THERMAL AND INDOOR AIR QUALITY EFFECTS ON PHYSIOLOGICAL RESPONSES, PERCEPTION AND PERFORMANCE OF TROPICALLY ACCLIMATIZED PEOPLE HENRY CAHYADI WILLEM NATIONAL UNIVERSITY OF SINGAPORE 2006 THERMAL AND INDOOR AIR QUALITY EFFECTS ON PHYSIOLOGICAL RESPONSES, PERCEPTION AND PERFORMANCE OF TROPICALLY ACCLIMATIZED PEOPLE HENRY CAHYADI WILLEM (B.Eng.(Arch.), M.Sc.(Bdg Sc.)) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF BUILDING NATIONAL UNIVERSITY OF SINGAPORE 2006 A JOINT DEGREE PROGRAMME BETWEEN NATIONAL UNIVERSITY OF SINGAPORE AND TECHNICAL UNIVERSITY OF DENMARK Acknowledgment This thesis presents and synthesizes the outcomes of research conducted in the field laboratory of the Department of Building of National University of Singapore (NUS) as well as in three office buildings located in Singapore between August 2002 and October 2004 The research focuses on various occupants’ responses to the indoor environment I am deeply grateful and indebted to many individuals for this research opportunity First, I would like to gratefully acknowledge the supports given by the Department of Building of NUS in conducting this research I am also grateful for the research scholarship granted by the National University of Singapore I thankfully acknowledge the support and warm welcome from the International Center for Indoor Environment and Energy of the Technical University of Denmark during the period of study in Denmark under the joint PhD degree program of the National University of Singapore (NUS) and the Technical University of Denmark (DTU) I express my highest gratitude to A/Prof Tham Kwok Wai for giving me the opportunity to be part of this research, for sharing his ideas and knowledge, and above all, for trusting and believing in me all the way with his unfailing supports and encouragements It has been truly a great experience and a privilege to know, to interact and to learn so much from a person who has been a role model to me and many others I also thank A/Prof Pawel Wargocki for sharing his experiences in this area of research Working with him has been an illumination to my understanding about various aspects within and without the human-environment interactions It was also a great experience to be part of his research team in conducting field studies during my study in Denmark I am indebted to Prof David P Wyon as one of my mentors in formulating the research design, for sharing his seemingly unlimited ideas, and for the review of and suggestions to the results obtained from the research I would like to thank Prof Bjarne W Olesen as my academic supervisor during my study in the Technical University of Denmark I shall gratefully acknowledge his comments and suggestions in the interpretation of the research results I also thank him for supporting my application for an overseas conference grant I express my sincere gratitude to A/Prof S Chandra Sekhar and A/Prof David Cheong, in particular, for the time and the numerous advices during the initial stage of the research work I deeply appreciate their encouragements throughout my study in NUS I also express my fond admiration and appreciation to Prof P Ole Fanger for the inspiring research work, ideas and visions on thermal comfort and indoor air quality research I iii thank him for sharing his knowledge through the lectures, giving advices, and showing the next important stage in the indoor environmental research Thanks are also due to A/Prof Geo Clausen for his time and effort in processing my enrolment as the PhD candidate of the Technical University of Denmark I warmly thank Prof David Koh, Ms Vivian Ng and Mr Andrew Wee from the School of Medicine of the National University of Singapore for their time and effort in the processing of the saliva samples and for sharing their knowledge about the applications of salivary biomarkers Special thanks are due to Ms Afizah, Mr Alvin Ang, Mr Asokan, Mr Foong, Ms Lily Koh, Ms Madeleine, and Mr Tham Khong Wing from the call center managements for their generous support, patience and kind cooperation during the preliminary stage and actual experimental period in the call centers I sincerely thank Prof Jan Sundell for sharing his knowledge in the interpretation of some results from the biomarkers data I warmly thank A/Prof Jørn Toftum for sharing his research work and giving useful suggestions for the post-analysis of the results and their interpretations I thank Prof Kirk Smith for sharing his passion in research for the betterment of air quality in the poor and developing countries I truly enjoyed our