A Study on Fire Hazards of Vertical Greenery Systems due to Window Flame Plume

Vertical greenery systems (VGSs) are increasingly popular features of building facadesall over the world. However, the fire hazards of VGSs have not yet been thoroughlystudied. Many countries have neither fire safety codes nor standard fire tests specificallydesigned for VGSs. In particular, a fire scenario in which a window flame plume movesout of a room fire should be scientifically investigated in the context of VGSs. Plantsand the associated combustible components of a VGS located near a window can beignited easily. The heat, flames, toxic gases and particulate matter emitted would spreadupward along the green facade. Burning leaves and branches in the VGS may fall andfirebrands may blow to other locations, causing greater hazards. In addition, as anoutdoor attachment, VGSs might easily catch fire from burning materials from a fire atanother location or as a result of arson.The major aim of this project is to conduct a thorough investigation of the behaviour ofVGSs in the above fire scenario. The fire behaviour of three VGSs – the panel system,the felt system and the container system – will be studied and compared. Three popularspecies of green plants – ivy (Hedera helix), Chinese evergreen (Aglaonema or ‘LadyValentine’) and baby rubberplant (Peperomia obtusifolia) – will be investigated. Ignitionof plants by a flame and their consequent burning will be affected by the moisturecontent, which varies with the plant species and irrigation conditions. The plants will bestudied with three moisture contents: normal watering, no watering for 10 days and nowatering for 20 days. The likelihood of igniting the plants and the accessories in theVGSs will be evaluated with a cone calorimeter. The heat and smoke emitted will bemeasured. The vertical upward fire spread over the green facade will then be examinedusing physical reduced-scale experiments. The results of the mathematical models offire spread will be combined with the cone and the physical reduced-scale modellingexperimental results to achieve an integrated understanding of the fire hazards of VGSs.Experiments will be carried out on a portion of a real-scale VGS to verify thephenomena observed in the scale modelling experiments and the predictions from themathematical models. The results will be used to develop standard fire tests for theassessment of VGSs. Appropriate fire protection, fire-fighting and rescue strategies forbuildings with VGSs can then be recommended.