Designing the Window to Fit a Shading Device: A Reversed Method for Optimizing Energy Efficient Fenestration

摘要

Solar radiation penetrating a window Increases cooling loads and energy use, especially in hot climates. Most energy efficiency CAAD tools help designers to optimize a shading device protecting a given window, usually a rectangle. It is hard to protect some window parts, such as lower corners. Enlarging shading device to protect them Increases lighting and heating loads, as well as their complexity, visual impact and cost.Changing the shape of the window by cutting these corners may reduce the size of the shading device considerably, which opens way to a different - or even a reversed - approach : "Designing the window to fit a shading device instead of designing the shading device to fit a window !".This approach has several potential applications. The building form itself sometimes works implicitly as a shading device. For example, a building of U shape plan shades parts of its walls, the window can be designed to fit the shadow pattern caused by the building, changes in the building profile gives similar shadow. Conceptually, this approach makes energy efficiency a form giving attribute, helping to create innovative facades, while giving an energy efficient configuration of window and shading device. CAAD tools can help designers adopt this approach, by proposing the window shape that suits an arbitrary shading device.This paper validates the approach and introduces a method for developing a software module to be integrated with current CAAD tools; handling complexity of solar geometry and intensity, and the geometry of the window and shading device.