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Countering climate change with cool pavements

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Re: Countering climate change with cool pavements

#31

Post by moonchrome »

clairity wrote: post #3

> “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…

How do you get trees to avoid destroying concrete/pavement with roots ?

We have a lot of old trees around and the pavement around them is bulged, cracked and deformed.

Re: Countering climate change with cool pavements

#32

Post by Retric »

clairity wrote: post #27
BurningFrog wrote: post #21

Earlier quoted context omitted.

One logical answer is "Artificial trees". That is, constructed shade structures that provides shade without being unpredictable living things. There are probably real problems with that approach too. What are they?

mainly cost. trees are cheap (~$100-300) compared to tarps or other fixed shade options, though i'm down for any and all shade. for comparison, bus shelters are estimated to cost $5K-30K each ( https://pedestrianobservations.com/2019/04/12/little-things-... ).

That ignores a lot of costs such as leaf collection. Trees are only cheap if you don’t need to worry about stuff around them.

Re: Countering climate change with cool pavements

#33

Post by harmmonica »

clairity wrote: post #25
harmmonica wrote: post #13

Earlier quoted context omitted.

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 abuse…

LA has an woefully underpublicized street (and lawn) tree program, where you can get free trees if you agree to take care of them (which is mostly just periodic watering), so you wouldn't even have to buy them yourself. for street trees on the parkway (the patch of ground between the sidewalk and street), you don't technically even need the permission of the owner, although the owner might not be amenable to watering…

it's true, that's exactly how we got our street tree, but a) it took an extremely long time to get the tree in the first place and b) the tree itself was rather lackluster, though now we're on year 3 of it and it's... ok. if I knew then what I know now I would've just gotten my own tree (one of the ones on the approved list) to get a nicer tree up front.

as for planting the trees without the permission of the resident responsible for that parkway, like I said in that previous comment, it doesn't do much good if the folks don't take care of them. we've also learned the hard way that doing things that seem additive to the hood are not always taken that way by neighbors and can cause conflict. been on the end of that a couple of times already. that said, maybe I'll stop talking about doing this and actually try it and see what folks say.

Re: Countering climate change with cool pavements

#34

Post by clairity »

moonchrome wrote: post #31
clairity wrote: post #3

> “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…

How do you get trees to avoid destroying concrete/pavement with roots ? We have a lot of old trees around and the pavement around them is bulged, cracked and deformed.

primarily by choosing an appropriate tree that doesn't do that. countersinking the tree can work in some cases too (often with a metal grating around the base of the tree so people don't fall in and hurt themselves). i don't know that you can "fix" the roots once the tree has become well established, without seriously damaging the tree and potentially creating additional hazard.

Re: Countering climate change with cool pavements

#35

Post by clairity »

Retric wrote: post #32
clairity wrote: post #27

Earlier quoted context omitted.

mainly cost. trees are cheap (~$100-300) compared to tarps or other fixed shade options, though i'm down for any and all shade. for comparison, bus shelters are estimated to cost $5K-30K each ( https://pedestrianobservations.com/2019/04/12/little-things-... ).

That ignores a lot of costs such as leaf collection. Trees are only cheap if you don’t need to worry about stuff around them.

i mean, leaf collection for street trees is like 10-15 minutes of work a week during growing season? you could give a neighborhood kid $5 to do that along with the occasional watering (we actually have a volunteer organization in my neighborhood that does this, though not weekly). artificial shelters need cleaning/maintenance too, so it doesn't seem to be a significant net difference.

Re: Countering climate change with cool pavements

#36

Post by berikv »

pharmakom wrote: post #5
clairity wrote: post #3

> “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…

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.

The pavement replacement won’t be free either, I suppose. I’ve never heard of a government cutting trees as a cost saving, however I didn’t look for that either. I think that, once trees are there, people will be happy to pay the few dollarcents per year for their maintenance.

Re: Countering climate change with cool pavements

#37

Post by sa1 »

BurningFrog wrote: post #21
puffyvolvo wrote: post #16

Earlier quoted context omitted.

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…

One logical answer is "Artificial trees". That is, constructed shade structures that provides shade without being unpredictable living things. There are probably real problems with that approach too. What are they?

Trees also affect weather on a larger scale by transpiration - I'm just pointing out shade structures are not directly comparable.

Note that buildings are also shade structures but they contribute to the heat island effect.

Re: Countering climate change with cool pavements

#38

Post by Nbox9 »

na85 wrote: post #29
aaaaaaaaaaab wrote: post #15

Earlier quoted context omitted.

I’ll save you some time: absolutely not.

Why so certain?

I’m in the 98% not feasible category for a few reasons. I’m open to new information or arguments, but I can’t see a way over a few very large hurdles.

1. Pavement is a very poor conductor, energy doesn’t move easily through it.

2. The Delta between ambient air temp and pavement temp low. Generating power would most likely include moving energy between the higher temp pavement to the lower temp air and capturing some of it during the transition. This is possible at any delta, but were really talking about a maximum of about 30 degree C temperature delta.

3. There are more efficient ways to generate power. Build wind turbines, solar panels, dams, etc. These are all very good ways of generating power.

4. There are more efficient ways to keep pavement cool. Change the pavement materials, plant trees, build shade sources for the pavement.

Re: Countering climate change with cool pavements

#39

Post by Retric »

clairity wrote: post #35
Retric wrote: post #32

Earlier quoted context omitted.

That ignores a lot of costs such as leaf collection. Trees are only cheap if you don’t need to worry about stuff around them.

i mean, leaf collection for street trees is like 10-15 minutes of work a week during growing season? you could give a neighborhood kid $5 to do that along with the occasional watering (we actually have a volunteer organization in my neighborhood that does this, though not weekly). artificial shelters need cleaning/maintenance too, so it doesn't seem to be a significant net difference.

This is where it’s more open to interpretation. Wet leaves on pavement are a significant fall hazard and should be removed more frequently, but that’s optional.

Tree trimming and eventually removal can cost 500-1000+$ for older trees which you eventually need to do to avoid having limbs and eventually trees fall on nearby cars. Roots damage local pavement again if you let the trees grow large enough. They also start taking up significant space requiring much wider sidewalks.

Of course you can remove them and add new trees regularly, but that’s another cost and tends to upset locals. Etc. granted his is usually in comparison to an empty sidewalk as it’s unusual to have other forms of public shade.

Re: Countering climate change with cool pavements

#40

Post by stackbutterflow »

harmmonica wrote: post #13
clairity wrote: post #3

> “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…

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 abuse…

I've never been to LA so let me try. Rolling hills, Park estates, coastal san Pedro?

That's all I got after 5 minutes on Google maps.

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