Is air conditioning making cities hotter?
euronews.com
euronews.com
The bulk of urban heat island effect is driven by the radiative absorption of non-porous materials of the built-environment. Other heat waste put into the area accounts for less than something like 5% of the additional heat added when compared to rural areas.
Seems like a constant in doomsday "science": making a model that bear ressemblance to reality as much as SimCity does, run it to get the expected conclusion, then extrapolate and conclude with newsworthy title that X or Y is true in reality.
It's worth noting that this portion is generally done by science reporters rather than the scientists. It's quite often the case that alarmist articles refer to research with much more measured and less sweeping claims.
https://plato.stanford.edu/entries/simplicity/
Of course, you are more than welcome to voice concrete concerns about this specific study, if you have any (beyond what the GP already said).
Please don’t condescend people and definitely don’t go around arguing that science holds unrealistic simplicity as a core tenant.
The comment I replied to seemed to make the following reasoning: "a lot of junk science uses oversimplified models; this work also uses an oversimplified model; therefore, this work is also junk science".
And my intention was to point out that this kind of reasoning is invalid, because simplification is an important aspect of the scientific process.
So whilst I cant find a copy of the study, and I recognise your comment on the modelling and approach being simplistic, the above also demonstrates that other factors like increased number of vehicles on the road, can be a factor as they contribute to ground level ozone and many also come with an air conditioning unit built into the car as standard today.
[1] https://uk-air.defra.gov.uk/research/ozone-uv/moreinfo?view=...
[2] https://en.wikipedia.org/wiki/Light#/media/File:EM_spectrum....
[3] https://www.gov.uk/government/statistics/air-quality-statist....
And a car engine is producing far more direct heat than the increase in ground-level ozone from exhaust pollution is increasing heat (from that same car).
Also the fact that cars have air conditioners is a total non-sequitur. The air conditioner in the car requires negligible energy compared to the force required to move 4000 pounds and 1-5 people at 70mph.
This link [1] suggests traffic jams can increase temperatures by 7 degrees Celcius.
A typical solar panel absorbs ~20% of the sun's energy blasted on to a city rooftop. If that's used to power air conditioning it's doubly effective. You're reducing the heat urban heat island effect from the sun's energy, and you're also not adding additional heat from external power sources in to the city.
On a large scale this would really help make cities more livable. On a hot summer day here in northern Kentucky I noticed a massive difference (I've roughly measured it at a 5-7F difference) going from less developed areas to the more urban areas.
However, plants also reflect a lot of energy, unlike black/asphalt roofs that most people in the US install.
The solar panels will still absorb and radiate heat back so you won't get as much cooling as you would have just with passive radiative cooling paint, but it'd be better than just solar on a regular roof in both ways (solar output and thermally).
So just put the PV panels on top, and a reflective layer below.
Reflects 98.1% of the suns rays.
However if an entire downtown or subdivision does it? Possibly.
https://creativelyunited.org/wp-content/uploads/2019/02/temp...
Those nice trees take a few decades to grow, need serious pruning, will cause foundation problems next door, and increase building setbacks anyway. We also waste two entire lanes for street parking, have basically no businesses on either side anyway, and the street is still too wide. It might be urban, but it's still a car centric hellscape, just with some shade.
An ideal mirror reflects 100% of the light, and so does an ideal white surface. The white surface just spreads out the light.
If you light a mirror evenly from all angles, it will be indistinguishable from a white surface.
By making the sun hit at a layer above the ceiling (and assuming you have proper air circulation below), your attic area will heat less, hence your house will get less hot.
(This is similar to the effect you get by staying under a tree shadow)
As per the article, yes, if everybody had air conditioners city wide that would increase the city temperature. But that would require everyone to blast it at the same time
You've just made a ~100% efficient heat capturing machine. The 98.1% reflecting paint will be much more efficient, with the added bonus of not being dependent on the grid.
It would be nice if the cells were highly reflective at a range of wavelengths between the range they can actually use and the range where they radiate waste heat.
https://news.ycombinator.com/item?id=27782370 ("Passive radiative cooling below ambient airtemperature under direct sun")
Some work on surfaces of this kind have shown promising results, being able to fall below ambient temperature even in full sunlight.
Do it yourself: https://www.youtube.com/watch?v=KDRnEm-B3AI
However... that means they don't radiate well at night (they have low emissivity and are not well thermally coupled to the roof). Painting the roof white is ideal.
It tends to be newsworthy when it goes wrong, because the results can be things like buildings cooking nearby objects at certain times of day. Spicy stuff.
https://www.upi.com/Odd_News/2013/09/03/Skyscraper-melting-c...
"All will be simultaneously unveiled at 12 Midday tomorrow, citizens, so, ...take care out there!".
(shared link, readable even without a sub)
https://www.nytimes.com/2021/11/10/realestate/cool-roofs-cli...
Your reasoning is a bit like assuming solar panels stop flooding because they prevent the roof from getting wet.
Indeed it would be nice to power the AC with solar power, but how does this help the city to cool down? You would cool down the houses, but the heat from the houses would remain in the city, it would even get hotter.
As others have pointed out, you might do better bouncing the incoming radiation back out of the city with white roofs. And still others say you can do a bit of both.
Also, you could definitely do well to reduce your roof albedo by switching to white/reflective roofs. This point has been made endlessly over the last 30-40 years. No one actually does it. People are actually installing solar panels.
