HI Again all-

Thanks for everyone for their assistance earlier this week, it really helped
me progress with this model adjustment. I am currently at another dilemma.
This is DCV not for typical occupancy, but for ventilating infrequent diesel
fumes.

I have two systems modeled as one, a constant volume packaged unit along
with an exhaust system (no heating/cooling). The exhaust system will
operate separate from the packaged unit and the proposed case includes a
fraction in the operation schedule to reflect DCV operation. That schedule
doesn't affect the package unit except it will have less heating/cooling
load due to the DCV. I don't see the DCV affecting the fan sizing or
operation of the baseline packaged unit. The packaged unit is constant
volume. So, the LEED comments refer to identically modeling the base and
proposed systems, for fan volume and fan power, on this exhaust system.
I've worked out matching the exhaust system well enough, but now I'm
wondering if I need to match the supply also. The simplistic answer would
be "yes", even if the comments refer only to the exhaust system I am
concerned a cursory review may still not be happy with the supply fan
volume/power not matching. I think not matching is valid and it is
definitely more favorable, so that's what I'd rather do.

The baseline system has a larger supply fan, and will have a greater
heating/cooling load (no DCV). The proposed system will have a smaller
supply fan and a smaller heating/cooling load. I think the base case fan
sizing is more accurate since it is based on the actual loads of the
baseline building. If I use the fan sizing/power from proposed, the project
will take a big hit. Basically I think this means in theory that not
matching the supply fans, even though they are tied to the exhaust DCV, is
an accurate estimation of savings from baseline to proposed.

Right now I'm inclined to leave the supply not matching, and provide an
explanation. However since there has already been one review, I don't like
the potential that they will just come back with a response of eliminating a
certain number of points. If they don't think my response is adequate, I
don't think they will give me another chance, correct?

For those that requested their actual response, I finally got my hands on a
document I could copy text:

1. "The Baseline fan power calculations and the SV-A reports for the
Baseline model indicate that the exhaust fan systems (SF-1 and SF-2, as
indicated in the mechanical schedules provided for PI Form 4: Schedule and
Overview Documents) have not been modeled identically in the Proposed and
Baseline cases. All independent fan systems of the HVAC systems in the
actual design must be modeled identically between the Proposed and Baseline
models at actual equipment capacities (fan volume and fan power) as required
by Table G3.1.10 in the Proposed building column, since the fan design air
flow rates and fan power per Sections G3.1.2.8 and G3.1.2.9, respectively,
only applies to system types 1 through 8 in Table G3.1.1A. Revise the
Proposed and Baseline model so all independent fan systems of the HVAC
systems are modeled identically between the Proposed and Baseline model. In
addition, provide revised SV-A reports for the Proposed and Baseline model
reflecting the changes.

Thoughts? Must I go simplistic and make supply match? Am I offbase
thinking not matching is a valid energy consumption model comparison?

Thanks

Laura