Comparing mixing and displacement ventilation in tutorial rooms: Students' thermal comfort, sick building syndromes, and short-term performance

Abstract While mixing ventilation (MV) and displacement ventilation (DV) are widely used to regulate the indoor environment, very few studies compared occupants' responses under these two systems in the field. In this study, a field experiment was conducted in two identical tutorial rooms to compare human subjects' thermal comfort, sick building syndromes (SBS), and short-term performance under MV and passive displacement ventilation (PDV). Experimental results showed that MV could lead to significantly larger overall draft sensation than PDV due to high air velocity from the overhead diffusers. PDV on the other hand, led to significantly higher draft and colder sensation in the lower body level, while draft distribution was perceived relatively homogenous in the vertical direction in the MV room. Seat arrangement could lead to inhomogeneous sensations in the horizontal direction in both the MV and PDV rooms. Higher CO 2 concentration was the main factor causing SBS related to head, while both higher CO 2 concentration and lower relative humidity (RH) contributed to SBS related to eyes. As a consequence, SBS resulted from high CO 2 concentration and low RH could lead to decrease in short-term performance. In addition to the experiment, the results of the real-life occupants' feedback also resembled the experimental findings.

[1]  W. Fisk,et al.  Is CO2 an Indoor Pollutant? Direct Effects of Low-to-Moderate CO2 Concentrations on Human Decision-Making Performance , 2012, Environmental health perspectives.

[2]  Dan Norbäck,et al.  Respiratory symptoms, perceived air quality and physiological signs in elementary school pupils in relation to displacement and mixing ventilation system: an intervention study. , 2011, Indoor air.

[3]  W. Fisk,et al.  Association of ventilation rates and CO2 concentrations with health and other responses in commercial and institutional buildings. , 1999, Indoor air.

[4]  O Seppänen,et al.  Ventilation and health in non-industrial indoor environments: report from a European multidisciplinary scientific consensus meeting (EUROVEN). , 2002, Indoor air.

[5]  P V Nielsen,et al.  Distribution of exhaled contaminants and personal exposure in a room using three different air distribution strategies. , 2012, Indoor air.

[6]  P. Fanger,et al.  Upper limits for indoor air humidity to avoid uncomfortably humid skin , 1998 .

[7]  B. Griefahn,et al.  Evaluation of draught in the workplace , 2002, Ergonomics.

[8]  P V Nielsen,et al.  Dispersion of exhaled droplet nuclei in a two-bed hospital ward with three different ventilation systems. , 2006, Indoor air.

[9]  Xiao Wang,et al.  An experimental investigation into the pull-down performances with different air distributions , 2015 .

[10]  Runming Yao,et al.  A review of the performance of different ventilation and airflow distribution systems in buildings , 2014 .

[11]  Jelena Srebric,et al.  Performance of three air distribution systems in VOC removal from an area source , 2004 .

[12]  David Tong,et al.  Questionnaire design for sick building syndrome: An empirical comparison of options , 1996 .

[13]  K. F. Fong,et al.  Evaluation of thermal comfort conditions in a classroom with three ventilation methods. , 2011, Indoor air.

[14]  Q Chen,et al.  Air flow and particle control with different ventilation systems in a classroom. , 2003, Indoor air.

[15]  K. Roth,et al.  Modulating Compressors for Residential Cooling , 2004 .

[16]  M. Tarvainen,et al.  Measurements of skin temperature responses to cold exposure of foot and face in healthy individuals: variability and influencing factors , 2011, Clinical physiology and functional imaging.

[17]  C. H. Wyndham,et al.  Comparison of weighting formulas for calculating mean skin temperature. , 1969, Journal of applied physiology.

[18]  P Wargocki,et al.  Perceived air quality, sick building syndrome (SBS) symptoms and productivity in an office with two different pollution loads. , 1999, Indoor air.

[19]  How-Ran Guo,et al.  Higher Prevalence of Dry Symptoms in Skin, Eyes, Nose and Throat among Workers in Clean Rooms with Moderate Humidity , 2009, Journal of occupational health.