To the contrary -- at least in NYC it's extremely common. The vast majority of "tenement" apartment buildings have silver roofs, for this reason.
Just fire up Google Maps in satellite view over Manhattan and see for yourself. White-looking roofs everywhere (but silver in reality).
New construction with roof decks tends to use things like white-ish floor squares as well. They're obviously much cooler to walk on in the summer.
(While, sadly, contrary to your assertion, virtually nobody is installing solar panels in NYC. Landlords don't seem very interested so far.)
https://flatroofdoc.com/silver-coating-protecting-a-rubber-r...
Elsewhere I find a claim that the aluminum paint used was a 20th century thing, but now white paint is preferred as being more reflective.
Los Angeles has building codes for cool roofs:
https://www.ladbs.org/docs/default-source/publications/ordin...
Black is hotter in the day and colder at night. In the desert you want light colors, which do the opposite.
https://creativelyunited.org/wp-content/uploads/2019/02/temp...
It seemed a bit odd, because my roof is fully lit up, but only for a few hours a day- one half is covered most of the morning, and the other half most of the evening.
Sadly, it's not even really nice trees, just gigantic cottonwoods that litter leaves and twigs and sticky leaf pods like crazy.
The more immediate problem with climate change isn't that there won't be enough places to live/farm, it's that it's all going to move causing destabilization of societies.
The long term effects of running out of arable land are a considerable distance in the future.
Also your framing of the question *you* are bringing up is weird. Climate change will make for climate conditions that will make agriculture *harder* in general, I don't think your model of "Oh well we'll go to cold places that have become warmer" is really relevant and by the way arable land is already a resource some states are competing for.
The problem with solar is that unlit panels behave like a diode and no current flows. Chain together a lit and unlit panel and you get nothing. Put the inverter ahead of the interconnects and that's not a problem.
I'd love to do solar, but the only way I can make the numbers work is if I DIY'd the full install.
US skilled labor costs are insane. It makes all construction costs ridiculously high.
At the office building, the estimated payback was all of two years.
People also stuff like leasing that adds overhead.
Your 5-10k range installs will be $10-20,000 AFTER the tax credit, which might be a little higher now than when that graphic was put together.
Of course, this doesn't account for things like needing to re-do existing electrical work to get affected areas up to code, or if you need to replace the shingles on your roof while you're at it because it's typically recommended to do both at the same time if you're going to add solar.
Then again, you may also have the problem of ensuring your roof will withstand the extra weight, depending on the system. Most people are probably fine here, but for older houses in snowy climates it's worth thinking about as well.
I've looked into solar for my house. Aside from not getting enough sun throughout the day due to tree shade, there's also the problem that every solar calculator available wants to pretend that energy prices are going to go up 5% a year. Well, I've lived at my current house for 5 years and they haven't gone up once. The real payback for me is 20 years, if I'm lucky, even without the trees in the way.
For that matter, can solar panels be wired in parallel instead of in series?
One that wouldn't work. Two, those trees would have fallen on his house in ten to fifteen years because his house was east of the trees, and 'lions tail' tree pruning creates a giant lever arm and the roots will lose that battle in the first wind storm after a rain storm. That pattern had just played out ten years prior all over town. Big pruned Doug Firs falling onto people's houses.
What you want is to be able to be able to walk under a tree with your arms over your head and not hit branches. No more, no less.
My neighbor shields much of my house from the sun. We had issues when his branches started touching my roof, but we made sure it was trimmed in a way to still give us the shade it has all these years.
Of course, this is spot heating, and over a whole house the effect will be diminished, but it tells you how quickly things can get hot.
We've got plenty of freshwater in these parts, but in other places freshwater availability will be the limiting factor. Famously, swamp cooling works great in the desert if you can spare the water.
Trees are great, let's just be real about what they can and can't do.
(Of course those are being watered regularly.)
Leaves block the Sun relatively high off the ground, meaning people are in the shade during the hottest part of the day and feeling as much radiation off buildings and streets in the evening.
Beyond cooling they’re also good for water management. Most street trees don’t need any watering (at least in the Midwest) they live off rainwater. When it rains, water pools on the leaves and evaporates from there, reducing the amount of run off and keeping the street drier and less humid on days with light rain.
In cooler months (and places where this is relevant) the leaves fall and you can still get the warming benefit of sunlight.
Maybe it’s a disagreement of terms? I guess they aren’t technically “cooling” the area in an active sense, but they absolutely keep it cooler even when it’s 95 and the dew points over 70
To be fair, things like insulation are also good here. You want something outside to get hot when the sun shines on it instead of whatever space you're cooling.
(There are, of course, many heat sources inside that are annoying. I was running some fuzz tests yesterday and was annoyed to watch my air conditioner scale up in power to remove the heat that was wasting. I guess that's why people use The Cloud for everything. You can heat up someone else's city while enjoying the comforts of home!)
I live in Vietnam. It is 8am right now and the dew point is 80. It only 80 at the moment but is supposed to get up to 90 later in the day. I assume the dew point will also go up to around 90.
AccuWeather says the "RealFeel" will be 97 and "RealFeel Shade" will also be 97, so being in the shade does almost nothing, since it is overcast and raining very slightly at the moment.
We're not in a heat wave or anything, this is just normal weather basically year round. If anything it's been especially rainy and cool the past few weeks.
