Modelling Thermal Comfort and Energy Saving Enhancements in an Office Room Served by Stratified Air Distribution Systems

A numerical study is performed into the effects of the location of exhaust diffusers in relation to the room heat sources on thermal comfort and energy saving. A new concept of the combination of indoor heat sources and the exhaust outlet was also employed in this investigation. The results showed that the indoor thermal environment and energy saving were greatly improved by combining the exhaust outlets with some of the room’s heat sources. For further improvement, this concept was also used along with a novel local exhaust ventilation system in the modelled office room. This system was adopted and developed for use in office spaces, where the exhaust opening was combined with the office workstation into a single unit. The main aim was to help extract the warmed and contaminated air locally before it could disperse across the room. Three different amounts of recirculated air and three different heights of the combined system were analysed. The results showed a significant improvement in energy savings and inhaled air quality in the room using the new ventilation system. It was also found that the performance of this system was greatly influenced by the height factor. In addition, in this research, the LES method was employed to investigate the complex characteristics of airflow and temperature distribution in the office room which used the concept of combining the exhaust outlet with room heat sources. The results revealed that the airflow and temperature distribution were highly unsteady and unstable, particularly in the regions where buoyancy works effectively to cause a high number of perturbations. The developed CFD models were thoroughly validated.