**4. Discussion and Conclusions**

Historic buildings require special consideration because they represent a large proportion of Italian buildings. The desire to achieve energy saving, global costs management, and environmental impact goals is growing, aiming to reduce CO2 emissions and other greenhouse gases, and to improve in internal quality air and comfort. In fact, the objective of this research was to investigate the energy and environmental assessment systems and the tools that allow their implementation.

The research proposes different approaches to obtain an energy and environmental audit for historic buildings:


This paper highlights some other findings. The energy diagnosis requires benchmarks that refer only to the museums [12], and the research lacks quantitative analysis of the interventions from economic and financial viewpoints. The investigation into supply costs, time of return of investments, and comparisons with the Superintendent references need to be further analyzed.

The proposed method was tested on to LEED rating system and was developed according to the characteristics of the LEED O+M credit system. Even if LEED rating systems have a standard structure, each protocol includes different requirements, connections, scores, and weighing. Future developments should focus on validating the proposed method and finding a robust system for the credits selection that is applicable for different LEED protocols.

Notably, the application of the methodology indicated a Silver level LEED O+M certification cold be attained through the calculation of a list of 10 credits for a maximum total score of 53 points, which could be implemented with other credits in relation to the characteristics of the projects.

As previously described, the proposed methodology is an upgrade of the GBC Historic Building system proposal [44] and the research is revising and deepening the application to other protocols with the aim of defining Equation (3) and improving the method to increase its applicability:

$$\text{ratio} = \frac{\text{summark}}{\text{required documents}}\tag{3}$$

This study was conducted as part of a research program that includes different phases; therefore, some weaknesses and uncertainties still need to be studied. For example, for Ca' Rezzonico, the certification process and the credits completion are still ongoing, so the methodology is being verified with the progression of the credits achievement. The paper presents a calculation method that has only been analyzed in some historical buildings and therefore, in future developments, we intend to validate the method on other cases, including both museum and other types of buildings.

A weakness of the study is the lack of applicability to all LEED protocols, precisely because the structure of the credits and categories in O+M is substantially different from most rating systems. The research intends to develop the application for other protocols to create a method for preliminary evaluation of certification achievement in terms of documentation, score, and difficulties. After verifying the prerequisites and the selected credits using the generic formula in Equation (3), in the case of non-achievement of a satisfactory score or obstacles, a change of rating system could be considered during in a first phase of a check.

**Author Contributions:** Conceptualization, E.M. and T.D.M.; methodology, E.M. and T.D.M.; formal analysis, E.M. resources, E.M. and T.D.M.; data curation, E.M. and T.D.M. and F.P.; writing-original-draft preparation, E.M. and F.P.; writing—review and editing, T.D.M. and P.R.; visualization, E.M.; supervision, F.P. and P.R.; project administration, T.D.M.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.

## **References**


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