An air exchange unit is designed and developed based on the principle that when air is supplied to one side of a sealed room and exhaust from the other, a "new air flow field" is formed inside. It relies on mechanical air supply and exhaust to forcibly create a new air flow field within the system. It is a new type of environmentally friendly electrical appliance that constantly maintains indoor air cleanliness and freshness. This independent indoor air replacement and purification circulation system, while removing polluted air from the room, introduces fresh natural air, which is first filtered, sterilized, heated, and oxygenated before being introduced into the room.