## 3 Experimental Setup and Results
### Results--Energy Consumption and Saving Evaluations  
The average electric power required by the system to generate these effects, including water treatment, was measured to be equal to 34.67 kW. Overall energy consumption during the test period was 17,655 kWh. The fuel consumption calculation was more complex, as LPG fuel is used not only for domestic hot water (DHW) production but also to obtain steam used in the SPA (Wellness Center) and the laundry in a closed loop. Because the two plants are linked to the same reservoir tank it was not possible to identify LPG consumption for each of the two uses. The following points were thus considered in estimating the LPG fuel needed for DHW production. Domestic water consumption is strongly related to guest numbers, i.e., it is a function of hotel occupancy. In order to understand the effectiveness of the application, it was necessary to carry out a comparison between the LPG consumption during the testing period and its consumption during a previous period, characterized by a similar occupation. From hotel records, it was possible to collect LPG consumption for the months from August to November. It was also possible to obtain the room occupancy ratio, calculated based on the hotel's total capacity, for each month (Table 4). The data show that October had an occupation very similar to November, and thus was considered the reference month for comparing consumption. Average LPG consumption in October was 371 L/day while in November, during the testing period, it decreased to 207.1 L/day. The difference, of 163.9 L/day, represents 44% of total LPG consumption. As noted earlier, total LPG consumption is due to two uses (steam production and domestic water heating) carried out by means of two different systems. During the test period, the existing boiler, devoted to domestic water heating, was not required. In other words, all domestic water heating was performed by the integrated system. Experimental results are confirmed by means of a rough energy calculation based on the domestic water consumption. The maximum temperature of the \begin{table}
\begin{tabular}{c c c c c} \hline
**DHW Production** & **August** & **September** & **October** & **November** \\ \hline LPG consumption [L/day] & 359.5 & 360.3 & 371 & 207.1 \\ Room occupancy [\%] & 59 & 43.9 & 48.7 & 51.4 \\ \hline \end{tabular}
\end{table} 
Table 4: Fuel consumption for domestic hot water (DHW) related to room occupancy. Figure 10: Thermodynamic processes of the airflow in the integrated system. existing plant, as noted, was set at 55 \({}^{\circ}\)C, and the average temperature of the domestic water was 40 \({}^{\circ}\)C. The temperature of the external aqueduct water was 10 \({}^{\circ}\)C. Allowing for 140 dm\({}^{3}\)/day of hot domestic water consumption for each guest, daily domestic consumption is about 21,950 dm\({}^{3}\) in November. Assuming an LPG inferior calorific value of CLPG = 24.012 MJ/dm\({}^{3}\), and the existing plant efficiency of 0.7, fuel consumption related to domestic water heating can be calculated to be equal to 164 dm\({}^{3}\)/day. The net thermal power, \(\varphi\) = 120 kW, of the integrated system heats this volume of water in about 6 h. The details of the calculations are shown in Table 5. In the case of 100% occupancy, the integrated plant will take about 12 h to cover the heating needs. In order to estimate the energy saving related to the fresh and dry airflow supplied to the laundry area, comparison with a traditional, but efficient, air conditioning system was made. As noted earlier, a ratio of 13 air changes per h, i.e., 5850 m\({}^{3}\)/h of fresh air, was taken into account, corresponding to humid air airflow Gha = 1.958 kg/s. A plant with an energy efficiency ratio (EER) of 3.5 in average November climate conditions and a heat recovery system for post heating (33% of efficiency in terms of enthalpy) were considered as reference, to obtain the same temperature and relative humidity achieved by the integrated system, with an environmental airflow of 6000 m\({}^{3}\)/h.