In this paper, the current status of office buildings in Japan was taken as an example to explain the importance and the needs of the concept of productivity in building environment. A conceptual diagram for the evaluation of the effect of indoor environmental quality on productivity was proposed. COOL BIZ campaign in Japan is explained. The results from subjective experiments revealed that human responses were important for the evaluation of productivity. The relationship of performance and the level of fatigue and the level of satisfaction with the indoor environmental quality were described. Individual satisfaction for the environment is close related to the performance. One example of currently constructed office buildings, which took accounts for the concept of productivity into design, was introduced. Productivity and sustainability are keys for modern office building design.