Urban heat islands

[RIP - VTEnviro]

I'm with DLeg. If it's the greatest thing since sliced bread, let's see some documentation or a case study or something to back up your assertion. This isn't my first rodeo either.

Most of the engineers I work with (many of whom are licensed in NH) want nothing to do with the stuff. It's always a planner or landscape architect who's pushing for it because it sounds like it will solve all your site's stormwater issues but they are not well versed in what goes into either paving or drainage design.

I agree with DLeg that this is not addressing quality issues, just quantity. My big question, and the one that nobody who's pushing the stuff can answer for me, is what happens when the ground freezes. The frost line in northern New England can go down 3-4 feet. Where does your water go then? Does it stay in the pores of the pavement and cyclically freeze and thaw and ruin your surface?

I have various other questions as well as I've stated above. I've read that manual you linked to cover to cover. It says a lot, but doesn't say much.

 

[RIP - VTEnviro]

And to unhijack this thread and answer the original question. Ktulu, I recently became LEED accredited so I've studied the manual pretty well.

Using porous pavement doesn't count toward the non-roof urban heat island credit. What does apply is an open-grid paving or grassed pving system (like this) or a standard pavement with a high solar reflectance index (SRI).

I was wondering if anyone here has any knowledge of using porous pavements to acquire LEEDs credits for reducing urban heat islands. This is something my firm wants to get more familiar with, and I thought this was the perfect place to ask.
Thanks in advance,

ktulu

 

[C-Dog]

On a related topic - LEED and parking lots,

Can you get LEED points if you design smaller parking spaces and aisles (design for compacts like Ford Focus, VW Golf...)? This way you can potentially restrict bigger than big SUVs and other gas guzzlers?

 

[RIP - VTEnviro]

Nope, neither the alternative transportation or heat island credits cover that.

Parking stall sizes and numbers are generally dictated by city zoning regs anyway. You can help to contribute toward achieving alternative transportation credits by providing the minimum required parking spaces. (i.e. do not exceed zoning reqs)

 

[Dleg]

I hate designers who put in alll (or mostly) "compact" spaces, just to meet a number of spaces requirement. Because most people drive monster SUVs these days, and so you end up with these chaotic parking lots where people end up just parking all over the place, over the lines, etc., and you get about half the real parking capacity you would have if you had just designed the lot with the standard 9 foot stalls.

Well, at least, that's what happens around here.

 

[RIP - VTEnviro]

^ Seriously. There's a reason most places specify 9 x 18 stalls, they work.

 

[C-Dog]

I hate designers who put in alll (or mostly) "compact" spaces, just to meet a number of spaces requirement. Because most people drive monster SUVs these days, and so you end up with these chaotic parking lots where people end up just parking all over the place, over the lines, etc., and you get about half the real parking capacity you would have if you had just designed the lot with the standard 9 foot stalls.
Well, at least, that's what happens around here.

I agree, if you are doing it as a way to meet a number of space requirement it is not a good solution. If you are doing it to promote more efficient transportation (via size) , then it is a good idea - which then one would think you get some LEED credits for.

 

[Tad]

And to unhijack this thread and answer the original question. Ktulu, I recently became LEED accredited so I've studied the manual pretty well.
Using porous pavement doesn't count toward the non-roof urban heat island credit. What does apply is an open-grid paving or grassed pving system (like this) or a standard pavement with a high solar reflectance index (SRI).

So...would, or could, whitish porous concrete meet the LEED standard? The porous concrete parking lots I've seen in my area have all been a fairly whitish gray color, and with white coloring could have been made whiter.

I have another question for Dan I'll do another post...

 

[Tad]

Actually it is proven and is now becoming a staple in our EPA letters when we exceed 10,000 sf of wetland fill. Ask you client if he wants to install a 1 acre pond or would he prefer to add another 20,000 sf of retail space.

Question for danbalfour, but anyone else too...I just noticed this thread happened in March...anybody still out there?

The one acre pond, at 2.5 feet avg. depth (not real deep), can hold/detain, about 100,000 cubic feet water.

If I get about 35% porosity in the stone subbase and 25% in the porous pavement,

and if I put in 2 foot thick stone subbase (pretty thick) plus 6 inches of porous pavement,

then my pavement area would need to be about 2.8 acres to capture the same 100,000 ft3. Hope I figured that right. That's if all is designed and constructed well.

A rough comparison. May be situations where depending on infiltration rate and storm water quantity control design standards, you would not need quite as much porous pavement storage as with a pond; could be the other way around too I guess.

 

[Tad]

No I actually do not work at UNH.
for others that asked for the link

http://www.unh.edu/erg/cstev/

Yes I agree it is a very bold statement but if you have the time to be on this board, you have time to research it. Look at the numbers in regard to stormwater quality. No net gain in TMDL will be the catch phrase in 2009 and porous technologies actually provide the solution.

Dan is certainly right, this is a favored technology when talk moves to TMDL.

Uhhmmmm, question for those who've designed porous parking...

Do you end up with all the parking lot porous, or only the parking spaces, or only some of the spaces, or part of all the spaces, or part of some of the spaces...?

If only part of the carpark is porous, do you generally slope the other areas of the lot toward the porous?