On an innovative integration strategy of renewable energy system in historic building with public function

Energy efficiency of existing buildings is becoming an increasingly important research issue, given the slow building renovation and new construction development in Europe. Additionally, most of the buildings in the old city centers in Mediterranean area, and all around Europe in general, often present important architectural and artistic elements to be preserved even in retrofit interventions. This aspect makes the energy efficiency optimization even more difficult to implement, and historic buildings are typically considered as low performance buildings by definition. In this panorama, innovative strategies and integrated assessment to be specifically designed in historic buildings represent a fundamental research development, aimed at improving the environmental sustainability of Italian and European city centers. This paper concerns the integrated evaluation of multiple retrofit scenarios on a historic building case study for public auditorium use. Several active technologies and passive solutions are compared in terms of (i) cost, (ii) energy performance, (iii) technical feasibility, for intrinsic constraints deriving from the characteristics of the ancient structures and the positioning of the case study. This building is a large space built in the historical city walls, where the municipality office would like to install an auditorium and training space for public use. Specific solutions have been elaborated focusing on the building characteristics and the final use of each thermal zone. The overall cost-benefit assessment shows how the reduction of the conditioned volume in association with (i) the integrated geothermal plant and (ii) the methane boiler with absorption chiller represents the best overall solution after three years from the construction in terms of primary energy requirement for (i) cooling and (ii) heating, respectively.