Urban heat island is a phenomenon caused by increased urban activities and transformations in the natural environment. Increased urban population and increase in the height of buildings, particularly in metropolitan areas, have led to vast changes in the urban geometry, amount of released heat, pollution rate, and meteorological parameters. All these factors contribute to the occurrence of heat island phenomenon in urban areas. Sky View Factor (SVF) is one of the main factors related to pollution, temperature variations, heat island, and other environmental parameters. Housing density policies stipulated in Tehran's detailed plan would possibly have several impacts on the sky view factor. The SVF axis of the Envi-met software uses various parameters such as topography, wind velocity, and urban morphology to simulate and measure sky view factor. This study aims to evaluate impacts of the future high rise developments, in the Narmak neighborhood of Tehran, through modeling future changes in the sky view factor. For this purpose, data related to Haft Hoz square located in the Narmak neighborhood were obtained, simulated and analyzed using SVF. Results indicate that in the business as usual scenario the factor's value would be in a range between 0.19 and 0.77. Whereas, by implementing the scenario proposed in the detailed plan the factor will decrease to fall in a range between 0.08 and 0.69. This reduction in the intensity will possibly increase heat island impacts in the study area. This study emphasizes the necessity of taking compensatory policy measures and incorporating environmental considerations in urban development plans.