Hygrothermal performance of ventilated prefabricated sandwich wall panel from recycled construction and demolition waste – A case study

Abstract

Construction and demolition waste has been used for production of recycled aggregate concrete (RAC) with high replacement ratio (50%) of natural coarse aggregate. Upscaling RAC from material laboratory testing to new product implementation – ventilated prefabricated sandwich wall panel, which at the same time tackles the problem of natural resources conservation and extensive energy consumption in buildings, requires a proof-of-concept. This paper presents an experimental investigation of dynamic hygrothermal performance of developed building envelope system under real outdoor climate conditions and with real occupants living in the house for a one-year period in 2017/2018. Temperature and relative humidity distributions through all characteristic layers of panel showed that the positive effect of air ventilation on hygric (no highly moist conditions) and thermal (damping and time shifting of peak temperatures) performance was most pronounced for south panel adjacent to conditioned living room, while the less pronounced effect was for north panel subjected to unconditioned staircase. Furthermore, transient hygrothermal simulations using measured boundary and initial conditions showed that ventilated RAC wall panel has significantly outperformed both wall panel with closed air cavity and wall with applied ETICS system during summer, which indicates that naturally ventilated air has positive effect on wall's thermal performance in summer period. Additional simulations according to new EN ISO 52016-1:2017 Standard confirmed that high thermal mass of ventilated RAC wall panel has significant influence on dynamic building energy performance. For intermittent occupancy, it is beneficial when cooling energy is observed, while contrary to that it can require more heating energy compared to building with no heat storage capacity. However, when switching to continuous operating mode, high thermal mass of building envelope is beneficial from both of these energy aspects. This pattern has been confirmed in two different Croatian climates – continental and littoral.