Mitsubishi Electric’s next-generation office building sets global standards for energy efficiency and comfort.
In a major recognition for sustainable architecture, Mitsubishi Electric Corporation, Mitsubishi Jisho Sekkei Inc., and Waseda University announced that their Net Zero Energy Building (ZEB) demonstration facility “SUSTIE” in Kamakura, Japan, has won the ASHRAE Technology Award (2025–2026) for Excellence in Asia in the Commercial Building – New Construction category. The award ceremony took place on August 16, 2025, in Suwon, South Korea.
The ASHRAE Technology Award, hosted annually since 1999 by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), is one of the world’s most prestigious honors in environmental building design. Projects are evaluated based on real operational data, including occupant comfort, indoor air quality, and energy efficiency. With this win, SUSTIE will now advance to compete at the global level.
SUSTIE stands out as the first medium-scale office building in Japan (over 6,000㎡) to earn three top-level certifications simultaneously: ZEB recognition under BELS, an S-rank in CASBEE Smart Wellness Office, and WELL Platinum certification. This positions it not only as an energy-saving building but also as a model for occupant comfort and health.
Its design combines passive strategies (north-facing windows, natural ventilation, and daylighting) with active systems (radiant air conditioning and high-efficiency equipment) to achieve both comfort and energy savings. Supported by AI, IoT, and digital twin technologies, the building continually improves its performance, embodying the concept of an “evolving architecture.”
SUSTIE generates more renewable power than it consumes, thanks to a 360kW rooftop solar system, achieving an annual self-sufficiency rate above 100% and meeting ZEB standards for two consecutive years. Furthermore, lifecycle carbon emissions are reduced by optimizing equipment size and refrigerant use.
As a prototype for “future offices” that balance environmental responsibility with workplace wellness, SUSTIE is expected to accelerate the spread of ZEBs in Japan and inspire global progress toward carbon-neutral societies.
Keyword Explanations
- ZEB (Net Zero Energy Building): A building that reduces annual primary energy consumption to net zero, with SUSTIE serving as a rare mid-size model in an urban context.
- Passive & Active Design: A hybrid approach that uses natural elements like sunlight and ventilation (passive) alongside advanced systems like radiant HVAC (active) to maximize both efficiency and comfort.
- Digital Twin + AI Operations: Creating a virtual model of the building to optimize daily operations with AI, ensuring constant improvement in energy efficiency and user comfort.
