The Howzkhaneh is an indigenous passive cooling design that uses an indoor central pool to maintain the indoor climate through natural ventilation and evaporative cooling. Systematic investigations of their thermal performance across various climatic regions are scarce, even though they have historical importance. This study fills this gap by studying the Howzkhanehs in three cities of Iran, which have three distinct climatic conditions, i.e., Tabriz, Shiraz, and Yazd, using computational simulations. The aim is to determine their capability for thermal comfort at different internal heat loads. The simulation was carried out across three scenarios (0 kW, 10 kW, and 20 kW cooling load) to evaluate temperature and humidity variations, as well as the dynamics of evaporation. Results show that the Howzkhaneh systems have the potential to lower the temperature of the indoor air by 21-23 degrees C (starting with the outside temperatures of 38-44 degrees C) and raise relative humidity, depending on the city. They can maintain almost comfortable indoor temperatures (22-27 degrees C) to cooling loads of 14 kW in Yazd, 15 kW in Tabriz, and 16 kW in Shiraz. In Yazd, evaporation rates reached 10.5 g/m2 & sdot;s, which demonstrates the effectiveness of the system in arid regions. Howzkhaneh systems are found capable of delivering temperatures down to 21 degrees C and raising relative humidity to near-saturation (90-100 %) with no external power source, and thus are viable, sustainable cooling options. These systems can be used as a guide for retrofitting heritage buildings and developing new climate-adaptive buildings in arid and semiarid areas, providing comfortable indoor conditions (22-27 degrees C) with cooling loads of 14-16 kW. The results are quantitative and can be used to justify the application of conventional passive cooling techniques in modern-day green buildings.