Abstract
In this study, focusing on building energy usage (BEU) reduction, a solar system was added to HVAC system to reduce its energy demand. The evaluation of the usefulness of incorporating the solar system for three climatic zones in Saudi Arabia (Najran, Sharorah and Taif) was studied. The annual calculations showed that solar collectors filled with water-EG (70:30 wt%) reduced BEU by 14,790 kWh (for Najran), 16,440 kWh (Shrorah) and 12,420 kWh for Tiaf climate regions. This means under the climate of Sharorah, solar collectors were more efficient than others. The addition of CuO nanoparticles improved the performance of collectors in all three regions. In Sharorah, the energy saving in the presence of CuO (at 25 ppm) was calculated to be 18,730 kWh, and with the addition of more alpha, the energy-saving reached 19,440 kWh (at 50 ppm) and 20,430 kWh (at 100 ppm). Finally, it was found that owing to using a solar system equipped with CuO nanoparticles, BEU reduced by 45.1% (for Najran), 35.7% (for Sharorah) and 38.4% (for Taif) under the best conditions.