## 2 Experimental Set-Up  
### Scaling Strategy and Crib Configuration  
Wood cribs are utilized to replicate the fire source in experiments. One of the advantages of wood cribs is their ability to release thermal energy in an inconsistent yet prolonged manner throughout the experiment, keeping the fire in an active burning phase. This behavior accurately reflects the real evolution of a fire in terms of HRR and temperature over time [25; 26]. Unlike a fluid-aggregate fuel source, wood cribs exhibit more pronounced development due to their significantly larger combustion surface area relative to the same thermal load. Therefore, to achieve feasible results, a clear definition of the wood crib configuration [27] is necessary through full-scale testing in room-sized stands, conforming to specific guidelines [28]. The objective of this work is to experimentally replicate the destructive effects of an office fire and measure the interior temperatures to which the occupants might be exposed. According to the referenced standard [29], the density of the thermal load is 420 MJ/m\({}^{2}\). A full-scale experimental stand with a usable area of 16 m\({}^{2}\) was utilized, built as part of a research program. Using a specialized program [27], designed in compliance with standard [28], a theoretical HRR generated by burning a crib of a specific configuration was determined. The configuration of the wood crib has a significant influence on the final HRR value. According to the reference [27], this configuration involves defining several input parameters, as shown in Figure 1:  
* cross-section of the wood stick (D\({}^{2}\));
* spacing between sticks (S);
* crib height (h\({}_{\text{C}}\));
* number of sticks per row (n);
* ventilated area (A\({}_{\text{v}}\));
* height of the ventilated area (h\({}_{\text{v}}\));
* initial mass of the crib (m\({}_{0}\));
* heat of combustion (H\({}_{\text{U}}\)). The HRR value is directly proportional to the calorific power of the combustible material and the mass loss rate. In our experiment, this calculation included both the ethanol and stack components, with adjustments made to account for ethanol's minor caloric impact. By integrating HRR over time, we obtained the total thermal energy released during combustion, expressed in kJ, and ensured accuracy despite challenges such as data discontinuities caused by partial or total stack collapse. These corrections allowed for a precise experimental determination of the cumulative heat release rate. To determine the HRR evolution for an office fire with a source constituted by nine cribs, as depicted in Figure 1, a preliminary controlled full-scale experiment with a single crib was necessary. This experiment allowed for the monitoring of the fuel's mass loss,  
Figure 1: Wood crib dimensions. and hence the HRR, as well as the temperature inside the stand (as shown in Figure 2a,b). This was made possible by significantly lower temperatures, which permitted the use of a thermally insulated scale capable of withstanding the conditions during combustion. Referring to similar studies in the field [27; 30], the single-crib experiment [31] determined an experimental HRR value of a 745 MJ fire. Considering that the specific heat of combustion of the fuel material remains constant, and the temperature evolution does not follow a direct proportionality with the HRR but rather a dependence characterized by HRR'(2/3), as described in reference [32], measuring the temperature in the experiment involving nine cribs provides a valid benchmark for estimating the HRR value. Since the total mass of fuel can be proportionally scaled with the number of cribs, it was possible to extrapolate the HRR evolution for this extended configuration (Figure 2c), thereby creating the conditions for conducting an experiment with a wood quantity nine times greater to correspond to an office fire with a thermal load of 6720 MJ, in compliance with current standards [11]. Figure 2: Experimental stand: (**a**) left view; (**b**) front view; (**c**) interior view.