[Equest-users] FCU Fan Control Question

[Robert Des Rosiers]

Does anyone have any thoughts regarding the question posted below?

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Robert Des
Rosiers
Sent: Monday, June 28, 2010 9:48 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] FCU Fan Control Question

 

All:

My building has individual 4-pipe FCU's attached to a central plant.  I am
seeking clarification as to how eQuest interprets an undefined 'fan
schedule' versus creating a fan schedule.

 

It is my understanding that, per the help topics, if a fan schedule is left
'undefined' the "program assumes the fans are always available when needed."
This seemed to be a viable option when designing a baseline building.  Since
I know the fan schedule I created one; on during occupied hours, off during
unoccupied with night-cycling enabled (per ASHRAE section G).  This had a
significant impact on steam consumption, changing from 415 MBTU in the
'undefined option' versus 228 MBTU in the 'scheduled option'.  Since I am
forcing the fans to be on in the scheduled option one would think it would
result in higher energy consumption values.

 

Could someone clarify why adding a fan schedule would impact energy
consumption so significantly?  Could it be left as 'undefined' simply
allowing the fans to operate when they're needed?  Does this schedule,
listed as a 'cooling' fan schedule only operate cooling and if 'yes', is the
heating schedule defined under the 'Heating' --> 'Coil Cap/Control'
'Availability Sch' (which I have as 'undefined'?

 

Thank you all in advance for your assistance.

 

Robert Des Rosiers, LEED-AP

STUDIO MA

130 N Central Avenue, No.300 Phoenix, Arizona 85004

Telephone 602 251 3800

Fax 602 251 3100

 

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