This study explores the role of double-layer and electrochromic windows compared to simple single-layer windows in energy conservation within buildings. The study investigates the energy-saving potential of these advanced window technologies by analyzing their thermal performance, daylighting capabilities, and overall impact on building energy consumption. A comparative analysis evaluates each window type's benefits and limitations, considering factors such as insulation properties, solar heat gain control, and visual comfort. The findings suggest that double-layer and electrochromic windows offer significant advantages over traditional single-layer windows in reducing energy usage, enhancing occupant comfort, and promoting sustainable building practices. The building under study is modeled in DesignBuilder, and the impact of these three types of windows on the application is analyzed. On the hottest day of the year, the operative temperature is 1.3 degrees Celsius lower when utilizing double-layer windows compared to single-layer windows, and 0.2 degrees lower compared to electrochromic windows. On the coldest day of the year, using double-layers results in an operative temperature of 14.14 degrees Celsius, which is 1.3 degrees higher than single layers and 0.13 degrees lower than electrochromic windows.