[Bldg-sim] Spam:Re: LEED modeling requirements for existing buildings

Jay Keazer JKeazer at tmecorp.com
Tue Aug 19 07:41:34 PDT 2008

What about the baseline envelope assemblies?  As an example I have an
existing building where the windows are being replaced and insulation is
being sprayed on the outside of a built up roof.   


In the same column of Table G3.1, requirement (b) states that "Opaque
assemblies used for alterations shall conform with 5.1.3" and requirement (c)
states that "The fenestration areas for envelope alterations shall reflect
the limitations on area, U-factor, and SHGC as described in 5.1.3."


5.1.3 states that "Alterations to the building envelope shall comply with the
requirements of Section 5 for insulation, air leakage, and fenestration
applicable to those specific portions of the building that are being


My interpretation is: because the windows and roof are being altered, I have
to use the appropriate U-factors and SHGC from the tables for the baseline
windows and roof.  However, the walls are not being altered, so I can use the
existing construction for the baseline walls.  


Does anybody have a different interpretation?




Jay Keazer,  EI

Energy Engineer

TME, Inc.

2039 N Green Acres Road

Fayetteville, AR  72703


ph   479.521.8634

fax  479.521.1014

jkeazer at tmecorp.com <mailto:email at tmecorp.com> 

www.tmecorp.com <http://www.tmecorp.com/> 




From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Eric O'Neill
Sent: Thursday, August 14, 2008 3:16 PM
To: Mark Sorensen; bldg-sim at lists.onebuilding.org
Subject: Spam:Re: [Bldg-sim] LEED modeling requirements for existing


Under ASHRAE 90.1 Appendix G, Table G3.1, Section 5, "Baseline Building
Performance" column, requirement (f) (take a breath...) it states that "For
existing building envelopes, the baseline building design shall reflect
existing conditions prior to any revisions that are part of the scope of work
being evaluated". So the rotation doesn't apply to you. Also, I interpret
that to mean the windows don't need to be redistributed either. Hope that

Eric O'Neill 
Mechanical Engineer 
Energy Division - Michaels Engineering 

811 Monitor St. Ste 100 
La Crosse, WI 54603 
v: 608-785-1900 x521 
f: 608-784-2270 
elo at michaelsengineering.com 
http://www.michaelsengineering.com <http://www.michaelsengineering.com>  

From: Mark Sorensen [mailto:DEnergyServices at comcast.net
<mailto:DEnergyServices at comcast.net> ]
Sent: Thursday, August 14, 2008 10:40 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] LEED modeling requirements for existing buildings

When modeling an existing building, is required to calculate the proposed
building window to wall ratio and equally redistribute the glass area to the
baseline building and prepare models for the four rotation exposures? My take
is that for a proposed existing building, there is not an opportunity to
position the building to the most advantageous exposure and you could end up
being penalized if the baseline energy use is averaged for all rotations but
I have not been able to find any reference in LEED or ASHRAE to support this.
I'm not sure what to think about equal redistribution of the glass areas. 

Mark Sorensen 
Diversified Energy Services 
5890 E. Pontaluna Rd. 
Fruitport, MI 49415 

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