Natural Ventilation and Energy Consumption in Heating Ventilation and Air Conditioning Systems with Effects on CO₂ Concentration and Predicted Mean Vote

During the design and operational phases of a building's lifecycle, Heating, Ventilation, and Air Conditioning systems are one of the primary sources of energy consumption. This study investigates the effects of different window orientations, opening sizes, and occupancy levels on energy use, indoor air quality, and thermal comfort in spaces using Single-Split-Type cooling systems. Results indicate that north-facing configurations in both January and July offer notable energy-saving benefits, reducing consumption by up to 22.76%. Diagonal window openings with appropriate occupancy effectively maintain both predicted mean vote and CO₂ concentration within acceptable comfort ranges. This research provides practical insights for natural ventilation and energy-efficient design.