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NC-v4 EAp2:Minimum energy performance

baseline system selection for building with very different internal gains in different zones.

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Moses Chong
Mechanical Engineer
WSP
LEEDuser Basic Member
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Hi!

I'm working on a project that has a lot of different manufacturing process, and the internal gain varies a lot (more than 10 btu/h-sf) in each zone. The building is bigger than 150,000 sf all electric no gas, so the baseline system should be system 8. But G3.1.1 exception b states that I should use system 4 when peak thermal loads are differ by 10 btu/h-sf. So do I simply create a system 8 for one zone from each level then use system 4 for other zones, or one system 8 for each level, or do I simply use system 4 thoughtout? 

Thanks!

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Wed, 02/26/2025 - 06:05

Hello, I would find the average peak thermal loads for all zones, put all zones that are within the 10 Btu/hr/sf range into system 8 (modeled floor by floor) and assign System 4 to the ones exceeding 10 Btu/hr/sf limit. (modeled per zone). If the variation is large enough that all zones exceed the 10 Btu/hr/sf limit compared to average, i would use System 4 for all zones. Curious to hear other people's thoughts on this. 
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Anurag Ghosh
Assistant Sustainability Manager
L&T Construction
LEEDuser Basic Member
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Wed, 02/26/2025 - 07:26

Hi Shashank, Did you mean difference between a random zone peak thermal load and average peak thermal load (sum of peak thermal loads for all zones) should not differ by 10btu/hr/sqft?
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
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Wed, 02/26/2025 - 16:20

It is important to note that 90.1 is not intended for manufacturing facilities. LEED has us try to squeeze such projects into a standard that technically does not even apply. Without knowing considerably more about the facility I would tend to make sure I took the most conservative approach (i.e. the one that produces the lowest level of energy savings). I would apply the exception to the non-manufacturing spaces like the offices, locker rooms, etc. You would then substract off this area and re-eneter Table G3.1.1A and see what system I end up with then. Rather than some sort of mathematically solution I wouuld seek to do what is a fair comparison and what makes sense relative to the space heating and cooling needs of each zone.

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