The study analyzes the thermal environment and energy-saving performance of nearly net-zero energy apartments in Japan during winter by measurement and questionnaire. Results show the average indoor temperatures exceeded 18°C even without air conditioning, due to superior insulation performance. Energy consumption for heating was 58.9% to 62.9% of the national average, and residents perceived their homes as warmer, leading to lower temperature settings of air-conditioner. However, there were several challenges, such as the low ratings by residents of non-heated rooms during winter.
