Good shading device settings would adjust their form and dimensions to adapt to the facade facing and fenestration system. The main function of the shading device proposed in this study is to provide shelter from solar heat gain and energy saving in Taiwan. This study provides a methodical procedure to establish summarized correlation for evaluating shading performance of horizontal shading devices based on the shading ratio and shading coefficient via the simulation of shading variables of 22-25 degrees latitude north in Taiwan. These values have both been used to indicate and analyze shading effectiveness. Three main independent variables, the ratio of device depth to window height, the width to height ratio of an opening, and the facing azimuth, are used to determine a correlation to generate shading ratio models for a whole year. Furthermore, the yearly correlation models between shading ratio and shading coefficient for Hengchuen (22 degrees N), Tainan (23 degrees N), Taichung (24 degrees N), and Taipei (25 degrees N), respectively, are established as well. Summarized correlation models of the shading performance of horizontal shading devices can be useful under general condition for buildings. Most importantly, an optimal design and strategy regulations could be chosen to enable more suitable utilization and peak effectiveness of shading device systems for sustainable and energy-savings buildings. (C) 2013 Elsevier Ltd. All rights reserved.