Turning solar-facing thermal mass from liability into asset through parameterized control

Building interior thermal mass is known to be a potential energy storage medium for thermal comfort regulation or for electrical demand-shifting. Building exterior thermal mass, such as the solar-facing trombe wall, is known to be a potential store of solar heat gain, a source for night-time convective and radiative cooling, and a driver of buoyancy-driven ventilation. For such functions to be reliably harnessed in both building interior and exterior thermal mass, however, the flow of thermal energy through this mass must be more reliably controlled, due to the well-documented risk of over-heating or over-cooling. Research in this field is largely confined to digital simulations and small-scale prototypes, and lacks building-scale physical validation. We seek to fill this gap by presenting a four-month study of a full scale, actively used residence containing a poorly functioning trombe wall. Our dataset contains three unoccupied multi-week periods of experimental manipulation, which we analyze to demonstrate that active solar shading, night-time forced ventilation, glass wall openings, airflow damper position, and building windows are parameters that can be used to control the capacitance of the trombe wall. We demonstrate with an energy model that the resulting thermal comfort delivery comes with a reduction in building operational energy expense. This progress shows that with further research, the parameters can be developed into a thermal-mass energy-control system and turn uncomfortable building structures into thermally enjoyable living spaces. Critically, this would contribute to household-scale energy savings, and to grid-scale resilience in the face of a changing climate.