This article was originally published in the March/April 1996 issue of Home Energy Magazine. Some formatting inconsistencies may be evident in older archive content.


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Home Energy Magazine Online March/April 1996

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Thermal Scientists Convene

Building scientists from all over the United States and Canada descended on Clearwater Beach, Florida, for a week of information exchange December 4-8, 1995. Thermal Performance of the Exterior Envelopes of Buildings VI also drew researchers from Belgium, Sweden, Norway, Finland, Denmark, France, and Italy to the Sunshine State. But thermal envelope specialists never really escape the cold; it accompanies them in research papers, graphs, charts, slides, and ongoing discussions about how to keep heat inside buildings.

Thermal VI provided a forum to link understanding of scientific principles with construction expertise. The conference was therefore organized along two tracks-principles and practices (attendees could attend sessions in both tracks). As one presenter stated early in the conference, what we should be concerned with is where theory meets reality and where the component meets the crack.

So what's new with building scientists? Well, for one thing, there are several new or improved computer tools to help practitioners design and evaluate buildings. Presenters discussed and demonstrated improved software for modeling windows (WINDOW 5); an interactive computer learning tool for solving moisture problems; updated software for using the Model Energy Code (MECcheck); a design program that can be integrated into architectural software such as AutoCAD (Softdesk Energy); and a new version of the DOE design software PowerDOE, which will allow users to do heating and cooling load calculations (and equipment sizing) for new and existing buildings.

A field trip to the Center for Applied Engineering's Material Testing Laboratory allowed conference participants to see how materials are tested for thermal and acoustical properties. Visible in the background here is an enormous fan used to test the ability of building materials to withstand high winds.
In forging the link between principle and practice, the presenters made it clear that the models they produce are tools for representing reality, not reality itself. The refrain All models are false; some models are useful was heard several times in various manifestations. And buildings to which the models or theories could be applied were displayed with all their faults laid bare in many a presenter's slide tray.

For instance, Joseph Lstiburek of the Building Science Corporation in Chestnut Hill, Massachusetts, presented several sessions on moisture problems and indoor air quality, with an abundance of revealing slides. He explained that indoor air quality problems are caused by the four Ps-people, pollutants, path, and pressure-and that pressure is the key to controlling air quality. Leaky and poorly designed air distribution systems created many of the problems displayed in his slides. Lstiburek also emphasized the importance of having a material that serves as a drainage plane in an exterior wall assembly, to guide water out of the wall.

Several researchers from Canada focused on the building's air barrier. Bill Brown from National Research Council Canada discussed designing an air barrier by intent, rather than throwing together several materials and hoping one of them will create an air barrier. Once the air barrier is defined, it has to be made continuous in order to work. Another speaker, Paul Duffy, noted that one material that should not be used as an air barrier is exterior insulating foam, because it expands and contracts with temperature, causing joints to fail.

Not to be left out of the envelope discussions, windows were the topic of three sessions at Thermal VI. Some presenters discussed new technologies, such as electrochromic windows and better-insulating spacers, while others emphasized the importance of proper installation to ensure that windows don't leak. Researchers from Canada discussed their energy rating program-the energy rating combines conductivity and solar heat gain performance in one number (for heating only).

The Thermal Performance conference is sponsored every two to three years by ASHRAE, the Building Environment and Thermal Envelope Council, the Chartered Institution of Building Services Engineers, the Energy Efficient Buildings Association, Oak Ridge National Laboratory, the U.S. Department of Energy, and National Research Council Canada. Proceedings are available for $75 from Denise Overton, ORNL, P.O. Box 2008, Bldg. 3147, Oak Ridge, TN 37831-6070. Tel:(423)574-4129; Fax:(423)574-9338. E-mail:

In a few years, researchers will share the results of new projects at Thermal Performance of the Exterior Envelopes of Buildings VII. Don't miss the opportunity to infiltrate and circulate among the scientists.

-Jeanne Byrne

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