Comparison of Thermal Energy Saving Potential and Overheating Risk of Four Adaptive Façade Technologies in Office Buildings

Adaptive façades are gaining greater importance in highly efficient buildings under a warming climate. There is an increasing demand for adaptive façades designed to regulate solar and thermal gains/losses, as well as avoid discomfort and glare issues. Occupants and developers of office buildings ask for a healthy and energy-neutral working environment. Adaptive façades are appropriate dynamic solutions controlled automatically or through occupant interaction. However, relatively few studies compared their energy and overheating risk performance, and there is still a vast knowledge gap on occupant behavior in operation. Therefore, we chose to study four dynamic envelopes representing four different façade families: dynamic shading, electrochromic glazing, double-skin, and active ventilative façades. Three control strategies were chosen to study the dynamic aspect of solar control, operative temperature, and glare control. Simulations were realized with EnergyPlus on the BESTEST case 600 from the ASHRAE standard 140/2020 for the temperate climate of Brussels. A sensitivity analysis was conducted to study the most influential parameters. The study findings indicate that dynamic shading devices and electrochromic glazing have a remarkable influence on the annual thermal energy demand, decreasing the total annual loads that can reach 30%. On the other hand, BIPV double-skin façades and active ventilative façades (cavity façades) could be more appropriate for cold climates. The study ranks the four façade technologies and provides novel insights for façade designers and building owners regarding the annual energy performance and overheating risk.