## 4 Results and Discussion
### Flux from the Walls and Roof Flames  
Adding horizontal openings not only changes the thermal environment at the door but also changes heat fluxes to the surroundings near to the new openings in the roof. The effects of this must be checked to quantify any additional benefits or risk induced. The changes in flux between experiments are due to different wall temperatures and the addition of flame plumes at the roof as a radiant heat source.  
Heat fluxes were measured at 15 cm from the centres of the side and back walls at the height of the dwelling. The data are analysed over the same steady-state phases as used in the previous analyses (Figure 15). Again, it is proven that slot opening cases were more efficient at reducing heat flux to the surroundings. For all cases at both the back and side walls, an opening area of 0.04 m\({}^{2}\) produced the highest maximum fluxes. However, the increase in flux relative to the closed case was significantly larger for the corner opening cases. The largest such increase across all corner cases was a 131% increase (6.6\(\rightarrow\)15.2 kW/m\({}^{2}\)) produced by the 0.04 m\({}^{2}\) Polycarbonate corner case at the back wall (Figure 15b). Across all slot cases, the greatest increase in peak flux was only 69% (5.6\(\rightarrow\)9.5 kW/m\({}^{2}\)) produced by the 0.04 m\({}^{2}\) polycarbonate slot case at the side wall (Figure 15d).  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Material Identification** & **Example Flux Variance** & **Time to ignition Variance** \\  & **Range, kW/m\({}^{2}\) (\% Increase)** & **across Given Flux Range, s** \\  & & **(\% Decrease)** \\ \hline
1 Structural timber & 20–50 (+150\%) & 224–18 (\(-\)92.0\%) \\ \hline
11 Thin cardboard & 12–30 (+150\%) & 253–9 (\(-\)96.4\%) \\ \hline
14 PU foam & 9–20 (+122.2\%) & 249–7 (\(-\)97.2\%) \\ \hline
28 Pink curtain & 26–50 (+92.3\%) & 81–7 (\(-\)91.4\%) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Example materials from informal settlements that show a high degree of flux-sensitivity [38].  
Figure 15: Peak and average heat flux in the steady-state phase at 15 cm for the following opening-wall combinations: (**a**) corner-back, (**b**) corner-side, (**c**) slot-back, and (**d**) slot-side.  
The 0.16 m\({}^{2}\) slot cases reduced the peak and average steady-state fluxes by 39% and 51%, respectively, on average, from both the side and back walls relative to the closed case. The corresponding corner cases succeeded in reducing the steady-state average fluxes by 36% on average; however, the largest reduction to the peak flux was only 13% (open-side wall), with one case actually increasing the peak flux by up to 75% (poly-back wall). In addition to the 0.16 m\({}^{2}\) cases, reductions below the closed case peak and average values, though not as great, are achieved by all of the 0.09 m\({}^{2}\) slot cases, whereas the corresponding 0.09 m\({}^{2}\) corner cases do not achieve this. Overall, the efficacy of the slot cases relative to the corner cases has again been proven, showing the ability to reduce heat fluxes to the surroundings by a greater margin and at smaller areas than the corner cases. Similar to the situation at the door, corner cases show a greater degree of variability in flux, presenting an unintended additional risk if flux-time-sensitive materials are present.