This section presents the results using the proposed methodology in this study for the BIM-based WEA. To compare the difference between the current state-of-the-art methodologies and the presented proposal, a comparative table (
Table A1) was produced with the domain of each methodology evaluated. All the analysis processes were carried out on a Windows 11 Home 64-bits OS, Intel i5 CPU 2.7 GHz processor and 8.00 GB RAM personal computer.
The first step of the methodology examined the elements related and unrelated to the BIM model under the identification module, as is shown in
Table 3. All the plumbing fixtures, mechanical equipment, and planting details were extracted and sorted from the BIM model under the piping and architecture filters and areas (Gross Building), mechanical equipment, piping systems, and plumbing fixtures categories. The special equipment domain does not apply to this project because there are no systems with this attribute.
The next stage of the proposed methodology is the BPT module to evaluate the subcategories presented in
Table 3 under the three domains mentioned in
Section 3 of this paper. The criteria and design guidelines of the hydraulic-plumbing system are described the Mexican Standards [
46,
47,
48] and Guidelines of Plumbing Systems [
49].
4.1. Analysis of Water Usage According to Plumbing Fixtures and Inhabitant Demand per Day
The results, as shown in
Figure 9, indicate a positive impact from the perspective of water savings. By applying the plumbing fixture type criteria and modifying the plumbing fixtures from non-efficient to efficient, there was a global saving of 43% percent. This percentage can be reduced if we consider the savings achieved by using treated water. Further analysis shows that a reduction in potable water due to the use of treated water, using a standard configuration of the plumbing fixtures, is up to 23% less potable water, and up to 32% with an efficient configuration of the plumbing fixtures. If we turn to the analysis of filtered stormwater, results demonstrated no significant increase in water savings due to the rainfall intensity in Santa Catarina. However, with a successive increase in the rainfall intensity and rainfall duration, a significant increase in water savings could be achieved. Yet, rainfall intensity and duration of rainfall are random variables and are technically challenging to measure because of external factors.
The next section of this domain was concerned with water usage according to inhabitant demand per day according to local standards. The
Table 4 illustrates the consumption of water per level, room, and the total water usage.
4.2. Sizing Analysis of Hydraulic-Plumbing System Using the Flowrate Calculation Method
The sizing analysis of hydraulic-plumbing system due to the flowrate calculation method domain revealed the importance of accurate methods to calculate the flowrate. In this case study, two methods were used to calculate peak water demand: (1) Hunter’s method and (2) the water demand calculator (WDC). The first method is the standard for calculating peak water demand in Mexico [
49]. The WDC was developed in 2020 as part of a research project founded by the International Association of Plumbing and Mechanical Officials (IAPMO), the American Society of Plumbing Engineers (ASPE), and the Water Quality Association (WQA). It predicts peak water demand by applying exhaustive enumeration, the Wistort method and the modified Wistort method algorithms [
50].
From the data in
Figure 10, the greatest demand by far is calculated using Hunter’s method. Of interest here is the fact that the use of these values for peak water demand increases the size of the plumbing system elements such as water pumps, expansion tanks, piping, valves, and water heaters. Closer inspection of the two method’s results shows that by applying WDC there was a substantial reduction in the sizing of the plumbing system due to the lower values of the flowrates. This situation represents a positive impact on the construction industry since it makes it possible to reduce construction costs within the design parameters of the standards.
4.3. Analysis of Alternative Systems Using Harvested Rainwater and Treated Water
In the final part of the BPT, the analysis of alternative systems using harvested rainwater and treated water was evaluated. The combination of the results obtained in the first and second domain were used to analyze the benefits of using harvested rainwater and treated water. This first prototype for WEA evaluates the most critical conditions obtained from the BIM model. Under these criteria, the usage of water according to plumbing fixtures and inhabitant demand per day, and the highest peak water demand value with the maximum value of simultaneous probability were evaluated.
The data presented in
Figure 11 are quite revealing in several ways. First, counterintuitively, the use of efficient plumbing fixtures was not the best option to improve water efficiency in mixed systems. Comparing the two results in
Figure 11b, when the specifications of the plumbing system were efficient, the amount of wastewater generated was only 12% of the total water consumption. This result is somewhat counterintuitive to implementing a water treatment plant. On the contrary, when the specification was non-efficient, the amount of wastewater produced was up to 40% of the total water consumption. Further analysis of inhabitant demand per day revealed the feasibility of using a mixed water system as is shown in
Table 5.
In the final part of the third domain, an analysis of peak water demand was performed as is presented in
Figure 12. This analysis was performed at a global scale considering all the plumbing fixtures using Hunter’s method and WDC. The single most striking observation to emerge from Hunter’s method was that the mixed water system significantly increases the flowrate up to 33% by using treated water. If we now turn to the WDC analysis, no numerically significant difference between a full potable water system and a mixed water system was found using WDC. What stands out in this is the similarity between the flowrate calculated between both systems using WDC.
In the overall context of the proposed methodology, the ability to adequately perform the WEA can be highlighted. As mentioned in the literature review for BIM-based WEA, this methodology was developed to fill the current gap in the research. Traditional WEA focuses only on the assessment of one domain, such as rainwater harvesting, clash detection, 3D visualization, and rating systems. Usually, those methodological approaches report the potential and feasibility to develop WEA in digital environments. However, most of the current studies only provide assumptions or partial water simulation analysis. Consequently, there is a gap between the industry and academic research.
The proposed structure of the methodology combines simplicity in design analysis with an integral evaluation of the main domains of the hydraulic plumbing system and related systems such as HVAC or FP. The suggested domains and their customization increase the modularity of the methodology, making it possible to decrease or increase the size of the project with practical applicability. This means that designers and professionals are able to rapidly identify key elements and parameters during the design stage to improve water savings and increase the performance of the system in the following stages of the project. Furthermore, the proposed methodology could be used as a guide for the use of digital technologies in WEA since there are no regulations or standards governing WEA. This lack of standards limits the accuracy of analysis for each region, as is the case with Mexico. However, more data are needed to perform the analysis during the operation stage. Perhaps the most unexpected results were obtained in the third domain with the use of efficient plumbing fixtures in a mixed water system. What is curious about this result is that efficient plumbing fixtures do not contribute to the implementation of treated water systems. These systems could only be feasible in large buildings with several services and with a predominance of toilets and urinals, such as a stadium. This observation may support the hypothesis that non-efficient plumbing fixtures contribute to the implementation of treated water systems due to the high flowrate of water. With further research on different types of building and economic analysis, the potential of the methodology could be enhanced to develop a full picture using this methodology for WEA.