The most widespread application of renewable energy is heat production, mainly related to biofuels and solar water heaters (SWHs). Considering that SWHs are essential in energy supply, the present work aims to investigate the heat requirement of a residential apartment in Pakistan using a radiator system in 32 investigated stations. The daily water requirement is 160 L, and the ideal water temperature is 50 oC. It should be considered that hot sanitary water is needed for all 365 days. The investigations were carried out with TSOL Pro 5.5 software to simulate the heat of the desired locations. Also, after the analysis, we found that the selected location's SWH and thermal energy supply have high efficiency. The total heat supply using renewable energies is 18-42% for the investigated stations, and the rest of the required heat is supplied with fossil fuel. Since SWHs are one of the simplest and most economical ways to provide hot water for homes, offices, schools, hospitals, etc., Pakistani people can save a large amount of energy by investing in this field. Considering that Pakistan has good radiation potential, we hope that the present work results will lead to more use of SWHs. تفاصيل المقالة