[Bldg-rate] Baseline System Selection for Energy Modeling forLEEDEAc1

Mon Aug 2 19:18:02 PDT 2010

If it's going to make a big difference in terms of LEED points, run an
estimate of how big of a deal it is (in credits), and explain the
situation to your architect to see whether the building's gross area can
be recalculated to be 800 SF less (or whatever the difference may be
considering unconditioned space).  For LEED v3/2009, you are being
checked against the gross area as it's pulled from some other credit
template (I'm not sure which, but it's one our architects typically fill
out), so it's on her/him to determine your baseline system, ultimately.
This total is reflected on the EA prereq 2 template, first page.

I've used "non-predominant conditions," per G.3.1.1.a, to model two
baseline system types in one case.  It was a large (>100,000 SF)
building with about 40,000 SF of "residential" sleeping areas (baseline
System 1) and 60,000+ SF of Office/Classroom area (using baseline System
3).  The text in parentheses in  G.3.1.1.a tells us you can go that
route if you have >20,000 SF using a different heating source (gas vs.
electric) or with a different occupancy type
(residential/non-residential).

As a practice, I personally do not count on a LEED reviewer ever siding
with me in a way that would earn points.  Not to say that hasn't
happened before, but I wouldn't plan on it.  

~Nick

NICK CATON, E.I.T.

PROJECT ENGINEER

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

Check out our new web-site @ www.smithboucher.com 

From: bldg-rate-bounces at lists.onebuilding.org
[mailto:bldg-rate-bounces at lists.onebuilding.org] On Behalf Of Cara
Martin
Sent: Monday, August 02, 2010 9:15 AM
To: Dana Troy
Cc: bldg-rate at lists.onebuilding.org
Subject: Re: [Bldg-rate] Baseline System Selection for Energy Modeling
forLEEDEAc1

What's the best course of action if I don't have enough unconditioned
space to get below 25,000 sf?

Thanks,

Cara Martin, LEED AP BD+C

Novus Engineering, P.C.

25 Delaware Ave.

Delmar, New York 12054

518.439-8235

518.439-8592 (fax)

CMartin at novusengineering.com

From: Dana Troy [mailto:DTroy at glumac.com] 
Sent: Monday, August 02, 2010 10:10 AM
To: Cara Martin
Subject: RE: [Bldg-rate] Baseline System Selection for Energy Modeling
for LEEDEAc1

Per App G, it is 25k of conditioned space, so find some unconditioned
space in your building and justify removing it from the square footage
calculations. 

-Dana

Dana Troy

Senior Energy Analyst

GLUMAC | 503.227.5280

From: Cara Martin [mailto:CMartin at novusengineering.com] 
Sent: Monday, August 02, 2010 7:09 AM
To: bldg-rate at lists.onebuilding.org
Subject: [Bldg-rate] Baseline System Selection for Energy Modeling for
LEEDEAc1

Hello,

I am curious of others' experiences with the USGBC/GBCI in terms of
modeling review of the baseline system selection for EAc1 under LEED
2009 (v3) using ASHRAE 90.1-2007, Appendix G.  I am currently modeling a
roughly 25,000 square foot, 2-story building to be used for light
commercial and retail space.  The building is pursuing Core & Shell
certification and will house multiple tenants.  The HVAC system for the
proposed building will be packaged roof top units with natural gas-fired
furnaces and DX cooling.  

As per Appendix G, the HVAC system for the baseline building is
determined by size and number of stories as follows:

1.       Nonresidential and 3 floors or less and < 25,000 s.f. = System
3 (packaged RTU, constant volume, DX cooling, fossil fuel furnace)

2.       Nonresidential and 4-5 floors and < 25,000 s.f. OR 5 floors or
less and 25,000 - 15,000 s.f. = System 5 (packaged VAV with reheat)

My building is 2-stories and just barely over 25,000 s.f. (maybe 25,800
s.f. tops).  I would much prefer to model the baseline as System 3 as
this would more closely resemble the proposed building and provide a
more realistic means of comparison.  Under Table G3.1.1A, it states that
"where attributes make a building eligible for more than one baseline
system type, use the predominant condition to determine the system type
for the entire building."  How is the predominant condition determined?
Can I claim that the height of the building (2 stories) is more
important than the square footage?  Or will the USGBC/GBCI require that
I use System 5 as the baseline because I'm even one square foot over the
25,000 threshold?  

Any input from others in a similar predicament would be most
appreciated.

Thank you,

Cara Martin, LEED AP BD+C

Novus Engineering, P.C.

25 Delaware Ave.

Delmar, New York 12054

518.439-8235

518.439-8592 (fax)

CMartin at novusengineering.com

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