This study systematically explores the innovative application of computer technology in green building design using smart housing as a carrier. It combines BIM technology, parametric structural modeling and octree forest optimization algorithm to enhance design efficiency and building performance. Through the case study of a low-carbon demonstration community, we quantitatively compare the differences in energy consumption, system stability, and operation and maintenance costs between traditional design and intelligent algorithm-driven design by combining the Internet of Things (IoT) sensing and digital twin technology. The results show that the overall energy consumption of smart housing is reduced by 22.75% compared to traditional housing, the system stability and reliability reach the expected target, the number of operation and maintenance personnel is reduced by 66.67% compared to traditional housing, the maintenance response time is shortened by 66%, and the annual operation and maintenance cost is reduced by 39.2%. All energy consumption is significantly reduced, user satisfaction is increased by 27.23%, and the energy saving effect is outstanding.