Trees are nice but are not remotely a substitute for air conditioning. Trees do not lower humidity enough to stop the average European/American from sweating constantly just sitting still here.
that's not to say that the heat under a trees' shade cannot still be oppressive. merely that shade matters, as the existence of two "RealFeel" measurements you shared indicates
Well the whole thread was something arguing they are.
First post: "I love trees and want more of them in our cities, my only point is that they are not usually a substitute for HVAC"
Reply: "I guess we disagree on what trees do well"
I don’t think anyone (certainly not me) has intended to argue that trees can replace AC, just that they make the city around them (including indoors in many cases) much cooler than they would be without the trees
Of course, trees are great for many other reasons like air quality, but for temperature fundamentally they're just big evaporative coolers. I wish cities in more water-stressed areas would consider arcades + rooftop solar.
Which makes it a good solution only to suburban heating.
It's not that there's no trees, but you'll see them in parks and boulevards that might as well be narrow parks.
If anything, I see far more trees in the American midwest. Here the streets are very wide, with basically no foot traffic to speak of, and too much road for the number of cars that use the street in urban areas. You can definitely fit trees here, but that's because so much of that concrete is waste. The extra trees just mean more distances, and more distances means more parking lots and more concrete.
Paint roofs white - and then go plant some trees.
Some modern neighborhoods are trying living roofs with grass. Haven't taken off and the grass hasn't survived either.
Lastly, other day saw post about leaving grass uncut reduced surface temps notable amount.
Since the person you're responding to is talking about solar panels on roofs and you're suggesting trees instead?
As always it's likely a combination of solutions, and rooftop solar is a good idea for more reasons than just heat.
As it turns out, solar panels are often more reflective than the typical roof of a house in North America. So solar panels can actually reduce the heat island effect. But it is mostly independent of whether they are hooked up at all.
Reflective of what wavelengths? Isn't that an odd characteristic of something designed to absorb electromagnetic energy?
I think reducing the absorption of the roof and the walls would help, but even then you have still have a house sitting in 34C+ air temps for at least 10 hours per day, so it gets hot. But when I consider my dads house, which has 2m eaves all around, high ceilings, and massive roof space - it still gets hot. His house might feel nicer without a/c during early summer, but by mid+late summer it is hot too.
Maybe better insulated doors+windows would help? My house is double brick walls. Maybe the "outer layer" needs to be able to get hot, and then the "inner layer" insulated from the outer as much as possible. That's a lot of change though. Instead I just run the a/c all day "for free" off my solar panels.
You’re not reducing energy here. If you gather and then release the energy again (make it do work) it’s simply being re-released.
Do they behave like heat pumps in some fashion where that energy is converted?
Oh I see now you say 20% so okay, some but definitely not even half.
Still, we're going to need every bit of help and I guess that 20% might be 30 or even 40% decades down the road.
The effect is stark and incontrovertible. There is the heat being removed plus some heat from the compressor and fan. Everyone in public and private spaces will be better off if we reduce AC usage as much as possible in favor of other solutions
In Asia, 7-Eleven is famous for its chilled air, but also has the walls covered with refrigerators for cool drinks, and there may be freezers for meat, seafood and ice cream.
It just makes no sense to me.
First, you are now pumping air from inside the building to outside. You aren't creating a vacuum inside, so all that means is somewhere else in the building the air is being replaced from the only place it can... from outside...
Second, the air you are pumping outside contains some of the air from the inside space that you just spent electricity cooling...
I use a mobile AC unit like this because it's really the only type of unit that will work in my apartment, but I use a dual hose unit. The unit has 2 air loops. Air from the room is drawn in from the back of the unit, heat is absorbed by the heatsink, and then cool air is blown out the front of the unit into the room.
Then to dissipate the absorbed heat as well as the heat from the electricity being consumed, air from outside is sucked in through 1 hose, runs through the other heatsink, and then is expelled back outside again from the other hose.
It just makes so much more sense, and if you can stick 1 hose in your window, it's really not that hard to stick 2.
It's worth doing too - you'll normally get almost the double the cooling effect from a double hose unit of the same wattage as a single hose one, just due to the fact you aren't wasting coolness out of the window.
If you do this, note that it's important to use extra large and short (insulated) hoses, simply because the blower fans in your unit aren't designed for so many yards of hose.
"ASHRAE empirical research determined that "acceptability" was a function of outdoor (fresh air) ventilation rate and used carbon dioxide as an accurate measurement of occupant presence and activity. Building odors and contaminants would be suitably controlled by this dilution methodology. ASHRAE codified a level of 1,000 ppm of carbon dioxide and specified the use of widely available sense-and-control equipment to assure compliance. The 1989 issue of ASHRAE 62.1-1989 published the whys and wherefores and overrode the 1981 requirements that were aimed at a ventilation level of 5,000 ppm of carbon dioxide (the OSHA workplace limit), federally set to minimize HVAC system energy consumption. This apparently ended the SBS epidemic."
Same with mini-split systems and central AC systems.
The vast majority of AC systems don't cycle air for their heat transfer.
Not saying that cycling fresh air isn't important, but I don't necessarily think it's the job of the heat pump to do that.
