Retrofit actions on the envelope of an existing historical public building: energy and economic analyses

Several European directives invite Member States to take measures in order to reduce both energy consumption and pollution associated to existing buildings, especially those of public services. The energy and economic impact of several retrofit actions on an existing historical public building is evaluated in this paper. The study is aimed at both proposing a general operational methodology as well as highlighting a best-practice for the Italian territorial context, which has several historical buildings needing restoration. The analysis has been focused on the Abbey of San Lorenzo ad Septimum, that is located in Aversa (southern Italy) and hosts the Department of Architecture and Industrial Design of the Second University of Naples. First of all, the current energy demand of the building during winter has been estimated. At a later stage, three different retrofit actions were simulated and analyzed: 1) utilization of thermostats to regulate the target of indoor air temperature; 2) increase of thermal insulation of the external opaque walls; 3) reduction of both thermal transmittance and air draught associated to the fenestration systems. The influence of each action on the building performance has been carefully evaluated in terms of both primary energy consumption and operating costs, with the main aim of estimating the potential benefits associated to the proposed measures.