The heat transfer coefficient of the wall of a building used to be measured in the wind tunnel test or obtained from field test with a small heat flow panel attached to the building wall, but there is a problem to adopt the value as the surface heat transfer coefficient of the entire building. Consequently, it is necessary to newly develop and expand the measurement method for the architectural heat transfer coefficient. For this purpose, the authors developed a method of measuring the convective heat transher heat flux in the field, using a SAT meter and pyrradiometer, and reported the heat transfer coefficient of the rooftop surface exposed to the sunshine in the previous paper. In this paper, the convective heat transfer heat flux of the rooftop at which surface condensation is caused due to upward terrestrial surface radiation at night time is obtained from the thermal conductive heat flux of the large SAT meter, nocturnal radiation and dew weight changes, and the heat transfer coefficient in downward heat flow is discussed.
