[TRNSYS-users] type 56 validation/BESTEST/ ASHRAE heat balance method?

Diego A. Arias daarias at wisc.edu
Fri Jul 13 08:39:24 PDT 2007

Dear Eleni,

I am not a building expert, but I will try to do my best; please find 
below my answers.
> I am trying to find information related to the calculation engine of TRNSYS and its liability.
> First of all, I find it difficult to identify in the documentation of the software which is the
> method used for the calculation of the thermal load of the building component. Does the type 56
> using the ASHRAE heat balance method? 
The fundamentals of Type56 are based on the thesis by Seem, J. E., 
(Ph.D., 1987), "Modeling of Heat Transfer in Buildings".
> I am also interested in any research addressing the validation of the type 56. Has been assessed
> through BESTEST? 
I would recommend that you take a look at these two papers:

- Experiences with and Interpretations of Standard Test Methods of 
Building Energy Analysis Tools
David E. Bradley, Michaël Kummert and Timothy P. McDowell
ESIM (International Building Performance Simulation Association – 
Canadian Chapter) Conference Proceedings, June 2004

- Converging on a Recommended Set of Interpretations and Assumptions in 
Applying Standard Tests to Energy Analysis Tools
Timothy P. McDowell, David E. Bradley, Jeff W. Thornton and Michaël Kummert
IBPSA-USA SimBuild 2004

They indicate that TRNSYS16 with Type56 compares well with the standard 
ASHRAE140, but there may be some differences in the modeler's 
interpretation of the standard and settings in the program.

> Further to these, feedback from other users who also focus on the building side of the system would
> be more than welcomed. I am interested in experience with the type 56 and in the potential
> limitations/ problems associated with that. I am a new TRNSYS user and I am an architect, so I want
> to see up how detailed the building description in TRNSYS can be...
I think that you will get very mixed responses, as it depends on the 
kind of project that you want to simulate. TRNSYS and Type56 have a 
steep learning curve, and may not be for all kind of projects. But I 
think many people will agree with me if I say that once you are past 
that first learning curve, TRNSYS offers you tremendous flexibility, in 
particular, when you want to integrate it with the conditioning system. 
If you are doing systems that are not conventional, you have the 
flexibility of modeling new devices and connecting them to the building 

I would recommend that you look at the list of publications that have 
used TRNSYS. We try to keep an updated list in this link:

I will appreciate comments from the building experts on this list.
Best regards,


Diego A. Arias
TRNSYS Coordinator
Solar Energy Laboratory
University of Wisconsin - Madison
1500 Engineering Drive
Madison, WI 53706

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