Windows, which are responsible for 45% of overall heat loss, play a major role in a building’s energy performance. Therefore, it is critical to measure window energy performance for existing buildings. This study aimed to evaluate the energy performance of windows to determine if replacement of windows is necessary. The evaluation was based on window location, height, orientation, and weather condition in a high-rise residential building. A thermal camera was used for measurements and statistical analyses were performed for measured data. Analysis results showed different performance of each side and floor of the building with a significant difference at the 0.05 level due to various temperatures, wind speeds, and directions. This study suggests using more efficient windows on upper floors, particularly from the fourth floor and above is beneficial as well as considering dominant wind speed and direction for the best configuration of window design.