[Equest-users] LEED Fenestration Modeling Question
James Hess
JHess at tmecorp.com
Tue Apr 16 11:46:03 PDT 2013
Robby, Paul, and Nathan
This is all excellent info you have followed up with. I appreciate your follow up responses.
I definitely need to do some more research in this area.
The cost mentioned below by Robby doesn't seem unreasonable, especially for larger projects, and especially given the architects preference for more glass on buildings. With regards to the total project budget, $5K to $10K is rounding error! :)
In addition, I probably will start informing the architects we work with that they are responsible for ensuring the NFRC Label information is provided, in accordance with LEED and ASHRAE requirements, and that gets the monkey off our back. The architects in turn will ask us what to ask for, and after reading that document, I can tell them.
Thanks! :)
Regards,
JAH
James A. Hess, PE, CEM, BEMP
Energy Engineer
TME, Inc.
Little Rock, AR
Mobile: (501) 351-4667
From: Nathan Miller [mailto:nathanm at rushingco.com]
Sent: Tuesday, April 16, 2013 1:05 PM
To: 'Robby Oylear'; James Hess
Cc: equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] LEED Fenestration Modeling Question
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.
[cid:image001.png at 01CE3AA8.ADEDC280]
Nathan Miller - PE, LEED(r)AP BD+C, CEM
Mechanical Engineer/Senior Energy Analyst
RUSHING | D 206-788-4577 | O 206-285-7100
Our new web site: www.rushingco.com<http://www.rushingco.com/>
From: equest-users-bounces at lists.onebuilding.org<mailto: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<mailto: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<mailto: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. :)
Sorry for the long email response.
Thanks! :)
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<mailto:robbyoylear at gmail.com>]
Sent: Tuesday, April 16, 2013 11:56 AM
To: James Hess
Cc: equest-users at lists.onebuilding.org<mailto: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<mailto: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! :)
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> [mailto: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<mailto: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<tel:203-415-0082>
www.pdigliollc.com<http://www.pdigliollc.com>
________________________________
From: "Bishop, Bill" <bbishop at pathfinder-ea.com<mailto:bbishop at pathfinder-ea.com>>
To: Paul Diglio <paul.diglio at sbcglobal.net<mailto:paul.diglio at sbcglobal.net>>; "equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>" <equest-users at lists.onebuilding.org<mailto: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>
bbishop at pathfinder-ea.com<mailto:wbishop at pathfinder-ea.com> www.pathfinder-ea.com<http://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> [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<mailto: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<tel:203-415-0082>
www.pdigliollc.com<http://www.pdigliollc.com>
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