[Bldg-sim] Number of unmet hours

Ashu Gupta kce2 at kamalcogentenergy.com
Mon Dec 5 02:45:26 PST 2011


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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