The project I am working on consists of a huge machine shop on one side of a glass wall and offices on the other side of the glass wall. I am assuming that the dividing glass wall is "tight" and that the construction details at the roof, floor, etc will also be tight.
Providing the entire gigantic machine shop with negative pressure will cost a lot of energy.
We already have "air locks" between the office and machine shop spaces--i.e: one must pass through two doors when going between the spaces. If the air lock has self-closing doors and significant negative pressure compared to the office space, would that be a meaningful subsitute for negatively pressurizing the entire machine shop?
A more general question: what is the purpose of the negative pressure? Is the negative pressure meant to keep pollutants from leaking through the walls/floors/ceilings? Or is the negative pressure meant to keep pollutants in while the door is open? Or both?
If the meaning is just to keep pollutants on one side of an open door, I would think that the air lock solution would be reasonable?
Thanks in advance for your help and insight!
David Gibney
Technical Director for Sustainable DesignM+W Group
23 thumbs up
March 19, 2014 - 10:25 am
Hi Raina, I'm not a mechanical engineer, but I doubt the LEED reviewer would accept this solution. In theory if you have positive pressurization in the machine shop and a negatively pressurized vestibule separating it from the office space, this vestibule would serve as a "vacuum", sucking up air from the machine shop. People entering this negatively-pressurized vestibule could then be subjected to potentially contaminated air from the machine shop. Here's an idea: if this vestibule was positively pressurized then one might be able to make the argument that it would be contaminant-free and thus the office space would not be subjected to bad air from the machine shop. You probably would need to have a significant pressure differential between the vestibule and the machine shop to convince the LEED reviewer that this would work, and it might even take a CFD model to prove to them the efficacy of this strategy. Also, depending on the door swing direction you might need to have stout door closers to overcome the positive pressurization in the vestibule, which can be difficult without using security grade doors. If you think this is a potentially viable design option, prior to doing it I would certainly submit a CIR for pre-approval.
To answer your question, I believe the purpose of the negative pressurization is both.
My two bits.... Good luck! David