Installing energy-efficient windows and improving attic insulation enhances energy efficiency of detached houses. However, realization of the potential benefits depends on the adoption of such measures, which further depends on homeowners’ need and perception of the measures. To analyze these issues, we conducted a survey of 1500 owners of Swedish detached houses during May – July 2008. About 37% of homeowners, selected by Statistics Sweden (SCB) using stratified random sampling method, responded. The majority of respondents was satisfied with their existing windows and attic insulation and did not plan to improve the thermal performance of them over the next ten years. Homeowners who were dissatisfied were more likely to implement an energy efficiency measure. The most common reasons for dissatisfaction were poor performance of existing installations and/or high energy cost. We also studied homeowners’ perception of energy-efficient windows and attic insulation with respect to variables like annual energy cost, investment cost, and environmental benefits. Homeowners perceive that improved attic insulation had greater advantages than energy-efficient windows for a majority of such parameters. Furthermore, more homeowners would recommend attic insulation over energy-efficient windows to their friends and peers. Still, a higher proportion of respondents had planned to replace their windows rather than improving attic insulation. This trend may be because more homeowners were dissatisfied with their windows compared to attic insulation and hence may be more inclined to change their windows. Along with this the financial incentive available for installing energy-efficient windows may influence the adoption, as respondents gave high priority to investment cost in their adoption decision.