[Equest-users] LEED Fenestration Modeling Question

[Robby Oylear]

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 3
> rd 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****
>
> ** **
>
> [image: 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****
>
>  ****
>
> *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 <wbishop 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<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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