The aim of the presentation was to present the results of research of a fire development in a multi-storey residential building, without corridors. The research was carried out on a specially created test stand in a 9-storey building. The research space included an apartment and an adjacent staircase. The research included several fire tests. Typical apartment furnishings were used in the fires, including a sofa, pillows, tea table, carpet, dressers, small set of kitchen furniture, table and chairs.A smoke ventilation system was installed in the staircase with variable make up air supply. Tests were carried out for the following configurations of smoke ventilation systems:

• Natural smoke exhaust with natural/gravitational make-up air
• Natural smoke exhaust with mechanical (fixed volume value of 14000 m³/h) make-up air inlet.
• Natural smoke exhaust with variable mechanical make-up air inlet

An additional variable was a position of the door between the staircase and the apartment with fire. In some tests the door remained open. In other tests, the door was opened only for a short time, which would be needed to evacuate people, and next was closed. Every fire was initiated on the sofa and its development was observed. The temperature in the test room, the adjacent corridor and the staircase were measured. The test stand has been equipped with more than 40 thermocouples. Additionally, light transmittance in the staircase and pressure difference between the staircase and the external environment were measured. The flow of the air and smoke through the smoke damper was also measured. Several cameras were placed in the test room, which allowed to create video recordings of the tests. The results of the research show that the system of gravitational smoke ventilation is susceptible to ambient conditions such as temperature. In some tests it was observed that smoke could fall below the storey covered by the fire.The conducted research allowed to determine the best way to reduce the amount of smoke in the staircase. The use of mechanical air supply in smoke ventilation system allowed for fast smoke removal from the staircase and for proper air and smoke flow direction (from test room to smoke exhaust devices).The use of mechanical make up air supply in the smoke ventilation system allowed prevent falling smoke below the storey covered by the fire, so that the staircase on the floor covered by the fire remains free of smoke in the lower part, providing a way of escape from the level covered by the fire.

Summary: The conducted research allowed to determine what is the best way to reduce the amount of smoke in the staircase. The use of mechanical air supply in smoke ventilation system allowed for fast smoke removal from the staircase and for proper air and smoke flow direction (from test room to smoke exhaust devices). The results of the research show that the system of gravitational smoke ventilation is susceptible to ambient conditions such as temperature.