In the Palestinian cities; especially the city of Nablus, there is not enough open green areas. This research aims at developing or creating more green areas and spaces in the city of Nablus by implementing the concept of roof gardens. This research analyzes the current structure of the city (Nablus) roofs. It also determines to what extent people will be satisfied and feel comfortable by the application of green roofs. Computer simulation (Autodesk Ecotect) will be used to find out the effect of green roofs on the city of Nablus by comparing three roofing types (regular roof, green roof and insulated green roof) to clarify the difference in thermal behaviour. Results indicate that the city residents are willing to add green roofs to their buildings, but have some concerns over the cost of green roofs. The simulation results indicate that green roofs reduce the energy consumed for heating or cooling.