[HN Gopher] Countering climate change with cool pavements
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Countering climate change with cool pavements
Author : 35_candelas
Score : 34 points
Date : 2021-08-22 21:17 UTC (1 hours ago)
(HTM) web link (news.mit.edu)
(TXT) w3m dump (news.mit.edu)
| guerrilla wrote:
| > "cool pavements" [..] reflect more solar radiation and emit
| less heat than conventional paving surfaces.
|
| Darn, I thought they were going to talk about using heat pipes
| driven deep into the ground to turn the pavement into a heat sink
| and was wondering how they were going to get the pavement to
| conduct heat to the heat pipes. Now I'll never know. ;)
| 14 wrote:
| I am surprise we are not doing more reflective roofs while at it.
| Black rooftops are so hot.
| mrfusion wrote:
| This would be so amazing for tennis and pickleball courts! People
| would pay good money for this.
| clairity wrote:
| > "Conversely, by reflecting light -- called incident radiation
| -- onto nearby buildings, cool pavements can warm structures up,
| which can increase AC usage in the summer and lower heating
| demand in the winter."
|
| this is one of the reasons why i'm an advocate for street trees,
| and urban foliage in general (cuts down both incident and
| reflective radiation), and why i'm maddened when i see urban
| trees cut down or cut back (as been happening quite often in my
| urban neighborhood in LA). the tree trimmers i see doing this
| have no idea what they're doing, being low-paid laborers paid
| only to run a chainsaw/trimmer, not to contemplate consequences
| or consider other options. trees take decades to become effective
| shade, and minutes to butcher irreparably.
|
| that's not to put down cool pavements, which are really cool
| (haha), but that trees can provide all the same benefits and
| more, which makes it the better first option, with cool pavements
| being reserved for where tree shading is difficult or impossible
| (like roadways and parking lots).
| harmmonica wrote:
| from one LA resident to another, amen to that. we were just
| walking down our street this morning and discussing, for the
| umpteenth time, whether our neighbors would actually be willing
| to take care of trees if we went out and bought them and
| planted them. the problem, as other commenters have pointed
| out, is that they do require upkeep, but since they're
| living/breathing things the more hardy ones can really be
| abused and _still_ survive. The question is how do you
| incentivize the people who benefit from the trees--the
| residents, businesses, other local stakeholders--to actually
| maintain them?
|
| on our street there are countless trees that were likely
| planted decades ago, but a lack of care by the residents makes
| them mere shadows of their potential.
|
| and for anyone interested, LA's a great example of how trees
| provide a return on investment (actual dollar return outside
| the tremendous ecological benefits). go onto google maps and
| look at the satellite view. people who have never been here can
| point out the expensive neighborhoods because they are the
| greener ones.
| puffyvolvo wrote:
| While I initially would prefer the idea of more street trees
| the nagging voice in the back of my head continues to worry
| about unintended consequences.
|
| A big one regarding more trees is more maintenance, you've
| already pointed out how terrible maintenance can be, and lawns
| alone are an incredible example of just how inefficient we
| handle plants in the name of some arbitrary aesthetic, tons of
| water wasted, many hours spent trimming things to some ideal
| size that turns out to be terrible for the plant itself, etc.
|
| Of course my paranoia doesn't ignore cool pavements either; the
| reflectivity does bring some mild worries: some skyscrapers are
| known to cause large amounts of concentrated reflective heat,
| but those are due to the more mirror-like reflective properties
| of glass rather than the diffusive matte grey/whites of these
| pavements. I also worry about visibility, could we end up
| having a "snow blindness" effect? Would driving be affected as
| the harsh unnatural dark contrast of a typical road is very
| easy to spot compared to...everything else. I'm ofcourse aware
| not all roads are this black but you can't deny bright yellows
| and whites of road markers on a deep black road would be easier
| to pick up on than on a greyish road.
