Smoke Control in Special Structure

Building codes of almost all countries generally have a ‘size limitation of building and compartment’ which states a maximum floor area and cubical content for various uses and configuration. If the maximum compartment size is exceeded, there is usually provision for relaxation of the codes which will involve at least some of the following: a) occupancy levels, b) means of escape, c) sprinkler system fitted, d) smoke control system fitted. This paper is concerned for the latter, recognising the need for adequate smoke control methods in structures such as large space buildings, basements, shopping complexes, atria, factories and warehouses for the protection of life and property and to reduce fire damage. It recognizes that research over many years by reputable organizations in a number of countries (UK, Japan and USA) have produced substantial knowledge about smoke flow within complex buildings to allows the expected condition of temperature and mass of smoke to be quantified quite accurately. From this research [1-11], an Engineering approach to the control of smoke in complex structures is likely to produce a far more reliable end result in a real fire condition than a solution based on current available prescriptive basic codes which rely on designs which merely consider the volume of the space or the floor area. The paper deals with the physics of smoke and highlights the speed at which smoke will flow through a building, cutting off escape routes and increasing temperature with related dangers. Design methods and sample calculations are given for establishing smoke flow rates and possible smoke flow patterns in multi-storey complexes and atrium designs. The paper covers a number of misconceptions in these areas. Finally, the choice of equipment to effect smoke removal must be suitable and must operate under fire conditions. Unsuitable equipment may act in reverse to that intended. This paper is generally based on U.K. research and requirements and brings together salient concepts and design ideas for the general awareness of the features and benefits of adequate smoke extract measures.