Sustainability-oriented innovation of a multilayered cement-based roof element

Sustainability of cement-based construction components is becoming a key point of the structural design process, since the implementation of green strategies favors an overall reduction of economic and environmental impacts. In the framework of a regionally funded research project, an innovative multi-layered roof element for the retrofitting of existing industrial buildings was developed at Politecnico di Milano. The development followed a holistic approach focusing on two main levels: 1) the optimization of the transverse section, aimed at minimizing the employment of cementitious composites such as High Performances Fiber Reinforced Concrete (HPFRC) and Textile Reinforced Concrete (TRC) and 2) the improvement of the energy performances, through the selection of adequate insulating materials (polystyrene and glass foam were considered) and the design of Building-Integrated PhotoVoltaics (BIPV). In this paper, preliminary considerations pertaining to the sectional and structural behavior of a 2.5 × 5 m [8.2 × 16.4 ft.] secondary panel are followed by the numerical/experimental evaluation of the thermal transmittance U and the BIPV performances. In this regard, a small demo roofing system housing three full scale panels was monitored throughout two Summer weeks, leading to the assessment of photovoltaics Performance Ratios (PR) and effectiveness of the architectural integration.