Since Mitsubishi Heavy Industries, Ltd. (MHI) began using unit and panel sizes of 840 mm and 950 mm, respectively, in 1990, these dimensions (sizes) have become the de facto standards for ceiling cassette four-way type indoor climate control units that are well-suited to most buildings. Without changing these dimensions, demands are high for environmentally friendly products with low energy consumption. This paper discusses products with improved air comfort characteristics and maintainability to preserve a comfortable environment.