NUMERICAL STUDY ON FIRE HAZARD ASSOCIATED TO EXTERNAL THERMAL INSULATION CLADDING SYSTEMS

Abstract

The significant increase in the price of energy resources leads today's society not only to a reconsideration of energy conservation policies but also to the encouragement of architects, builders, and building owners to use thermal insulation and exterior wall finishing systems. The design of thermal insulation for facades is a constructive decision, in which the layer with thermal insulation properties is fixed on the load-bearing side of the walls, with the help of adhesives and/or by mechanical means, followed by the application of a reinforcement and finishing layer. These operations have the role of ensuring the normative values of the thermal indicators specific to the wall structures, their protection against environmental influences, ensuring the optimal microclimate of the interior compartments of the building as well as providing an attractive, aesthetic appearance to the facades and structural elements. Wet exterior cladding or composite thermal insulation systems using polystyrene (ETICS) provide a complete and very cost-effective solution to meet the above-described goals. However, multiple examples of fires in the scientific literature, with the spread of fire on the support of thermal insulation and finishing systems of buildings, indicate their particular danger. This fire risk is directly related to the chosen structural solution for cladding and the type of thermal insulation material used, being also influenced by noncompliance or violation of specific technical regulations or rules on the fire safety of materials and buildings. Through the application of CFD-based computational fire field models, the associated risks for a custom 7-storey building with external cladding were considered in this study. The aim was to observe the fire spread on one side of the building, insulated using the ETICS exterior insulation and finishing system. As an insulating material, two types of expanded polystyrene (EPS) were used, with different fire resistance properties. The study results demonstrate the importance of choosing the right technical solution in terms of fire safety and the need to apply methods to limit the vertical spread of fire.