[Bldg-sim] Number of unmet hours

[Bishop, Bill]

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

 

  <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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