I got a comment on a project that said G3.1.1 exception c means that all qualifying lab spaces would be assigned to one system 5/7 for the whole building not one per floor. Is that correct?
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Tyler Thumma
7GroupLEEDuser Expert
60 thumbs up
December 16, 2021 - 10:06 am
Yes, since the exception states to use a single system of type 5 or 7 serving only those spaces. I'm not sure it would make a big difference though. The fan power allowance (in W/cfm) for a single larger system might be lower (due to a higher motor efficiency), but the cooling efficiency (if System 5) could be lower.
Cory Duggin
Senior Energy WizardTLC Engineering Solutions
51 thumbs up
December 16, 2021 - 10:20 am
With that in mind and 90.1-2010 addendum cn being added, does that mean I should have one lab system for all lab spaces that meet the 5000 CFM of exhaust threshold for G3.1.1 exception c and another for lab spaces with less than 5000 CFM of exhaust? I have been told before to go back to the definition of a space in 90.1, which essentially is any enclosed space, so labs open to one another would have their exhaust added together for consideration towards G3.1.1 exception c. How should supporting lab areas that are separately enclosed be considered? Are they part of the other lab even though they are separately enclosed or would they be considered towards G3.1.1 exception c separately?
Tyler Thumma
7GroupLEEDuser Expert
60 thumbs up
December 20, 2021 - 8:28 am
I wouldn't model them as separate systems but would combine all lab spaces to which G3.1.1 exception c and/or addendum cn apply into a single lab system. You'll need to use your discretion with supporting lab spaces, because the standard doesn't spell out exactly how to treat those. I would say if they are lab-related and the lab exhaust would include air transferred from those spaces then they should be considered as part of the lab. If they are isolated and served by separate non-lab systems in the design, then they would be part of non-lab Baseline system.