[20]  Shinichi Tanabe,et al.  Effect of humidity on human comfort and productivity after step changes from warm and humid environment , 2007 .

[21]  Arsen Krikor Melikov,et al.  Human response to local convective and radiant cooling in a warm environment , 2013 .

[22]  Dejan Mumovic,et al.  Analysis of thermal comfort and indoor air quality in a mechanically ventilated theatre , 2008 .

[23]  Chang-Chuan Chan,et al.  Office Workers’ Sick Building Syndrome and Indoor Carbon Dioxide Concentrations , 2012, Journal of occupational and environmental hygiene.

[24]  K. Miki,et al.  Evaluation of mean skin temperature formulas by infrared thermography , 1997, International journal of biometeorology.

[25]  J. Toftum,et al.  Draught sensitivity is influenced by general thermal sensation , 1996 .

[26]  J. Juto,et al.  Eye trigeminal sensitivity, tear film stability and conjunctival epithelium damage in 182 non-allergic, non-smoking Danes. , 2004, Indoor air.

[27]  G He,et al.  Removal of contaminants released from room surfaces by displacement and mixing ventilation: modeling and validation. , 2005, Indoor air.

[28]  Peder Wolkoff,et al.  "Healthy" eye in office-like environments. , 2008, Environment international.

[29]  J. D. Spengler,et al.  ESTIMATES OF POTENTIAL NATIONWIDE PRODUCTIVITY AND HEALTH BENEFITS FROM BETTER INDOOR ENVIRONMENTS: AN UPDATE , 1999 .

[30]  Zhang Lin,et al.  Experimental study of the influence of a moving manikin on temperature profile and carbon dioxide distribution under three air distribution methods , 2015 .

[31]  Huijuan Chen,et al.  Numerical investigation of ventilation performance of different air supply devices in an office environment , 2015 .

[32]  K. F. Fong,et al.  Comparison of performances of displacement and mixing ventilations. Part I: thermal comfort , 2005 .

[33]  Andrius Jurelionis,et al.  The impact of the air distribution method in ventilated rooms on the aerosol particle dispersion and removal: The experimental approach , 2015 .

[34]  R. Wålinder,et al.  Comparing mixing and displacement ventilation in classrooms: pupils' perception and health. , 2011, Indoor air.

[35]  Richard Greenough,et al.  Acceptance of thermal conditions and energy use of three ventilation strategies with six exhaust configurations for the classroom , 2015 .

[36]  D P Wyon,et al.  The effects of indoor air quality on performance and productivity. , 2004, Indoor air.

[37]  P S Burge.  Sick building syndrome , 2004, Occupational and Environmental Medicine.

[38]  Zhang Lin,et al.  Experimental study of airflow characteristics of stratum ventilation in a multi-occupant room with comparison to mixing ventilation and displacement ventilation. , 2015, Indoor air.

[39]  Jianing Zhao,et al.  Air distribution in a multi-occupant room with mixing or displacement ventilation with or without floor or ceiling heating , 2015 .

[40]  Zhang Lin,et al.  An experimental study of the influence of a walking occupant on three air distribution methods , 2015 .

[41]  K. F. Fong,et al.  Comparison of performances of displacement and mixing ventilations. Part II: indoor air quality , 2005 .

[42]  D. Wyon,et al.  The Acceptable Air Velocity Range for Local Air Movement in The Tropics , 2006 .

[43]  B Griefahn,et al.  The impact of draught related to air velocity, air temperature and workload. , 2001, Applied ergonomics.

[44]  A Melikov,et al.  Field study on occupant comfort and the office thermal environment in rooms with displacement ventilation. , 2005, Indoor air.

[45]  P. Fanger,et al.  Air turbulence and sensation of draught , 1988 .

[46]  A. Rosenfeld,et al.  Estimates of Improved Productivity and Health from Better Indoor Environments , 1997 .

[47]  Bjarne W. Olesen,et al.  Effects of different cooling principles on thermal sensation and physiological responses , 2013 .