Experimental analysis on a solar air heating façade system

Abstract

In this study, investigations on the thermal performance of a solar air heating façade system were carried out. The system consists of a double skin building envelope composed by an opaque internal face, with a novel solar absorbent layer and a glazed external face. This kind of system, particularly suitable to refurbish existing building envelopes, is designed to work as a fan-assisted air supply, which mitigates the heating and ventilation demand during the winter period. An experimental campaign was set up using a full scale façade module in order to thoroughly characterize its thermal behavior and the air flow rate. This module was also compared with a similar one, having a conventional dark flat surface instead of the above mentioned solar absorbent layer. The system has proven great potential in both reducing the energy demand and maintaining proper the ventilation rates in the winter period. In facts, results show that the cavity air temperature reaches values close to 90°C (unventilated buffer mode) and that, in fan-assisted mode, the air temperature introduced in the indoor environment was up to 25°C higher than the external one. Moreover, the supplied air flow rate was of about 26 m 3 /h, providing about 0.5 air changes per hour (ACH) in a typical residential room (16-22 m 2 of floor area).