Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
No, EnergyPlus doesn't use these as inputs, instead it calculates W and W/cfm from the fan efficiency, design air flow rate, and pressure rise (see Fan section of eplustble CSV or HTM file for fan power outputs). Because of this it requires some reverse engineering to predict what the fan power output will be from EnergyPlus.
For an Appendix G Baseline system I use USGBC's "Revised Section 1 4 Tables" XLS along with some fundamental power equations to solve for the required pressure rise to exactly match the allowed fan power. For an Appendix G Proposed system I use the data from the HVAC designer's schedule to calculate the fan power and then solve for the pressure rise. If fan BHP is given you can calculate the fan efficiency and if it's not I use the default from OpenStudio to calculate the pressure rise. This method for the proposed fan power will not predict the fan power exactly like the baseline method will, but it's close.
| | 2 | No.2 Revision |
No, EnergyPlus doesn't use these as inputs, instead it calculates W and W/cfm from the fan efficiency, design air flow rate, and pressure rise (see Fan section of eplustble eplustbl CSV or HTM file for fan power outputs). Because of this it requires some reverse engineering to predict what the fan power output will be from EnergyPlus.
For an Appendix G Baseline system I use USGBC's "Revised Section 1 4 Tables" XLS along with some fundamental power equations to solve for the required pressure rise to exactly match the allowed fan power. For an Appendix G Proposed system I use the data from the HVAC designer's schedule to calculate the fan power and then solve for the pressure rise. If fan BHP is given you can calculate the fan efficiency and if it's not I use the default from OpenStudio to calculate the pressure rise. This method for the proposed fan power will not predict the fan power exactly like the baseline method will, but it's close.
