Abstract
A simple theoretical equation was introduced to calculate the heat transmission and the heat loss coefficient for a multi layered film plastic house in winter. The results calculated by this equation from the temperature values measured at a cylindrical model for the plastic house showed that the temperature difference between inside and outside of the plastic house was affected not only by the quantity of heat applied to the house but also by the effective radiation from the ground. During high rate of effective radiation from the ground, it was interestingly recognized that the over-all heat transmission calculated was usually negative in appearance if the heating quantity was not so large, because the radiant heat dissipated at the film to the sky in such condition was conducted more from the outside air than from the inside air through the film in spite of the inside air temperature was kept higher than the outside air temperature by heating.
It was concluded that the rise of the inside air temperature at the multi film system was basically due to the simple mechanism in which the covering of the outtermost film acted as an artificial warm sky (about -2°C) in place of the natural cold sky (about -27°C), and the total thermal resistance becomes in general about twofold at the double layers and about fourfold at the triple layers.
