Human response to thermal environment and perceived air quality in an office with individually controlled convective and radiant cooling systems

Weixin Zhao,Simo Kilpeläinen,Risto Kosonen,Juha Jokisalo,Sami Lestinen,Yuxin Wu,Panu Mustakallio

doi:10.1016/j.buildenv.2021.107736

Abstract

The purpose of this study is to analyze the human response to the indoor climate with two individually controlled convective and radiant cooling systems: a low velocity unit combined with radiant panel system (LVRP) and a personalized ventilation system combined with a radiant panel system (PVRP). As a reference system without individual control, diffuse ceiling ventilation combined with a radiant panel system (DCV-RP) was also studied. In laboratory conditions, 10 males and 10 females gave subjective response to the indoor climate during various office activities. The indoor parameters and CO2 concentrations were measured. The results show that with the reference DCV-RP system, the indoor conditions were worse than with the LVRP and PVRP systems. The thermal sensation and perceived air quality with the PVRP system was better than the LVRP system. After a medium activity task, the thermal acceptability reverts faster with the PVRP than LVRP system. Both the LVRP and PVRP systems were able to create a micro-environment around the workstations and the CO2 concentrations near the workstation were slightly lower than at the exhaust grille. Compared with the PVRP system, the subjects preferred the higher airflow rate at the workstation with the LVRP system. Males preferred a higher airflow rate than females under the same conditions with both micro-environment systems. This research found that there was significant variation in the control preferences of the human subjects concerning the micro-environment, and this emphasizes the need for personalized control to ensure that all occupants are satisfied with the indoor conditions.

Highlights

1.1 BackgroundIn modern cities and urban societies, the influence of the indoor environment to human health and comfort is important (Haverinen-Shaughnessy et al, 2015; Wargocki & Wyon, 2017) because people spend more than 90% of their time indoors (Leech et al, 2002)
The performance of two novel systems: (1) low velocity units combined with radiant panels and (2) personalized ventilation combined with radiant panels were analyzed and compared to the performance of diffuse ceiling ventilation under the same test conditions
With the convective and radiant panel cooling systems, the performance with regard to indoor air quality, thermal comfort, and airflow characteristics with the low velocity unit and radiant panel system (LVRP) and personalized ventilation combined with radiant panel system (PVRP) were analyzed by physical measurement (Publications 3–4)

Summary

Introduction

1.1 BackgroundIn modern cities and urban societies, the influence of the indoor environment to human health and comfort is important (Haverinen-Shaughnessy et al, 2015; Wargocki & Wyon, 2017) because people spend more than 90% of their time indoors (Leech et al, 2002). Venkatasubbaiah and Jaluria (Venkatasubbaiah & Jaluria, 2012) and Harish and Venkatasubbaiah (Harish & Venkatasubbaiah, 2013) conducted studies on the buoyancy-induced flow with diffuse ceiling ventilation (DCV) utilizing CFD simulations. They revealed that flow behavior is significantly influenced by the size and location of the heat source. The results indicate a cause-effect relationship of the heat load strength and the heat load distribution on airflow characteristics that may have effects on air distribution These mentioned studies focused on the airflow fluctuation and turbulence scales in both symmetric and asymmetric conditions. It is important to consider the possible effect of heat load types and load distribution on air quality

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Conclusion