Overhang Design Methods

Windows in office buildings are thought to account for roughly a third of the energy used to heat and cool them. Shading a highly glazed facade is difficult because the goals conflict: blocking unwanted heat in warm periods, keeping useful solar warmth in cold periods, and preserving daylight and visual comfort indoors. This multi-objective optimisation problem is an active topic in building energy and daylighting research.

Overhangs are the oldest and most familiar form of window shading. They are simple to fit, inexpensive, need little or no upkeep, and leave the view outward open. This book reviews how overhangs can be designed to perform well both thermally and for daylighting. It opens with a historical account of approaches based on sun position and shading masks, then moves to the methods used in current research.

The central chapters cover how shading is calculated, how the thermal and daylighting effectiveness of an overhang can be quantified, and how multi-objective optimisation is applied, along with case studies that use these methods. The book also addresses newer designs, namely overhangs with NURBS-defined outlines and photovoltaic-integrated dynamic overhangs. An appendix sorts published overhang case studies by climate type and by the latitude of their locations.

The book is aimed at building energy researchers who study the optimisation of window shading devices. It is intended to help readers grasp how solar radiation, shading devices and indoor comfort affect one another.