Figure 1. Data showing the frequency of large façade fires worldwide from 1990 to present day. Data found from news articles online.
Figure 2. Images demonstrating the different levels of analysis when considering a façade. Currently, fire research focuses mainly on individual components, while large scale fire testing is used to assess façade systems.
Figure 3. Maximum U-Values allowed for external walls in progressive editions of the UK building code. The U-Value of a wall quantifies its overall thermal resistance - a lower value indicates a better insulating performance (HM Government, 2016).
Figure 4. Market share of German insulation products from 1989-2004 (Bozsaky, 2010). The market is divided between non-combustible mineral wool and more thermally efficient polymeric insulation.
Figure 5. Simplified sections of common façade systems: (a) Monolithic Façade, (b) Filled Cavity Façade, (c) External Thermal Insulating Composite System (ETICS) Façade, (d) Sandwich Panel (or Metal Insulated Panel), (e) Rainscreen Façade. Note: The vapor control layer and weather resistant barrier in (e) are shown on the warm side of the insulation, for a climate that has an annual desire for vapor to flow from inside to outside.
Figure 6. Plots illustrating how cavity width could hypothetically affect: (a) the heat flux on the cavity walls (radiation enhancement), (b) the heat released into the cavity (chimney effect), and (c) the total flammability (combination). The “flammability index” plotted in (c) is a hypothetical variable that quantifies the flammability of a facade. Currently, no such variable exists, but our research aims to create one.
Figure 7. Example of a Pareto front, minimizing flammability vs. U-Value. Each solution represents a particular façade system design. Crosses represent solutions that are feasible, but not optimal. Labels show where hypothetical systems using polymer foam or mineral wool insulation might fall. The “flammability index” plotted in (c) is a hypothetical variable that quantifies the flammability of a facade. Currently, no such variable exists, but our research aims to create one.
Table 1. Objectives in façade design (Herzog et al., 2017). Objectives are ordered by whether they are intended to be minimized or maximized, and from those that ensure the building is safe, to those that ensure the building is comfortable