This study investigates the role of insulation, in commercial buildings and how it affects energy efficiency and sustainability in different climate regions. Commercial buildings consume an amount of energy making them ideal candidates for energy saving measures. Insulation plays a role in maintaining indoor conditions reducing energy usage and minimizing carbon emissions by limiting heat transfer through the building’s envelope. By conducting simulations using the Hourly Analysis Program (HAP) this research examines how insulation thickness, climate conditions and building characteristics impact energy consumption and greenhouse gas emissions. The study covers climate zones with a focus on Afghanistan, semi-arid, arid and mountainous regions where sustainable construction practices are highly important. The findings demonstrate that insulation has an effect on enhancing energy efficiency particularly when it comes to heating. Additionally, economic factors, future research directions and broader implications, for construction practices are thoroughly discussed. Considering that the construction industry contributes significantly to carbon emissions this research provides insights into promoting sustainable building practices. By optimizing insulation strategies, architects, builders and policymakers can reduce the impact of commercial buildings while advancing energy efficiency and supporting a more sustainable urban future.