Forum discussion
NC-2009 SSc7.2: Heat Island Effect—Roof
We have a project where we have concrete eyebrows protruding from the building exterior. Would the area of those eyebrows count towards roof area?
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We don't know the SRI value of some roofing materials we are using. What should we do?
Do balconies and terraces need to be counted towards the roof square footage?
How does one calculate the square footage of a pitched roof?
Mara Baum
Partner, Architecture & SustainabilityDIALOG
674 thumbs up
June 18, 2013 - 8:14 pm
No - a "roof" for LEED must have conditioned space below.
Nicole Kimoto
Architects Pacific Inc.9 thumbs up
June 18, 2013 - 8:22 pm
thank you Mara! What if you have a pitched roof with 36" overhangs beyond the buiding walls (typical of residential), would you then also only count the area over the conditioned space, and the overhangs would not be counted, is that correct?
Mara Baum
Partner, Architecture & SustainabilityDIALOG
674 thumbs up
June 18, 2013 - 8:25 pm
You would also exclude that extension. Scroll up to the top of the page and scroll your mouse over the green words "roof area" - a definition should pop up that explains this.
Nicole Kimoto
Architects Pacific Inc.9 thumbs up
June 18, 2013 - 8:38 pm
I'm sorry, I see conflicting explanations of how to determine the area of a pitched roof on this forum page. "Roof area" says "as measured when prjoected onto a flat horizontal surface (i.e. as seen in Roof Plan view)", but further above it says, "The square footage of a pitched roof (or a dome) should be determined by calculating the surface area of the roofing material itself, not the area as seen from above."
Which one is correct?
Mara Baum
Partner, Architecture & SustainabilityDIALOG
674 thumbs up
June 24, 2013 - 1:04 pm
Good question. I haven't done a pitched roof building in years, but I would think that the very specific FAQ would trump the generic roof area definition. I'll punt the question to Tristan for clarification.
Lyle Axelarris
Building Enclosure ConsultantBPL Enclosure
60 thumbs up
March 21, 2018 - 4:46 pm
any update on this? It seems odd to me that overhangs should be excluded. This credit is about solar reflectance, and I don't think the sun rays care about whether or not there is conditioned space below the roofing material.
Summer Minchew
Managing PartnerEcoimpact Consulting
LEEDuser Expert
164 thumbs up
March 21, 2018 - 5:05 pm
Roof area that is not covering project gsf (such as an overhang or eyebrow as described above) would not be included in area calculations for SSc7.2 but would be included as an "architectural structure" for SSc7.1.
Lyle Axelarris
Building Enclosure ConsultantBPL Enclosure
60 thumbs up
May 10, 2018 - 4:53 pm
I believe you, I just think that this is very strange and does not conform to the credit intent. I have submitted the entire roof area (including overhangs and canopies) on several LEED projects without it ever being questioned.
I'm curious why the SS TAG would believe that canopies and overhangs should be treated differently from the rest of the roof. If you go for 7.2 but not 7.1 (which I believe is very common), than the canopies and overhangs would get ignored from a heat island perspective.
Also, just to be clear: the canopies and overhangs are included in the "building footprint", correct? I've seen "dripline" referenced several times on this site.
Summer Minchew
Managing PartnerEcoimpact Consulting
LEEDuser Expert
164 thumbs up
May 14, 2018 - 5:40 pm
GBCI has provided guidance on my previous projects that materials directly covering project GSF are considered "roof" and materials directly covering area that is not project GSF are considered "non roof" (which would include building eyebrows, parking canopies, shading structures, etc.) regardless of specific material type. On one project for example I had the same material in the same roof plane and one portion was considered roof because it covered project GSF within the building and one portion was considered non-roof because it covered an exterior walkway. In LEED v4 roof and nonroof credits are combined which eliminates your concern that specific materials may be excluded entirely if either Heat Island Effect credit is not pursued. I hope this helps.