[Equest-users] Unmet Load Hours Calc

[Brett M. West]

I have a question regarding the way unmet load hours are calculated in
eQuest. I have received the following comments from the USGBC reviewer
after submitting my energy model. 

 

1. The response narrative to preliminary comment 1 states that the SS-R
reports have been used to determine the number of unmet load hours for
each case however this method does not take into account coincident
hours. Additionally, the number of hours any system outside of
throttling range is not the number of hours the HVAC system is in
operation but rather it is the number of hours each zone exists during
the building simulation, or 8,760 hours. Therefore the number of unmet
load hours is 333 in the Baseline case and 508 in the Proposed case and
the simulation does not meet the requirements of Section G3.1.2.2. If
appealing this credit please revise both cases using the prescriptions
of Section G3.1.2.2 until the number of unmet load hours is less than
300 for both cases and the number in the Proposed case does not exceed
the number in the Baseline case by more than 50.

 

I thought the unmet load hours were calculated only during times when
the fans are actually running in the simulation. This is why I always
pull my unmet hours from the SS-R report, adding up the unmet hours for
both cooling and heating for each individual unit. I can also go into
the SS-E report and calculate the number of hours my fans are actually
running and then calculate the total number of hours by using the
percentage of hours outside the throttling range given in the BEPS
report. 

 

If you calculate the hours in the manner the reviewer has outlined then
there is no way to show which hours are heating and which are cooling
and you have to provide that breakdown in the EAc1 template. 

 

Any input on this topic would be greatly appreciated.

 

Thanks in advance.

 

 

BRETT M. WEST

 

RMF ENGINEERING

T: 843.971.9639 ext. 1499

F: 843.971.9641

bwest at rmf.com <mailto:bwest at rmf.com> 

 

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