I have an office building that i am modeling that has 3 above ground floors
and one below ground floor. the total square footage is 32,000. would this
qualify as a VAV for the baseline or a single zone constant volume?
The below ground floor is the part that is making me have second thoughts.
my first thought was VAV, but i figured i would pose the question to get
some healthy conversion.
thanks,
--
Rob Hudson
Rob,
first of all---its just not that simple. It depends on:
1. what guidelines are you supposed to use for the baseline? If this is
a LEED project which version of LEED will dictate which ASHRAE 90.1 version
you reference. If it is not a LEED project who is the 'authority' that is
approving your baseline--they will have guides that they want to see used
for the baseline.
2. What are the proposed building systems for the building design--what
has the ME designed and what type of heating source is being used. When you
use ASHRAE 90.1 App. G, the baseline system selection table depends on the
size of your building, the classification (non-res, res), and the heat
source being used in the actual building design.
3. There really shouldn't be any impact of your below ground floor on the
decision/selection of your baseline systems, what is the below ground space
and how is your ME designer conditioning that space per the design drawings.
4. If you do not have any design direction from your ME, then you will
have to take a more "assumptive" approach as the simulator and this can be a
very tricky approach if you "assume" incorrectly--but many factors to help
identify a valid assumption will go back to whatever your case is for the
first three points I have shared.
Do you have a copy of the ASHRAE Standard 90.1? We are happy to help, but
we will need more detail from you so that we can point you in the right
direction.
Pasha
Rob,
Assuming you are looking at Table G3.1.1A in Standard 90 the key would be in
the use of the word AND: 3 stories or less AND less than 25,000 sf for PSZ
vs 5 stories or less AND between 25,000 and 100,000 sf for VAV. So I think
you should use VAV and that the below grade floor doesn't even come into
play.
Others?
Carol
I am using ASHRAE 90.1 2007 for LEED accreditation. The system is electric,
as of right now. My company is only the modelers and not the designers, so
things may change. This was why i left it a little vague because i can't
say for certain if it will be electric or fossil fuel (75% certain it will
be electric). I'm not sure if the below ground floor makes a difference
because it is a combination of conditioned office space and
storage/mechanical space.
thanks for your response
That is what my original thought was, but if the below grade floor (total of
7100 sqft) is disregarded, then it drops into the PSZ catagory and out of
the VAV catagory.
The below-grade floor is a floor. Count it.
Timothy Howe, MS, LEED? AP
Oh, yeah, you did say 32,000 sf total, didn't you. I'd go with Timothy then.
Carol
thanks, everyone, for the input. solution = VAV system