Single hose portables are bad in countries where air con is practically essential, but are fine or even desirable for countries where only a handful of % of people have AC - the purchases will be for use cases like attics and top floor apartments where inside can be easily hotter than outside
In a way it's worse than seeing strip mining, or those people who fish with dynamite, or people who litter. At least all those people are benefiting from their environmental destruction.
There could be a short term spike as the AC rejects interior heat from buildings to the outside, but that will be balanced out later as outside heat is absorbed by the cooler buildings, or as cool air leaks to the outside.
Moving an electric vehicle causes motion, but that motion is absorbed by the air and ground via friction with both, aka heat.
Light is just energy in a photon — when it hits a surface that absorbs it, it becomes heat. And it can be quite a lot actually! If you put your hand in front of a really bright flashlight, you’ll notice a warm feeling. If you turn off the flashlight, it goes away immediately, proving that is the light itself causing the heat.
Approximately all of the energy we use as electricity is just changing something into heat with some useful work in between
Manufacturing products via endothermic processes does not turn all of the energy into heat, but then again exothermic processes can exceed the energy used.
It's all heat in the end.
Waste light and sound get absorbed by surfaces, thus, turned into heat (unless the waste light is in the right IR band to pass out through the atmosphere).
We're still pretty far from that limit, but unless your plan is to never erase bits, you're going to waste energy.
Eventually most of the energy for earth either becomes heat in the earth, gets radiated into space, or slows the earths rotation around the sun, or spin. Of all of these things the dominant two are heat radiating into space (this is by far the largest), and heating the earth, with a few things like the tides slowing the rotation of the earth.
A little bit of it gets stored as chemical energy through plants and animals, but eventually those get burned either through fire, or chemical decomposition.
To give you an idea of how much heat escapes, if the sun stopped, and we used our nuclear arsenal to replace it, we'd have about 30 minutes of sunlight.
The idea that AC causes heat in cities to any real extent is laughable, if AC was capable of changing the temperature of the earth to any meaningful degree we'd just water cool the heat exchanger and solve global warming by dumping the heat into the ocean.
https://www.amazon.com/Kiss-Ground-Reverse-Climate-Ultimatel...
Here is a downtown weather station: https://www.wunderground.com/weather/us/tx/austin/KTXAUSTI18...
This site allows you to check various weather stations and see temps as recorded at the location.
You can compare your location to others less or more urban and see this while its happening. Next time you're awake at 3AM with nothing to do check it out! Compare downtown Austin to the suburban area of your choice. I saw a 2-3 degree difference pretty regularly last I looked.
Heating up the 40 square kilometers of city outside by 2.4 degrees reduces 1 sqkm of inside temperature from a sweltering 30 to 23 degrees (note, made up numbers).
So whether there is temporary localised cooling depends on the quality of the insulation but overall and over time there is no cooling due to the additional input.
- you're always getting some "free warmth" through the sun, so on average you need to pump less energy to heat than to cool (for same temp difference)
- Hot air rises, cold air sinks, not sure how that works in a city environment, probably concentrates the cold more
So, yes if you consider the differential in-house current-target temperature yes, but difference of outside/inside temperature no.
AC is an individual solution to global warming, and actually making things worse. And deincentivizes us from fixing the actual problem.
Anyone has a reference about that? Last time I tried to research it, it seems like it was mostly fixed at least in Europe with the most harmful gases being banned for new sales.
R-410A, commonly used in Europe, has a GWP of 2088. Worldwide, R-22 still is the most common refrigerant. That’s a HCFC, so stratospheric ozone depleting, and with a GWP of 1960.
https://climate.ec.europa.eu/eu-action/fluorinated-greenhous... is the list of alternatives with corresponding GWP for EU.
Not saying the phase-out isn’t happening, but there are, and there will be for quite some time, millions of units leaking climate pollutants (which was the question).
These same smooth-brains are probably extolling the benefits of heat pump water heaters not realizing they have the equivalent of an AC attached to them.
If your unit leaks refrigerant it needs to be repaired. This is not normal.
But sometimes they do.
We don't use this outlier data to refer to them as conflagrations-on-wheels and assert it's a normal function of the device just to strengthen our biased case.
Car air conditioners maybe, but it seems unbelievable for fixed systems of any reasonable quality…
They definitely aren't supposed to leak.
AC should be as sealed as a fridge, and you don't hear people having to recharge their fridges every few years.
Even ignoring the environmental concerns of refrigerant leaks, it's wasteful of your money too.
Obviously for a window unit or split where the compressor is on the building's wall -- those are going to heat the air in the street. Ground level units most of all.
But a lot of buildings place all their compressors on the roofs. And since hot air rises, does that produce any noticeable effect at ground level?
Meanwhile my parent's home is much cooler, no AC needed because they have trees between the blocks
Now, how did the air inside these structures get warmed up in the first place? Under normal conditions, is the air inside the structures WARMER than the ambient air? Does the structure itself somehow more efficiently harness the suns energy to warm the structure more than the ambient outside air?
If the same energy source is heating the ambient air and the air inside the structures - and it is - its the sun here, don't we have a constant amount of energy warming the area? Some of that energy warms outside, some of it warms inside, but the amount is constant.
So how could a device that removes heat from structures to vent it outside be responsible for a warming of the outside air? Unless the AC itself added some extra heat energy in the process OR the structures somehow more efficiently turned solar energy into heat, how could moving heat around cause a temperature increase?
