The DOE-2 simulation used for the ASHRAE 90.1 and Nonresidential Performance calculations is not able to simulate an exhaust fan with variable flow at the zone. The solution is to model this as part of the return fan for the HVAC system, and this may also mean that the system is marked as being 100% outside air.
This edit would be made by removing the exhaust fan from the Zone level of the Tree, and inputting it as part of the HVAC system, which is one level up in the building tree.
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