Retrofitting for improving energy efficiency: The embodied energy relevance for buildings' thermal insulation

Thermal insulation is a well-known strategy to increase energy efficiency of buildings. This paper considers two archetypes of an apartment block typology largely diffused in the Italian building stock and evaluates the energy savings resulting from the application of three insulation materials: polyurethane foam, rock wool and resin bonded fibre-board. The energy requirements for winter heating and summer cooling are assessed with EnergyPlus and then compared to the embodied energy of the insulation materials. Hence, the energy and carbon paybacks are calculated, and a cost analysis is proposed to provide an insight on the market impact for the retrofit materials' choice. The apartment block model is analyzed in three main cities (Rome, Milan, Palermo) allowing to assess the climatic conditions impact in terms of minimization of primary energy consumption and environmental emissions. Simulations showed that the thermal insulation has a higher impact on winter heating and slightly affects the summer cooling requirement. In Milan, the refurbishment gains relevance as the energy and carbon payback periods are shorter than those of the city of Palermo characterized by a warmer weather. Considering the embodied energy impact, this method allows to estimate the maximum potential for energy savings in existing buildings and provides an estimation of achievable results in short-medium period.