The inside air temperature variations of the glasshouse during the nighttime are discussed. The weighting functions of the glasshouse are derived from the responses to the unit step functions of outside air temperatures.
Having linearized the effective radiation heat exchange, the response of the glasshouse to the outside air temperature and to the effective radiation are calculated. Then, the inside air temperature is obtained by making use of Duhamel's integral. Nighttime observations in the model experiment do not conform to the theoretical calculation. The departures are not surprising in view of the after-effect of the solar radiation which is not taken into
account in the present study.
The same method of analysis is applied to the examination of the cold protection of the glasshouses whose constructions are the same as that of the model in the present analysis.
The following conclusions can be deduced from these results, that is, the phase lag of the inside air temperature behind the outside temperature increases with the increase of β (the ratio of floor area to total glass surface area) and the decrease of μ (the ratio of air volume of the glasshouse to the floor area), and the amplitude of the inside air temperature variation decreases with the increase of β and the decrease of μ. The effect of net radiation on the inside air temperature is shown not only through the parameter β but also through the view factor of the glass surface to the sky. It is also shown that in the present model, the air temperature observed in the glasshouse is lower than the out door temperature during the nighttime.
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