Human response to personalized ventilation and mixing ventilation

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The response of 60 human subjects to a personalized ventilation system (PVS), providing control of positioning of the air terminal device and the airflow rate, was compared with the response to mixing ventilation (MV). Perceived air quality, thermal comfort, intensity of Sick Building Syndrome symptoms and performance of subjects were studied during 3 h 45 min exposures. In case of MV alone the room air temperature was 23 degrees C and 26 degrees C. The PVS supplied outdoor air at 23 degrees C or 20 degrees C or recirculated room air at 23 degrees C when the room temperature was 23 degrees C, and outdoor air at 20 degrees C when the room temperature was 26 degrees C. The PVS providing outdoor air improved perceived air quality and decreased SBS symptoms compared to MV alone and when the room air was re-circulated through the PVS. The percentage dissatisfied with air quality, 3 min after initial occupancy, decreased from 22% with MV to 7% with PVS; and from 49% to 20%, at room temperatures 23 degrees C and 26 degrees C, respectively. Over time, these differences in percentage dissatisfied decreased markedly. Headache and decreased ability to think clearly were reported as least intense when the PVS supplied outdoor air at 20 degrees C, while the most intense symptoms occurred with MV. PVS increased self-estimated performance. Personalized ventilation can improve occupants' thermal comfort, perceived air quality and decrease the intensity of SBS symptoms compared to mixing ventilation. Occupants will use the provided individual control of airflow rate and positioning of the air terminal device to obtain preferred microenvironment in rooms where the air temperature is within the range recommended by indoor climate standards. Development of more efficient air terminal devices is recommended.