Ventilated active façades with PCM

► A real-scale ventilated active façade with PCM in its external layer was studied. ► Phase change in the PCM led to an increment of the heat absorption from solar gains. ► Simulations were performed to compare the new façade with other traditional envelopes. ► Results showed large thermal inertia and good thermal response of the façade. ► Further research should be done in order to optimize some design variables. This article describes an evaluation of the thermal performance of a new type of ventilated active façade that includes a phase change material (PCM) in its outer layer. The research was carried out experimentally by means of a real-scale PASLINK test cell facility, located in the city of Vitoria-Gasteiz in Spain. The results of an experiment performed in March 2010 are presented and evaluated. The behavior of the façade was compared with different traditional constructive systems, using the results of computational simulations performed with the Design Builder software. The experimental results showed that the melting–solidification processes that take place in the PCM led to an increase in the heat absorption during the phase-change temperature intervals, which reduced overheating of the façade. The air circulating through the ventilated chamber was overheated up to 12°C during the daytime. Because of the PCM solidification, 2.5h after the solar radiation faded out, the air circulating through the chamber was still warmed by 2°C. The energy efficiency of the façade during the testing period is attributable to the 10–12% incident radiation gains. This efficiency was found to be a function of the circulating air flow rate. The simulations results showed that the thermal inertia of the ventilated façade with a PCM is higher than that of the four traditional solutions evaluated in the study. Further research is required to study the influence of the air flow rate through the ventilated chamber.