To reduce CO2 emissions in the residential sector, the installation of high-efficiency energy supply equipment and the development of smart residential buildings are progressing. It is important to appropriately select energy system configuration, such as the number of installing equipment and capacity, for rational energy use. The purpose of this study is to analyze the trends of the relationship between optimal configuration and household characteristics. After that, we evaluate and analyze the derived configuration from a long-term perspective. We assumed the smart residential building consisted of 50 dwelling units, installs photovoltaics and battery as shared assets, and can power-sharing. Also, we assumed each household must install any one of 3 types of thermal equipment, which is a gas-fired water heater, heat pump water heater (HPWH), and solid oxide fuel cell cogeneration systems (SOFC). As a result, all the households select HPWH after 2025. Focusing on the number of occupants, the increased tendency to install HPWH before 2025 correlates with the number of occupants. In the long-term evaluation, the system configuration consisted of 35 HPWH and 15 SOFC is best from the viewpoint of CO2 emissions. The configuration can reduce 21.9 % CO2 emissions from 2020 to 2030.