AbstractOne of the most important functions for windows is to connect the interior space to the outside, as well as having a role in ventilation and natural lighting. However, as it is considered the weakest link in the building envelope, in terms of thermal insulation, designers in the areas with severe climatic factors, tend to minimize the window ratio, without taking into account the importance of the other functions, in providing the user’s comfort. This research aims to investigate the ability of electrochromic glazing to solve limited ratio problem and give designers more flexibility. A case study located in a hot and dry area was compared with several scenarios where electrochromic glazing was used in various ratios. Simulations were made using parametric design tools based on Rhinoceros and Grasshopper, which are among the most used software by designers. The study concluded that electrochromic glazing was useful in increasing the window-to-wall ratio and improving the building opening on the outside without having a negative impact on building energy performance.