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Jon, Bill, Sam, et. al.; For LEED EA Cr1, and EPACT analyses, the
method should be Appendix G Performance Rating, not Chapter 11 Energy Cost
Budget. Appendix G has its own tables and sections, which lay out
the "Baseline." Comparing campus CHW costs with electric
cost for DX seems to be what App G requires if you are modeling dorm rooms with
fan coils, but this raises a host of problems with extra costs (CUP amortization
and O&M) which may be included in CHW rate but not in the DX system's
electric rate. But an ill-considered CIR re-iterated that's how it should be
done. This method appears to conflict one of the prime directives of baseline
and budget comparisons: G2 SIMULATION GENERAL
REQUIREMENTS G2.1 Performance
Calculations. The
proposed building performance
and baseline building performance shall be
calculated using the following: (a) the same simulation program, (b) the same weather
data, and (c) the same energy rates. I think there are proposals to allow
accounting for just the energy costs embodied in the CHW, however the ones I've
heard of would also require "modeling" a portion of the campus CUP
and distribution system even though it is outside the scope of the project and
associated CDs (which was a limiting prime directive of any code-centered
building simulation). USGBC does already recognize that for cogen CUPs. (https://www.usgbc.org/ShowFile.aspx?DocumentID=1354
). I bet the EA Cr1 reviewers are allowing modeling of campus CUP, under the
"existing HVAC systems" clause, expanded in scope from the CIR that
allowed modeling of a portion of a new high school and part of the associated
chiller plant. The LEED ref guide for EA Cr1 vaguely refers to using the
"existing HVAC system, such as a central plant on campus..." in a
paragraph that is sandwiched between two other paras specifically about
baseline definitions, so it appears to be discussing baseline model system
definition. However, the referenced text in ASHRAE applies only to the proposed
building model. I think App G should return to the ECB
methodology for building heat/cool source (CHW vs. CHW, steam vs. steam) in all
cases, but LEED should have a separate (easier) EA Cr1 points scale for campus
CUP-served buildings. Maybe combined with a separate "LEED for CUPs"!
Sorry if this isn't helpful. I guess
folks disagree about what a fair revision to this would be. If anyone wants to
comment to ASHRAE on Appendix G, now is the time. Go to http://www.ashrae.org/technology/page/331#672
and download the 90.1-2007 Addendum R zip file under Oct 12-Nov 26 public
review. This includes forms and instructions for suggesting specific changes. Below
is the forward to the addendum: FOREWORD This addendum changes Informative
Appendix G Performance Rating Method into a Normative Appendix. Additionally,
some language has been modified to make the Appendix Enforceable. Please note that the entire content
of this Appendix is open for public comment as the entire Appendix is changing
from Informative to Normative. Note: In this addendum,
changes to the current standard are indicated in the text by underlining (for
additions) and strikethrough (for deletions) unless the instructions
specifically mention some other means of indicating the changes. In addition,
the remainder of the text is open for public comment. Do we need a separate mailing list for
baseline (LEED, ASHRAE, EPACT, IRS, GGHC, Labs21!) banter? Is this what
building simulation has come to? This is what my lunch break has come to. -- Fred W. Porter, B.S., LEED A.P. From: Jon Evans
[mailto:jevans@xxxxxxxxxxxxxx] Sam and others, I have a follow-up question related to
your response on 9/25 to purchased chilled water and LEED modeling. I have a baseline building using ASHRAE
90.1 System 1 (PTAC Units). The proposed building is using campus chilled water
and fan coil units or water source heat pumps. Do I use electric as the
source for the PTAC cooling, or the campus chilled water? Using campus chilled
water with PTAC units is not a realistic option, but it seems like 90.1/LEED
requires this (Table 11.3.2A in 90.1-2004)- would USGBC consider this fuel
switching? Also, as a general survey, what are the
going rates for campus chilled water and steam? I have seen ~$0.70/therm
chilled water (generated by absorption chillers) and $0.35/therm for steam for
a college dormitory. I think these rates will vary by campus and end use. Thanks for your guidance in advance. -Jon From:
BLDG-SIM@xxxxxxxx [mailto:BLDG-SIM@xxxxxxxx] On
Behalf Of Sam Mason Yoko, In note 5 under Table 11.3.2A, 90.1-2004
says for systems using purchased chilled water, no chillers shall be modeled
and CHW costs shall be determined using the adopting authority’s utility
rates. For both the baseline and proposed buildings, you would not
include central chillers and instead use purchased chilled water. Sam -- From:
BLDG-SIM@xxxxxxxx [mailto:BLDG-SIM@xxxxxxxx] On
Behalf Of Yoko Matsuyama Hi, everyone, I am modeling a building that is served chilled water from a central
chiller, and the building doesn't have any individual chiller. I am wondering if the baseline model (by ASHRAE
90.1-2004) should follow ASHRAE specified "type and number
of chillers" (TABLE G3.1.3.7, ASHRAE 90.1-2004) depending on building
conditioned floor area, or it should be modeled with a
Central chiller as proposed/designed model. Thank you for your help YM Graduate Mechanical Engineer ==================You received this e-mail because you are subscribed to the BLDG-SIM@xxxxxxxx mailing list. To unsubscribe from this mailing list send a blank message to BLDG-SIM-UNSUBSCRIBE@xxxxxxxxnt>0pt'>BLDG-SIM-UNSUBSCRIBE@xxxxxxxxxx received this e-mail because you are subscribedto the BLDG-SIM@xxxxxxxx mailing list. To unsubscribefrom this mailing list send a blank message toBLDG-SIM-UNSUBSCRIBE@xxxxxxxx=====================================================You received this e-mail because you are subscribed to the BLDG-SIM@xxxxxxxx mailing list. To unsubscribe from this mailing list send a blank message to BLDG-SIM-UNSUBSCRIBE@xxxxxxxx |