Ageing populations and the necessity to reduce environmental impact raise new challenges on our living buildings. Convergence of home control systems (air conditioning, light management) and computer science, or house automation, allows to enhance comfort, security and health of inhabitants, and reduce energy consumption. Each of these abilities can be perceived as a service provided by the house automation system. Starting from this point, we developed EnTiMid , a middleware able to make systems from different brands cooperate in a single service-based platform. Yet the proliferation and variability of such services, and needs to tailor each system to a particular building, make the design of these systems complex. In this prospective paper, we explain how the notion of dynamic software product line facilitates such designs by providing sophisticated techniques for managing variability across services from design time to runtime and allowing their automatic composition.