For example - on a warm day in a little European village, everyone lights a gigantic fire and adds non-solar heat to their homes. The devices that remove the heat would then be adding new energy to constant solar energy heating the town. Ambient temperatures would likely rise. But did the AC cause the temperature increase? Didn't the AC unit just move heat from structure to ambient? The AC added no heat in this case.
Greenhouse effect + no wind.
The infrared emitted by heated objects are reflected by the glass, heating the room even more
"There is the heat being removed plus some heat from the compressor and fan."
The answer to the problem is a large increase in surface area of passive cooling technologies to reject sun energy during the day and to cool the surfaces at night through the atmospheric window.
You can use huge water mains to transfer the heat
Cities are hotter than outside because:
- they absorb more heat :: concrete, asphalt absorb much more than grass or trees and disperse far more slowly. Just go walking in a bush, measure temperature at 1.5 m from soil, do the same in grass covered area and the same over a road. You'll see and feel the difference;
- in cities there are MANY ICE vehicles whose engine produce much heat, much more than any electrical motor;
- in cities there is less air circulation than in the open nature due to the high and heat-absorbing buildings;
- in many cities glass coated skyscraper works like any other glass keeping much of Sun IR radiation inside.
These are the reason why cities are hotter. Another proof? They are ALSO hotter in winter, not just in summer. In winter you can count extra heat from badly insulated heated buildings, little cold pushed outside by the so far limited percentage of people heating with some heat pumps that have air on their exterior side, but look at the numbers and you'll see they are more hotter than mere heats spread outside by badly insulated heated buildings.
People should learn two things:
- cities WAS a necessity to evolve in the past, but with the '80 logistic revolution they lost one of their last reasons to exists, manufacturing became cheaper to do far from customers, so far from cities. With the remote work the last remaining reasons vanish as well. As a result dense cities and high rise buildings have NO REASONS TO EXISTS anymore. Try to keep them and sell them as green, good for the future etc is just a push toward intensive human farming to keep people dependent on service they don't own, living to operate them so they can pay them. Since in the modern era cities can't be sustained the push needs to makes people accept bad living condition as a new normal;
- we need to switch from a high density model, too dense for today state of tech and society, climate etc to a new less dense one, that's hard and that's means MANY will be simply "overflowing humans" to be put somewhere, since no one like that role, if told in such a crude way, some try to advertise such role with various "bells and whistles" but that's simply BULLSHIT.
If you try reasoning about the above you'll understand a thing: such move to put aside a significant percentage of humans can't really work, never worked in history. It does work if the set aside cohort is very limited, the poorest, very isolated and very dependent, but at modern scale can't work.
The populations of dense cities use fewer resources than the same population spread out in low-density settlements, especially when those cities are laid out to be properly walkable. It's just basic economy of scale.
> in cities there are MANY ICE vehicles whose engine produce much heat, much more than any electrical motor;
In cities, not having a vehicle is an option. Outside of them, it's basically required in most places.
Economies of scale aren't a goal on their own. Scaling something up will always have side effects... in the case of too dense urban areas, it's for example the sheer amount of traffic. For example, a quarter full of high-rises, no way you can get away without expensive high-capacity subterranian trains to handle commuters, and surface traffic is going to be a hot mess even with just shuttling the basic supplies for supermarkets, restaurants and the likes in one direction and waste on the other direction. In contrast, even a standard European mid-sized city can get away with cheap bus and tram lines. And it's harder to provide other essentials to meaningful life in a city as well, particularly where children are involved - land is too valuable to leave it as a park, and children can't have outdoor places to play either in kindergarten because it's too expensive, so you have even more traffic just from parents bringing their kids to kindergarten/school/playgrounds/whatnot.
Another effect of urban over-density that's often neglected is human health, both physical (we've seen that with COVID, just how fast pathogens can spread in urban areas) and mental. I mean, even here in Munich or Berlin we're not at the US levels of mental health and housing issues with people defecating on the sidewalk, but still it's noticeable how cities tend to have more anti-social behavior, as poverty and boredom are definitely contagious especially when not backed by the implicit social control that life even in smaller cities brings.
But that high-capacity transit more than pays for itself (just the land value increase alone is more than the cost of building it). Yes there are costs to building densely (obviously to build a skyscraper at all costs more per square metre of floor space than building on the flat), but the end result is that more people can live (and more productively) for less total cost.
> Another effect of urban over-density that's often neglected is human health, both physical (we've seen that with COVID, just how fast pathogens can spread in urban areas) and mental. I mean, even here in Munich or Berlin we're not at the US levels of mental health and housing issues with people defecating on the sidewalk, but still it's noticeable how cities tend to have more anti-social behavior, as poverty and boredom are definitely contagious especially when not backed by the implicit social control that life even in smaller cities brings.
Do you have any evidence for that? The last results I've seen are that suburban living is significantly worse for mental health than dense urban cores (and I wouldn't be surprised if that was true for physical health as well), and frankly that fits with my experiences.
Another classic scam: metros are very energy efficient in travel time, when loaded enough. But you need to move at any time of the day, differently by many others needs and desire, as a result OR you make the service run 24/7 nearly empty most of the time or you can't satisfy personal traveling needs most of the time. Beside that the mere cost of a metro respect of "glorified electric golf cart" for a less dense are is ENORMOUS and no, it does not pay up. Not only why keep moving in a city? Most activities there are doable from remote, just cutting such commuting to move only for pleasure and the reaming needs is FAR cheaper.
