Effects of Manual and Automatic Natural Ventilation Control Strategies on Thermal Comfort, Indoor Air Quality and Energy Consumption

Occupants of naturally ventilated buildings can tolerate wider ranges of temperature and Indoor Air Quality (IAQ) if they have more control over their environment. Meanwhile, due to the complexity of advanced natural ventilation (ANV) strategies, introducing some form of automatic control is essential despite the fact that they limit the occupants’ control over their environment. Therefore, it is essential to understand the performance of ANV systems and occupants’ behaviours in order to identify a balance between automatic and manual controls to enhance the performance of ANV systems while maintaining the occupants’ comfort. The aim of the work reported in this paper is to evaluate the effects of a retrofitted ANV system with manual and automatic controls on thermal comfort, indoor air quality and energy consumption in an open-plan office building in the UK. Physical measurements were used to study the building performance in terms of thermal comfort, IAQ and energy consumption. The results revealed that occupants were much more aware about thermal comfort compared to IAQ. Therefore, relying on the occupants to control the ventilation system would considerably increase the risk of poor IAQ in buildings. Moreover, introducing automatic controls did not affect the thermal comfort conditions for those who understood and actively controlled the ANV system, while the situation improved for those occupants who were not active. Results of this study showed that introducing automated natural ventilation helped to reduce energy consumption by 8%.