This paper presents a parametric analysis where WWR and color glass was varied to determine their influence in the thermal performance of an office building’s room. Design Builder tool was used to calculate the thermal load and the internal gains. The WWR variation in different orientations resulted in a significant increase of the thermal load. The reflective glass allowed a better thermal performance of the room. With the use of computer simulation was possible to analyse many constructive and design characteristics of the facade and its influence on the results, when considered together.