[Equest-users] 2007 90.1 Appendix G3.1.2.4

[Paul Diglio]

Brad:

Did you intended to post a message?

G3.1.2.4 is unclear.  First it states that the supply fan shall run continuously 
during the occupied hours and shall be cycled to meet heating and cooling loads 
during unoccupied hours.  Ok , I get that.

Then it states that if the supply fan is modeled as cycling and the fan energy 
is included in the EER, then the fan energy shall not be modeled explicitly.   
That is confusing.  When is it permissible to model the supply fan as cycling.  
Is AHSRAE talking a supply fan serving a space that is never occupied?  
Obviously, there is no such thing, someone will sometime do something in the 
room.

Then G3.1.2.4 goes on to state that the supply, return or exhaust fans will 
remain on during occupied and unoccupied hours in spaces that have heath and 
safety mandated minimum ventilation requirements during unoccupied hours.

This requirement does not cover many of the scenarios that I model.  For 
example, natural ventilation provided by operable windows.  It does not make 
sense to keep the fan running if it not supplying ventilation air.  I am 
presently modeling a residential high-rise.  No one keeps their apartment supply 
fan running 24X7.  Especially if there are operable windows.

Another example is a commercial property that has a DOAS supplying minimum air 
directly to the zone HVAC system or supplying minimum directly to the zone 
without isolation dampers.  If I supply the 62.1 minimum air required by the 
DOAS, then why run the supply fan?

I would be interested to hear other interpretations.  Perhaps Jason Glazer can 
give us his unofficial opinion.

Paul Diglio





________________________________
From: Brad L. Huff <BradH at BVHis.com>
To: "equest-users at lists.onebuilding.org" <equest-users at lists.onebuilding.org>
Sent: Fri, June 10, 2011 10:10:50 AM
Subject: [Equest-users] 2007 90.1 Appendix G3.1.2.4


Modelers,
 
Brad Huff, E.I.T., LEED Green Associate, Mechanical EngineerI BVH Integrated 
Services I860.286.9171 tel I860.242.0236 fax I50 Griffin Road South, Bloomfield 
CT 06002 I .bvhis.com Itwitter.com/bvhis I Hartford  Boston 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20110610/3b4eaf3e/attachment.htm>