I am having difficulty determining if my project can comply with this credit. There is an inconsistency between the wording of the credit narrative and the results calculated in the BCTR spreadsheet and clarification on which calculation is intended would be helpful.
The narrative states (page 2, paragraph 2):
No more than 15% of the glazed area in Façade Zone 1 can have a Threat Factor higher than 75.
I interpret this to mean that if I have 100sf of glazing, no more than 15sf of that glazing can have a Threat Factor higher than 75. However, in the spreadsheet’s calculation of Z1 HGF (line 17) it is dividing the HGA by the total Z1 material area, not just the glazed area.
In my project, I have 1,476sf of glass and all of it has a Threat Factor of 100. Therefore, if I interpret the narrative literally the number I should get from the spreadsheet for the Z1 HGF is 100% (hazardous glazing area / glazed area). Instead, the spreadsheet reports 4.4% (hazardous glazing area / total Z1 material area). Should the narrative actually read:
No more than 15% of the material area in Façade Zone 1 can have a Threat Factor higher than 75?
Or, is the narrative correct and it’s the spreadsheet that requires revisions?
Also in the spreadsheet, the calculations are broken if one’s building has zero Zone 2 area. It’s not clear to me what the intended weighting is behind multiplying Z1 x2 and dividing (Z1x2)+Z2 by three. So does this formula need to change for buildings of three floors or less? Or does Z1 x 2/3 give the desired BCTR?
Also, for purposes of credit documentation, how does one define ‘story’ and ‘building height’ in the spreadsheet? My project has only one floor but a portion of it is a 50’ high maintenance bay. Also, the building has three distinct parapet heights – is the credit interested in the tallest height? All of them?
Chloe Bendistis
Sustainability Technical ManagerThe Sheward Partnership, LLC
21 thumbs up
December 12, 2012 - 12:19 pm
Hi Joe - I came across the same issue. It appears that there are TWO requirements related to the building facade.
1. No more than 15% of the glazed area in Facade Zone 1 can have a Threat Factor higher than 75. This is noted as "Hazardous Glass Area" in the provided spreadsheet. I'm not sure if the provided spreadsheet calculates this requirement correctly. I will provide my own calculations.
2. Achieve a maximum total building Bird Collision Threat Rating (BCTR) of 15 or less. This calculation includes glazed and opaque surfaces. Once again, the provided spreadsheet has some errors. I will provide my own calculations.
Hope this helps!