An integrated adaptive façade system using a glass block filled with phase change material: Cooling energy load and performance enhancement

• Energy-saving and thermal performance of PCMs in building façades were studied • A double-skin façade was designed with glass blocks containing RT27 paraffin PCM • Temperature profiles, heat and solar transfers entering the structure were elaborated • The PCM effectively adjusted the surface temperature and solar thermal transfer The building sector demands innovative envelope solutions that can face the current challenges posed by urban transition. Adaptive façade systems appear as a promising solution to fulfil these demands. This study introduces a novel type of double-skin glass block (GB) façade coupled with latent thermal energy storage. Thermo-optical responses of phase change materials (PCMs) integrated into transparent façade elements were investigated. The primary objective was to scrutinise the effects of the PCM latent heat capacity on the heat transfers and temperature profiles within a double-skin façade, focusing on its effectiveness in regulating thermal dynamics during peak cooling demands. The experimental approach employed a series of measurements and analyses conducted in real-world environments. The application of PCM in a double-skin façade can reduce the energy load by 20% during the day and provide 6.6 kWh/m 2 of thermal gains at night. In addition, the peak external temperature of a sample with PCM can be reduced by 15 K and its onset can be delayed by 2 h, thus reducing the energy load by up to 1.14 kWh/m 2 under high impinging solar radiation (3.18 kWh/m 2 ). The results underscore the effectiveness of PCMs in mitigating thermal peaks, modulating the daytime solar energy transfers (up to 50%), regulating the surface temperatures (up to 22°C during three melting phase hours), and curbing the heat transfer (up to 30% reduction). These effects contribute to enhanced indoor comfort and decreased cooling loads. Double skin façade