Smart cities and smart buildings have attracted recently considerable attention. They provide smart environments considering the use of technologies such as the Internet of Things and Ambient Intelligence. Smart environments enable to improve the quality of life and well-being of the people satisfying their demands and needs. For this, smart environments can personalise and improve their services considering opinions, choices and preferences of the users. This process is known as the empowerment of the users or ‘democratisation’. In addition, smart environments provide usually shared services. Thus, they should be able to maximise the welfare of multiple users considering individual preferences. This master thesis implements a voting platform which allows users of a smart environment to express their preferences about services. For this, blockchain technology is used. It provides secure communication platforms. The functionality of the platform is provided by the implementation of a Social Choice model. It provides voting methods which enable to consider individual preferences to obtain an overall social representation. Moreover, an ontology is defined. It is used by the voting platform in order to improve the understanding of the information provided and facilitate the integration with other systems. In addition, a mobile application is designed and implemented. It can be employed by the users of the smart environment to use the voting platform. Finally, approaching an Internet of Things and Ambient Intelligence deployment involves a considerable economic and time cost. Because of this, a model of simulation is implemented. It is used to study voting methods in a case of use based on improving the thermal comfort of occupants in a smart building.