| NumberWangMan wrote:
| I agree with you on the matter of lawns, but not on street
| trees. Yes, they require maintenance, but they make a massive
| difference in the comfort of people walking, which is a big
| factor in people deciding to walk rather than drive, as well
| as increasing the general attractiveness of the area to
| potential residents who might otherwise live in a car
| dependent suburb of something. When you add up all the
| benefits, I'd consider street trees to be analogous to
| brushing your teeth-takes a bit of effort but the cost of not
| doing it is far greater.
|
| This of course applies mostly to areas that are hot for a
| good portion of the year.
|
| And I have the same concerns as you about the reflective
| pavement.
| pharmakom wrote:
| I also like urban trees but remember they cost a fortune to
| maintain! For example, urban trees have to be expertly managed
| for disease along transit lines.
| frosted-flakes wrote:
| Why would they cost a fortune to maintain? Apart from leaf
| collection and end-of-life removal, what costs are associated
| with street trees?
| MichaelGroves wrote:
| Tree limbs die all the time. Normally when disease or
| damage kill a tree branch, it isn't a big deal because the
| tree is in a forest and probably won't fall on anybody or
| damage any property under it. In a city, you can't ignore a
| widowmaker. The risk of it damaging property or flat out
| killing somebody is too high, you have to pay to get it
| safely removed. Often this becomes "end-of-life removal"
| because it's deemed safer or cheaper in the long run to
| remove the tree entirely. So now you have a green mostly
| alive tree being chopped down because one of the limbs
| died, and everybody in the neighborhood thinks you're a
| tree butcher but nobody else wants to chip in to have it
| maintained.
| godelski wrote:
| They require water, which requires irrigation (may not
| already be in place and of course has logistical problems),
| trees also root systems can lift and crack
| sidewalks/pipes/other things, you now have biological
| contaminants, there's bugs and fungus and things that can
| spread, and so much more.
|
| I'm not saying we shouldn't do this. I really like seeing
| plant life in cities and I think it really makes a
| psychological difference (I _love_ living in a city with a
| lot of green spaces and trees everywhere). But it is
| nowhere near as simple as placing a tree in the ground and
| cleaning the leaves.
| ClumsyPilot wrote:
| "now have biological contaminants, there's bugs and
| fungus"
|
| Dude, we have rats running around, pigeons nesting and
| pooping, what biological contaminants?
| godelski wrote:
| Just because biological contaminants exist doesn't mean
| adding more creates more issues. More trees also means
| more rats and pigeons. What's your argument? That just
| because we already have a bad thing doesn't mean that a
| similar bad thing isn't bad? That doesn't make much sense
| and is a pretty lazy argument.
| burlesona wrote:
| It's interesting that the effects are so complex and nuanced. I
| also wonder - they didn't specify - just how reflective these
| surfaces need to be, and how "bright" they are to look at. I
| could see glare being a potential safety hazard if the surface is
| reflective enough, but I'm assuming that any surface rough enough
| to make good pavement won't be _too_ bad to look at.
| berikv wrote:
| Why wouldn't you just plant some trees. You don't need any fancy
| pavement if it is below a tree.. European cities are filled with
| trees to cool the streets below them. Obviously, you'd need
| smaller streets that fit pedestrians and bicycles instead of
| massive urban highways for trees to be effective.
| Adrox wrote:
| Well in Portugal (thats is kind of hot) we use limestone or other
| kind of white stones:
| https://fotos.web.sapo.io/i/o90119e17/18254271_eGMbD.jpeg
|
| Not only is cooler, it looks much better than cement... It can be
| expensive as it uses a lot of hand labour.
| na85 wrote:
| This totally nerd-sniped[0] me, and now I'm going down the rabbit
| hole wondering if there's a business opportunity for generating
| electricity via the thermoelectric effect[1] and thus literally
| cooling the pavement by pulling some energy out and putting it to
| good use.
|
| [0] https://xkcd.com/356/
|
| [1] https://en.m.wikipedia.org/wiki/Thermoelectric_generator
| aaaaaaaaaaab wrote:
| I'll save you some time: absolutely not.
| llukas wrote:
| https://www.ucdavis.edu/news/anti-solar-cells-
| photovoltaic-c...
|
| Not pavement but still
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