As a results of rapid development of engineering science in Japan, new technics are being put in practical uses in the field of air-conditioning, electric lighting and other mechanical installations of buildings lately, and the need of new design data to comply with such new technics has become ever more pressing. However, some of the design data presented in the past has become to be totally impracticable to apply to new buildings without modification, and it is clearly evident that these established data must be surely re-examined. What is needed, therefore, is new data based on new findings that can be used as design criterion or data for the buildings of tomorrow. This paper describes an analytic solution, which hcs been formulated through analysis of innumerable statistical data summed up in the past several years on the electrical equiment and installations of the buildings so that they may be conveniently apply to the electrical design. By the use of this statistical solution, the capacities of electrical load and transformer per unit area of office, store, hotel and residential buildings can be summarized as shown on Table-11. And up to now, the following equation has been generally used to assume the approximate area of the substation of a building. A_t=3.3W_t^<0.5> where, A_t=Area of substation (m^2) W_t=Total transformer capacity (kVA) However, it is considerd from the results of the investigation that areas of the substations of the buildings constructed during the past six years are distributed in closer proximity along the lines of the following equation than the established equation referred to hereinbefore. A_t=K_sW_t^<0.7> where, K_s=A constant based on the design of the substation =0.96 for high tension receiving voltage
