Aim: The aim of the article is to attempt to answer controversial questions asked for many years in Poland: Is it appropriate to extend the length of exit routes when jet-fan ventilation is used? Are the two-exitway directions in the event of evacuation are an important factor affecting the safety of people? Can computer simulations be a sufficient tool to assess the safe evacuation of car-park users, regardless of the length of exitways, as prescribed in the applicable regulations? What are the factors that actually determine the effectiveness of smoke-exhaust systems in car parks?

Introduction: Fire safety in car parks, especially underground car parks, is one of the main topics of many symposia and conferences in Poland. The discussions are particularly related to their smoke-control systems. For many years, two alternative smoke-control systems – jet fans and ducts – have been competing with each other. Their effectiveness is often different. Designers, in order to achieve and verify fire-ventilation systems, rely both on regulations and the available sources of technical knowledge and computer simulations. Although most computer analyses allow unequivocal assessment of safety conditions in a specific car park, where a duct or jet-fan ventilation system is installed, there are ongoing discussions over theoretical differences in the effectiveness of these systems, specific requirements set out in the regulations in force, etc. This controversy inspired this article and motivated its authors to answer the most important questions centred around the problem of the designing of fire-ventilation systems in car parks.

Methodology: The paper was developed based on the latest literature and the results of the authors’ own CFD (Computational Fluid Dynamics) analyses of smoke and heat spread in sample underground car parks. The presented conclusions are supported by the authors’ longstanding, practical experience in analyses of car-park smoke control systems, utilising engineering methods and performed all over Poland.

Conclusions: The assessment of the CFD computer simulation results presented in the article leads to the conclusion that the current Polish regulations for fire protection in car parks are inadequate. The most appropriate approach to the assessment of the level of car-park user safety is usually an individual analysis using engineering methods and computer simulations. Looking at the applicable Polish law, it is worth paying attention to how the requirements differ from those in place in other countries, particularly in the case of requirements which are significantly different, especially as regards the maximum permitted lengths of exitways. The most important problem in Poland seems to be the lack of a difference between the maximum length of exitways where there is only one exit route (one direction) and where there are more exit directions.

Keywords: smoke ventilation, jet fan systems, exit way, CFD, simulations

Type of article: review article