The “Cost Optimality” approach for the internal insulation of historic buildings

The Directive 2010/31 UE (EBPD) introduces the “Nearly Zero Energy Buildings” linked to cost optimality, where energy benefits are related to economic benefits. The “Cost Optimality” methodology is applicable both to new and existing buildings, as introduced in the Regulation 244/2012. This methodology has been largely applied to existing building, but the literature on historic buildings lacks. However, given the potential of energy retrofit of this kind of buildings, it would be appropriate to develop a specific methodology for the economic valorization of the heritage, considering also the conservation and the historic value of the patrimony. In fact, on the one hand this methodology could be useful for the “energy valorization” of a historic building in relation to the minimum requirements of European and national legislations and budgets. However, on the other hand, we noted the absence of shared information at national level and examples of the “historic reference buildings”. For this reason, case studies on historic buildings become an important starting point to create common typological and repeatable models for applying this methodology. This research aims at evaluating the economic benefits of energy retrofit of a traditional historic masonry, using the “Cost Optimality” methodology. This method is structured into the following parts: (i) definition of the type of masonry; (ii) selection of the insulation systems; (iii) assessment of the energy benefits related to the insertion of various insulation materials; (iv) evaluation of the Life Cycle Costing; (v) evaluation of the optimal insulation performance and cost-effectiveness; and (vi) comparison of energy consumption and Life Cycle Cost to define the most appropriate interventions for the historic wall.