## 3 Framework Application
### Results and Discussions  
* Generated Retrofitting Plans
* BIM Revit 2020 software was used to construct the 3D model of the building, and the current energy consumption was simulated (Figure 2). The cooling requirement was retrieved from the software after estimating the annual energy consumption after each retrofitting plan (Figure 3). Binary Integer Linear Programming was used to create the model and suggested that for the energy retrofitting strategy, the integer variables should be restricted to 0 or 1. Cooling load parameters and the different alternatives for building retrofitting measures were added to the thermal load constraint to select those corresponding to the optimum air conditioner capacity. Additionally, the needed lamps to reach the required illumination level for each space was added to the illumination constraint. Table 4 presents different retrofitting plans, along with their retrofitting measures, budgets, energy savings, payback period, and return on investment. Retrofitting plans 1 and 2 focus on the electrical equipment, while retrofitting plans 3 and 4 include both building envelope and electrical equipment retrofitting measures. For example, the energy retrofitting plan 3, which includes both building envelope and electrical equipment measures, requires a budget of SR 254,000 (USD 68,000), decreases energy consumption by 33%, and has a payback period of 10.5 years and a ROI equal to 17.3%. The depicted scenarios show that some of the retrofitting measures are adopted in multiple scenarios. This is due  
Figure 3: Energy consumption (in Kwh) after retrofitting (Plan 1). Figure 2: Energy consumption (in Kwh) before retrofitting. to the fact that in every scenario, the most efficient measures are adopted and others are added when the budget increases. For instance, retrofitting plan 3 (with a budget of SR 254,000) adopts the same electrical equipment retrofitting measures as those existing in retrofitting plan 1 (with a budget of SR 50,000). The sensitivity analysis was conducted to investigate the effect of the budget on the energy savings, the payback period, and the ROI. Figure 4 indicates that the allocation of sufficient budget improves energy savings; however, some energy retrofitting measures may have a limited impact on energy savings while requiring higher investments. For example, the energy savings for retrofitting plan 1, corresponding to the budged of SR 46,000, is equal to 22%, while retrofitting plan 4 energy savings is equal to 26% for a budget of SR 246,000. In fact, for this case study, electrical-equipment-only retrofitting measures (plan 1 and plan 2) lead to greater energy savings than building envelope retrofitting measures (plan 3 and plan 4) while requiring a smaller budget. In terms of return on investment (Figure 5), electrical-equipment-only retrofitting plans (plan 1 and plan 2) provide an ROI of more than 20% while the retrofitting plans that combine both building envelope and electrical equipment retrofitting measures (plan 3 and plan 4) provide a return on investment of around 17%. From an investment point of view, plans 1 and 2 seem to be more attractive as they require less than a quarter of the budget for plans 1 and 2 while offering a significant and more competitive ROI.