[Equest-users] BDL Error

[Nick Caton]

Thomas/Kelsey:

 

A little while ago Adam Boyd put forward a very handy resource I'm attaching.  

 

You're right in that the root issue here is that you can't really model a wall with no mass.  When you specify a layer by U-value only (simplified method), notice that you cannot enter a mass for that layer.  If you read the associated help files you'll learn this method of specifying materials is only intended for things with negligible mass (i.e. air films).  Specifying a whole construction with layers and ignoring mass means you have a wall which is going to act really weird when it comes time to figure out heat retention/transfer behavior with the exterior.  It works fine in simpler loads/modeling programs that assume information for you, but in eQuest you have to account for mass in your constructions.

 

That said, Appendix G and Appendix A do not explicitly tell us the thermal mass properties of the intended baseline construction layers, but helpful fellows like Adam have shared the legwork of looking these items up - read the thread below, examine and try to import the attached .inp into your model.

 

~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: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Kelsey VanTassel
Sent: Wednesday, June 02, 2010 8:43 AM
To: Thomas Vu; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] BDL Error

 

Hello Thomas,

I don't think you can make a construction where all the layers are R-value inputs. For a construction to have layers the program must be able to calculate some mass for the wall. If you want to specify only the thermal resistance of the wall choose "u-value input" when you create a new construction and put in the overall u-value for the wall assembly.

 

Kelsey Van Tassel

Mechanical Engineer | kvantassel at sustaineng.com

 

 

 

We've moved. Please see below for my new contact info.  

 

901 Deming Way, Ste. 201

Madison, WI 53717

608.836.4488 ext. 20| Fax: 608.836.4477

 

2009 Dane County Small Business Award Recipient

 

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Thomas Vu
Sent: Tuesday, June 01, 2010 7:38 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] BDL Error

 

All,

 

I get the following BDL error in my model

 

WALL has no heat capacity. U-Value used.

 

I am modeling the baseline envelope as prescribed in Appendix G of 90.1-2004.  Referring to Appendix A of 90.1-2004 to model the baseline envelope, I  created layers for the wall construction seen in the attached screenshot.  The resulting U-value for the wall is 0.124.  Can I not model a wall in this manner?  It seems specifying the U-value alone in the construction layer would do the same thing.

 

Thomas Vu, E.I.

Graduate Student

Dept. of Mechanical and Aerospace Engineering

University of Florida

vietdrum at ufl.edu

 

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Adam.Boyd at CH2M.com
Sent: Tuesday, April 27, 2010 10:36 AM
To: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] 90.1 and Appendix A Materials

 

A while back I developed an INP file that contained all the baseline constructions for every climate zone. If you've got the ASHRAE Fundamentals handbook for looking up material properties, this was a pretty routine process. First create the new materials/layers/constructions in detailed edit mode, Appendix A has some detailed descriptions on what those should be (see A3.3.1 for steel framed wall). Next open the inp file and delete everything except the materials, layers and constructions. You can then import that inp file into any project using the eQuest import function. I've attached the file I created for this and just ask that you let me know if you find any mistakes!

 

I've been considering creating a similar file with the ASHRAE recommended schedules from the 90.1 User's Manual, but not sure if this would be as useful.

 

Adam

 

From: Seth P. Spangler [mailto:sspangle at rmf.com] 
Sent: Tuesday, April 27, 2010 5:26 AM
To: Paul Riemer; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] 90.1 and Appendix A Materials

 

Paul,

 

I've been browsing through the ASHRAE DOE-2 files since receiving your email. I believe I have been following the same rabbit trail that Nick has so it would be great to have canned constructions. Can you explain the best method for importing the ASHRAE constructions into a model? I assume the edit must be made in the INP file. I typically try to avoid editing the INP file since my knowledge of the "code" behind eQuest is limited.

 

Thanks

 

Seth Spangler, LEED® AP 

Project Engineer

 

RMF Engineering, Inc 

Ph: (843) 971-9639 ext:1497

Fax: (843) 971-9641 

sspangle at rmf.com

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Paul Riemer
Sent: Monday, April 26, 2010 5:00 PM
To: 'Nick Caton'; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] 90.1 and Appendix A Materials

 

Nick,

The DO2.1e input files available as part of the 90.1 User's Manual rely on the DOE2 library of construction materials.

 

Paul Riemer

Dunham

 

 

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nick Caton
Sent: Monday, April 26, 2010 3:43 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] 90.1 and Appendix A Materials

 

Has anyone invested the time to create or otherwise stumbled across an *.inp file that contains the materials defined in Appendix A9 for easy import/use?

 

I had a model reviewer (not USGBC) who was unsatisfied with the material thermal properties in the default DOE2 library.  I ultimately went through the enormously entertaining exercise of defining materials with matching prescriptive R-values, while still using library data to retain appropriate thermal massing properties to avoid construction errors from weightless constructions.

 

This was an isolated case, but I could see such a file being a very handy resource for most modelers, particularly if it contained the contents of Tables A9.2A and 9.2B to pull the effective insulation/framing properties into our custom construction layers.

 

If this is flying over anyone's head who's interested, attached is a partial example of what I'm talking about - if you click File à Import File... and navigate to this file, you'll have a couple defined materials ready to access for your project within seconds - conceivably everything within 90.1 if someone had the time to invest...

 

On a related note... and I should have asked before, but does Section A9.2 possibly exempt the rest of Section A9 for eQuest users who rely on unmodified default library entries to define their custom envelope constructions?

 

~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 

 

 

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