In this study, we conducted a questionnaire survey and actual measurement to examine the relationship between indoor thermal environment, insulation efficiency, and physical activity. Results indicated that, first, people who perform less physical activity in winter compared with fall tend to live in colder houses. Second, after adjusting for biological factors, socioeconomic status, lifestyle, and outdoor temperature, greater physical activity was associated with higher minimum temperature of the lavatory and corridor. Lastly, high insulation efficiency can be considered effective for promotion of physical activity, as shown by the correlation between indoor thermal environment and insulation efficiency.