## 8 Discussion, Implications and Future Developments  
The analyses provided in the current research gave an example of integrated AWG machine application and its potentialities to cover two issues at the same time: to offer an alternative source of drinking water and to provide a HVAC plant revamping. The results show that such a kind of machine, in Dubai, was able to produce meaningful water quantities, more than one thousand and half litres a day, overcoming, at the same time, the energy consumption issue, related to water extraction from the air, by means of a smart use of the by-side products of the water extraction cycle. Taking into account the economic considerations, it is easy to calculate that, even if the water would not be evaluated, thus given for free, the actualised PBT would be about 5 years. It is worth mentioning that the hypothesis of 120 h of machine stop is a very conservative one, because such a machine requires a maintenance comparable to that of the chillers of equal cooling power. The main  
Figure 17: NPV evolution in the time horizon of 10 years. The positive return is underlined by the green colour.  
research implication is that the water extraction from air could already be effective if the integration approach is pursued. Lately, the atmospheric water harvesting research field has been concentrating on desiccant substances study and on passive systems. Nevertheless, as already remembered in Section 2, with such an approach, specific yields are comparatively low, some litre day per squared mater of plant and, when desiccants are employed, often the energy consumption remains an issue. The integrated approach can be a mean to provide meaningful quantities of water, thousand L/day, with a comparatively low space requirement, overcoming, at the same time, the energy issue. The water extraction from air sustainability, that is one of the current research questions, can be actually pursued with such an approach.  
Nevertheless, more studies are required, not only to extend the results to other cases and climates but also to explore other potentialities of the integrated approach in water extraction for uses such as agriculture, industrial, etc., different from human consumption. For the current case study, the economic sustainability is clear enough; thus, it would be very interesting to understand how such a solution could be extended to other similar building installations, worker villages, in other climatic regions. Such a hypothesis will be the object of a future study, which will be developed also with the help of the Global Efficiency Index (GEI) [38] calculations in order to provide a comparison metric between the existing and the improved (adding the integrated machine) plant configuration. The study could be a mean to define a sort of revamping standard based on the integration approach that considers water as important as energy efficiency.  
Other future developments will concern the possibility to equip such dwellings with photovoltaic fields, covering at least a part of the electrical energy demand, whose cleaning could be carried out by means of part of the water coming from the integrated system, as described in ref. [52]. Finally, further evaluations about the environmental impact will be carried out considering the CO\({}_{2}\) emissions that can be avoided with the integrated approach.