The construction sector consumes large amounts of energy during the lifetime of a building. This consumption starts with manufacturing and transferring building materials to the sites and demolishing this building after a long time of occupying it. The topic of energy conservation and finding the solution inside the building spaces become an important and urgent necessity. It is known that the roof is exposed to a high amount of thermal loads compared to other elements in a building envelope, so this needs some solutions and treatments to control the flow of the heat through them. These solutions and treatments may be achieved by using nanomaterials. Recently, nanomaterials have high properties, so that this made them good elements to the strategy of energy conservation in the architectural field. Accordingly, the research problem lay in "the lack of studies that deal with strategies to use nanomaterials in the roof of the building (especially the administrative building) in order to achieve energy conservation within its spaces". Then the research aims to: "Determine the efficient of nanomaterials in the roof to improving the thermal performance and achieving energy conservation in the indoor environment of the buildings in Iraq". This research's theoretical aspect has focused on using nanomaterial and their applications in roof systems. While in the experimental aspect, an administrative application to test a mass of identical administrates building in the design. In this research, simulation of the standard roof with nanomaterial, cool roof, and standard roof systems has been done using the Ecotect program. The results obtained in this research showed that the nanomaterial affected the thermal performance and achieved the indoor environment's quality by reducing to energy-consuming in the administrative building in the hot-dry climate of Iraq.