Hi,
We are doing the Energy Model for SCHOOL Building. The client has proposed Air cooled chiller.
Class rooms are served by individual FCU, Meeting rooms are served by split units, and Auditorium, Lobby spaces are served by AHU. Separate FAHU will be used to provide fresh air to all those areas.
In Base Case, we have considered packaged VAV and Fan power has considered as as 0.0013 bhp/cfm (Total Fan Power = 17 kW).
In Proposed Case - We have considered FCU Fan power as 0.55 W/LPS (Total Fan Power = 7 kW)., AHU Fan power as 1.2 W/LPS (Total Fan Power = 5 kW).. FAHU Fan power as 1.6 W/LPS (Total Fan Power = 8 kW)
Total Fan power Basecase= 17 KW
Total Fan power Proposed case= 20 KW
1) In our software, not possible to model FAHU, so we have distributed the total fan power (of FAHU) 8Kw to FCU’s and AHU’s. This total KW has converted into BHP and this BHP value has used to calculate BHP/CFM. Finally BHP/CFM for FCU,AHU has been entered in the software. Is this correct or Whether we need to remove FAHU from energy model
2) Whether the BC Fan power 0.0013 bhp/cfm (from Table G3.1.2.9) should be considered only for supply air
3) Whether we can consider FAHU in base case also? (Because while considering FAHU only in PC, we are getting negative savings)
4) For what kind of fan system (like FCU,AHU,FAHU, Kitchen Exhaust and Toilet Exhaust) , table G3.1.2.9 will be used and is there any spread sheet?
Thanks for your suggestions,
Regards,
Sam
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5868 thumbs up
May 25, 2016 - 9:43 am
1. The Proposed must be modeled as designed so the FAHU must be included. The method you propose to model the FAHU appears correct.
2. The Baseline fan power includes all of the fans (supply, return, relief and exhaust) but the allowance is calculated using only the supply airflow. You can distribute the baseline fan power anyway you like. We usually do it in proportional to the proposed systems.
3. There should be no FAHU in the baseline.
4. There is a spreadsheet in the Documentation Toolkit above that can be used for the baseline fan power calculations. G3.1.2.9 is only applied to the baseline fans that are related to the space conditioning equipment.