## 2 Description of the Two Case Studies: The Inverted Roof and Water-Covered Roof
### Water-Covered Flat Roof, MUA Building: Museum of the University of Alicante  
The water-covered roof is part of the thermal envelope of one of the exhibition halls of the University Museum of the University of Alicante (MUA), in the municipality of San Vicente del Raspeig near Alicante, Spain (Figure 3). The site is a building complex within the university campus and is composed of multipurpose exhibition halls, an open-air auditorium, the Eusebio Sempere Exhibition  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{2}{c}{**Q\_R\_1. Inverted flat roofs\_Total thickness = 0.467 m**} \\ \hline \multicolumn{2}{c}{**Horizontal Construction and Upward Flow**} & \multicolumn{2}{c}{**Thickness (m)**} \\ \multicolumn{2}{c}{**Outside environment**} \\ \hline
16 & Paving file & 0.015 \\
08 & Mortar bed & 0.015 \\
05 & Membrane: Non-woven geotextile & 0.001 \\
04 & Thermal insulation: XPS [0.032 W/[mK]] & 0.030 \\
13 & Water proofing membrane: LBM-30-FV, & 0.006 \\
06 & Mortar bed & 0.015 \\
09 & Aerated concrete & 0.070 \\
27 & Reinforced concrete & 0.300 \\
22 & Trim and plaster & 0.015 \\  & Inside environment & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Construction features of the flat’s/housing block’s roof.  
Figure 2: Image of the construction of walkable inverted flat roof of a housing block.  
Hall and the \"Caja\" (box) building. The whole complex is underground, delimited by a water-covered roof and interrupted by a courtyard in which the \"wooden box\" is erected as one of the exhibition spaces. The space under study is the Sempere Hall, with a useful surface area of 366 m\({}^{2}\). It is distributed in an exhibition area, an office area and warehouses. The hall has two entrances. The main entrance gives on to the central courtyard of the museum complex. The second access point, a side entrance, is used only for maintenance tasks. The main facade of the hall, which the main entrance, Exhibition Hall and warehouse give onto, is oriented 110\({}^{\circ}\) East with respect to the South. As the construction is a buried building, the two facades that close the room are enclosures in contact with the terrain (Figures 3 and 4).  
The construction section of the water-covered roof consists of the following layers (Table 2):  
Figure 4: Image of the facade of the Sempere Hall from the inner courtyard. The roof of the Sempere Hall is in red. On the right, the floor plan.  
Figure 3: Image of the Museum of the University of Alicante (MUA). The Sempere Hall is below the water-covered roof, on the left.  
The room's air conditioning system consists of an all-air HVAC system with flow regulation. The conditioned air is produced in the facility room which is separate from the building and situated alongside the parking. It consists of two Air Conditioning Units with a 77,000 m\({}^{3}\)/h flow and a maximum power of 200,000 W each, Daikin VRV AHU model. Conditioned air is distributed via rectangular fiberglass ducts covered in aluminum foil, which run down the hall's false ceiling and propel the flow of air through double deflection ventilation grilles and circular aluminum diffusers.  
Throughout the annual period under study, the thickness of the water sheet of the hall's water-covered roof varied between 10 to 20 cm. This was due to the loss and gain of water by evaporation and rain. The roof does not have a self-filling system that maintains a constant level of water. An average value of 15 cm was considered for this study.