> Do you have any evidence for that?
In most of the world life expectancy in cities is LESS than outside by few years, gut microbes are far less in people living in dense area not to count pollution effects.
I think you missed or added some words there, so it's not very clear what you were trying to say. The cost/benefit of metros stacks up, that's why cities build them - not necessarily in terms of value that can be captured by charging fares, but certainly in terms of overall benefit.
> Not only why keep moving in a city?
Because the agglomeration effect still works; the more people within a 30 minute commute range, the more useful stuff they can do in less time. Again people wouldn't pay what it costs to live in a megacity if it wasn't worth it.
> Most activities there are doable from remote, just cutting such commuting to move only for pleasure and the reaming needs is FAR cheaper.
If there's less need for commuting then surely by your own argument that makes the case for living in a big city stronger, since there'll be less need for underground metros.
> In most of the world life expectancy in cities is LESS than outside by few years
Is that after controlling for wealth?
> gut microbes are far less in people living in dense area
Is that good or bad?
> not to count pollution effects.
Pollution is important though. The more you can walk or cycle, and more generally the lower the per capita energy use, the less pollution and the better for human health.
- cities material costs (meaning raw materials, energy etc) is enormous compared to the same people of any city living a far less dense area with single families homes AND commerce around intermixed. In such scenario moving with light electrical vehicles, mostly recharged from local p.v. since it's effective in most of the inhabited word is FAR cheaper (again in resources) than collective transports in a dense city;
- WFH in a dense city is a nightmare, because you miss nature and social contacts together. I came from a large EU city, now living in the Alps, WFH. In the city I have had a FAR LESS social life, simply because it's limited to a small number of selected friends doing service-based activities, like eating together in a restaurant, going to some events etc. Here being less dense anyone (almost) interact with almost any other, normally, and that's completely change the social paradigm compensating the "alienation" of working at home, distant from your peers. As a result I can WFH and remain a social animal in a not so dense area, where I can goes around, find people etc WITHOUT services, and the anonymity of the crowd. I probably can't in cities. Doing so means also I travel LESS (no commute) and longer trips are almost meaningless since I mostly recharge from my p.v. I keep more stuff at home, so I have less "impromptu trip" to buy something and so on. I'm more in nature, more social, more resilient (for instance no long series of stairs if there is a blackout and still have my home powered).
About health:
> Is that after controlling for wealth?
I do not know if most studies have taken family economy into account BUT so far people in cities are normally a bit more wealthy than outside, and still, they tend to live less.
> [gut microbe] Is that good or bad?
Perhaps not definitively clear, but typically healthy people have a significant set of gut microbes...
> Pollution is important though. The more you can walk or cycle, and more generally the lower the per capita energy use, the less pollution and the better for human health.
In toxicology pollution is measured in density, too little oxygen and we die, too much and we die as well. Similarly a poison below a certain threshold it's harmless. Try looking at ANY city, there are some more polluted than some others, but all are more polluted than far enough surroundings. People activities do pollute. You can walk, but the truck bringing you food does not.
How do you figure that? Single family homes are inherently enormously costly - more concrete, more energy to heat or cool, and more roads to access them. A couple of subways don't outweigh that.
> In such scenario moving with light electrical vehicles, mostly recharged from local p.v. since it's effective in most of the inhabited word is FAR cheaper (again in resources) than collective transports in a dense city
A dense city is the place where ebikes or golf carts are most practical - people are more able to live close to work (or leisure activities). Just look at the mode share numbers. Electrical transmission is extremely efficient, worrying about "local" electricity makes little sense. Metros in a city don't displace walking/cycling, they're displacing car use.
> In the city I have had a FAR LESS social life, simply because it's limited to a small number of selected friends doing service-based activities, like eating together in a restaurant, going to some events etc. Here being less dense anyone (almost) interact with almost any other, normally, and that's completely change the social paradigm compensating the "alienation" of working at home, distant from your peers.
Low density cities/suburbs are the worst of both worlds for social life, IME. The apartment complex I live in (in a dense megacity) has a similar population to the village I grew up in, and has the feel of a village too; I say hi to my neighbours and get some everyday social interaction despite WFH. But we're also close enough to meet and eat together without any fuss, whereas back in the village people would drive from one end to another. I don't think cities are inherently less social, they just enable people to be pickier about their socialisation - a village or small town is great if you fit in, but not so much if you don't ("the only gay in the village" may be a comedy sketch, but there's truth behind it).
> Doing so means also I travel LESS (no commute) and longer trips are almost meaningless since I mostly recharge from my p.v. I keep more stuff at home, so I have less "impromptu trip" to buy something and so on.
On average people in your position travel more, and in more environmentally damaging ways. And keeping a bunch of stuff ends up being pretty wasteful; I know I can walk to the shops to buy something whenever I want (hell, for basic stuff I only have to go downstairs), so I wait until I actually need the thing rather than pre-emptively stocking up on something that ends up going to waste.
Single family homes can be wooden frame on light foundations, tall buildings can't. Single family homes can be demolished and rebuild every passage (meaning 50-80 years) so they can be as efficient as "relatively recent" tech allow, tall buildings are a nightmare to evolve. I'm Italian, having left years ago a typical large enough apartments in the north-west of the country for a home in Sweden of similar size. The some in Linköping use LESS energy than the old apartment. Now I'm living in the french Alps, a new wooden frame home, about twice the size of the old one and I consume FAR LESS. Evolvability matter, much.
