Using energy simulation and real-time data monitoring to investigate thermal performance of exterior cavity walls

Integrated cavity-wall systems are typically designed to shade the exterior of buildings.  They can also eradicate daytime heat absorption by thermal convection. The combined heat loss through the natural nighttime sky radiation, the cavity wall shading effect, and the thermal convective loop results in a significantly improved building envelope performance. This paper outlines the design, construction, and monitoring of a south-facing cavity wall system integrated into a single-family residence in Southern Arizona.  Implemented as a ‘heat transfer regulator’, the cavity wall functioned as a thermal break between the external and internal thermal forces through the south wall of the building envelope.  The outside “Sol-air” surface temperatures of the cavity walls were found to be consistently lower than the standard non-cavity walls during extreme summer conditions.  This was due to the combined effect of shading as well as stack-ventilation heat loss triggered by solar radiation received by the south cavity walls.  Results from the field data monitoring and computer simulated results yielded a minimized operation of mechanical system, reduction in energy consumption, and optimized human thermal comfort.