Results from long-term monitoring studies conducted in Finnish residential buildings indicate changes in occupant behavior following repairs and improvements made in energy-retrofitted buildings. This paper presents findings on changes in occupant behavior related to perceived indoor environmental quality and health, at three stages: 1) before the energy improvements, 2) approximately one year after, and 3) 5–10 years after. Furthermore, energy consumption simulation model was validated with measurement data providing a basis for evaluating the efficacy of various retrofit strategies. According to home satisfaction and monitoring surveys, energy retrofits led to increased home satisfaction and improved indoor air quality. Among the energy retrofits, enhancements to the air handling unit and increased attic insulation were found to be the most effective for further reducing heating energy consumption in the studied house.