This invention relates to a method for delivering humidified gas to a user or patient during respiratory gas ventilation support, such as, but not limited to, mechanical ventilation, continuous positive airway pressure breathing, and bi-directional positive airway pressure breathing； the method comprising the steps of heating a humidified gas from a humidified gas reservoir； transferring the heated humidified gas to a patient； receiving expired gas from a patient； heating the expired gas； and transferring the heated expired gas to a gas outlet； wherein the humidified gas and the expired gas are heated to different temperatures. Also disclosed is a humidified gas delivery system, which finds utility as a breathing circuit of a respiratory gas humidification system by delivering humidified gases to a user or patient during mechanical ventilation, continuous positive airway pressure breathing, bi-directional positive airway pressure breathing, or other mode of respiratory support provided to users or patients.
