SEDL / STP / STP779-EB / STP38693S

Humidity Measurement and Modeling in a Residential Attic

Ford, JK
Center for Energy and Environmental Studies, Princeton University, Princeton, N.J.

Pages: 31    Published: Jan 1982

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Abstract

Dry and wet bulb temperatures of the outdoor air and the air at three locations within an occupied residence in Pennington, N.J. have been measured. The water vapor pressures of the attic air are very variable and cannot be correlated with either outside or living space water vapor pressures. Extremely good correlation, however, is obtained between the dew point temperature of the attic air and the temperature of the underside of the roof. Evidence of condensation and mold growth was found on the exposed roof sheathing. A computer program is used to assess the potential for condensation on the roof sheathing under specified ambient conditions. The implications for the standards writer also are discussed.