This research, through the analysis of existing programs, presents a simplified logical program which can show the thermal performance of a system, based only on hourly weather data and the system design data. This program is applicable for analyzing a system of direct heating or recirculation heating which may enhance the performance of an existing solar house. Using these system in the existing systems a little raise in performance. The model analysis of a $100;m^2$ solar house in the seoul region shows that the following figures are the most efficient and suitable; 1. Installation an81e of collector: $45^{circ}$ 2. Collector size: $34.56;m^2$ 3. Capacity of main storage tank: $25;m^3$