Mathematical Analysis of Moisture and Heat Transfer in the Roof Cavities of Manufactured Housing.
Mathematical Analysis of Moisture and Heat Transfer in
the Roof Cavities of Manufactured Housing.
Burch, D. M.; Walton, G. N.; Tsongas, G. A.
Challenges of the 21st Century. Roofing Technology,
Fourth (4th) International Symposium. Proceedings.
First (1st) Edition. U.S. National Institute of
Standards and Technology, U.S. National Roofing
Contractors Association, Canadian Roofing Contractors
Association, National Research Council of Canada,
International Waterproofing Association, CIB, RILEM.
September 17-19, 1997, Gaithersburg, MD, 390-400 pp,
roofs; moisture; manufactured housing; air flow; heat
transfer; ventilation; standards
A mathematical model is presented that predicts moisture
and heat transfer in ventilated cavities such as attics,
roof cavities and catherdral ceilings. The model
performs a transient moisture and heat balance as a
function of time of year and includes the storage of
moisture and heat at the construction layers. The model
includes both molecular diffusion and capillary transfer
within the materials. Radiation exchange among the
entilated cavity surfaces is predicted using a
mean-radiant-temperature-network model. Airflow from
the house into the ventilated cavity is predicted using
a stack effect model with aggregated effective leakage
areas. Air exchange between the ventilated cavity and
outdoor environment is predicted by a semi-empirical
model. The relative humidity in the house is permitted
to vary during the winter and is calculated from a
moisture balance of the whole building.