*2.3. The Proposed Methodology*

The proposed methodology starts from the green energy audit, then adding specifications in terms of:


A phase of monitoring energy values post-intervention is added at the end of the process. The effects of the energy requalification interventions are introduced to the scheme, where the auditor examines indicators such as energy consumption for heating, cooling, or domestic hot water.

The green energy audit aims to improve the sustainability of the building. For this reason, the selection of intervention measures must be evaluated according to the contribution in terms of energy savings, economic costs, and environmental impacts. This evaluation should be assessed by the adoption of a rating system that certifies a level of sustainability with a global score determined by the adopted design strategy and the achievement of selected credits, so, the proposal is to follow the environmental assessment on the basis of LEED O+M scheme. A workflow is proposed for achieving the certification score using a new classification of prerequisites and credits that consider the points of

credits and the document to be delivered. This method references previous studies [40] that aimed to identify the credits necessary to achieve the minimum score to attain the certification label with the better use of resources in term of time and costs. This step consists of two phases:

	- (a) Sub-phase 2A involves the selection of credits
	- (b) Sub-phase 2B applies a credits classification according to the same approach in phase 1.

All the sections described for each prerequisite and credit are considered, for example, intent, requirements, relations, score, and options, according to the structure fixed by the LEED rating system (Figure 1).

**Figure 1.** Structure of prerequisites and credits according to the LEED rating system definition [16].

Subsequently, a scoring system, described in Table 1, was developed considering the following parameters: the number of required documents, (listed in the required documentation section), the connected prerequisites (listed in the related credit tips section), and the effort level to fulfil the forms requested by USGBC (as described in the intent and requirement section).

**Table 1.** Scoring system for prerequisites according to options: parameters are the requirements in each prerequisite and the score is the score system. In detail: 1 point is assigned for each document required for the achievement of the intent; 1 point is assigned for each prerequisite listed in the section of related credits tips; different points are assigned related to the procedure of the performance period; different points are assigned in relation to the different levels of commitment difficulty in completing and collecting data.


As an example, the possible score for the prerequisite p2 of the Minimum Energy Performance (EA category, Table 2) is presented with two options requiring a total amount of four or eight documents to be completed according to the chosen option; there are two related prerequisites: EA p1 Energy Efficiency Best Management Practices and EA p3 Building-Level Energy Metering. The performance period requires 12 continuous months of metered energy data collected before the end of the performance period; the form includes the data collected to fulfil the Energy Star Rating or similar energy audit. Therefore, a partial score could be achieved for each prerequisite option by the application of the method, as explained in Table 1, and the total score of the prerequisite is determined by the average values of the options.

**Table 2.** Example of a score calculation for prerequisite EA p2 Minimum Energy Performance: the number of options proposed by the prerequisite requirement; the amount of documentation, listed in the documentation required section; the number and types of prerequisites; period and description of performance period; forms requested from USGBC; partial score for each option; and normalization of total score through calculation of average partial scores.


As shown for prerequisite EA p2, the procedure concludes with the assignment of a final score for each prerequisite, obtained by the normalization of the partial score and the number of options contained in the prerequisite description.

The result is a classification of prerequisites for LEED O+M v.4 (Figure 2), organized from higher to lower scores, also listing the relationships. It represents a workflow for applying the certification process as it lists the prerequisites in order of importance. In case of a correlation (for example EA p3, EA p1, and EQ p1 with EA p2) the prerequisites with a lower score (EA p1 and EQ p1) lose the score because the relationship allows pursuing the same documentation and data for the item with

the higher score (EA p2), receiving the same higher score and the same relevance in the classification and workflow.


**Figure 2.** Work classification of prerequisites for LEED O+M; scores of prerequisites related to other prerequisites are struck through. LEED's goals drive the weighting of points toward certification. Each credit is allocated points based on the relative importance of its contribution toward the goals. The results present a weighted average: credits that most directly address the most important goals are assigned the highest weight [42].

The classification proposed in Figure 2 reveals the most important areas for attaining the certification according to the LEED O+M perspective. The main area of concern for the management of energy performance, the EA category, is the most important topic, followed by signed policies such as requested in the EQ and MR category.

After pursuing mandatory prerequisites, credits allow receiving a score to determine the level of certification: USGBC assigns different points to each option of each credit. Since the complexity of the requirements and the large number of credits and documents, this study tries to simplify the selection process with the aim of receiving higher LEED certification by evaluating the minimum number of documentations for each credit and its relevance to the system. A calculation was developed for assessing the weighing of each credit and for credit selection considering the following parameters: score, relationship, and frequency. Relationship considers the number of credits listed in the related credit tips section of the same credit; frequency counts the quotes for the considered credit in the related credit tips section of other credits.

Phase 2A involves selection process. First, credits are listed and ranked in relation to the number of documents/reports to be completed according to the options. Then, the methodology proposes a new parameter called the "summary credit", as defined in Equation (1), which considers the maximum points achievable (score), the number of correlated prerequisites and credits (relationship), and the quote in other prerequisites/credits (frequency):

$$\text{Summary } \text{credit} = \text{point} + \text{frequency} + \text{relationship} \tag{1}$$

The method identifies a choice of credits with the best value as defined using Equation (2). Considering the required documentation (*y*) and the calculated summary credit (*x*), the result is a list of best credits (Figure 3) for LEED O+M v.4:

$$y \le 3/10 \text{ x} \tag{2}$$

**Figure 3.** Selection of 10 important credits: on x axis, number of summary credit, on y axis, number of documents, in particular minimum documents in (**a**) minimum documents and (**b**) maximum documents; the chosen credits lay below the line, according to function *y* ≤ 3/10*x*.

Credits are organized in phase 2B, developing a score system that considers the internal options (Table 3) in the requirement for the credit structure: one point is assigned for each requested document, for each connection with prerequisites and credits; different points are assigned based on the performance period and on the level of complexity and difficulty in completing the forms requested from USGBC.

**Table 3.** Scoring system for credits according to internal options: parameters are the requirements for each credit and score is the scoring system. The system is the same for prerequisites, but more points are assigned in relation to the number of prerequisites and credits listed in the tips section.


While the previous analysis was only dedicated to the prerequisites, this process was also developed for classifying the credits. The classification of credits has been implemented with the correlation between both credits and prerequisites (Figure 4).


**Figure 4.** Work classification of credits for LEED O+M; scores of credits related to other credits are crossed out.

The credits classification shows how the management of energy use is relevant, as with the prerequisite classification. Particular relevance is assigned to the human health topic presented in the EQ and LT categories, as listed in the management of air quality, the interior lighting, and the incentive to use alternative transportation.

The methodology identifies a list of 10 credits. The application and calculation of the requirements of these credits could achieve a total score of 53 points according to the scorecard, achieving the Silver level of certification [41] for LEED O+M systems, achievable when a project earns 50–59 points.
