[Equest-users] Unmet Hours

John Aulbach jra_sac at yahoo.com
Fri Mar 16 08:07:08 PDT 2012


I will look at your run later. But for the VAVs, make sure your thermostats are reverse acting, then increase the deadband to 4 or even 6 deg F.

John Aulbach
Partner Energy

 From: Matt Clough <mclough at kme-inc.com>
To: "equest-users at lists.onebuilding.org" <equest-users at lists.onebuilding.org> 
Sent: Friday, March 16, 2012 8:00 AM
Subject: [Equest-users] Unmet Hours

All right Folks,
It’s time to do that thing again where we talk about unmet hours.  I’ll give a little background first:  I’m new to equest and to the HVAC industry, so bear with me.  The project is a 1F school building (pre-k) with a clerestory, split into 10 zones and predominantly served by series VAV terminals using chilled water and hot water loops.  It’s in Houston , 
TX so and are no economizers.  I’ve spent the majority of the past few days reading previous discussions and trying a variety of changes.  I have attached the INP and PD2 for convenience.
I initially tried to represent the system based on the mechanical/electrical schedules, but that yielded many unmet hours (99%), so it is currently set to auto-size, but am still at about 600 unmet hours (7%).  7 of the zones are series VAV, 2 are single-zone with reheat, and one is a packaged single zone for the MDF room.
	* Changing to an auto-sized system provided a large reduction in UH.  
	* am trying to not manipulate the data by adjusting the cooling/heating ratio.  
	* The setpoints are 75c/72h.  I tried changing them a few degrees in either direction, but did not get a large enough reduction.  
	* have the fans cycling at night (no OA), which did help reduce the hours 
	* switched into DDE and set actual CFM from the mechanical plans.  This resulted in an increase 
As I am looking through the LS-B report, it seems like some of my zone loads might be a little high with some of the heat generation loads at about 12kbtu/h.  I think my inexperience hampers my ability to troubleshoot some of the problems because I don’t necessarily have a good sense for what a reasonable result/prediction is.  
I appreciate any assistance on this matter and am open to suggestions as far as proper modeling techniques and troubleshooting methods.
Matt Clough
Mechanical Designer
KME Engineering
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