Saving energy is always a matter of concern in all countries. Buildings are responsible for 48% of all energy consumption and greenhouse gas emissions (U.S. Energy Information Administration 2009). The window has an important role in influencing energy consumption for buildings. The study focuses on evaluated the impact of window-related designs on energy consumption in office buildings using eQUEST. Three key objectives of the study are window-to-wall ratio, sunshade, and number of windows. After this study, the results suggest larger window-to-wall ratios in the north and south directions, and smaller window-to-wall ratios in the east and west directions. Also, sunshades play an important role in saving energy, and the number of windows has little impact on the energy consumption.