Hi Steve,
I've used both "averaging" approaches and "per system" calculations with
success for per-zone baseline system types. I would reason project size
/ sheer system quantities into my decision to go one way or the other.
I think it's key in any case to be consistent in your
documentation/calculations.
Note the GBCI LEED spreadsheet has support for (paraphrasing) "typical
of ## systems" baked in. At some point, it would be silly from all
fronts (review and documentation) to separately document tons of nearly
identical units in separate columns. If the reviewer should wish to
spot check a couple individual cases, you can always provide complete
SIM reports for the systems. If going along the "averaged" route, I'd
use some of that time saved to clearly show my work for coming up with
averaged system inputs as supporting documentation (and reference that
upload in the Section 1.4 workbook alongside your "typical" system so
that's clear, for context).
I also don't think there's precedent for forcing any particular doe-2
system type - you should be free to choose any system that best
approximates what's required.
Regarding # of systems per apartment: Whatever you do... don't let any
of that "real world common design sense" muddy the waters for
interpreting baseline appendix G requirements!
In all seriousness though, if there exists an actual design for
reference showing a given apartment is actually multiple systems/zones,
the onus falls on the modeler to determine those separate systems/zones
(& even apartments) may be reasonably blocked together for having
similar system properties & load profiles. If you aren't comfortable
making such assertions (and dealing with the consequential extra legwork
for determining/documenting things like "average system size" for
efficiency calculations later), then you can always fall back to drawing
up zoning to reflect as many systems/zones as will actually exist. I
try to weigh such end-to-end considerations at the outset of model zone
mapping, where applicable.
~Nick
------------------------------------------------------------------------
------------------------------------------------------
Nick Caton, P.E.
Senior Energy Engineer
Energy and Sustainability Services
North America Operations
Schneider Electric
D 913.564.6361
M 785.410.3317
E nicholas.caton at schneider-electric.com
F 913.564.6380
15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States
