Sustainable Sites 7.2 - Heat Island Effect - Roof
January 30, 2008 – 9:09amRoof
Intention:
- Reduce heat islands
- Minimize impact on microclimate and habitats
Implementation:
- option 1:
- 75% roof material should be:
- SRI 78 for a slope less than 2:12 (low-sloped roof)
- SRI 29 for a slope more than 2:12 (steep-sloped roof)
- 75% roof material should be:
- option 2:
- Install a vegetated roof for at least 50% of the roof area
- option3:
- combination of options 1 & 2:
- Calculation of (Area of SRI roof /0.75) + (Area of vegetated roof / 0.5) is greater than total roof area.
- combination of options 1 & 2:
Codes/Standards Applied:
- ASTM
Extra Credit:
- 100% of project’s roof area (excluding mechanical equipment, photovoltaic panels, and skylights) is composed of green roof system
Submittal Phase:
- design
Links from Reference Guide:
Other Sustainable Sites Credits
- SS P1 - Construction Activity Pollution Prevention (prerequisite)
- SS 1 - Site Selection
- SS 2 - Development Density & Community Connectivity
- SS 3 - Brownfield Redevelopment
- SS 4.1 - Alternative Transportation - Public Transportation Access
- SS 4.2 - Alternative Transportation -Bicycle Storage & Changing Rooms
- SS 4.3 - Alternative Transportation - Low Emission & Fuel Efficient Vehicles
- SS 4.4 - Alternative Transportation - Parking Capacity
- SS 5.1 - Site Development - Protect or Restore Habitat
- SS 5.2 - Site Development - Maximize Open Space
- SS 6.1 - Stormwater Design - Quantity Control
- SS 6.2 - Stormwater Design - Quality Control
- SS 7.1 - Heat Island Effect - Non-Roof
- SS 7.2 - Heat Island Effect - Roof
- SS 8 - Light Pollution Reduction
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10 Responses to “Sustainable Sites 7.2 - Heat Island Effect - Roof”
The first edition NC 2.2 gives exemplary performance as 100% vegetated roof. Just wanted to confirm it really is 100% SRI roofing and not 100% veggie roof. Thanks!
By Aaron on Feb 29, 2008
Aaron,
You are correct. I checked my resources and one of them was incorrect, and thats the one I put down. I apologize for the mixup. 100% veggie roof = exemplary performance.
By Pat on Feb 29, 2008
For a very ambitious minute I thought about memorizing all the actual names of the ref. standards… and then I thought, “this is crazy! look at these names!”
Then, I said to myself, let me see what Pat did in intheleed… cause if Pat “the sleek-LEED-freak” put them there, I must learn them then.
Thank you Pat for liberating me of such torturous and treachorous path!!
By Sofia on Apr 26, 2008
For a very ambitious minute I thought about memorizing all the actual names of the ref. standards for this credit… and then I thought, “this is crazy! look at these names!”
Then, I said to myself, let me see what Pat did in intheleed… cause if Pat “the sleek-LEED-freak” put them there, I must learn them then.
Thank you Pat for liberating me of such torturous and treachorous path!!
By Sofia on Apr 26, 2008
same happened with me,,it took me e long half an hour to read and try to grasb.memorize all these standards.. and then thought i’d check ur website first,,such a great relief knowing they’re not required!!
By cynthia on May 9, 2008
In Option 3, I am having a hard time visualizing the equation….. as to what the roof would actually LOOK like,
when they are saying that the combo of sri and veggie roof need to be equal (fine) or GREATER than the total roof ? how is that possible? pehaps I am not getting the factors .75 and .5 what are they factors of ? I thought the total roof area but combined they are GREATER than the total roof area…
I’m just not seeing it…anyone care to draw me a picture?
(Area of SRI roof/0.75)+(Area of veggie roof/.5)is equal to or greater than Total Roof Area
By valeria on Jun 29, 2008
Valeria,
I can see where this equation might be confusing, but you have to remember that when you divide by a percentage, the valuve of any number becomes greater.
Just for an example, lets say we have a roof area of 100 SF and we’re using option 3.
If we have 50% (or 50 SF) as SRI, and 25% (or 25SF) as green roof, the equation would look like this:
50SF/0.75 = 66.667 SF
25SF/0.5 = 50 SF
66.667 + 50 = 116.667.
The SRI area (50SF) isn’t greater than 75% (or 75 SF) as per option 1, and the veggie roof (25SF) isn’t greater than 50% (or 50SF), but with the equation, you can see the final calculated number is greater than 100 SF, therefore using 50SF SRI and 25SF veggie roof works for option 3 in this case.
I hope this helps.
By Pat on Jun 30, 2008
Hi
I do see how the formula was followed in the example but I can’t ’see’ how a 100 sf ft roof yields in combination of whatever area sri divided by the required %i and veggie roof area divided its required % exceed the area on that said roof!
I can follow the formula to calculate, but the final value expressed in sf ft is throwing me as far as what it looks like…here, you demonstrated that if you cover only 75% of the roof, (in actuality) in the above combination, the calc is 116..667sf…it loses meaning…when i try to see it on the roof!
I guess it helps in that these sq ft perhaps are only in regards to a ‘threshold’
and not directly the roof, I think I would better grasp if it wasn’t expressed in sq ft…! So are these sf, the ‘good heat island fighter sq ft’ that live soley on the credit letter template?
By valeria on Jul 4, 2008
Will i qualify for exemploary performance if i use high albedo material for 100% roof?
By ahamed on Jul 11, 2008
Will-
Good question check out Aaron and Pat’s exchange above; you can not get EP for high albedo only veggie!!
Aaron,
You are correct. I checked my resources and one of them was incorrect, and thats the one I put down. I apologize for the mixup. 100% veggie roof = exemplary performance.
By Pat on Feb 29, 2008
By Brandie on Jul 23, 2008