There are currently several systems for home automation and energy management available on the market. These systems are intended to reduce the use of energy, while ensuring optimal and customizable comfort conditions. The advances in technology (Internet of Things, sensors, cloud computing, data processing and thermal modelling) and in the design of interfaces should facilitate the adoption of convenient behaviours by final users, thereby producing more sustainable use of energy at home. Conversely, the effectiveness and efficiency of smart home systems for thermo-regulation is a complex activity, requiring the collaboration of multiple stakeholders and experts. In this paper, the authors report a case study about the design of a system for thermal regulation at home developed in a multidisciplinary research team for research and industrial purposes. The paper reports results including: a discussion on a number of issues involved in the design of smart home solutions for sustainability and on the importance of developing an integrated approach to their design; the needs analysis of users and of their functional requirements based on investigation with residents and profiling; final remarks about the role of User Experience Design methods and tools in the development of smart home solutions, understood as socio-technical systems.