[Equest-users] outside air flow during unoccupied/setback hours

Patrick J. O'Leary, Jr. poleary1969 at gmail.com
Thu Apr 26 07:16:04 PDT 2012

just looking in the advanced energy modeling for leed manual (from aug 
2010) i can't find anything about the reviewer's comment, though it does 
mention 90.1-2004 addenda for appendix g did change the language for 
schedules, outside air, to match the 90.1-2007 appendix requirement i 
quoted below.

have you tried contacting the review team thru the project resources?  
for leed 3/2009 there is an option buried in the submittal process that 
allows some communication w/the review team so either you, or the 
project lead, should be able to ask the reviewer to clarify the source 
of the comment requirement prior to marking your comment responses as 
done & possibly getting the same comment again.  i've found it useful to 
respond to reviewer's comments by referring to ashrae chapter, section, 
and verse (90.1-2007 in this case) and quoting the relevant text so if 
there's a usgbc interpretation that is different from the ashrae text, 
addenda, or interpretations the reviewer ends up telling what the source 
of the comment is.

there could be a usgbc cir addressing the subject, does anyone know?  
the usgbc position on simulating non-tradable exterior lighting the same 
in both proposed and baseline cases is in an old cir only - not in the 
usgbc modeling guide, not in 90.1, not in the usgbc handbooks.

On 4/26/12 6:16 AM, Ramana Koti wrote:
> Patrick, it is a LEED 2009 (v3) project. I'm slightly confused by this 
> one but trying to follow the reviewer's suggestion. Thanks for 
> pointing this out.
> RK.
> On Tue, Apr 24, 2012 at 7:52 PM, Patrick J. O'Leary, Jr. 
> <poleary1969 at gmail.com <mailto:poleary1969 at gmail.com>> wrote:
>     is this a leed 2.2 or 3.0 project?
>     i'm guessing, without looking in my leed manuals, this is a usgbc
>     requirement for at least 2.2.  for leed 3, 90.1-2007, appendix g,
>     table 3.1, no. 4 schedules, specifically states the "hvac fans
>     that provide outdoor air for ventilation shall run continuously
>     whenever spaces are occupied and shall be cycled on and off to
>     meet heating and cooling loads during unoccupied hours." 
>     90.1-2004 doesn't specify fans specifically for outdoor air for
>     ventilation, it just says hvac fans - which is the same as the
>     system supply fan in a non-doas/economizer capable of completely
>     closing the outdoor air damper system so the outdoor air can't be
>     shut off.
>     so the comment is contrary to the 90.1-2007 (and/or 2004 depending
>     on systems) simulation requirement.  the 90.1-2004 user's manual
>     appendix g section doesn't address the scheduling for hvac fans
>     during unoccupied modes.
>     On 4/24/12 9:54 AM, R B wrote:
>>     I normally have a min sch specified at the zone level - 0 for
>>     unoccupied hours and -999 for other hours that takes care of this
>>     comment.
>>     There is an hourly report for fan coming on during night cycle
>>     flag (or something similar). If you do not have the fan coming on
>>     or do not have the night cycle control, you should be ok. You can
>>     also look at the hourly report for OA ratio and whether fan is
>>     on/off during the unoccupied time.
>>     -Rohini
>>     On Tue, Apr 24, 2012 at 11:23 AM, Ramana Koti
>>     <ramana.koti at gmail.com <mailto:ramana.koti at gmail.com>> wrote:
>>         Dear All,
>>         One of the LEED review comments on a university building
>>         project I'm working on suggests to verify that all systems
>>         in baseline and proposed models contain zero outside air flow
>>         when fans are cycled on to meet setback temperatures during
>>         unoccupied hours.
>>         What is the best way to go about verifying this? In the
>>         'Hourly Report Block' options under a system, I find 'Hourly
>>         summed zone OA CFM for DCV calculation (cfm)' and 'Hourly max
>>         zone OA/total flow for DCV calculation (cfm/cf/). Is one or
>>         both of these options under an hourly report, the way to go
>>         or is there a better way of doing it?
>>         Thanks,
>>         Ramana.
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