Achieving carbon neutrality by 2050 is an enormous challenge confronting science and technology. At the same time, we must not sacrifice people's prosperity, comfort, health, or industrial development for the sake of decarbonization; rather, we must build a brighter future society while achieving sustainable growth.
Solving this complex challenge cannot be achieved simply by combining technologies that have each been advanced within their own specialized fields. We need a new academic framework that crosses architecture, mechanical engineering, electrical engineering, information and control, energy, and human science, and that can analyze and design differing physical phenomena and human values alike on the basis of shared underlying principles.
For more than fifty years, our research group has worked to build theory for the unified analysis of different engineering fields and energy conversion systems. At the core of this work is the idea that even systems with differing physical properties—electrical, mechanical-dynamic, thermal-energy, and others—can be modeled, analyzed, and designed in a unified way by expressing them through circuit theory as a common analytical structure.
Rather than applying a different analytical method to each individual device or system, this theoretical framework treats the transfer and conversion of energy, matter, and momentum as a shared structure. This has allowed us to rationally describe the phenomena that occur within complex energy systems, and to advance research that leads to improved performance and optimal design.
Moreover, we have not stopped at building theory alone; we have pursued fundamental elucidation of phenomena, experiments and measurement, the construction of mathematical models, and the development, control, and demonstration of devices and systems as a single, integrated effort. Generating concrete technologies from theory and embodying them as devices and systems that actually function is an essential characteristic of our research.
These many years of research achievement were recognized as work on "rational system analysis theory," earning the Commendation for Science and Technology from the Minister of Education, Culture, Sports, Science and Technology (MEXT) in fiscal year 2022. We understand this award not merely as recognition of a single achievement, but as an endorsement of our broader research direction: connecting different engineering systems through common principles, and addressing societal challenges from the standpoint of both theory and real-world systems.
Building on the system analysis theory and thermal engineering expertise we have cultivated, we are now extending our scope from individual devices and energy systems to the "human spaces" in which people live, work, learn, and move. We are advancing the construction of "Human Space Design Engineering" as a new academic field that integrates architecture, mechanical engineering, information and control, energy, and human science.
Human spaces take many forms—homes, offices, educational facilities, commercial facilities, factories, agricultural and food-related spaces, mobility, and even the interior of clothing or outer space. Within these spaces, buildings, equipment, energy supply, information and control, and the behavior and senses of users interact with one another, giving rise to values for people such as comfort, health, safety, and productivity.
One of the key physical phenomena at the heart of this is "heat." Heat is a major factor in energy consumption and greenhouse-gas emissions, while also serving as the foundation for values essential to society, including human comfort and health, production processes, product quality, and food safety. We must therefore stop regarding heat merely as a loss to be reduced, and instead consider where it is generated and how it is transported, stored, converted, used, and controlled, as part of an overall system that includes both people and space.
In Human Space Design Engineering, we use thermodynamics as a key common language to mathematically describe the interactions among the elements that make up a space, evaluating value for people and energy conservation and decarbonization at the same time. By fusing experiments, mathematical models, simulation, digital twins, AI, optimization, and control, we aim to establish a methodology for designing human spaces that rests not merely on the accumulation of experience and individual technologies, but on shared underlying principles.
Our research is not confined to spaces on the demand side alone. We treat everything from the energy supply side—renewable energy, distributed energy resources, hydrogen, and electricity and heat supply networks—through to the demand side—housing, workplaces, production sites, agriculture and food distribution, and mobility—as a single, integrated system, and we design a new relationship between energy and human space.
Furthermore, we make use of experimental environments in which building and spatial conditions can be flexibly altered, test facilities that simulate actual usage conditions, and a range of measurement and analysis platforms, advancing our work from the elucidation of fundamental phenomena to the verification of integrated systems. By connecting physical space with digital space and cross-validating theory, experiment, and simulation, we translate our research findings into social implementation.
Research of this kind cannot be achieved by a single laboratory or a single field of specialization alone. It is essential for universities, companies, government agencies, and research institutions to bring together their respective knowledge and technologies, connecting theory, experiment, products, buildings, communities, social systems, and institutions.
We are pursuing collaboration at every stage, from basic research through technology development, device and system development, demonstration, evaluation, standardization, commercialization, and policy proposals. Through joint research, consortium activities, exchange of personnel, the development of demonstration fields, international collaboration, and other means, we hope to work together with you to create diverse forms of collaboration suited to each challenge and objective.
Our next challenge is to carry forward the theory and technology we have accumulated to date while extending their scope to people, space, energy, and society, building a new academic framework and a new social system. We look forward to collaborating with all of you who are willing to conduct research together with us and to jointly implement our work in society, as we move beyond the boundaries of specialized fields and organizations toward spaces of genuine value for people and a sustainable future society.
Kiyoshi Saito, Waseda University
