## 5 AGEI Application to a Case Study
### Discussion of Results  
The analysed configurations are complex mixes of equipment, combined to provide three useful effects. The evaluation tool simplifies the analysis by giving straightforward numerical results. In order to facilitate a comparison among them, monthly AGEI values are plotted in a graph, as shown in Figure 8.  
The graph above shows clearly that Configuration B can be considered the most efficient over the whole year. In particular, it is far better than the original plant, represented by configuration A. This outcome confirms the suitability of AGEI for the assessment of  
Figure 8: AGEI behaviour represented by monthly averages. Figure 7: Configuration C: original original plant assisted by an electrical heat pump. hybrid complex plants because it is in compliance with the detailed analytical calculations provided in [23], where each energy input and output was calculated in detail and the higher efficiency was numerically calculated. The AGEI allows users to carry out an immediate assessment with comparatively few steps. In fact, the assessment is obtained by considering only the useful effect indicators and the role played by each piece of equipment in meeting the requirements. On the basis of the index results, it comes that Configuration B is three to four times more efficient than Configuration A. The best behaviour of the hybrid system comprising the AWG is during the summer months, reflecting the increased behaviour of the integrated machine during such a period, as confirmed by the detailed analysis. As detailed in the previous section, Configuration C includes a high-performance heat pump covering the heating needs. This equipment replaces the most obsolete systems, represented by the electric and LPG boilers, and indeed, its AGEI value is far better than that of configuration A. Nevertheless, Configuration C is less efficient compared to Configuration B. This is due not only to the higher WET value achieved by the integrated AWG system but also to its contribution to both cooling and heating, resulting in a greater integration in this hybrid configuration. In Table 16, the average yearly AGEI results are compared, showing that Configuration B achieves an average efficiency improvement of approximately three and a half times compared to Configuration A, while Configuration C is about three times more efficient than Configuration A. The AGEI results highlight also that Configuration B performs 14% better than Configuration C.  
Returning to the graph illustrated in Figure 8, it is clear that Configuration B exhibits more variability throughout the year in comparison to the other two configurations. This is due to the detailed data available for the integrated AWG system. Notably, this type of machine is designed to maximise water extraction; thus, its performance strongly depends on environmental conditions. As discussed in [34], in the Dubai climate, at least the monthly variability should be considered in order to provide reliable results. It is worth mentioning that, for the current analysis, hourly data, coming from [23], have been taken into account and the results were arranged into monthly averages to facilitate comparisons. Regarding the other pieces of equipment, it can be stated that the efficiencies of the electric and LPG boilers, as well as the air conditioning EER, were considered constant, in accordance with the data collected on-site [23]. In Configurations A and C, the bottling system WET remains reasonably constant throughout the year, as the calculation is based on variables that do not depend on environmental conditions. The heat pump COP of Configuration C is given as a yearly average, as detailed data were not available. It should be noted that even if more details about the monthly equipment behaviour of the other two configurations, A and C, were available, the AGEI calculation would still retain its simplicity and straightforward applicability.