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9 years ago I think we should follow the guidance from the 2008 ACM, which is really quite
simple (even if it doesn't exactly match what happens in practice):
1. If a space is marked as "Unconditioned", all internal loads are 0, and the
ventilation rate is 0.
2. If a proposed design space is marked as "Unconditioned", the matching space
in the Standard Design shall also be unconditioned.
3. Unconditioned spaces that have any exterior envelope components shall have
infiltration rates following the same rules as conditioned spaces.
4. We should have appropriate flag/checks/exceptional conditions when a
"significant" fraction of the space is designated as unconditioned.
5. We could have a few descriptive unconditioned space types (Unconditioned
Stairwell, Unconditioned Atria, ..., Unconditioned Other) that would function
identically, but make it easier for the plan reviewer to identify spaces
modeled as unconditioned.
Any space, including a computer room, storage area, that has a non-zero
occupancy requires ventilation per the Standards and ACM requirements. If we
decide we want to make the occupancy zero for an electrical room or some
special space, I am ok with that, but I don't see why we need to, since
occupancy and hence ventilation rates are prescribed in the ACM.
A heated only warehouse is still considered a conditioned space.
For example, a mid-rise office building that has unconditioned stairwells for
emergency entry/exit: if these are modeled as unconditioned and not ventilated,
that is the easiest modeling option. If they have some form of ventilation but
are unconditioned, we could try and model this, but I don't think it is worth
it. Perhaps a note on the compliance forms that the designated space(s) have
ventilation complying with 120.1 of the Standards.
Indirectly conditioned space - this term is only used in the context of
identifying demising surfaces and prescribing their requirements. From the HVAC
perspective, the space is considered conditioned or unconditioned. No transfer
air from other conditioned spaces is considered in the compliance model. A
naturally ventilated space that is not actively controlled (in my opinion) is
considered an unconditioned space.
Recommend clarifying ACM rules with the above intent, and moving to "Resolved".
There are some limitations with this approach in not being able to directly
model a ventilation only system, but since there is no clear baseline for this
type of system, no significant tradeoffs and no clear requirement to include
it, I say, don't.
Original comment by JohnJArent on 30 Oct 2013 at 5:04
- Changed state: Discussion
Original issue reported on code.google.com by
da...@360-analytics.comon 26 Oct 2013 at 8:18