A fresh air system is used for indoor air circulation and quality improvement. It introduces fresh air and exhausts stale air to achieve indoor air circulation and renewal. Fresh air systems utilize high-efficiency filters and sensor technology to filter harmful substances like particulate matter, bacteria, and viruses from the air, ensuring clean and healthy indoor air. The system can intelligently adjust based on parameters such as indoor/outdoor temperature, humidity, and CO2 concentration to achieve a balance between energy saving and comfort. Fresh air systems are widely used in residences, offices, and commercial buildings to provide a high-quality indoor environment for residents and workers, promoting health and comfort.