What is in your opinion the baseline for the following building:
Floor area:12,000 sqm (130,000 sqft)
Floors: 5 above grade, mostly conditioned. 5 underground parking, mostly
unconditioned apart from some conditioned spaces in the first below grade
floor.
Predominant Use: Office (85% of sqft),
Secondary use: bank in PB and below grade; Kitchen, below grade; control
security room, below grade.
I'm in between baseline 6 or 8. If conditioned spaces below grade fall
under exceptions to G3.1.1 b. then can I consider for the baseline that the
predominant building has 5 floors instead of 6?
Thanks in advance.
Santiago.
In my opinion the *system type 8* would be applicable. As the *total
conditioned area *is not explicitly mentioned so i presume it is more than
150,000 sqft (above grade floor+basement floor areas).
Here are couple of reason which i could think of:
i) per G3.1.1, HVAC systems in the baseline building design shall be based
on usage, number of floors, conditioned floor area, and heating source as
specified in Table G3.1.1A and shall conform with the system descriptions
in Table G3.1.1B.
ii) per Table G3.1.1A, system 8 would be applicable if either of the
condition is met number of floors OR conditioned area OR both
iii) exception G3.1.1a would be applicable once you are decided with
the *predominant
system type* based on number of floors or conditioned area OR both per
section G3.1.1. I strongly feel that exceptions are applicable only when
the modeling scenario can not be addressed by the main sections which in
your case is G3.1.1.
Hope this helps!
I would also go with 8, for simplicity. You pretty clearly have 6 levels
with conditioned spaces.
Even if you do go through the effort to declare each underground level
conditioned space as subject to G3.1.1 exceptions, that doesn?t reduce the
quantity of floors with conditioned spaces for the whole project.
That said, this is one of those situations where I?d subjectively agree
it?s within the realm of reasonable interpretation to pursue the direction
you?ve described with System type 6. I might be more motivated to make
that case if packaged DX systems per-floor are a closer approximation to
the actual design equipment than a chiller plant. I suspect it may
ultimately be more effort than it?s worth however.
~Nick
*NICK CATON, P.E.*
*Owner*
*Caton Energy Consulting*
1150 N. 192nd St., #4-202
Shoreline, WA 98133
office: 785.410.3317
www.catonenergy.com
*From:* Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] *On Behalf
Of *Javed Iqbal
*Sent:* Thursday, July 02, 2015 2:55 PM
*To:* Santiago Velez
*Cc:* bldg-sim at lists.onebuilding.org
*Subject:* Re: [Bldg-sim] 90.1 Ap. G System selection: 5 stories +
Underground - System 6 or 8?
In my opinion the *system type 8* would be applicable. As the *total
conditioned area *is not explicitly mentioned so i presume it is more than
150,000 sqft (above grade floor+basement floor areas).
Here are couple of reason which i could think of:
i) per G3.1.1, HVAC systems in the baseline building design shall be based
on usage, number of floors, conditioned floor area, and heating source as
specified in Table G3.1.1A and shall conform with the system descriptions
in Table G3.1.1B.
ii) per Table G3.1.1A, system 8 would be applicable if either of the
condition is met number of floors OR conditioned area OR both
iii) exception G3.1.1a would be applicable once you are decided with
the *predominant
system type* based on number of floors or conditioned area OR both per
section G3.1.1. I strongly feel that exceptions are applicable only when
the modeling scenario can not be addressed by the main sections which in
your case is G3.1.1.
Hope this helps!
I agree with both of you. I guess my argument was that since these below
grade conditioned spaces would be served by separate HVAC system anyway,
then they match the intention of the G.3.1.1.b. But I agree this is grey
area.
Good news is, this is early energy modelling to drive design, so it is
Baseline definition that will determine proposed HVAC system. First
proposal was an air cooled VRF system, which in my experience against
baseline 8, will have difficulties (or be costly) achieving the substantial
targeted savings (34% again 90.1-2007 App. G). This would be more
achievable against a system 6.
Anyway, thanks for the insights!
Santiago.
Santiago Velez