Multi-criteria Decision-Making for Thermal Insulation of an Existing Office Building Considering Environmental, Energy, and Economic Performance

As climate change increasingly becomes a priority issue, there is an active need for powerful solutions to reduce the environmental impact of buildings, a major source of CO2 emissions. This study addresses the choice of better performing thermal insulation under environmental, energy, and economic point of view. The analysis is conducted through a dynamic energy simulation, carried out using the software DesignBuilder, upon a calibrated model of an existing office building in Southern Italy. A comparison is made between 20 thermal insulation scenarios, obtained by simulating the installation both internally or externally of 10 different insulating materials belonging to the following categories: cellular, porous, fibrous, plaster, innovative materials. The yearly Primary Energy (PE) consumption, yearly Global Warming Potential (GWP) reduction, Discounted Payback Period (DPB) are the KPIs considered in the study to rank the alternatives with TOPSIS method, a multi-criteria decision-making (MCDM) approach. Thermal insulation of walls offered a medium reduction in thermal energy needs of 30% in winter and 2% in summer. On average, in summer, internal insulation reduces thermal energy demands by half as compared to external positioning. In winter, internal insulation reduces thermal energy needs by 1% more as compared to exterior positioning. TOPSIS analysis showed that best performing thermal insulation materials among the analyzed ones are expanded perlite followed by expanded clay. On the other hand, materials providing the worst overall performance for the analyzed KPIs seem to be vacuum insulation panels and aerogel insulation, due to high embodied CO2-eq emissions and very long payback periods.