## 4 Results and Discussion
### Phase 3--Analysis of the Unit Energy Retrofit Costs  
With regards to the different typologies of energy retrofit interventions to be implemented in a building made of reinforced concrete using the Superbonus (at least two energy labels upgrades), the main operations could concern (i) the insulation coating installation on the opaque perimeter walls, (ii) the insulation of the flat roofs with thermal insulating material or coating with reflective material, (iii) the insulation of sloping roofs, (iv) the replacement of fixtures and any subframes, and (v) the fitting of solar shading.  
The determination of the unit energy requalification costs has been carried out by implementing a comparative methodological approach, by using the data collected from costs estimates developed with reference to (i) interventions aimed at improving the energy performance of buildings located on the Italian territory and (ii) official data reported by Cresme [10]. In this sense, the detected unit redevelopment costs have been appropriately adjusted through the building renovation costs reported by Cresme with regards to the \"residential renewal\" category and the building parameters already defined. Therefore, a sufficient number of costs estimates relating to energy retrofit initiatives to be implemented or already started on the Italian territory through the Superbonus mechanism have been consulted. Finally, for each Italian provincial capital considered, starting from these unit costs, those to be considered in the analysis have been adjusted through the parametric unit costs detected by Cresme.  
Phase 4--Data Collection of Properties Selling Prices with High Energy Label (\"A\", \"B\", and \"C\") and Low Energy Label (\"E\", \"F\", and \"G\")  
In order to determine the economic benefits associated with energy improvement interventions in terms of the value variations between the post-energy intervention and ante-energy intervention situations, for each provincial capital considered in the analysis, a sample of recently sold residential properties has been collected. Thus, for each city, the assessment of the market value differential has been carried out by selecting, respectively, (i) fifteen individuals in total for each provincial capital, i.e., five residential properties located respectively in each central, semi-central, and peripheral municipal trade area, and by taking into account the functional and constructive characteristics previously identified for the definition of the prototype, i.e., multi-story residential building type, in reinforced concrete, of about 100 m\({}^{2}\) (range considered 80 m\({}^{2}\)--100 m\({}^{2}\)), of three and more floor levels without basement, with elevator in the building in which the property is located, characterized by medium finish quality and by high energy label--A, B, and C--(post-energy intervention situation); and (ii) fifteen individuals with similar characteristics but with the low energy label--E, F, and G (ante-energy intervention situation).  
In general terms, the energy label represents a significant characteristic for the samples collected to obtain the Superbonus, the energy requalification interventions must help to improve the energy performance of the residential property by at least two energy labels, i.e., by determining an upgrade of building energy performance.  
Finally, it should be pointed out that the selection of the samples of each municipal trade area has allowed one to obtain a heterogeneously distributed sample on the territory of each provincial capital analyzed.