Mitsubishi Electric’s Net Zero Energy Building Test Facility “SUSTIE” is Asian Regional Winner in ASHRAE Technology Awards Program

​​Mitsubishi Electric Corporation, Mitsubishi Jisho Design Inc. and Waseda University jointly announced today that Mitsubishi Electric’s Net Zero Energy Building Test Facility “SUSTIE,” located in Kamakura, Kanagawa prefecture, was selected as Regional Winner (Regional Level Technology Awards 2025-2026 Regional Winner) in the Commercial Buildings (new) category of the ASHRAE🄬 Technology Awards program. Organized by the Asian Region (ASHRAE Region XIII) of The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), the program is one of the world’s biggest technology award initiatives focusing on environmentally friendly building design.

ASHRAE Technology Awards, one of the world’s biggest technology awards program for environmentally friendly buildings

​The ASHRAE Technology Awards program, held annually since 1999, is one of the world’s biggest such programs, recognizing innovative environmentally-friendly buildings for their occupant comfort, indoor air quality and energy conservation, with evaluations based on the building’s verifiable operating data. In the Asian region selection, SUSTIE was the Regional Winner in the New Commercial Buildings category at the ASHRAE Region XIII Chapters Regional Conference. This award will ensure SUSTIE is reviewed by ASHRAE as a representative project of the Asian region in the worldwide selection process. Mitsubishi Electric, Mitsubishi Jisho Design and Waseda University will continue in their efforts to realize “the World’s Most Environmentally Friendly Building.”

ASHRAE: American Society of Heating, Refrigerating and Air-Conditioning Engineers (based in Atlanta, US) was established in 1894, and is the largest international body focusing on air conditioning. It has more than 50,000 members across more than 130 nations. ​​

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Japan’s first medium-scale office building to achieve three certifications in the highest grade of environment, occupants’ comfort and health

SUSTIE is Japan’s first medium-scale (over 6,000m2) office building to achieve the highest grade in three separate certification categories. The『ZEB』 certification^*1awarded by the country’s Building-Housing Energy-efficiency Labeling System (BELS) was achieved as a result of thorough energy conservation and the whole-life carbon reduction processes incorporated in SUSTIE. The building also achieved Rank S in the CASBEE-Smart Wellness Office program,^*2and Platinum certification under the WELL Building Standard🄬^*3in recognition of its comfortable and healthy indoor environment. Since the completion of SUSTIE, Mitsubishi Electric, Mitsubishi Jisho Design and Waseda University have pursued continuous improvement in the energy efficiency of the building, leveraging AI, IoT and simulation technologies during its operation.

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Four aspects of SUSTIE that are a model forthe “prototype building” of the future

Improving the popularity of Net Zero Energy Buildings is urgently required in order to realize a carbon-neutral society. At the same time, creating comfortable workplaces that improve office workers’ health and productivity is becoming an important factor of office design, as companies adapt to the decline in the working age population. SUSTIE achieves leading levels of energy conservation and occupants’ wellness, thereby addressing both of these social issues.

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A『ZEB』building designed to adapt to urban environments

As a part of the overall default design, smart architectural features such as openings and eaves have been utilized to maximize the use of natural energy. As an active design component, highly energy-efficient equipment has been deployed, resulting in significant energy conservation. Finally, photovoltaic panels with a generating capacity of approx. 360 kW have been installed on the roof of the building and protruding eaves to maximize on-site energy generation, thereby verifying the feasibility of medium-scale『ZEB』 buildings even in dense urban areas demanding highly efficient use of space.​​​​​​

3.
“Active design” facility that meets both Zero Energy Building and wellness requirements

Ceiling chamber pneumatic radiant air-conditioning systems were installed in three office rooms to heat and cool the air using ceiling-type air-conditioners, which adjust indoor temperatures and avoid uncomfortable draughts by using the radiation effect of the aluminum ceiling panels delivering thermal energy to the rooms. Various types of facility design have been deployed across the whole building to achieve thorough energy conservation while maintaining occupants’ comfort.

With these initiatives, SUSTIE has also achieved『ZEB』energy performance levels in terms of its actual annual energy consumption. In addition, Mitsubishi Jisho Design is working to achieve embodied carbon^*5reduction through a reduction in equipment capacity and air-conditioning refrigerant levels, as well as an easy-to-navigate equipment layout that facilitates maintenance work, aiming to achieve a reduction of the building’s overall CO2 emissions.

Evaluation of "SUSTIE" in Japan

"SUSTIE" has received the following awards to date (as of July​ ​2025, only major awards):