[Bldg-sim] Number of unmet hours

[Hintz, Scott Fredrick. (KSC-ISC-4011)[URS Federal Technical Services, Inc.]]

Unmet hours for occupied hours only has been discussed but there was no good consensus on exactly how to do this. So, yes, unmet hours are of the entire (8,760) simulation and are building level, meaning one zone or all zones unmet that hour is still just one unmet hour.

Trane CDS has a good document for combating unmet hours in TRACE 700. I think it's probably generic enough to be used for any tool.

Scott Hintz
CEM, LEED-AP BD+C, BEMP

HVAC & Energy
Sustaining Systems Engineering (SSE)
[cid:image002.png at 01CCB372.DF76CBD0] Federal Technical Services
PO Box 21025, M/C: ISC-4011
Kennedy Space Center, FL 32899
Building: M6-493, Office: 1100H2
(321) 867-8533 office
(321) 867-5810 fax
scott.f.hintz at nasa.gov<mailto:henry.d.turner at nasa.gov>

From: Bishop, Bill [mailto:wbishop at pathfinder-ea.com]
Sent: Monday, December 05, 2011 9:03 AM
To: Rathna Shree; bldg
Subject: Re: [Bldg-sim] Number of unmet hours

Rathna,

The simulation covers 8760 hours, but this does not imply 8760 hours of fan operation. I don't see anything in Appendix G that requires you to prorate the 300 unmet load hours based on the schedules of building operation. So, just stick with the 300 hour threshold.

I suggest you follow your four-step procedure (in eQUEST or other DOE-2), except that I've never had unmet plant loads so I'm not sure how I would take that into account. I disagree with Ashu - adding up all the unmet hours in all SS-R reports can double-count (or more) coincident unmet hours.

Regards,
Bill

[cid:image003.png at 01CCB372.DF76CBD0]<mailto:wbishop at pathfinder-ea.com>


From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Ashu Gupta
Sent: Monday, December 05, 2011 5:45 AM
To: 'Rathna Shree'; 'bldg'
Subject: Re: [Bldg-sim] Number of unmet hours

Hi Ratnashree,

You can directly see no of unmet hours for each system from SS-R report and total number of hours (all systems) should not be exceed 300 hours.

Thanks!
Ashu

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Rathna Shree
Sent: Monday, December 05, 2011 3:59 PM
To: bldg
Subject: [Bldg-sim] Number of unmet hours

Dear All,

The following is the procedure i use to calculate unmet hours:

1)    Percentage of Plant and system unmet is got from BEPU report.

2)    The number of hours fan is on is got from SS-E report.

3)    Percentage of system unmet(BEPU) multiplied by number of fan on hours(SS-E) gives the Unmet hours.

4)    Plant and system unmet together should not exceed 300 hours.

But as per ASHRAE 90.1, the 300hours of unmet is w.r.t. a simulation for 8760 hours. If the building is only 8 hours working 5 days a week, then the fan on hours vary. Will the same 300 hours hold good for 3500 hours of operation also.

The maximum percentage of Unmet for 8760 hours of operation is 3.4% amounting to 300 hours. Do we have to take 3.4% of the total fan on hours to calculate maximum unmet hours if the fan on hours is anything other than 8760?

Please help.

Regards,
Rathnashree
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