[Equest-users] LEED Fenestration Modeling Question
Paul Diglio
paul.diglio at sbcglobal.net
Tue Apr 16 11:02:02 PDT 2013
James and Robby:
Some good points and information.
I always ask the architect to provide the NFRC rating. Usually they contact the
vendors for that information. I actually get acceptable data about 20% of the
time.
I have taken to informing the design team during the DD phase of the project (I
provide Enhanced Commissioning Services also, so am involved early) that I need
the NFRC ratings, so they should verify the vendors can provide this before they
commit to a specific product.
Paul Diglio, CEM, CBCP
87 Fairmont Avenue
New Haven, CT 06513
203-415-0082
www.pdigliollc.com
________________________________
From: James Hess <JHess at tmecorp.com>
To: Robby Oylear <robbyoylear at gmail.com>
Cc: "equest-users at lists.onebuilding.org" <equest-users at lists.onebuilding.org>
Sent: Tue, April 16, 2013 1:53:36 PM
Subject: Re: [Equest-users] LEED Fenestration Modeling Question
Robby,
I appreciate the excellent feedback. The document you referenced is excellent
info.
The current energy code in Arkansas is ASHRAE 90.1-2007, so we have similar
requirements regarding fenestration requirements; we just don’t have the
enforcement part, and we don’t address this area in anywhere near as much
detail as other parts of the country, like Seattle.
The rest of my commentary is more from the viewpoint of energy modeling for
LEED.
I would have thought that when Kawneer provides performance values that they say
are in accordance with NFRC 100 and 200, it would be acceptable to use those
for energy modeling purposes.
The document you reference basically says no. It basically says that an
approved 3rd party must develop the NFRC label certificate specifically for
each and every project, and that this certificate would be the basis for
determining energy code compliance. We can infer that the values from the
certificate should also be the values used for energy modeling for LEED.
It should be noted that per the document you submitted, we can also infer that
using energy simulation programs to calculate the assembly values, or using the
Window program to calculate the assembly values ourselves, is not allowed
either, per strict reading of NFRC requirements and ASHRAE 90.1
This sure is a can of worms we have opened here. The USGBC/GBCI reviewers have
not to date enforced these very strict fenestration requirements of the energy
code. I’ve worked on and submitted ~ 30 LEED projects and I’ve never been asked
once to provide an official NFRC Label Certificate for the entire project by an
NFRC licensed independent Certification and Inspection Agency (IA).
All the LEED reviewers have asked (which is quite reasonable in my opinion) thus
far is that we adequately factor in the effects of the framing on the overall
fenestration performance. The methods allowed in the past have included using
the Window program to estimate performance, using the energy modeling program
itself to account for framing, using the charts provided by curtain wall mfg’s,
etc.
I’m going to continue using these methods until the USGBC/GBCI puts its foot
down and says all projects have to include a copy of the NFRC Label certificate.
However, I will research this with our local framing vendors to see what all is
required to get this certificate and if it’s something they can help with.
If this is simply a matter of requiring the framing vendor to provide a report
that certifies that the combination of their product + glazing is NFRC
certified, this doesn’t seem like a big deal.
However, if the framing vendor is not allowed to do that, but instead a 3rd
party has to certify NFRC compliance and issue the NFRC Label Certificate, that
may be a bigger deal, or may not be. I have no experience with this. It seems
like it would add to project costs, which building owners and developers may
frown on.
We can ask the architects to add these requirements to the project and see what
happens. All we can do is ask, but if we don’t get that information, then we
will fall back on the methods we have already been using successfully,
unless/until told to change by GBCI/USGBC. J
Sorry for the long email response.
Thanks! J
Regards,
JAH
James A. Hess, PE, CEM, BEMP
Energy Engineer
TME, Inc.
Little Rock, AR
Mobile: (501) 351-4667
From:Robby Oylear [mailto:robbyoylear at gmail.com]
Sent: Tuesday, April 16, 2013 11:56 AM
To: James Hess
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] LEED Fenestration Modeling Question
Just as an aside, in Seattle we've been dealing with NFRC requirements for at
least the last six years. Our local energy code requires NFRC certification for
all glazing products, otherwise you must use similar default values to ASHRAE
90.1 Appendix A which obviously costs the project money making up for the
terrible default values.
The way to get proper NFRC values is to inform the architects about the
requirements for a LEED project and make sure the project specifications require
the curtainwall manufacturer to provide an NFRC certified product. This usually
comes in the form of an NFRC Simulation Report which is a preliminary
simulation that is certified prior to installation on the site.
For more information on how the City of Seattle enforces these requirements you
can read the following: http://www.seattle.gov/dpd/publications/cam/cam403.pdf
On Tue, Apr 16, 2013 at 8:18 AM, James Hess <JHess at tmecorp.com> wrote:
FYI, another practical way to account for the effects of the framing is to use
the charts provided by the curtain wall framing manufacturers.
For example, here is the detailed catalog for the Kawneer system 1600 type 1:
http://www.kawneer.com/kawneer/north_america/catalog/pdf/1600_Wall_Sys1__E--A.pdf
The charts and data (from pages 32) on allow us to estimate overall u-value and
SHGC based on center of glass values and the ratio of Vision Area to Total Area
(%).
