Energy Efficiency and Resident Health in Zero Energy Houses: A Japan-Based Study

A recent study has shed light on the importance of energy efficiency and behavioral changes in reducing energy consumption in residential sectors, particularly in Japan. The study, conducted by researchers from Waseda University, investigated the impacts of thermal insulation performance and lifestyle behavior on energy consumption, health, and economic efficiency of a Zero Energy House (ZEH)-certified dwelling installed with a dual-generation system combining photovoltaic panels and a solid oxide fuel cell. The findings highlight the significant role of behavioral optimizations, such as controlling lighting and water heating, in reducing energy consumption and improving economic efficiency.

Key Takeaways:

• The energy consumption of the residential sector in Japan is significantly high, making insulation retrofitting and behavioral changes crucial for energy efficiency.
• The study investigated the impacts of thermal insulation performance and lifestyle behavior on energy consumption, health, and economic efficiency of a ZEH-certified dwelling in Japan.
• The simulation model was validated using energy consumption and indoor temperature data from the winter of 2024, and resident interviews were incorporated to reflect their behavior.
• Results showed that the primary energy consumption exceeded the ZEH design values, mainly owing to higher-than-expected lighting and gas consumption.
• Operating floor heating systems for only approximately 3 h per day was sufficient to maintain indoor temperatures above 18 degrees C, the WHO-recommended minimum in winter.
• Lower thermal insulation performance resulted in an increase in blood pressure to 137.6 mmHg, exceeding the 135 mmHg threshold, indicating potential health risks.
• Behavioral optimizations, such as controlling unnecessary lighting, high-efficiency appliances, and water heating systems, reduce energy consumption by 15% and improve economic efficiency by 33%, without compromising health.
• Even when operating 24-hr floor heating, these behavioral optimizations contribute toward reducing energy consumption by 11% and improving economic efficiency by 25%.

Statistics:

• 15%: reduction in energy consumption through behavioral optimizations
• 33%: improvement in economic efficiency through behavioral optimizations
• 11%: reduction in energy consumption when operating 24-hr floor heating
• 25%: improvement in economic efficiency when operating 24-hr floor heating
• 127.5 mmHg: estimated morning blood pressure of residents
• 137.6 mmHg: increased blood pressure due to lower thermal insulation performance
• 135 mmHg: threshold indicating potential health risks

Sources:

• "Validation of Energy Simulations for Multi-family Residences With Photovoltaic Power and Gas Cogeneration: Case Study On Balancing Energy Efficiency and Resident Health" (Energy and Buildings, 2025;345)
• Waseda Research Institute for Science and Engineering
• Osaka Gas Corporation
• Waseda University
• Elsevier Science Sa
• Energy and Buildings (www.journals.elsevier.com/energy-and-buildings/)