Please comment on the following:

Based on Table G3.1.10.a, for an HVAC system in the proposed design, the system is determined by the following:

"Where a complete HVAC system exists, the model shall reflect the actual system type using actual component capacities and efficiencies."

In design of AHU systems, the scheduled or nameplate flow rate of the equipment is typically higher than the design flow rate of the system, as calculated by the simulation software. The system fan power calculation is based on the efficiency of the fan and ultimately the design flow rate of the fan. Also, in operation the fan typically does not operate at 60 Hz at peak flow rate, suggesting that the operating flow rate in this condition is more in line with the design flow rate calculated by the simulation software, rather than the nameplate flow rate of the equipment.

For these reasons, it is likely the case that the fan power calculation should be based on the design flow rate calculated by the software, rather than the nameplate flow rate.

Thanks,

Nick Blanton
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