The important results which have been obtained in the investigation can be recapitulated as follows. 1. As demostrated by the experimental results and analyses concerning their effects in the on-ground type mushroom house, the constructions in relation to the side wall and ceiling of the experimental houses showed a sufficient heat insulation on effect to protect insides of the houses from outside climatic conditions. 2. As the effect on the solar type experimental mushroom house which was constructed in a half basement has been shown by the experimental results and analyses, it has been proved to be effective for making use of solar heat. However there were found two problems to be improved for putting solar houses to practical use in the farm mushroom growing: (1) the construction of the roof and ceiling should be the same as for the on-ground type house, and (2) the solar heat generating system should be reconstructed properly. A trial solar heat generating system is shown in Fig. 40. 3. Among several ventilation systems which have been studied in the experiments, the underground earthen pipe and ceiling ventilation, and vertical side wall and ceiling ventilation systems have been proved to be most effective for natural ventilation. 4. The experimental results have shown that ventilation systems such as the vertical side wall and underground ventilation systems are suitable to put to practical use as natural ventilation systems for farm mushroom houses. These ventilation systems can remarkably improve the temperature of fresh air which is introduced into the house by heat transfers within the ventilation passages, so as to approach to the desired temperature of the house without any cooling or heating operation. For example, if it is assuming that x is the outside temperature and y is the amount of temperature adjustment made by the influence of the ventilation system, the relationships that exist between x and y can be expressed by the following regression lines. Underground iron pipe ventilation system …… y=0.9x-12.8 Underground earthen pipe ventilation system …… y=0.96x-15.11 Vertical side wall ventilation system …… y= 0.94x-17.57 5. The experimental results have shown that the relationships existing between the admitted and expelled air and the Co₂ concentration can be described with experimental regression lines or an exponent equation as follows: 1) If it is assumed that x is an air speed ㎝/sec. and y is an expelled air speed in ㎝/sec. in a natural ventilation system, since the y is a function of the x, the relationships that exist between x and y can be expressed by the regression lines shown below: 2) If it is assumed that x is an admitted volume of air in ㎥/hr and y is an expelled volume of air in ㎥/hr in a natural ventilation system, since the y is a function of the x, the relationships that exist between x and y can be expressed by the regression lines shown below. 3) If it is assumed that the expelled air speed in ㎝/sec and replacement air speed in ㎝/sec. at the bed surface in a natural ventilation system are shown as x and y, respectively, since the y is a function of the x, the relationships that exist between x and y can be expressed by the following regression line: G.E.(100%)-C.V.(50%) ventilation system… y=0.54X+0.84 4) If it is assumed that the replacement air speed in ㎝/sec. at the bed surface is shown as x, and CO₂ concentration which is expressed by multiplying 1000 times the actual value of CO₂ % is shown as y, in a natural ventilation system, since the y is a function of the x the relationships that exist between x and y can be expressed by the following regression line: G.E. (100%)-C.V. (50%) ventilation system …… y=114.53-6.42x 5) If it is assumed that the expelled volume of air is shown as x and the CO₂ concentration which is expressed by multiplying 1000 times the actual of CO₂% is shown as y in a natural ventilation system, since the y is a function of the x,