for heating/cooling/dehumidifying (it's a nice system, a little expensive, but better than resistance electric heat and window units). We're in an old house without ducts, and compared to traditional systems it was cheap to install ($10k for 1500 ft sq).

Seriously, what's with the AC-shaming in this thread and in this article, which doesn't once mention the energy required to heat homes, and that it's several times that to cool [1]. Must be some northern elitism.

[1] https://www.eia.gov/todayinenergy/detail.php?id=10271

Heating/cooling is one of the few large energy consumers in a home with a strong behavioral component. Many appliances that consume a lot of energy don't have the same opportunity for behavioral intervention. I mean, it's not like you're going to unplug your fridge to save energy.

I think one of the key difference between heating and cooling is that the majority of energy used for heating is natural gas while AC uses electricity. Natural gas flows through pipes into the home when you need it without much change on the utility side, while electricity requires the utility to be generating more than enough energy. It's not easy/efficient to store electricity, which is a good reason to try to use less of it.

Heating uses more energy in part because more people live in areas with more heating degree days (HDD) and fewer cooling degree days (CDD).

[1] https://www.eia.gov/energyexplained/index.php?page=about_deg...

Because nearly all warm weather is objectively livable, whereas cold weather is actively dangerous. If you're using AC to be able to survive then you aren't the target. The target is the Walmarts that cool the building to 68 degrees when it's 80 and beautiful outside or the people who just refuse to open a window and use AC instead, or the people who can't stand a single iota of sweat or slight discomfort.

The same applies to heating. Even when it is below-freezing people heat buildings to the point that you can wear a t-shirt indoors. Instead of wearing more clothing, or enduring slight discomfort, people waste energy.

One particularly annoying example is the train. The trains always have the heat blasting. I, like most people, have to walk to the train, and stand on the (often outdoor) platform, so I wear clothing that will keep me comfortable while walking, and while waiting on the platform. As soon as I'm on the oven-like train, I have to strip off all layers to avoid sweating. I assume this is for the benefit of people who do not dress appropriately for the cold. I would prefer that they optimised for the opposite.

The heat on the train may be 'free', as waste head from the engine? In that case cooling it is the real cost.

I don't think that is the case. If it is, I am fine with it.

We probably don't need to do much of anything about air conditioning specifically, we just need to price in the externalities of energy use generally.

But it might make sense to incentivize (whether through positive incentives or negative incentives on traditional AC, or both) use of geothermal heat pumps instead of air-source heat pumps, since the latter is, pretty much by definition, least efficient when most needed—long-term, they are already a net win for the consumer as well as the environment, but the payoff time is long enough and traditional AC culturally-established enough that it doesn't even tend to be considered as an option enough.

In Toronto we have this huge system of underground cooling that transfers cool from the lake. It's great.


Pretty cool! One thing to note is the cooling capacity is limited to the consumption rate of the city based on how it's designed right now.

> The cold water drawn from Lake Ontario's deep layer in the Enwave system is not returned directly to the lake once it has been run through the heat exchange system. The Enwave system only uses water that is destined to meet the city's domestic water needs. Therefore, the Enwave system does not pollute the lake with a plume of waste heat.

And then it goes down the drain in the homes an goes ….?

Double great because it only cools using water that the city was planning on using anyway. If they heated the water up and sent it back into Lake Ontario, the temperature differential would have a drastic impact on the wildlife in the area.

It is probably cheaper, and more fungible, to incentivize clean renewables generation for AC use than expensive ground loops for geothermal/in-ground heat pumps.

Clean energy can be used for anything, but sunk copper or plastic piping in the ground on a property is fairly constrained in what it can be used for.

Actually, it turns out modern inverter-driven air-source heat pumps (either mini-splits or the highest-end ducted systems) are almost as efficient as ground-source heat pumps, at a much lower installed cost. Basically, GSHPs are now sort of a boondoggle, except in the coldest climates that don't have access to natural gas. Yet the government of the U.S. still incentivizes installing them with a huge 30% tax credit, with nothing for high-quality ASHPs.

So its actually a good thing that most people don't consider GSHPs, they should instead be considering 20+ SEER ASHPs.

Really? I live where it gets below freezing for months. At these times the ground continues to be what, 55 degrees F. How can an air-source pump be anywhere in the ballpark of efficiency?

In very cold climates, you're better off with just burning fuel (natural gas is available in most of the U.S. very cheaply, although this is probably not the case outside the U.S.). But it turns out that GSHPs have a lot of losses related to pumping and other inefficiencies to where the difference in efficiency between a state of the art inverter-driven ASHP and a GSHP really isn't that high. Especially considering the often HUGE upfront cost of installing a GSHP.

Google for "Inverter Air Source Heat Pump vs Ground Source" or similar. For example, see: https://www.homepower.com/articles/solar-water-heating/domes...

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