This paper is a discussion. expansion and partial revision of existing computer techniques used to evaluate Window Shading devices. Several approaches have been used in this area. Unfortunately. the most versatile applications and the most accurate results have been obtained by methods involving tedious data input which severely limit the usability of these methods. This paper is a continuation and expansion of various ASHRAE pUblications. notably work completed by Tseng-Yao Sun in ASHRAE Technical Paper No. 2059.