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NC-2009 EAc1: Optimize Energy Performance
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Fan operation for System 6
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
April 29, 2013 - 1:26 pm
The fans in the PFP boxes are outside the requirements of G3.1.2.4.
Main supply fan in AHU is on during occupied periods and off during unoccupied periods.
VAV box (zone) fan only operates in heating mode as follows:
Occupied:
T’stat satisfied, box at minimum position, fan off.
Call for heat, zone fan energizes (tempers cooling air with warm room/plenum air).
Continued call for heat – reheat energized.
Unoccupied: Zone fan and reheat cycle as required to maintain setback temperature.
The allowance of 0.35 W/cfm (based on 50% of the peak primary supply airflow) in Section G3.1.3.14 is in addition to the AHU system fan power.
Francesco Passerini
engineer90 thumbs up
April 30, 2013 - 3:37 am
Thank you, Marcus.
For System 6 shall both fans in AHUs and fans in PFP boxes be VAV?
You wrote “Main supply fan in AHU is on during occupied periods and off during unoccupied periods”, but it shall be cycled to meet cooling loads during unoccupied hours, right? Otherwise, if cooling is needed during the unoccupied periods, how could it be provided if the supply fan in the AHU is off?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
April 30, 2013 - 9:24 am
The fans in the PFP boxes can be constant.
Yes the main fans cycle during unoccupied.