This paper examined the energy consumption characteristics in six different buildings including apartments, offices, commercial buildings, hospitals, hotels and education facilities. Then 5-hectare (50,000m2) development site for respective building's type was assumed as case study to evaluate the viability of Combined Heat and Power (CHP) energy systems. A CHP system was selected according to their characteristics for each type building. And HEATMAP, a district energy system analysis software, was used to evaluate each system's energy saving, environmental effect and economic efficiency. The results can be summarized as follows: in hotels and hospitals at the proposed site, the CHP system is an attractive option in Japan. In others buildings, especially commerce buildings and offices, the introduction of CHP system is unreasonable.