Generally, a disaster breaks out and spreads over with extremely complicated mechanism. It goes without saying that the building fire is made no exception of it. For this reason, most of disasters causing human deaths and injuries have allowed to trace their development, but not allowed prediction.

Since fire protection problems involve various factors, an one-sided approach is not sufficient for protecting measures against fire. For this reason, fire regulations intend to secure occupants against smoke by various measures, including the prevention of outbreak and spread of fire, smoke control and early evacuation etc. However, these invididual regulations are not organically integrated, lacking sufficient relation among one another. They are uniformly applied ignoring individual characters of buildings. These laws and regulations sometimes seem to be obstractive designing a building. These problems are attributable to the peculiarity and the diversity of fires and the dependence on specifications regulated in the Building Code.

Fire protecting measures should be based on engineering design techniques and rationally integrated within designing a building. It is not an overstatement to say that these problems cannot be fundamentally solved without such an approach.

It goes without saying that these problems of safety require adequate understanding of their relation with society and economy. However, understanding the essentiality must precede all others. In other words, the physical phenomena of smoke must be analyzed at first to solve the problems of personal safety against smoke in building fires.

Based on this point of view, the study on the fire protection at the Building Research Institute have been mainly directed to the analysis of phenomena in efforts to establish an engineering system of fire protection design. The study summarized by the title of this paper is a part of the studies that have been conducted in attempts to establish a smoke protection design system. The present paper describes the outline of a series of studies, summarizes a field fire experiment conducted at the building of the Welfare Ministry and gives an analysis on smoke behavior during the Sennichi Building fire.