Moisture accumulation due to air leakage

After the energy crisis in the 1970s the application of thermal insulation materials in buildings increased. As a result, moisture problems in lightweight insulated envelope parts were also experienced and studied in countries with moderate climates. Many of the building researchers in the United States and Western Europe adopted similar conclusions and recommendations as were recommended earlier for cold climates [19-22]. 

While the identification of air leakage as a source of moisture problems is half a century old, the prediction of its effects is more recent. During the past decade the understanding of the moisture performance of building envelopes has increased with the development of powerful computer models. Hens [24] gave an extensive survey of the state-of-the-art of heat, air and 

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