Here I have an EV and domestic p.v. in an apartment I've had a garage, but no p.v. possible, also consuming space for a heat-pump water heater and for main heating is not that easy, in a home no issues.
Not only, in term of mere raw materials just grab a project of any high rise buildings and compare that with any single-family home project multiplied by the number of apartments: you'll easily see that the high rise building demand MUCH MORE materials than many homes.
> A dense city is the place where ebikes or golf carts are most practical
And they demand large supply chain as well, witch means highways, railways of a significant size, because people need to eat as well and they are many in a restricted area, enlarging even more the infra costs... Roads in a spread areas are lighter, do not demand much complex infra. Moving with light personal vehicles instead of moving heavy trucks, even if in smaller numbers, is FAR less consuming. The hard part is organize the logistics but with IT we can.
> Electrical transmission is extremely efficient, worrying about "local" electricity makes little sense. Metros in a city don't displace walking/cycling, they're displacing car use.
Electricity grids all over the world are LESS and LESS reliable due to growing demands, generation issues and climate change, there is NO WAY to keep them up reliably in a changing world, so the same for roads, rails, water supply and so on, that's why we talk about "resiliency", because modern countries, cities are damn fragile and inflexible.
> Low density cities/suburbs are the worst of both worlds for social life, IME.
beware US-style suburbs are horrific because they are residential only, you can't do anything else than stay at home or have a trip with a car. Mixed low density areas are another beast. Where I am now we are few homes spread in a dead-end road, but with a small park aside, few activities a 10' walking, a small lake a 12', a small river with enough water in the spring to canoe a bit on the north side and so on. It's far different than a big lot of homes and nothing else. So it's different the social life part: in large cities I normally not even know many if not most of my neighbors, here's families pass kids one to another normally, (almost) anyone cheers (almost) anyone else and casual parties in the garden are far common from spring to autumn. Something never seen in cities. At maximum there we go to a restaurant or a shopping center and so on.
> On average people in your position travel more, and in more environmentally damaging ways
In mere km-terms yes. In impacting terms no. I mean WFH I can recharge my EV almost on PV most of the time except winter. When I was in city I goes every weekends around, almost reaching the same kilometer range of now, but in more stressful way between traffic inside, highways and so on. Here I go calmly for beautiful roads. Roads that can be (some are, many are not) also full of small passages underneath to drain water and allow small animals to pass, having few small bridges to allow bigger animals to pass, cut the "forest" enough to obstacle eventual large fires to spread. No giant infra needed.
Keeping stuff to me means waste FAR LESS, well, because I'm attentive on what and how to keep. For instance means less packaging: I do not buy pre-cut cured meat under plastic, I buy entire hams, mortadella etc I cut in 2cm thick slices, freeze them, unfreeze one at a time, slicing them as thin as I wish. I do not buy bottles of wine but a couple of demijohns at a nearby producer, filling them with a pump, and i bottle them at home, with the same bottles every years. Similarly i buy olive oils in 10l batches filling the same bottles as needed. Of course I also eat salmon who happen to came from far away, so for shrimps, but some foods and beverage are local, and with far less packaging. Having more appliance if one breaks I'm not in a rush for another so potentially on scale the delivery of a new one and disposal of the old one can be scheduled for maximum efficiency. In case of a disaster the resulting emergency is far less "urgent" than in a city because most homes have a certain degree of autonomy and we are able to help ourselves and each others. So again, far less impacting.
It's not easy to dimension anything but try and i've no doubt you'll reach the same conclusions I've reached.
That stuff is inherently a lot less efficient to do on individual scale. In a city you can have shared boilers, CHP plants piping steam to the neighbourhood and the like.
> Not only, in term of mere raw materials just grab a project of any high rise buildings and compare that with any single-family home project multiplied by the number of apartments: you'll easily see that the high rise building demand MUCH MORE materials than many homes.
I doubt that claim even for skyscrapers, and they're the exception rather than the rule even in a megacity. Terraces of 5 stories or thereabouts - the stereotypical Paris building or New York brownstone - very clearly use a whole lot less material per person than single family homes.
> And they demand large supply chain as well, witch means highways, railways of a significant size, because people need to eat as well and they are many in a restricted area, enlarging even more the infra costs... Roads in a spread areas are lighter, do not demand much complex infra.
You're forgetting to normalize by population! Low density areas need a lot more road per person and that all costs. If the same road is serving 1000x as many people, then even if they're getting their supplies from 100x as far (which is a pretty high estimate), that's still a huge reduction in infrastructure costs.
> Where I am now we are few homes spread in a dead-end road, but with a small park aside, few activities a 10' walking, a small lake a 12', a small river with enough water in the spring to canoe a bit on the north side and so on. It's far different than a big lot of homes and nothing else.
Yeah, people living in a place like that are consuming and polluting a whole lot more on average, as well as producing less. Producing all the good stuff we rely on - not least that EV and PV you're going on about - requires large numbers of people working in the same place. And people like to be able to choose what they buy and who they spend time with.
