Performance analysis and durability of environmental and energy sustainability interventions on existing buildings

The housing built in the '70s and 180s in Italy shows significant degradation on both energy consumption and environmental sustainability, particularly those realized with load-bearing structure made of r.c. walls and slabs casted together as the coffrage-tunnel technique provides. This technology shows high thermal dispersions due to thermal bridges and low thermal insulation of r.c. walls and slabs, due to their low thickness and great extension of concrete walls exposed to external climatic conditions. This paper presents a study on representative buildings of this technology in order to investigate the impact of the thermal bridges on the energy consumption. The chosen case study concems with the Sperone district realized in the '70s in Italy. For these buildings energy losses and thermal conductivity of the various technical elements of building envelope were evaluated both by analytical calculations and instrumental analysis (thermography) before and after retrofitting interventions, design.ed to increase energy performance of the buildings according to current regulations. The paper shows the inapplicability for the calculation of the thermal bridges detected in the couffrage-tunnel technology, of the standardized methods and databases, proposing an addition to the current legislation regarding with the specific types of thermal bridges, in order to provide designers with practical tools for their calculation.