Based on solar motion model and optical geometry principle,a mathematical model to analysis the dynamic shading effect of external sun-shading device in building was presented.

This article computed and analyzed the influence to residential buildings’ natural ventilation of 3 kinds of retractable shading-of-buildings in Nanjing area,pointed out that Venetian blind’s performance was the best.

Research on the sun-shading design of building in the zone of south Guangxi province;

A suitable sun-shading design can improve the indoor thermal environment,but the window with the sun shading has a negative effect on the room\'s lighting and ventilation.