Energy efficiency within the housing sector is progressing. In Vallastaden which is a newly developed city district in Linköping, Sweden, constructors together with the municipality have made attempts to create a sustainable built environment. One of the goals was to establish energy efficient residential buildings in Vallastaden. The overall aim of the study was to investigate the development of two energy plus buildings in Vallastaden and explore the potentials for the energy concept in these buildings to reduce the energy use. The perceptions of the occupants were included in the study since their views and practices play an important part for the buildings’ energy performance. Qualitative interviews were conducted with informants from two housing companies and three households. The findings show that the motives for the housing companies were try out new things and progress within the housing sector. The housing companies were however uncertain if their buildings would become energy efficient in practice since it depended on how the occupants would interact with the technology and the energy concept. There is a risk that the energy concept and the technology may not reach its full potential in reducing energy since the occupants either had no reflection about their role in the energy concept or were uncertain about the technology. The communication between the housing companies and the occupants needs to be strengthened for occupants to realize their influence on the energy use in these buildings.