These suits centered on moisturerelated failures of energy efficient building envelopes,” explained Andre Desjarlais, Group Leader, Building Envelope Research Group at ORNL. “We became involved in moisture, and its effects on efficiency, shortly after a rash of lawsuits were filed in the late 1990’s.

These current studies are grounded in a history of building envelope moisture durability research at ORNL, sponsored by the US Department of Energy (DOE) Building Technologies Office and industry partners. To better understand energy efficiency features and their interaction with moisture and ultimately durability, Oak Ridge National Laboratory (ORNL) has established a new experimental facility and initiated several studies, including an examination of the relationship between air tightness and moisture durability, hygrothermal performance of below grade construction as a function of soil type, and moisture levels associated with cool roofs. But what happens when solar-reflective exterior surfaces, and airtight and high-R envelope assemblies are thrown into the mix? This question becomes more significant when anticipating expanded retrofit activity to improve existing building envelopes. When moisture accumulation exceeds the ability of the assembly materials to store the moisture without significantly degrading performance or long-term service life, moisture problems result. Miscalculating the impact of environmental factors like rain, solar radiation, temperature, humidity, and indoor sources of moisture can cause significant damage to many types of building envelope components and materials, and also can lead to unhealthy indoor living environments.Īs described by Joseph Lstiburek, B.A.Sc., M.Eng., Ph.D., P.Eng., principal of Building Science Corporation, moisture accumulates in the building envelope when the rate of moisture entry into an assembly exceeds the rate of moisture removal. Moisture, and its accompanying outriders – things like mold, corrosion, freeze damage, and decay – present powerful threats to the durability and long-term performance of a building envelope.

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