In the architectural design technologies being changed recently, there is the study to develop the way that will enable the designers to get access logically to the processes of deciding the values of design factors which depend on the experience of the designers. This study, which is one part of those studies, has been carried out to develop the model that can decide the values logically for the design factors having the character that the design values are changed by the time variation out of design factors involved in the building energy saving design. As a result, the structure of the decision model which can decide the design values logically from the computer simulation that solve the problem by interpreting the real world as the probability distribution, has been established through this study. For the application and verification of these decision model, the case study has been carried out for the outdoor climate factors that stand for the design factors having the time variation.