Integration of sun-tracking shading panels into window system towards maximum energy saving and non-glare daylighting

Abstract

Vertical facades of buildings bear a great potential of solar exposures, especially for congested urban areas with numerous high-rise buildings. Previous studies on the sun-tracking shading devices strayed into the trade-off between energy consumption and glare protection. Here we first built the integrated models which couple window with sun-tracking shading panels for the southerly oriented window. Secondly, the control methods of one-direction-automatic-rotation (1-DAR) and two-direction-automatic-rotation (2-DAR) with sun-tracking function were mathematically proven to be not able to achieve either the minimum energy consumption or the completely non-glare daylighting, under the reasonable assumptions. Then, we have proposed an optimum rotation control method of perpendicular sun-tracking three-direction-automatic-rotation (3-DAR), and demonstrated that the 3-DAR combined with perpendicular sun-tracking method could realize the afore-mentioned goals. Based on the energy saving and glare protection, the movement trajectories and rotation orders of the shading panels throughout the year were explored. Research results show that the annual electricity use in a study office room located in Hangzhou (China), integrated with shading panels under 3-DAR control, is lower than the alternatives under 2- or 3-DAR control. Furthermore, the proposed 3-DAR incorporated with the perpendicular sun-tracking control method reveals a better protection against the sun-glare, and is also applicable to the horizontal windows (i.e., clerestory), by proposing the rotation orders and deriving the equations of movement trajectories in a similar way.