Building envelope design regulates the heat transfer in and out of a building and has a profound impact on building’s energy efficiency. Building greenery systems (BGS) provide an innovative solution to improve the thermal performance of a building through lowered energy consumption, and assists urban adaption to changing climate. With increasing global awareness to tackle climate change and to ensure sustainable and resilient urban development, the incorporation of BGS onto tall buildings becomes a favorable design option. BGS have been utilised in New Zealand buildings as interior surface finish and exterior façade on low- and mid-rise residential buildings. Despite the benefits, the concept of having combustible vegetation over building exterior creates a fire safety dilemma due to the risk of fire spread.

The disastrous consequences of 2017 Grenfell Tower fire are apparent, with rapid vertical fire spread that was beyond the firefighting capability. From fire safety perspective, different vegetation characteristics produce varying burning behaviour, depending on the species, moisture content and design of the support systems, thus more research is needed to ascertain the fire safety implication due to BGS design selection. A well-scoped PhD. research coupling multi-scale fire experiments (e.g. thermal analysis, cone calorimetry and full-scale setup) and numerical computational fluid dynamics (CFD) fire simulation is a feasible approach to assess the flammability of BGS and to develop suitable mitigation strategies, to prevent rapid vertical fire spread in tall building scenario. The proposed research tasks are as follows:

(1) Literature review and consultation with relevant experts e.g. BGS designers and Kaiārahi of Engineering, to identify a few designs of interest and explore the opportunity to enhance Māori biodiversity.

(2) Multi-scale experimental investigation, including material-scale simultaneous thermal analysis (STA), comprising differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) to determine the thermal decomposition behaviour of different vegetations, and bench-scale cone calorimetry and full-scale VGS setup to investigate the combustion characteristics and fire spread mechanisms.

(3) Numerical CFD modelling using complex pyrolysis model and sub-grid Lagrangian particles to predict the complex burning behaviour of multi-scale BGS, and to validate the accuracy of FDS pyrolysis model.

(4) Develop feasible fire spread mitigation strategies for BGS based on experimental and numerical research outcomes.

Key qualifications and skills

Relevant Bachelor or Masters qualification in Fire Engineering

Experimental experience on oxygen depletion calorimetry and thermal analysis (optional)

Numerical experience with Fire Dynamics Simulator (FDS) or similar (optional)

Does the project come with funding

Not specifically, but students can apply for the UC Doctoral Scholarship as part of the admission process

Final date for receiving applications

Ongoing

Keywords

vertical fire spread; façade fires; fire safety; building greenery system; green façade