Comparison of natural and hybrid ventilation strategies used in classrooms in terms of indoor environmental quality, comfort and energy savings

Numerous studies have shown that ventilation in classrooms is often insufficient or inadequate, leading to health risks, discomfort and a decrease in student learning performances. The aim of this study was to compare the performances of four ventilation modes used in identical and adjacent classrooms at the University of La Rochelle in terms of indoor environmental quality, overall comfort perception by the occupants and energy consumption. The different ventilation strategies included the use of balanced mechanical ventilation and natural ventilation by manual or automated window opening. Parameters related to air quality as well as thermal, visual and acoustic comfort were measured, and questionnaires were filled out by the occupants during the courses. The monitoring approach was conducted during summer and winter 2010 in order to classify the tested strategies during both seasons with reference to the requirements of standards and French regulations. The results showed that the automated window opening system controlled by air temperature and lighting level was really efficient in summer. In winter, none of the ventilation modes was clearly more adaptable for classrooms than the other. Thus, a good use of natural ventilation, controlled by well chosen parameters can provide a satisfactory solution for the academic environment.