Forum discussion
CS-2009 EAp2: Minimum Energy Performance
Hi LeedUsers,
I have one simple question. According to section G3.1.1 of ASHRAE 90.1 Standard each floor for system 5 through 8 shall be modeled with a separate HVAC system. I hope it doesnt mean that each floor shall have its own heating and cooling source but only AHU per floor and these AHUs will be supplied by one central heating/cooling source (or more central sources according to section G3.1.3).
I definitely prefer the second option but I rather ask.
Thank you in advance.
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
January 8, 2016 - 3:36 pm
For a system 5 and 7 the heating is a centralized boiler system. For system 5 and 6 each system has DX cooling. For system 7 it is also centralized cooling which is also the case for system 8. So whether the heating and cooling source is central or within each system varies depending on the system in question.
Samuel Sura
Mre-Dome
January 11, 2016 - 7:38 am
Thank you Marcus for your help.
I would like to ask another one question:
I have office building where 30 000 m2 (cca 323 000 ft2) is office space (system 7) and almost 15 000 m2 (cca 161 500 ft2) is for parking, what system type I should choose for the garage? Should I follow section G3.1.1b and choose system 3 because of significant difference in occupancy and process loads? And then eliminate heating and cooling loads for garage HVAC system by setting up an unachievable setpoints... Could it be like that?
Thanks!
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
January 11, 2016 - 4:12 pm
Sounds like the parking garage is unconditioned (no heated or cooled)? If so you don't model any system in either model.
Samuel Sura
Mre-Dome
January 12, 2016 - 4:36 am
Yes that's right, it is unconditioned space of course, but it is underground garage and there are several extract fans for removal of exhaust gases. So I thought that it is necessary to model every end-use load components as stated in Table G3.1.1a. Therefore I was looking for solution how to model energy consumption for parking garage fans in baseline building.
Please correct me if I'm wrong but I thought if proposed building has any energy consumption so the baseline has to have too.
Thank you.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
January 12, 2016 - 10:30 am
That table only applies to conditioned spaces.
The exhaust fans in the garage are process loads and would be modeled identically in both models. You can claim savings for demand controlled ventilation based on CO as an exceptional calculation if this strategy is not required or common practice in your location.
Samuel Sura
Mre-Dome
January 13, 2016 - 8:34 am
Thank you Marcus, I appreciate your help.