I routinely work on building designs that incorporate rooftop upblast fans over large industrial spaces such as this one:
When selecting these fans, as with every other fan, you need to determine the external static pressure that the fan will encounter. I have heard opinions ranging from "negligible" to 0.15" of static pressure up to 1" without any technical basis to back the responses up. Generally, they are exhausting a space at a slightly higher rate than the space is being supplied air in order to negatively pressurize the area relative to adjacent spaces, with an intent of maintaining 0.1" of static pressure.
What guidelines/calculations are available to allow the external static pressure for this fan configuration to be calculated?
