Thermal environment and air quality in office with personalized ventilation combined with chilled ceiling Aleksandra Lipczynska a, b, * , Jan Kaczmarczyk a , Arsen K. Melikov b a Department of Heating, Ventilation and Dust Removal Technology, Silesian University of Technology, Konarskiego 20, 44-100 Gliwice, Poland b International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark, Nils Koppels All e Byg. 402, 2800 Kgs. Lyngby, Denmark article info Article history: Received 16 March 2015 Received in revised form 17 May 2015 Accepted 27 May 2015 Available online 28 May 2015 Keywords: Personalized ventilation Radiant cooling Thermal comfort Contaminant distribution Personal exposure abstract The thermal environment and air quality conditions provided with combined system of chilled ceiling and personalized ventilation (PV) were studied in a simulated office room for two occupants. The pro- posed system was compared with total volume HVAC solutions used today, namely mixing ventilation and chilled ceiling combined with mixing ventilation. The objective of the study was to evaluate whether PV can be the only ventilation system in the rooms equipped with chilled ceiling. The room air tem- perature was 26  C in cases with traditional systems and 28  C when PV was used. PV supplied air with the temperature of 25  C. PV improved thermal conditions and was up to nearly 10 times more efficient in delivering clean air at workstations than mixing ventilation systems, which resulted in strong pro- tection of occupants from the cross-infection. In the room space outside workstations no substantial differences in thermal environment were found between studied systems. The room air mixing with PV working alone was at the same level as with mixing ventilation. No substantial differences in contam- inants' concentration distribution and air-change effectiveness were found between the studied systems in the occupied zone outside workstations. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Thermal environment and indoor air quality in offices affect health, comfort and performance of occupants [1e3]. HVAC sys- tems often consume more than 40% of total building energy needs. Thus creating comfortable conditions in spaces at low en- ergy use becomes an important challenge for HVAC engineers and requires development of new solutions. Centrally controlled total volume ventilation systems (e.g. mixing ventilation or displace- ment ventilation), which are typically used in offices, aim to create uniform indoor environment in the occupied zone of rooms which cannot satisfy all occupants. In the case of mixing ventilation air is supplied far from occupants and is mixed with polluted room air before reaching people's breathing zone. With the displacement ventilation cool and clean air is supplied at low level, near the floor and is moved upward by the buoyancy flows present in the room. Thus air should be cleaner in the lower (occupied) zone. However, in many practical applications the air cleanness is lower than assumed during design process [4,5]. The air cleanness especially decreases when the pollution source is located close to the occupant. In such situation the human boundary layer is transporting contaminated air to the breathing zone. Also movements created by walking people disturb the pollution stratification and decrease the cleanness of the air [6]. Moreover due to risk of draught at the feet its' cooling capacity is limited. The performance of total volume air distribution systems is dis- cussed in Ref. [7]. Promising air distribution is achieved by personalized ventila- tion. It delivers clean air directly to occupants' breathing zone and provides possibility for individual control of the micro- environment at each workstation [8]. Therefore personalized ventilation has potential to improve inhaled air quality compared to total volume ventilation [9e11]. Previous studies showed also that personalized ventilation decreases intensity of some Sick Building Syndrome symptoms in comparison with mixing venti- lation [9,12]. However, due to smaller airflow rates and limitation of the lowest supply air temperature personalized ventilation * Corresponding author. Politechnika  Sla ˛ ska, Katedra Ogrzewnictwa, Wentylacji i Techniki Odpylania, ul. Konarskiego 20, 44-100 Gliwice, Poland. E-mail address: aleksandra.lipczynska@polsl.pl (A. Lipczynska). Contents lists available at ScienceDirect Building and Environment journal homepage: www.elsevier.com/locate/buildenv http://dx.doi.org/10.1016/j.buildenv.2015.05.035 0360-1323/© 2015 Elsevier Ltd. All rights reserved. Building and Environment 92 (2015) 603e614