...is calculated automatically by the energy simulation tool we use according to appendix G13.1.2.9. However, we would like to check the outputs of the model against equation in G3.1.2.9 to verify that the fans are modeled appropriately.
Equation G3.1.2.9 for systems 3 through 8 indicates that the Fan Power equals to 746/Fan Motor Efficiency in Watts. Fan Motor Efficiency is "the efficiency from Table 10.8 for the next motor size greater than the input kW using the enclosed motor at 1800 rpm". What is it meant by "...input kW"? Do I check the size of my motor in Proposed and then choose the next greater corresponding one in Table 10.8, and use its efficiency (under enclosed motors at 1800 rpm) by dividing it with 746?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
August 23, 2013 - 9:29 am
It has nothing to do with the proposed motors.
The input kW is the electrical power into the motor as opposed to the output kW which is how much work (energy) the shaft produces. The difference is the efficiency. Input is typically derived and the motor nameplate provides the output.
The size of the baseline motors is determined by the supply cfm auto-sized by the baseline energy model. See Table G3.1.2.9. There is a spreadsheet under the Documentation Toolkit button above that does these calculations which you can use to check your modeling results.