[Bldg-sim] Window performance with frames

[Nick Caton]

Mr. Curcija and everyone:

 

If I may be so bold as to ask some "dumb" questions,

 

-          I'm an individual who regularly relies on the DOE2 Glass library (a large excel file attached to any eQuest installation) to find window constructions whose NFRC framed U-value, visible transmittance, and SHGC/SC values best match those prescriptive values given for actual design models and for 90.1 baseline models.  Am I to understand all of my past models have a "10% to 100% error" with regard to the modeled behavior of the glazing?  Please explain!

-          It sounds like the use of Window5 is pretty popular, and this ability to export a file which can be used by DOE2 has me intrigued - has NFRC or any other body decided to make representative report files to match 90.1's baseline envelope requirements to encourage this procedure for comparative studies?

-          Is Window5 the same thing as WINDOW?

-          Furthering Otto's original question, my reaction to a reviewer requiring "VLT including the frame" would be to first roll my eyes and then explain the frame has a VLT of zero, and is modeled distinctly from the glazing which has a VLT of ##%... am I misunderstanding the request there?

 

Thanks!

 

~Nick

 

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

Check out our new web-site @ www.smithboucher.com 

 

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of D. Charlie Curcija
Sent: Friday, July 16, 2010 9:16 AM
To: 'Andy Hoover'; 'Alex Krickx'; 'Otto Schwieterman'; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Window performance with frames

 

Important thing to remember with windows is that the real number is the one that account for actual size and that takes into account angle dependent properties of glazing.  In most cases, single performance indices at standard conditions are used (i.e., U-factor, SHGC, and VT at normal incidence and standard environmental conditions) in an energy model of a building, which can produce errors anywhere from 10% to a 100%!!  The correct procedure is to either specify correct configuration and size of the product, with glazing specified  layer by layer (possible in EnergyPlus) or use what is called DOE2 or EnergyPlus reports from WINDOW program (DOE2 report is used in DOE2 simulation program and E+ report is used in E+ simulation program).  This is the only way to fully account for changes in size, angular properties of glazing and actual weather conditions.

 

NFRC (National Fenestration Rating Council) has started to provide DOE2 and E+ report files in their new CMAST certification system, however number of products available is still relatively small and is limited to commercial projects.  EnergyPlus has also implemented in version 5.0 option to specify standard numbers at standard conditions (like the ones available from http://search.nfrc.org/search/searchDefault.aspx) and E+ uses then internal algorithms to provide glazing angular information and correction for actual conditions.  While it is best to model specific configurations for a window in THERM and WINDOW program (THERM is required to model frames and edge of glazing), this is not something that average user will be able to do, so getting whole product information from the NFRC web site and using E+ option to convert this data to something resembling real performance is still the best and easiest way to get actual information.  For commercial products http://cmast.nfrc.org provides full information that does not need any simplifications or corrections.

 

Our energy simulation tools DesignBuilder and EFEN use EnergyPlus simulation engine, with the full range of options mentioned above and also provide hundreds of predefined fenestration products that can be matched to your actual product.

 

D. Charlie Curcija 
DesignBuilder Software 
16 Bridge St. 
Millers Falls, MA 01349
  
Tel: (413) 256-4647 
Fax: (413) 256-4823 
cell: (413) 575-3487 
email: curcija at designbuildersoftware.com <mailto:curcija at designbuildersoftware.com>  
web: http://www.designbuildersoftware.com <http://www.designbuildersoftware.com/>  
  

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Andy Hoover
Sent: Friday, July 16, 2010 9:01 AM
To: 'Alex Krickx'; 'Otto Schwieterman'; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Window performance with frames

 

Hey all:

 

We do not know Alex at all but completely support his position that it is the entire assembly/full frame in use that counts.   We are a building envelope consultancy and deal principally in the built market and see this issue all of the time where the performance of window, storefront and curtain wall units is dramatically different than that 'calculated' or provided.   As a matter of fact, it is the unfortunate norm.  At the end of the day it is about actual in use performance and that performance versus what was calculated.  I will stay away from installation difference in this one J.

 

Anyway, we do agree with and have seen the truth to his assessment of frame differences.  It is only the performance of the entire assembly, at every level of a structure as a whole, that counts in the real world.  

 

Thanks and take care,

 

Andy 

 

Andy Hoover

Principal

The BEST Consultant, Inc.

Cell: 678-793-1159

Office: 678-200-7648

Fax: 678-827-0574

Email: andyhoover at thebestconsultant.com

Web: www.thebestconsultant.com

 

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From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Alex Krickx
Sent: Wednesday, July 14, 2010 4:57 PM
To: Otto Schwieterman; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Window performance with frames

 

Hi Otto,

 

Serious Materials provides full frame performance data here: http://index.seriouswindows.com/document-library/Datasheets/. I have also have some of our commercial packages modeled in curtainwall and storefront framing systems that I can provide upon request.

 

Firstly let me say that Window5 is a great tool - I use it often and love it. The only thing I would advise is that there can be a wide distribution in frame U-factors. The default U-factor for a thermally broken aluminum (TBA) frame in Window 5 is U-1.0. Using THERM and Window5 I've seen TBA frame U-factors vary from as low as 0.8 to as high as 1.5. The resultant full-frame U-factor using these 2 differing TBA frames (and the same glass package) is: 0.29 (R-3.4) for the poorer performing frame, and 0.22 (R-4.5) for the better frame.

 

I would say that putting either of those full frame u-factors in your energy model will yield pretty different results. 

 

I think it's really important that we, as simulators and modelers, look at full-frame performance because this is the system that will be installed in the building. Center-of-Glass data can be useful comparing two different glass packages, but at the end of the day, it's a framed system that will be installed and a framed system that should be analyzed. My 2¢.

 

Regards,

Alex Krickx

 

 

Alex Krickx

Building Energy Specialist

 

1250 Elko Dr, Sunnyvale, CA 94089

(t) 408.541.8124

 

Warning: The information contained in this e-mail may be privileged attorney-client communications or attorney work product and/or proprietary and confidential.  If the reader of this message is not the intended recipient then you have received it in error and any review, distribution or copying of this message is prohibited and you are to notify us immediately by reply e-mail and delete the original message immediately.

 

 

 

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Otto Schwieterman
Sent: Wednesday, July 14, 2010 1:10 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Window performance with frames

 

Does anyone know of a window manufacturer web site that has literature on its windows including the frame? I am using Trace 700 for EA Credit 1 and the reviewer asked for manufacturer data sheets for window performance values (U-value, VLT and SHGC) including the frame. 

 

Your help is appreciated,

 

Otto

 

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