As a major entity of smart cities, smart buildings are intelligent environments equipped with computing technologies to improve inhabitants daily life. Such systems are complex and have to take account several requirements of the targeted environment and users needs for design and implementation. The semantic aspect is important to take into account to model such systems. However, research about smart buildings development remains limited. In this paper, we define a smart building system architecture. Then, we present our methodology for smart building design and implementation and we conduct a case study to demonstrate our proposal with a validation and verification phase on systems by model transformations.