A CFD fire simulation model for external living walls

A CFD fire model for Living Walls (LW) is presented in this paper. The combustion of the LW support structure (plastic material) is modelled as an external cladding system within SMARTFIRE. The plants and growing medium of the LW system are represented as two groups of combustible porous materials, which consist of solid particles. The combined model provides a unique capability to simulate fires in external LW systems and is validated using data from a variety of LW fire experiments. The model produced good agreement for the measured HRR in an SBI fire test; comparable burning states and temperature profiles of two large-scale tests; and similar time to fail for a LW structure, without plants or growth media, in a BS 8414 test. It is found that although the simulated HRRs from the burning plants are sensitive to the moisture content, the plant mass, the surface area to volume ratio etc., the total HRR of the investigated LW system is dominated by the burning of the plastic structure. It is suggested that the fire risk posed by the investigated LW system is at least as high as that for a Grenfell type cladding system. • A CFD model has been developed to simulate living wall fires • Model validations utilise data from SBI, large-scale and BS 8414 fire tests • The fire risk of the explored living wall is dominated by the module material • The explored living wall system fails BS 8414 simulation in 225 s • Non-burnable living wall module is a potential fire risk mitigation measure