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Computer Modeling Programs for Durable and Energy Efficient Buildings

Posted on 6/13/2012 9:53:12 AM By Bob Braun
  

In this blog, in the ASC Building Products series, I will begin the move from focusing on the use of sealants and adhesives to control air leakage in buildings as discussed in blog #1-4. 

A few years ago I attended a training seminar on WUFI sponsored by Oak Ridge National Labs (ORNL).  WUFI is an acronym standing for “Wärme und Feuchte instationär” originated by the Fraunhofer Institute.  You might guess this was originated in Germany but has been jointly expanded and improved through the efforts of Oak Ridge National Labs as well.  Through ORNL efforts there has been a concentrated effort in upgrading and delivering this technology through frequent nation-wide seminars for several years now.  Perhaps you have also attended a WUFI seminar yourself.  In general this software does not emphasize the modeling of the types of gaps and cracks that sealants usually fill or the air or weather-tight seal that is achieved using various construction adhesives.  However, with a little creativity, the WUFI program can be adapted to this type study.  For example, one can shrink the modeled geometry to the appropriate size where it effectively becomes a mini-stud cavity.

One particular area of study using WUFI would be the perimeter area in window and door installation, for example, where a combination of both sealants and adhesives are utilized.  The critical material properties for each component in the assembly installation must be determined first…then the best configuration and materials can be modeled so that the assembly is not only energy efficient but designed to prevent moisture accumulation which of course would lead to premature failure.

Those interested in this science can go to several web sites to learn more and can sign up for a three day (or more) training seminar at various technical levels.  I have referenced appropriate links below.  Since there are still many questions related to the myriad of window installation details, this should be a desirable first approach to help direct the researcher to a lesser number of confirmation experiments to produce the best window installation design.  In this application, the complexity relates to the fact that there are numerous wall types (e.g. wood frame with many variances of sheathing and weather resistant barrier products, concrete, CMU, brick, California stucco, Florida stucco, etc.) and there are many specific window design products often intended for only one specific wall type!  Thus, a program like WUFI can help an architect select the best installation details and products that are the most energy efficient as well as durable.

For software for calculating the coupled heat and moisture transfer in building components, click here. You can learn more about the 2D WUFI features and find a training seminar as well.

wufi 

Here is a link to the Building Science Corporation that organizes seminars throughout the US.

National Building Science Corporation
1220 Rosecrans Street  #119
San Diego, CA  92106-2674
Phone (619) 450-6446, Fax (888) 317-3105

And, finally you can click here to view a sample WUFI simulation.
              

In Blog #6 I will detail the events for the upcoming ASTM C24 Meeting in San Diego on June 24-26, 2012.  Many C24 Subcommittees will meet there to both revise and initiate new Standards for sealants.  As the founding chairman for the C24.61 Foam Sealant Subcommittee I have been attending the C24 Executive meeting twice a year for more than 15 years now so I can report on other sealant standards as well and some of the new industry initiatives of C24.



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