> Electricity grids all over the world are LESS and LESS reliable due to growing demands, generation issues and climate change, there is NO WAY to keep them up reliably in a changing world, so the same for roads, rails, water supply and so on, that's why we talk about "resiliency", because modern countries, cities are damn fragile and inflexible.
Keeping a grid reliable is a lot easier than keeping a bunch of complex technology working in a spread out area. Who repairs your PV when it breaks? Who replaces the battery in your EV when it wears out, which they do pretty quickly? Where and how do they get the parts (and what do they do with the one they're disposing of)?
> So it's different the social life part: in large cities I normally not even know many if not most of my neighbors, here's families pass kids one to another normally, (almost) anyone cheers (almost) anyone else and casual parties in the garden are far common from spring to autumn. Something never seen in cities.
Seen in my city all the time. With the difference that those in minority groups also get a chance to socialise with people like them from time to time.
> Keeping stuff to me means waste FAR LESS, well, because I'm attentive on what and how to keep. For instance means less packaging: I do not buy pre-cut cured meat under plastic, I buy entire hams, mortadella etc I cut in 2cm thick slices, freeze them, unfreeze one at a time, slicing them as thin as I wish. I do not buy bottles of wine but a couple of demijohns at a nearby producer, filling them with a pump, and i bottle them at home, with the same bottles every years. Similarly i buy olive oils in 10l batches filling the same bottles as needed.
Bet that stuff ends up more environmentally damaging to produce that way. Overly stringent food safety rules are a separate issue, but generally that disposable packaging has won out because it's efficient.
> Having more appliance if one breaks I'm not in a rush for another so potentially on scale the delivery of a new one and disposal of the old one can be scheduled for maximum efficiency.
So you use extra appliances the whole time just for the sake of the rare case when one breaks?
> In case of a disaster the resulting emergency is far less "urgent" than in a city because most homes have a certain degree of autonomy and we are able to help ourselves and each others.
Depends. There are a lot more people in the city to help each other out, and there's a better mesh of connections. If someone falls down or gets lost, someone will likely find them (unless they're the kind of person who chooses to live very privately). If the local doctor is injured, there's another not too far away. If one road or rail line is blocked, there's a route around.
> It's not easy to dimension anything but try and i've no doubt you'll reach the same conclusions I've reached.
Nope. Like, maybe your personal lifestyle is more efficient than a city dweller, but the way you're talking about living is something only a tiny minority would ever do. Most people don't WFH, most people don't and can't set up or fix their own electrics, most people buy the biggest house they can and then fill it up with crap they don't use, most people won't put much intentionality into their shopping, most people want to socialize with particular people or particular kinds of activities that just won't exist in a small town. If you advocate for low density living, what you're going to get is endless car commuters who sleep out there but work and shop in the cities, not only consuming a bunch themselves but also bringing noise and pollution and demands for car infrastructure that mess up the cities for those of us who live there.
The part you are right about is that living in a real community where you know your neighbours is important, both for good living and for resilience. But that's got nothing to do with density; the west may have destroyed the community of its cities, but it doesn't have to be that way.
Aren't trains much, much more efficient than individual transport? Compare the average urban train with everyone driving their own car and it starts to look pretty good.
Only if well loaded and running most of the time well loaded. Meaning in practice they can't be more efficient than personal transports.
OR you make a service 24/7/365 (untenable, running nearly empty most of the time) or you can't satisfy personal moving needs most of the time. Beside that just look at single stations costs compared to people moving in less dense areas in glorified electric golf carts mostly recharged via local p.v.
It's an ancient scam to sell collective transportation as positive, actually it's positive only for the public-funded business owner.
No, that's just marketing try to convince people of that...
> In cities, not having a vehicle is an option. Outside of them, it's basically required in most places.
Again that's marketing
Did you try to think hoe many resources are needed just to build high rise buildings compared to an equivalent set of single family homes? Hint: their own structure need to be supported, just that and foundations impose MUCH MORE resources than light homes. Similarly for any implant inside, including elevators.
Sewage network? Metros and so on?
A city if you try to count raw material use MUCH more than an equivalent spread area.
Not only: single family homes can evolve, they can be wood based and rebuild every let's say 50 years. Meaning they remain aligned to contemporary needs and tech, while rebuild a high rise building is a nightmare.
If you have modern homes with EV in most part of inhabited world, WFH for eligible jobs, not suburb USA style but mixed spread are where your dentist is just a small building few km away, there is a small supermarket few km away and so on you can have small-battery EV mostly recharge via domestic p.v. in cities you can walk, sure, unfortunately groceries are not made there, they came from far away, as far as more dense is the area because anybody eat, but in dense area there is no local food production. As a result you consume less, comfortably ignoring the logistic behind anything you use locally.
Now enlarge yourself talking about soil sealing who kill humus, water cycle alteration due to the big impact of such large and concentrated usage and discharge and so on.
If you REALLY try to dimension a city you'll easy see that anything you believe is false, marketing pushed because dense cities means dependency on services, witch means big business for very few on the shoulders of many. Try just to imaging ready-to-eat food delivery in a spread are: there is no chance Uber Eat, Just Eat and so one model keep up. People have kitchen, stockpile of food and time to do whatever they like, far less waste, far less packaging. Oh BTW this was an ancient known scam in Europe: in the past schools have internal kitchen, then they was told to externalize to make anything more efficient. As a result food quality have dropped, costs ans waste and packaging use skyrocketed.