Study of ventilation strategies improving indoor environmental quality and comfort in scholar buildings
Ventilation is a key sector of building, whose role is to ensure healthy and comfortable air all over the year, which is rarely the case in school buildings, while minimizing energy consumption. Our work provides some answers and possible improvements for the development of appropriate ventilation strategies for schools, from experimental and numerical work.To achieve this, four modes of ventilation (natural and mixed ventilation modes) were tested in classrooms of the University of La Rochelle, and their performances were compared via a multicriteria evaluation based on the physical parameters characterizing the indoor environment, comfort indices (subjective, analytical and adaptive) and energy criteria. Normative methods of classification and estimates of energy consumption enabled us to conclude that the natural ventilation system by automated opening windows, controlled by the presence detection and thermal parameters (SOS), is the best compromise. However, we submit in this manuscript, some improvements to this system.Our contribution concerns also the understanding of the human comfort mechanisms and in particular its adaptive reactions, by defining the favorable conditions for a state of comfort and providing predictive models concerning overall comfort, personal adjustments and the individual control of the indoor environment by the occupants. These results aim to improve the consideration of the interactions between occupants and their environment in numerical simulations, and may serve as a basis for developing an optimized ventilation strategy.Numerically, we propose annual simulations of four ventilation strategies, very similar to those tested in situ, by using a combined heat and mass transfer multizone model (coupling Trnsys / CONTAM), that we have validated from selected experimental sequences. Taking into account a standard scenario of occupation and the annual weather conditions for La Rochelle, we have shown the importance to pre-heat the supplied air of a mechanical ventilation system, because of insurmountable heating demand consequences. By introducing an unlimited heating power, in order to maintain a minimum acceptable temperature and thus to simulate realistic learning conditions, it appears that the best indoor environmental quality is again obtained with the SOS system. Our model now gives us the possibility to increase the number of ventilation strategies, as well as the occupation scenarios, the weather conditions or any other parametric study in order to design the best ventilation strategies for each configuration.