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Credit language straight from USGBC
Need to check up on the exact LEED credit language from the LEED Rating System on the fly? LEEDuser includes the verbatim language. Members get:
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8 Comments
Roof Parapet
Hello,
We are trying to achieve this credit for one of our projects. The roof will have a white coating except for the parapet which will have a metallic aluminum cladding.
We thought initially this would not be a problem, but it turns out that the parapet will occupy a large proportion of the roof area.
As such my question is: Should the roof parapet be considered in the roof area calculations for the purpose of this credit ?
Many thanks !
Mara Baum replied Sustainability Coordinator, Anshen + Allen Architects Apr 13 2010
As per the Reference Guide, appurtenances are exempt from this calculation, along with mechanical equipment and PV panels. I typically think of parapets as appurtenances, because by definition they are a less significant element associated with the roof. It sounds like that might not be the case for your parapet, however, which leaves this as more of a judgment call.
Janika McFeely replied EHDD Architecture Jun 14 2010
Do you generally include walking pads on roofs or lump that into the excluded category as well? Thanks
Mara Baum replied Sustainability Coordinator, Anshen + Allen Architects Jun 14 2010
It's my understanding that walking pads are included. There are several walking pad products that meet the SRIThe solar reflectance index (SRI) is a measure of a material's ability to reject solar heat, as shown by a small temperature rise. Standard black (reflectance 0.05, emittance 0.90) is 0 and standard white (reflectance 0.80, emittance 0.90) is 100. For example, a standard black surface has a temperature rise of 90_F (50_C) in full sun, and a standard white surface has a temperature rise of 14.6_F (8.1_C). Once the maximum temperature rise of a given material has been computed, the SRI can be calculated by interpolating between the values for white and black. Materials with the highest SRI values are the coolest choices for paving. Because of the way SRI is defined, particularly hot materials can even take slightly negative values, and particularly cool materials can even exceed 100. requirements, although you can also require a conventional pad with an added coating. This can be pretty important, as walking pads can potentially make up a significant percentage of roof area.
Roof space under the perforated panel
Hello all,
Above the concrete roof of the project, there are the steel structure (about 10m high) with the perforated panels for wall and grid mesh at the top. The grid mesh has about 80% perforation. there are the cat ladder provision from the concrete rooftop to the top of the grid mesh roof. My question are:
1) does the concrete roof (10m below the grid mesh and well shaded with vertical perforated panels) need to comply with the SRIThe solar reflectance index (SRI) is a measure of a material's ability to reject solar heat, as shown by a small temperature rise. Standard black (reflectance 0.05, emittance 0.90) is 0 and standard white (reflectance 0.80, emittance 0.90) is 100. For example, a standard black surface has a temperature rise of 90_F (50_C) in full sun, and a standard white surface has a temperature rise of 14.6_F (8.1_C). Once the maximum temperature rise of a given material has been computed, the SRI can be calculated by interpolating between the values for white and black. Materials with the highest SRI values are the coolest choices for paving. Because of the way SRI is defined, particularly hot materials can even take slightly negative values, and particularly cool materials can even exceed 100. requirement?
2) does the cad ladder need to comply with the SRI requirement.
Appreciate your advice.
Thanks,
Grace
Mara Baum replied Sustainability Coordinator, Anshen + Allen Architects Aug 18 2010
The credit requires you to have at least 75% of the roof surface meet the SRIThe solar reflectance index (SRI) is a measure of a material's ability to reject solar heat, as shown by a small temperature rise. Standard black (reflectance 0.05, emittance 0.90) is 0 and standard white (reflectance 0.80, emittance 0.90) is 100. For example, a standard black surface has a temperature rise of 90_F (50_C) in full sun, and a standard white surface has a temperature rise of 14.6_F (8.1_C). Once the maximum temperature rise of a given material has been computed, the SRI can be calculated by interpolating between the values for white and black. Materials with the highest SRI values are the coolest choices for paving. Because of the way SRI is defined, particularly hot materials can even take slightly negative values, and particularly cool materials can even exceed 100. requirement. If I understand you correctly, then the mesh is only 20% solid, so this alone would not meet the requirement and at least part of the roof would have to comply. There are several CIRs under earlier versions of LEED that can give guidance on weighted calculations that take the shading into consideration.
Ladders and other appurtenances are not required to meet the SRI requirements.
Grace Ming replied ESD Consultant Aug 20 2010
Thanks Mara for your advice.
Actually, most of the concrete roof slab has M&E equipments and pipes. Since the M&E areas are exempted from this requirements, we would like to exclude the concrete roof slab from SRIThe solar reflectance index (SRI) is a measure of a material's ability to reject solar heat, as shown by a small temperature rise. Standard black (reflectance 0.05, emittance 0.90) is 0 and standard white (reflectance 0.80, emittance 0.90) is 100. For example, a standard black surface has a temperature rise of 90_F (50_C) in full sun, and a standard white surface has a temperature rise of 14.6_F (8.1_C). Once the maximum temperature rise of a given material has been computed, the SRI can be calculated by interpolating between the values for white and black. Materials with the highest SRI values are the coolest choices for paving. Because of the way SRI is defined, particularly hot materials can even take slightly negative values, and particularly cool materials can even exceed 100. requirements. Another reason is that gird mesh is located at about more than 10m high above conc slab and the conc slab is well shaded by vertical perforated panels. So, we wonder if the reflectance of the roof slabs will have impact on UHI.
Any comment or suggestion? Thanks,
Mara Baum replied Sustainability Coordinator, Anshen + Allen Architects Aug 20 2010
There are two different questions here (unfortunately). The first is whether or not the roof has much impact on UHI. The second is how you're supposed to treat it for the LEED point. You're probably right that the concrete roof surface doesn't play a big role. For LEED, you still have to document that you're mitigating the UHI effect -- if not by the conventional mechanisms, then by an alternative compliance path that is equally or more stringent. The simplest way to do this is to determine how much of your roof is not M/E equipment, and make at least 75% of that area cool. Part of this strategy may also include making the mesh cool as well (e.g. painting that white).
I definitely recommend checking out the different CRIs for more specific guidance regarding the shading -- you'll better be able to figure out what applies to your circumstance.
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