[Equest-users] LEED Fenestration Modeling Question
Nathan Miller
nathanm at rushingco.com
Tue Apr 16 11:04:54 PDT 2013
For what it is worth, the window manufacturers all grumble that "only
Seattle" enforces the NFRC requirements, even though it is state code
language.
Also worth noting that even though Kawneer is an international brand, they
seem reluctant to get their product NFRC certified, and you can't directly
look up their common storefront products directly in the NFRC Directory:
http://search.nfrc.org/search/searchDefault.aspx
Some of the local glazing suppliers have evidently had to spring for the
testing themselves to get Kawneer products accepted in Seattle. So, for
example you can find a few combinations of Kawneer 1600 or Trifab 451T
listed under the manufacturer "Goldfinch Brothers, Inc." I'm sure there
must be some other "hidden" examples as well of common glazing products
certified under local glazing company listings.
Nathan Miller - PE, LEEDRAP BD+C, CEM
Mechanical Engineer/Senior Energy Analyst
RUSHING | D 206-788-4577 | O 206-285-7100
Our new web site: <http://www.rushingco.com/> www.rushingco.com
From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Robby
Oylear
Sent: Tuesday, April 16, 2013 11:01 AM
To: James Hess
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] LEED Fenestration Modeling Question
James,
We've run into similar issues on projects outside of Seattle (enforcement
isn't equal across the State and in the case of Federal buildings they
don't have to comply at all). From what I've seen out of reviewer's
comments they are specifically allowing an exception for the use of the
LBNL Window program. It is not something that technically complies with
ASHRAE 90.1-2010, but from what I understand USGBC can choose to enforce
the code differently than one might for code compliance.
As far as project costs, I've heard estimates of around $5k-$10k for
simulation testing for a third party lab. For a large high-rise building
this may not be much, but I can see it causing heartburn for smaller
projects. As Mr. Reddy pointed out above, there exists a library of
certified values on the NFRC CMAST and CPD websites. Though NFRC
Certified values are project specific for site-built products, if you can
find a similar glazing/framing combination for the curtain wall system
your project is using I'm sure that would be an acceptable pathway to
showing compliance with ASHRAE.
-Robby
On Tue, Apr 16, 2013 at 10:53 AM, James Hess <JHess at tmecorp.com> wrote:
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 <tel:%28501%29%20351-4667>
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
Inline image 1
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 <tel:%28501%29%20351-4667>
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 <tel:%28585%29%20325-6004> Ext. 114 F: (585)
325-6005 <tel:%28585%29%20325-6005>
<mailto:wbishop at pathfinder-ea.com> bbishop at pathfinder-ea.com
<http://www.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
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