Refined distribution of frit. Method and design tool for improved thermal comfort in glazed spaces.

Abstract: Thermal comfort in highly glazed buildings has long proven to be a troublesome matter due to unwanted passive solar heat gains. Excessive solar gains are commonly counteracted with energy-intensive cooling systems and/or comprehensive shading devices. Shading devices are used to adjust solar heat transmission through glazing. Conventional devices may be protruding such as lamellas and overhangs or integrated such as a screens and coatings. These devices tend to be uniformly distributed across large shares of glazed façades, limiting both daylight availability and views to the exterior. To challenge conventional shading practice, a three step methodology was developed to correlate overheating in glazed spaces with local shading need. The method was further developed into a parametric design tool, scripted in Rhino/Grasshopper, providing users with information as to which areas of a façade are most in need of shading. The design tool successively suggests how shading should be distributed across the façade in order to most effectively counteract thermal discomfort for occupants. A generic office in Scandinavian climate was utilized as a reference case. A light, reflective ceramic shading device, known as frit, was employed as a shading device. Results show that the design tool is successful in reducing local peak temperatures in glazed office spaces. Results indicate the tool being most efficient for improving local overheating problems, decreasing in efficiency with increased analysis area. Moreover, reasonable overheating problems prove advantageous for the usability of the tool, indicating that it could be a beneficial complement to a functioning ventilation system. By concentrating shading where it is needed most, daylight and views in glazed spaces can potentially be enhanced using the developed method for shading. Both environmental and economic savings have promising potential with the applied reasoning of this work.