WUFI: It looks like an acronym your teenage daughter might text, but it’s going to be a necessity for any architect pursuing work with the U.S. General Services Administration (GSA). The software program, developed through collaboration between the U.S. Department of Energy–funded Oak Ridge National Laboratory and Germany’s Fraunhofer Institute of Building Physics, is meeting a push by the GSA and others to more accurately predict moisture problems that can arise in modern building enclosures.
The program is not new. Oak Ridge began working on it with Fraunhofer in the late 1990s in anticipation of a growing need for moisture modeling in energy-efficient buildings that can develop condensation problems if tight wall assemblies don’t use appropriate insulation and ventilation. The software is sold commercially overseas, but because the research receives federal funding, WUFI has been available for free in the United States since 2001. “But the GSA are really the first ones to make it real,” said Andre O. Desjarlais, leader of Oak Ridge’s Building Envelopes Group, of the software’s U.S. presence.
That was the GSA’s intention when it updated its P100 design standards reference document in 2010. Designers now must submit moisture control performance modeling with building enclosure proposals using ASHRAE Standard 160P, Criteria for Moisture Control Design Analysis in Buildings. Because WUFI is the only software that can perform this analysis, it will be a de facto part of new government projects.
WUFI (the name stands for Wärme und Feuchte Instationär, or “Transient Heat and Moisture Transport”) is endorsed by the Department of Energy, the National Institute of Building Sciences, and the National Building Enclosure Councils. But at a recent conference about facade design in New York, sponsored by this newspaper, only a handful of audience members indicated their familiarity with it. “You could see by the lack of hands in the audience that it is an area that is not yet mainstream in the architecture and engineering community,” said Dirk Meyer, national advisor for the GSA’s Building Enclosures Office, in an email. “The first step for raising that benchmark for performance is to prompt dialogue,” said Meyer.
A moisture-modeling requirement is not a panacea for the ills that can befall a poorly ventilated facade. “It still requires the knowledge of the designer to translate the model’s numbers into a risk assessment,” said Desjarlais. Currently, the WUFI development team is defining new gradations of building failures and new predictors for the onset of corrosion in metal buildings. “One thing we’ve focused on is making it simpler and quicker to use. We don’t expect an architect to spend the whole day on moisture analysis,” Desjarlais said.