Non-uniform indoor air in office building: performance of a personal ventilation system in an open plan office

© 2017 Dr. Nafiseh HamidiThis thesis focuses on examination and analysis of the viability of a new prototype of personal ventilation (PV) system called Task Air (TA). PV system was originally developed as a strategy to address the proven deficiency in ventilation performance of office buildings. Several studies have proved the effectiveness of the system; however the studies have mainly been based in a laboratory setting. This work is a contribution to the lack of accurate knowledge of field-based study on PV systems, the aim of which is to improve the basic knowledge required for the successful design of a usable PV system. The results indicated that the TA system could effectively enhance the thermal comfort of participants during the cold season by creating a vertical non-uniform thermal environment. However, during the warm season this non-uniformity was only able to slightly enhance the thermal comfort of participants. The user control of the system served to give participants a sense of control over the thermal environment, and consequently enhanced their thermal satisfaction (with over 95% thermal satisfaction in the warm season study); however the participants did not use the provided user control frequently. The TA system enhanced the air quality and reduced the experience of sick building syndrome symptoms by participants. Finally, in the context of vertical non-uniform thermal environments, this study confirms the viability of warming the head region to maintain the whole-body thermal comfort in ‘cooler’ environment. Furthermore, this study highlights the inconsistencies in the results of controlled laboratory-studies compared with the results of field-studies in the context of PV systems. This study further emphasises the critical contribution of ‘perceived control’ in enhancing thermal comfort. In addition, the performance of the studied PV system can be improved if its air distribution system was separated from the background air conditioning system, enabling creates an efficient and effective ventilation system for the office building by stimulated energy saving up to 50%