## 9 Conclusions  
The current paper presents a real case study concerning an integrated AWG machine of large size production, more than one thousand litres per day. The test of a real machine was carried out in a worker village placed in Dubai, where the drinking water provision is a current issue. The machine was linked to the existing HVAC plants by means of a pipe circuit and of an air duct and was able not only to produce drinking water but also to provide a flux of fresh air, cooled and dehumidified, and to heat domestic water. On the basis of real results, it was possible to calculate that the machine can cover the daily drinking needs of 792 persons and avoid, yearly, the plastic consumption of more than 11 Mg (tons) due to the avoided bottled water use. Moreover, the heating energy coming from the machine was calculated to be enough to cover the heating needs for the domestic water of two buildings, housing about 200 guests each, and 70% of the heating needs of one of the kitchen buildings. The cooled and dry air, coming from the water extraction cycle, can cover 87% of the fresh air required by common kitchens. The integrated AWG machine, on the whole, was evaluated to be able to provide the following savings: electrical energy equal to 824,769 kWh/year and LPG equal to 54,426.1 L/year. The water production exceeds 570 m\({}^{3}\) per year. An economic evaluation, to test the system sustainability, was also carried out. The investment, equal to about EUR 290,000, comprising the machine cost, materials for linking to the existing plants, manpower and transport, has a Net Present Value, after a time horizon of 10 years, of more than EUR 958,000 and has an actualised PBT of 2 years, while the simple PBT is less than 2 years.  
Conceptualization, A.M.; methodology, L.C. and A.M.; software, P.C.; validation, L.C. and P.C.; formal analysis, L.C.; investigation, L.C.; resources, L.C.; data curation, L.C. and P.C.; writing--original draft preparation, L.C.; writing--review and editing, L.C., P.C, and A.M.; visualization, L.C.; supervision, A.M.; project administration, A.M.; funding acquisition, A.M. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research received no external funding.  
**Institutional Review Board Statement**: not applicable.  
**Informed Consent Statement**: not applicable.  
**Data Availability Statement**: no further data are available.  
**Acknowledgments:** The worker village data, test data and photographs were provided by SEAS, Societe de l'Eau Aerienne Suisse.  
**Conflicts of Interest**: The authors declare no conflict of interest.  
**Abbreviations**  
**Acronyms**  
AED ISO code for Dirham  
AHU Air Handling Unit  
AWG Air to Water Generator  
AWH Air Water Harvesting  
COP Coefficient of Performance  
EER Energy Efficiency Ratio  
HVAC Heating Ventilation Air Conditioning  
ICP Inferior Calorific Power  
LPG Liquid Petroleum Gas  
NPV Net Present Value  
PBT Pay Back Time  
PET PolyEthylene Terephthalalate  
PLC Programmable Logic Controller  
WET Water Energy Transformation  
UAE United Arab Emirates  
UN United Nations  
UV Ultra Violet  
**Symbols**  
\(a\)  
dry air mass flow (kg/s)  
\(C\)  
water specific heat, 4.186 kJ/(kgK)  
_Cp_  
Inferior Calorific Power (kWh/L)  
_Cu_  
net cash flow (chosen currency)  
_en_  
energy (kWh) or (kJ)  
_en_  
heating energy (kWh) or (kJ)  
_en_  
electrical energy (kWh) or (kJ)  
\(i\)  
actualisation rate (%)  
\(j\)  
calculation model node number  
\(m\)  
water mass (kg)  
\(N\)  
time horizon (years)  
\(q\)  
water mass-flow (kg/s)  
_Qc_  
condensation energy (kJ)  
\(R\)  
coolant mass (kg)  
\(r\)  
coolant mass flow (kg/s)  
R.H. relative humidity (%)  
t dry bulb temperature (\({}^{\circ}\)C)  
_V(N)_  
residual value of the considered good at after the time horizon (chosen currency)  
\(v\)  
LPG volume (L)  
\(n\)  
efficiency (\(-\))  
\(t\)  
time period (year) or time step (s)  
_\(\varphi\)_  
energy flux (kW)  
z_  
index of the mass flow or energy flow exchange in the node