[Bldg-sim] LEED and existing envelopes

Nick Caton ncaton at smithboucher.com
Tue Oct 11 11:54:18 PDT 2011


I've never done a core & shell model, so take this opinion with a grain
of salt  (it's only my opinion):

 

This reviewer's interpretation seems to make a lot of sense to me.  Have
the baseline represent the actual existing building, and have the
proposed match the actual design.  To my understanding, the only reason
we make them match 1:1 for new construction is there isn't a better
means (like when you have an existing building) to define a baseline
that would treat evenhandedly all building types/climates/circumstances,
so we have them match to at least ensure level playing field.

 

Put another way, and in response to James' query, I think if adding
windows (nice or not) cause the energy bills to go up in an existing
building, then that should be reflected in the energy model.
Simultaneously, if you are interested to add daylighting "in
moderation," and locate/orient glazing & shading devices in a fashion
that lowers the annual bills, then that should also be reflected in the
energy model.  

 

It's important to remember not all exterior glazing is bad from an
energy perspective, particularly when daylighting controls for the
building interior lighting are added into the mix.  WWR is one area
where "engineers and architects" (or "energy and aesthetics," if that
better describes your design team) do not need to be on opposite ends of
the table!

 

~Nick

 

 

 

 

NICK CATON, P.E.

SENIOR ENGINEER

 

Smith & Boucher Engineers

25501 west valley parkway, suite 200

olathe, ks 66061

direct 913.344.0036

fax 913.345.0617

www.smithboucher.com 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Paul Riemer
Sent: Tuesday, October 11, 2011 1:46 PM
To: 'James Hansen'; Anne Juran; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] LEED and existing envelopes

 

I also agree with the reviewer.  The existing envelope condition
stipulation is a double edged sword.   Do you truly think it is a net
penalty on your LEED application to add windows?  Other LEED points
reward daylight and views, and the thermal energy impacts of the windows
are hopefully offset by electric lighting savings.  

 

Paul Riemer, PE, LEED AP BD+C 

DUNHAM

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of James
Hansen
Sent: Tuesday, October 11, 2011 1:31 PM
To: Anne Juran; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] LEED and existing envelopes

 

Thanks for the responses Anne and Bill.  But this seems ridiculous, and
goes against everything I've done to date.

 

So if we have an existing building with no windows, and we want to reuse
the building structure/skin (which LEED strongly encourages), we get
penalized for wanting some daylight in the building?  

 

I think all of the references to the "baseline building envelope shall
represent existing conditions" is intended to demonstrate that you can
use existing window and wall coefficients, NOT that you can't add
windows.  But what do I know...

 

Does anyone know for sure?

 

GHT Limited
James Hansen, P.E., LEED AP
Senior Associate
1010 N. Glebe Road, Suite 200
Arlington, VA  22201-4749
703-243-1200 (office)

703-338-5754 (cell)
703-276-1376 (fax)

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

 

From: Anne Juran [mailto:juran at summerconsultants.com] 
Sent: Tuesday, October 11, 2011 2:02 PM
To: James Hansen; bldg-sim at lists.onebuilding.org
Subject: RE: [Bldg-sim] LEED and existing envelopes

 

I find existing envelopes always tricky because the information is not
delivered in the clearest manner.  However, I think in this case the
reviewer is correct, based on 90.1 Table G3.1.5 item f under "Baseline
Building Performance" and page G-17 of the User's Manual.  Also, in item
c they explicitly state that it applies to new buildings and additions,
but do not list existing (other than the little blip about alterations
and 5.1.3.)

 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of James
Hansen
Sent: Tuesday, October 11, 2011 10:23 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] LEED and existing envelopes

 

I know this has been covered before, but I just received the following
comment from a GBCI reviewer for a v3 Core and Shell project I'm working
on.  The project is basically an existing 5-story warehouse with almost
no windows.  Part of the renovation is adding windows.  The comment is
as follows:

 

Table 1.4.1B indicates that the window-to-gross-wall ratio is identical
in both cases; however it is unclear whether any fenestration was added
or removed as part of the renovation. The baseline ratio must reflect
the ratio as it existed prior to the renovation and the proposed ratio
must reflect the ratio as it exists after the renovation. Revise the
Baseline and/or Proposed cases as necessary so that the
window-to-gross-wall ratio is accurately modeled and provide a revised
prerequisite form and updated energy model output summaries as
necessary. 

 

I didn't think that this was the case - I thought that if you had an
existing building, any EXISTING-TO-REMAIN windows would show up as the
existing window type, but any NEW windows in the proposed alteration
would be matched in the baseline model and comply with the Table 5.5
requirements.  Meaning the WWR remained the 1:1 as long as it was < 40%
glass.

 

I think this is just a matter of educating the reviewer on our building,
but I wanted to make sure that there hadn't been a shift in how GBCI
reviews existing buildings.

 

Thanks!

 

GHT Limited
James Hansen, P.E., LEED AP
Senior Associate
1010 N. Glebe Road, Suite 200
Arlington, VA  22201-4749
703-243-1200 (office)

703-338-5754 (cell)
703-276-1376 (fax)

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

 

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