An energy-efficient, space-saving, low-cost, waste-heat-utilizing ventilating air conditioning apparatus uses a honeycomb rotor having a function of adsorbing or absorbing contaminants such as carbon dioxide and VOC gas. The honeycomb rotor is disposed in a rotor rotating device having at least a processing zone and a re-generation desorption zone. Air to be processed is passed through the processing zone to remove contaminants such as carbon dioxide to produce supply air. Water is directly sprayed or dropped into a heat exchanger provided at an entrance of the re-generation desorption zone to evaporate the generated water film by heating. The generated saturated steam is introduced for desorbing carbon dioxide and pollutants, and the stream is discharged the stream outdoors. The ventilating air conditioning apparatus can operate without the energy loss associated with ventilation.