Adaptive biomimetic facades: Enhancing energy efficiency of highly glazed buildings

In this paper, we investigate the design of an adaptive biomimetic facade as a practical solution for enhancing energy efficiency of highly glazed buildings in the hot and humid regions. We present an adaptive facade that reduces solar heat gain and hence the energy consumption of the building, with minimal reduction in visual comfort (i.e., indoor lighting levels and visibility to the outer environment) of the users. The basic module of the facade consists of four shading devices that can be folded along both horizontal and vertical axes. The design enables shading under both high and low sun angles, without blocking visibility to the outdoor environment. To develop the facade, we explore and mimic the physical, physiological and adaptation properties of an Oxalis oregana—a leaf that has the natural ability to track sun path and change its angle/position accordingly. As a case study for the proposed facade, we take an existing 20-story office building in the hot and humid climate of Lahore, Pakistan. Our numerical results indicate that after retrofitting of the designed facade, the building's existing energy load decreases by 32%. Moreover, 50% of the interior space (as opposed to 55% before the retrofitting) still has lighting level within the recommended range of 500–750 lux. The investigation demonstrates that the proposed biomimetic facade can significantly reduce the energy consumption, with minimal reduction in visual comfort, of highly glazed buildings.