## 3 Results and Discussion
Therefore, 40 HUs had a final classification of C, and 14 had a final classification of D. The classification of the entire multi-family building was C.  
The representative Building D, approved in 2012, has 10 floors: A ground floor, with a garage on stilts and isolated common areas, and nine floors with standard apartments, in addition to a garage in the half basement. The right column does not have an apartment on stilts, and in the left column, the three bedrooms are on stilts. On each standard floor, there are two apartments, and both of them face east (Table 8). The balconies shade two of the three bedrooms and the living room. All EUSs meet the minimum lighting requirement (12.5%). However, only the living room and one of the three bedrooms meet the minimum ventilation requirement for BZ 8 (10%), as shown in Figures 5 and 6, and Table 4. The apartments have cross ventilation, and two of the three bathrooms have a natural ventilation. According to visits to the building while under construction, the walls are composed of ceramic blocks, and the tensioned flat slab is approximately 18 cm in thickness. For this analysis, the same composition as representative buildings A, B, and C was adopted, which is the most similar to the composition of the existing roofs in Annex V of the RTQ-R. The roof of the building is composed of fiber cement without a special paint or thermal blanket. The outer walls are all the same color, which is visually similar to the color 03, with an absorbance of 0.45. The walls comply with the RTQ-R thermal transmittance and absorbance requirements; however, the roofing does not comply. The apartments have individualized water and energy measurements. Toilets with attached boxes and a dual flush, showers with flow restrictors, and faucet aerators in the kitchens and bathrooms can be considered water conservation equipment in the HUs. Table 8 shows that the thermal performance of the naturally ventilated building envelope is better in the bedrooms with southeast-facing external walls and in the living rooms on the first and intermediate floors, all obtaining classification B. The balconies shade all the EUSs facing east, i.e., the living rooms and bedrooms 1 and 2. However, based on the shading angles scoring rule of the RTQ-R, it was not possible to classify room 1 (east facade and the window area is less than 25% of the floor area). The majority of the EUSs that were scorable had their classifications increased by one level due to shading. The worst performance was in the apartments on the top floor, particularly in the bedrooms with northwest-facing exterior walls. Thus, of the 18 apartments, 17 received classification C for the envelope performance for summer, and one received classification D. Regarding the relative refrigeration (artificial cooling) consumption, only the top-floor bedroom with southeast-facing external walls in the left column received classification C, whereas the others received classification D. The envelope performance for summer and the final classification of the apartments, includingthe water heating system, all presented the same results. Therefore, the classification of the entire multi-family housing building was C.  
The results show that the water heating system influences the energy efficiency of the building and may even change the final classification. Meeting the requirements for ventilation and natural light also influenced the change in the classification of some extended-use spaces. Despite being approved by the PMV as meeting the ventilation and illumination requirements of the municipality, none of the buildings met the minimum ventilation percentage requirements for all EUSs, and two met the percentage natural light requirements. The presence of shading elements positively affects the building energy efficiency. The compliance criteria for the thermal properties of the roofs for BZ 8 were not met in any of the buildings, although the compositions of the walls met the requirements.