It’s fairly straightforward to document the Vision Area, but a very good rule of
thumb is 90%.
For example, if we had glass with a COG U-value of 0.28 and 90% Vision Area
(i.e. 10% framing), the overall/System/Assembly U-value would be ~ 0.44
My experience is that this is completely acceptable for LEED/GBCI. These charts
were created by application engineers working for the framing companies, which
I’m assuming they know this stuff way better than I do. If you look at page
35, it says the U-factors, SHGC, and VT values are determined in accordance with
NFRC 100 and 200.
Other framing vendors, like EFCO, have similar charts that we can use.
In my view, this is good enough to document assembly performance. I would use
the charts and move on. If the new Table 1.4 includes space for a comment, I
would reference the charts, and submit the charts if asked.
There really is no other way to do this except try to calculate ourselves, which
why bother when we have these charts. If we ask the architects, often times,
they will not understand what we are asking for. They will probably only be
familiar with the glass properties, not the combination of glass + framing. The
glass vendor will only give you performance data for the glass, not the
combination of glass and framing. I’m not sure why section 5.8.8.2 exists,
except for packaged windows. I haven’t found anybody that will give you a
permanently installed nameplate or official certification for the entire
fenestration system, at least for custom systems often encountered in
commercial construction (i.e. curtain wall versus packaged windows). Maybe the
5.8.8.2 requirement are met in other parts of country by somebody, but for now,
I’ve found these charts from the curtain wall vendors to be very effective from
a cost and time standpoint.
I would welcome any additional feedback on this.
Hope this is helpful.
Thanks! J
Regards,
JAH
James A. Hess, PE, CEM, BEMP
Energy Engineer
TME, Inc.
Little Rock, AR
Mobile: (501) 351-4667
From:equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Paul Diglio
Sent: Monday, April 15, 2013 2:34 PM
To: Bishop, Bill; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] LEED Fenestration Modeling Question
Thanks Bill, the comment you received is encouraging.
Paul Diglio, CEM, CBCP
87 Fairmont Avenue
New Haven, CT 06513
203-415-0082
www.pdigliollc.com
________________________________
From:"Bishop, Bill" <bbishop at pathfinder-ea.com>
To: Paul Diglio <paul.diglio at sbcglobal.net>;
"equest-users at lists.onebuilding.org" <equest-users at lists.onebuilding.org>
Sent: Mon, April 15, 2013 2:45:18 PM
Subject: RE: [Equest-users] LEED Fenestration Modeling Question
Paul,
I recently received the following comment in a LEED review for a LEED-NC v2009
project:
This implies that Window v6.3 calculations are acceptable in lieu of NFRC
ratings. The comment does not exclude the modeler from performing the
calculation.
Of course, I have no idea if this is boilerplate language or if LEED reviewers
have discretion here. It is also possible that requirements will become
stricter for newer projects.
Regards,
Bill
William Bishop, PE, BEMP, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer
134 South Fitzhugh Street Rochester, NY 14608
T: (585) 325-6004 Ext. 114 F: (585) 325-6005
bbishop at pathfinder-ea.com www.pathfinder-ea.com
P Sustainability – the forest AND the trees.P
From:equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Paul Diglio
Sent: Monday, April 15, 2013 2:34 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] LEED Fenestration Modeling Question
Folks:
I am a bit confused when modeling unrated vertical fenestration for the proposed
model. 90.1 states that we need to use the values determined in accordance with
NFRC 100 or we can use the data in Table A8.2 for vertical fenestration per
Exception b, Section 5.8.2.4.
If so, the values in Table A8.2 exceed the maximum allowed fenestration u-values
listed in Table 5.5-5 (my zone), so will this not disqualify the proposed
building model?
I have often found it impossible to get the architect to supply the NFRC
assembly ratings of the glazing and field erected curtain-wall systems.
I have used the LBNL Window 6.3 program to calculate the vertical fenestration
ratings, but 90.1 Section 5.8.8.2 states that the fenestration product shall
have a permanently installed nameplate or the manufacturer shall provide a
signed and dated certification for the installed fenestration.
I don't see any wiggle-room where 90.1 allows the modeler to calculate the NFRC
rating of vertical fenestration.
Saying that, I have submitted projects where I calculated the fenestration
assembly u-values without any kick-back from the GBCI.
I am concerned that the reviewers will push this issue since it is now clearly
defined on the new Section 1.4 Table and if I submit my own ratings I will end
up remodeling the project and/or the proposed building envelope will be rejected
since it doesn't meet the mandatory requirements of Section 5.4.
Any thoughts?
Thank you,
Paul Diglio, CEM, CBCP
87 Fairmont Avenue
New Haven, CT 06513
203-415-0082
www.pdigliollc.com
_______________________________________________
Equest-users mailing list
http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
To unsubscribe from this mailing list send a blank message to
EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20130416/e941de02/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 27714 bytes
Desc: image001.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20130416/e941de02/attachment-0002.png>
More information about the Equest-users
mailing list