There is a large potential for improving energy efficiency in the existing Swedish building stock. However, how successful the implementation of the efficiency measures will be, depends on economical and technical factors as well as on the attitudes and perceptions of the relevant actors. In this paper we use Rogers’ diffusion of innovation theory to analyze various factors affecting implementation of energy efficiency measures in the Swedish detached houses and apartment buildings. Results of recent Swedish household surveys concerning adoption of heating systems showed that majority of the respondents were satisfied with their heating systems and did not intend to install a new one. Economic aspects and functional reliability were important factors in the choice of heating systems, while installers/vendors were the most important sources of information on heating system. We discuss upcoming empirical studies on implementation of other energy efficiency measures, e.g. energy efficient windows and additional insulation, including that of heating systems, in detached houses and apartment buildings.