## 3 Results and Discussion  
The normalized (expressed as a function of the FU) total consumption of PE and the total GWP resulting from the consideration of all the buildings of the university are represented in Figure 3. The total PE consumed during the use of the buildings was 5.6 MJ/m\({}^{2}\)-person and generated 0.13 kg of CO\({}_{2}\) eq/m\({}^{2}\)-person. The highest total monthly consumption of PE throughout the year corresponded, as observed in Figure 4, to the winter months, varying between 0.53-0.74 MJ/m\({}^{2}\)-person. In these months, more resources were required, both to heat the buildings and to illuminate them because the days are shorter and there are few hours of natural light. During the summer months, less energy was consumed, reducing up to 60.8%, due to the fact that the teaching activities are suspended. Nevertheless, there was still significant consumption due to the presence of researchers, management and maintenance staff, custodians or security personnel, as well as the activities in common areas, such as libraries or certain classrooms, so electricity consumption was maintained, both in air conditioning equipment and in the lighting of the spaces used. Water consumption followed a more regular trend throughout the year, without relevant differences between winter and summer, while paper registered higher use at the beginning of the semesters and during the exams. The months when PE consumption was lower corresponded to the summer months, ranging between 0.29-0.36 MJ/m\({}^{2}\)-person. Equivalent to the consumption of PE, Figure 5 shows the GWP attributable to the buildings in each month. The GWP exhibited a similar trend to the results obtained for PE. The largest emissionscorresponded to the winter months with values ranging from 0.012 to 0.015 kg CO\({}_{2}\) eq/m\({}^{2}\)-person, while in summer, the values were reduced and fell in the range between 0.008-0.010 kg CO\({}_{2}\) eq/m\({}^{2}\)-person. Figure 4: Total primary energy (PE) and global warming potential (GWP) of the buildings analyzed. Figure 5: Breakdown of the total primary energy (PE) throughout the year. Figure 3: Material and energy flow of the system under study. To determine the contribution of the different resources, the values of the total PE consumed were broken down to show the performance of electricity, natural gas, water, and paper, as observed in Figure 6. It can be observed that the highest value of PE was related to electricity consumption, which represents the value of 3.7 MJ/m\({}^{2}\)-person. However, the detailed analysis of the breakdown revealed the importance of taking into consideration the consumption of water and paper, since water contribution was 11.8% (0.67 MJ/m\({}^{2}\)-person) and even higher in the case of paper, with 22.8% (1.29 MJ/m\({}^{2}\)-person). The contribution of natural gas was minimal, representing only below 0.2%. Once the relevance of the energy requirements due to water and paper, which have not been considered traditionally for energy certification of buildings, further analysis was applied. Since water and paper involved production and treatment processes (they appeared as inputs and outputs of the system simultaneously), Figure 7 depicts the PE values corresponding to both production and treatment stages of water and paper. The results highlighted a great difference between both resources. While the consumption of PE needed to supply water to the buildings was minimal, the treatment phase required much more PE. This result can be explained by the characteristics of a wastewater treatment plant when compared to a spotabilization plant since the latter requires less mechanical and chemical processes to attain the objective [40; 41; 42; 43]. In the case of paper, the results showed the opposite trend: the manufacturing stage clearly consumed much more PE than the recycling treatment. The production of paper requires wood as raw material. The wood fibers have to be separated to remove impurities.