discussions during his visit to the Technical University of Denmark The presented research results in this thesis testify to the contributions from many participants in the field investigations as well as the simulated office studies I would like to extend many thanks and appreciations to all the participants for their commitments and patience I would like to thank all my friends, colleagues, laboratory officers, and the Departments’ secretaries from the National University of Singapore and the Technical University of Denmark for their friendships, supports, and all the time and fun we shared throughout my study I praise God for the opportunity to knowing you all Singapore, 18th March 2006 Henry Cahyadi Willem HT016860E (NUS) – 050783 (DTU) iv Table of Contents Acknowledgments iii Table of Contents v Summary x Chapter INTRODUCTION - 1.1 1.2 1.3 1.4 Chapter Thermal environment and indoor air quality parameters A unified model of mechanisms Productivity gain -Research objectives LITERATURE REVIEW 10 1.1 Thermal environment 2.1.1 Human thermoregulation -2.1.2 Physiological (biomarkers) responses to the thermal environment 2.1.3 Behavioral and sensory responses to the thermal environment - 12 13 Indoor air quality -2.2.1 Sick Building Syndrome (SBS) symptoms 2.2.2 Physiological (biomarkers) responses to indoor air quality 2.2.3 Sensory and perceptual responses to indoor air quality - 19 20 Effects on work performance 2.3.1 Overview of IEQ effects on productivity 2.3.2 Impacts of thermal environment on occupants’ performance -2.3.3 Impacts of indoor air quality on occupants’ performance 26 26 Work performance factors 2.4.1 Arousal 2.4.2 Attention/ concentration 2.4.3 Creative thinking 2.4.4 Speed and accuracy tradeoffs - 31 32 33 33 33 2.1 2.3 2.4 14 18 23 24 28 30 v Chapter EFFECTS OF AIR TEMPERATURE AND OUTDOOR AIR SUPPLY RATE IN THE FIELD STUDIES 35 3.1 3.2 Introduction - 36 Objectives & hypotheses - 37 3.3 Methods -3.3.1 Selection of call centers 3.3.2 Description of call centers -3.3.2 A Call center A 3.3.2 B Call center B 3.3.2 C Call center C 3.3.3 Selection of parameters and conditions -3.3.4 Experimental plan 3.3.5 Measurements of various indoor air parameters 3.3.5 A Physical parameters 3.3.5 B Chemical gaseous parameters 3.3.5 C Ventilation parameters -3.3.5 D Biological parameters 3.3.5 E Dust particulate level -3.3.6 Survey methods -3.3.7 Call performance metrics 3.4 Data analysis 49 3.4.1 Analysis of subjective data from questionnaire 49 3.4.2 Analysis of talk time data 51 3.5 Results -3.5.1 Indoor environmental parameters 3.5.1 A Results of objective measurements in Call center A 3.5.1 B Results of objective measurements in Call center B 3.5.1 C Results of objective measurements in Call center C 3.5.2 Perceptual responses and intensity of SBS symptoms 3.5.2 A Survey results of Call center A -3.5.2 B Survey results of Call center B -3.5.2 C Survey results of Call center C -3.5.2 D Derived subjective factors (SF) for each group of CSO (a principal component analysis) 3.5.3 Performance metric (talk time data) 3.5.3 A Results of talk time analysis of Call center A -3.5.3 B Results of talk time analysis of Call center B -3.5.3 C Results of talk time analysis of Call center C 52 52 Discussions 72 3.6 38 38 41 41 42 43 44 45 46 46 46 47 47 47 47 48 52 53 53 53 57 59 61 63 64 67 68 71 vi 3.7 Chapter Economical aspects 77 3.7.1 Benefits of increasing outdoor air supply rates - 77 3.7.2 Benefits of reducing room air temperature 78 GENERAL METHODS OF THE LABORATORY EXPERIMENTS 81 4.1 4.2 4.3 82 82 83 4.4 Measurements -4.4.1 Indoor environmental parameters 4.4.2 Subjective responses 4.4.3 Physiological responses -4.4.3 A Cutaneous responses -4.4.3 B Salivary biomarkers 4.4.4 Performance measures -4.4.4 A Mental performance tests -4.4.4 B Simulated office tasks 4.4.4 C Self-evaluated performance 85 85 86 87 87 88 90 91 92 93 4.5 Procedures - 94 4.5.1 Experimental set-up - 94 4.5.2 Preparation of subjects and schedules 94 4.6 Chapter Experimental designs Subjects Facility Data analysis 96 4.6.1 Data structure - 96 4.6.2 Data analysis procedures - 99 AIR TEMPERATURE EFFECTS ON HUMAN RESPONSES IN LABORATORY EXPERIMENTS - 101 5.1 5.2 Introduction - 102 Objectives & hypotheses - 103 5.3 Experimental designs 5.3.1 Experimental conditions 5.3.2 Other environmental parameters 103 103 104 5.4 Results -5.4.1 Indoor environmental parameters 5.4.2 Perceptual responses to the thermal environment 5.4.2 A Thermal sensation and thermal comfort -5.4.2 B Respiratory cooling sensation, perceived odor and