Associate professor Mae had been studying energy consumption in houses from his student days. He focused on hot-water use in houses, which use a lot of energy but a few scholar studied. And he examined energy-saving of hot-water use through measuring in many houses and many experiments. In Buiding Research Institute, he established the method of actual efficiency of hot-water supply system. Now, his field is extended to heating and cooling system,cross-ventilation, and so on. In the University of Tokyo, we aim to utilize environmental engineering for education and practice design.