## 2 Materials and Methods
### Simulation Study on Building Information Model (BIM) with Pitched Roof  
A simulation study was performed on a BIM, which was employed previously in [PERSON] et al. [38] for a different study, to project the resultant impact of the silica-aerogel-incorporated cement paste as render on the roof-top surface, coupled with the silica-aerogel-incorporated composite insulation board installed below the roof tiles, on the annual cooling load and energy savings. The BIM was created in Integrated Environmental Solutions <Virtual Environment> (IES <VE>) using its ModelIT module, as shown, in axonometric view, in Figure 3. The dimensions of the BIM were 4 m width, 4 m length and 3 m height, and they were determined as such to fulfill the minimum requirements of a habitable room in Malaysia as per the Uniform Building By-Laws 1984 [48]. The materials assigned to the BIM were adopted based on the materials employed in [PERSON] et al. [38]. The simulation data generated from the BIM in IES <VE> were already validated in [PERSON] et al. [38] against the data collected from test cells located in Universiti Teknologi MARA, ShahAlam, Malaysia, which were also employed in previous studies by [PERSON] et al. [49; 50], [PERSON] et al. [51], [PERSON] et al. [52; 53], and [PERSON] et al. [54]. Correspondingly, the location of Shah Alam, Malaysia, was also selected as the location of the BIM in the present study, as Shah Alam is subjected to a tropical climate and, hence, exposed to intense and prolonged solar radiation, as well as high amounts of rainfall.  
The thermal conductivity values of the silica-aerogel-incorporated samples with optimum amounts of silica aerogel, which were determined from the results of the thermal and strength performance tests, were assigned to the modeled layer of the silica-aerogel-incorporated composite cement paste that was applied as render on the roof-top surface, and the modeled layer of the silica-aerogel-incorporated composite insulation board that was installed below the roof tiles, which were embedded in the BIM using the ModelIT module of IES <VE>. The ApacheSim module of IES <VE> was then employed to project the annual cooling load and, accordingly, calculate annual energy savings. The configuration of the roof was varied based on the presence of the render on the roof-top surface and composite insulation board below the roof tiles, as well as the thickness of the composite insulation board. Accordingly, five roof configurations were employed for the simulation study, which are presented in Table 1. The thickness of the composite insulation board was varied at 100 mm, 200 mm, and 300 mm, while the thickness of the cement render coated on the roof tiles was fixed at 20 mm in accordance with conventional practices.  
\begin{table}
\begin{tabular}{c c c} \hline
**BIM Roof** & **Presence of Cement Render** & **Presence and Thickness of** \\
**Configuration ID** & **on the Roof-Top Surface** & **Roof Insulation Material** \\ \hline \(C\) & Without cement render & Without insulation \\ \(R\) & & Without insulation \\ \(R100\) & With cement render & With 100-mm thick composite \\ \(R200\) & & With 200-mm thick composite \\ \(R300\) & & insulation board \\ \hline \end{tabular}
\end{table}
Table 1: Roof configurations of the BIM employed for the simulation study.  
Figure 3: Axonometric view of the Building Information Model.