irritation, and perceived air quality 104 104 105 106 110 vii 5.4.2 5.4.2 5.4.2 5.4.2 5.4.2 5.4.2 5.4.3 5.4.3 5.4.3 5.4.4 5.4.4 5.4.4 5.4.4 C Perception of indoor environmental conditions, intensity of SBS symptoms and the subjective factors -C.1 Effects of air temperature on perceived indoor environmental conditions -C.2 Effects of time of exposure on perceived indoor environmental conditions -C.3 Effects of air temperature on the intensity of SBS symptoms -C.4 Effects of time of exposure on the intensity of SBS symptoms -C.5 Subjective factors (principal component analysis) Physiological (biomarker) responses -A Skin temperatures and sweat rates -B Salivary Cortisol and α-Amylase Performance measures -A Mental performance tests -B Simulated office tasks C Self-evaluation of performance - 114 114 115 116 118 121 124 124 128 130 131 134 137 5.5 5.6 Chapter Structural equation model - 138 Discussions -5.6.1 Associations between thermal sensation and thermal comfort -5.6.2 Respiratory cooling sensation and perceptions of air quality 5.6.3 Local thermal sensation, cutaneous responses and thermal-related symptoms 5.6.4 Room air temperature and the intensity of SBS symptoms -5.6.5 Perceptual constructs of subjective responses to the thermal environment 5.6.6 Salivary biomarkers as the indicator of cutaneous responses, psychological stress and mental activation 5.6.7 Effects of room air temperature on work performance and the mechanisms - 142 143 145 146 147 148 149 151 OUTDOOR AIR SUPPLY RATE EFFECTS ON HUMAN RESPONSES IN LABORATORY EXPERIMENTS - 155 6.1 6.2 6.3 Introduction - 156 Objectives & hypotheses - 157 Experimental designs - 157 viii 6.4 Results -6.4.1 Indoor environmental parameters and experimental settings -6.4.2 Perceptual responses at three outdoor air supply rates -6.4.2 A Perceptions of air quality 6.4.2 B Perceptions of indoor environmental conditions -6.4.3 Physiological (biomarker) responses -6.4.4 Performance measures -6.4.4 A Mental performance tests -6.4.4 B Simulated office tasks 6.4.4 C Self-evaluation of performance - 158 158 159 159 166 172 175 175 178 182 6.5 6.6 Chapter Structural equation model - 182 Discussions -6.6.1 Perceptual and sensory responses of the indoor air quality -6.6.2 Intensity of SBS symptoms and subjective factors 6.6.3 Stress-related biomarkers and their associations with perceptual responses -6.6.4 Effects of outdoor air supply rates on work performance and the mechanisms - 185 CONCLUSIONS AND RECOMMENDATIONS 192 185 187 189 190 7.1 Effects of air temperature 193 7.1.1 Field study in the call centers - 193 7.1.2 Simulated office environment - 194 7.2 Effects of outdoor air supply rate 195 7.2.1 Field study in the call centers 195 7.2.2 Simulated office environment - 196 7.3 Practical implications 7.4 Future studies - 197 198 References - 200 Appendix A Appendix B Appendix C Appendix D Questionnaire Used in Call Center Studies Main Effects Results of Call Center Surveys -Subjective Factors of Call Center Surveys Questionnaire Used in Field Laboratory Studies A-221 A-224 A-227 A-234 ix 42 40 45 48 44 48 45 Air warmness Air humidity Air stuffiness Air stillness Room darkness Room noisiness Room dustiness 47 Self-perceived effort 51 28 0.19 45 57 41 46 51 39 27 35 31 44 40 27 35 41 49 51 60 55 54 26 61 61 47 53 48 55 51 47 49 0.80 0.60 0.50 0.55 0.24 0.22 T2^ ** *** * *** ** ** * ** *** ** *** *** *** * P 46 26 -1.08 33 32 25 28 32 26 17 22 18 63 63 22 21 32 40 46 58 37 43 29 32 64 38 50 41 39 38 42 32 0.50 0.47 0.50 0.36 0.33 0.16 *** *** * ** * *** *** *** *** * * 50 35 *** -0.40 *** 35 31 25 32 35 26 19 20 23 30 38 23 22 34 44 51 58 51 51 29 35 68 45 50 42 53 53 50 56 0.73 0.42 0.43 0.50 0.21 0.13 Section T1 T2 P 56 45 28 -0.64 36 51 30 32 39 32 26 26 26 51 54 33 28 37 40 43 44 43 44 30 37 53 44 49 44 41 43 46 34 0.54 0.43 0.50 0.60 0.22 0.14 ** ** *** *** *** * ** *** *** *** *** * ** ** 54 47 35 ** *** -0.39 ** 36 51 28 37 38 30 23 26 24 40 42 29 25 36 42 43 43 43 45 28 40 55 44 50 45 51 51 52 53 0.56 0.52 0.60 0.58 0.19 0.13 64 49 18 -1.47 39 42 35 34 43 36 30 31 31 62 67 40 36 38 43 53 51 48 43 35 34 62 50 56 39 42 40 43 28 0.57 0.54 0.67 0.50 0.18 0.12 * *** *** *** *** *** *** 64 51 33 *** -0.72 *** 41 43 35 35 47 36 28 30 31 47 46 37 34 39 43 51 49 48 49 36 38 63 48 57 39 49 45 49 47 0.70 0.60 0.67 0.48 0.24 0.16 Intensity score Call center B Section Section T1 T2 T1 T2 P P ^: T indicates lower air temperature (set-point= 22.5°C) and T2 indicates higher air temperature (set-point= 24.5°C) Self-perceived productivity 50 50 65 63 Note: *** denotes 0