How is energy efficiency in low consumption buildings achieved? In the literature, there is often a separation between interventions on behaviors, on technical artifacts or on norms. The three components of a socio-technical system interact, and it is a question of modifying the complex system as a whole. In this pluridisciplinary thesis, we propose to analyze the technical, economic and social dimensions of the energy performance of low consumption buildings and to act on the system with an intervention combining social marketing and a Living Lab. How are energy services perceived by consumers in low consumption buildings? Are they ready to co-design energy conservation interventions? Do these ideas create value? How does one integrate different stakeholders in the co-design of an energy conservation intervention? Is there a "social performance gap" in energy services? How does one measure it? This thesis is based on two research projects, the Energy Living Lab pilot project and the UserGap project using sequential multi-methods. An empirical survey collects socio-demographic data. Qualitative face-to-face interviews highlight barriers to energy conservation practices. Next, a case study analyses the crowdsourcing process and measures the quality of the ideas generated. A second case study analyses the integration of different stakeholders in the co-design of a building energy management system. Then, a new conceptual model on the energy performance gap is induced from the data. We have found that consumers do not perceive the quality of energy services as long as the quality is good. Energy services are not strongly related to the satisfaction of living in low consumption buildings. If integrated into a co-design process, stakeholders have ideas that create societal and managerial value. Living Labs act as catalysts, as innovation intermediaries to orchestrate the co-design process in an ecosystem of actors. The key issue of "social performance" could be measured by the perceived quality of energy services. The multi- sequential methods used in this thesis are not easy to reproduce. The results are limited to the low consumption building sector. The case study method is not intended to be generalized but is exploratory. They should be followed by quasi-experimentation to generalize the results to other regions and measure the impact of co-design. The recommendation to the construction company, energy supplier and energy label certifier is to include stakeholders in the co-design of low consumption buildings and energy conservation interventions. A feedback loop could reduce the performance gap of existing buildings and a feedforward loop could help design future energy services. The societal implications could be the reduction of CO2 emissions and a better integration of the consumer as a co-creator of value. Inclusion of stakeholders could also increase social adoption. This thesis explores the co-design process in the energy services sector in low consumption buildings. It proposes a new conceptual model for understanding the energy performance gap. The method of social marketing in Living Labs makes it possible to develop a new process of innovation in the energy services sector.