The role of energy in the global economy may highlight the importance of energy. Accordingly, development and expansion of theories as well as the energy applications have led to novel methods for the issues associated with the energy and environment. A number of scholars have addressed solar energy and considered it an appropriate alternative for the fossil fuels. Therefore, using solar systems as one of the components of the buildings has become more common. According to 2015 census, Tehran urban have 20×10 6 residential buildings consuming a tremendous amount of energy derived from fossil fuels. Consequently, using solar energy could provide a part of energy consumed by residential buildings in Tehran urban. In the present study, residential buildings of Tehran city were considered as the sample, and the energy consumed for heating and hot water was calculated. The results indicate that the energy consumed by such buildings for heating and hot water accounts for 559. 88 kW which is equivalent to 4904111 h saved electrical energy. Therefore, the reduction of CO2, SO2, NOx, CO, and SPM pollutants as the result of saving in electrical energy for residential buildings is respectively 28. 08 Ton, 490 kg, 438. 4 kg, 0. 49 kg, and 52. 96 kg. Notably, using solar energy may lead to saving in fossil fuel consumption; furthermore, the costs associated with their production and handling are reduced.