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Communications and External Relations
ORNL helping Seattle solve crumbling building mystery
OAK RIDGE, Tenn.,
Dec. 17, 2001
If you mention the three m's to a group of researchers at the Department of Energy's Oak Ridge National Laboratory, they're apt to think of moisture, mold and mildew instead of the company from Minnesota.
That association may become more widespread as Jeff Christian of ORNL's Buildings Technology Center predicts that moisture, mold and mildew will soon replace lead and asbestos as some of the most dreaded words associated with building problems. The three m's have created a $1 billion nightmare in Seattle, where ORNL and collaborators are studying what has caused the costly damage to residential buildings.
"We're finding a connection between premature deterioration of buildings due to wind-driven rain penetrating the walls and the inability of the building walls to dry themselves out," Christian said. "We're also helping to develop repair solutions."
The costs of the problem are sweeping and dramatic. In 1998, an informal survey of multi-family residential buildings in the metropolitan area by Seattle's Construction Codes Advisory Board found that about 70 percent of structures surveyed reported moisture damage. And the problem isn't limited to Seattle. Atlanta, Wilmington, N.C., and other high-humidity areas also report growing problems from moisture damage to buildings.
Without this research uncovering the cause of these moisture-damaged buildings, there is the danger of relaxing the building codes and losing the energy efficiency gains made over the last decade, Christian said.
"As moisture accumulates within a building's walls, the apparent thermal conductivity of the insulation, wood and drywall increases substantially," Christian said. "The result is higher energy costs."
Christian noted that evaporation and condensation in building envelope components can increase energy transfer across components by up to 150 percent compared to transfer if the materials are dry. This results in additional wasted energy.
"For example, in dry insulation, heat transfers by conduction and radiation," Christian said. "When wet, moisture migrates from the warm side to the cold side, thus migration of moisture carries energy."
In the meantime, Andre Desjarlais, Christian and colleagues at ORNL are working with groups in Seattle to develop building designs and strategies to achieve energy efficiency and moisture control. Collaborators are Washington State University's Cooperative Extension Energy Program, the Seattle Construction Codes Advisory Board and several consultants and architects in the region.
The initial phase takes advantage of the Buildings Technology Center's moisture modeling capability, which will subject a typical western Washington building to a Seattle-like climate. Using computer programs to simulate the weather, researchers will also compare the relative thermal and moisture control performance of older and newer buildings.
"We expect this first phase to provide preliminary scientific evidence to support or refute widely held beliefs regarding moisture differences between older and newer structures," Desjarlais said. "We should also be able to determine the effects energy codes for state buildings, ventilation and indoor air quality have on hygrothermal performance."
In later phases, manufacturers of construction materials and envelope systems will be invited to participate in defining design guidelines for wall systems for Seattle's conditions.
Aside from the construction problems and expense to repair crumbling buildings, Christian notes that mold and mildew can cause significant health problems, particularly among people with severe allergy and respiratory problems. Researchers are developing mold growth prediction tools that will be verified by visual inspection of the interiors of outside walls that can discolor if poor moisture control exists after five to 10 years of performance.
ORNL is a Department of Energy multiprogram research facility managed by UT-Battelle.