Investigating the influence of design parameters on the indoor environmental quality and thermal comfort in primary schools in ho chi minh city, vietnam

Department of Architecture and Built Environment INVESTIGATING THE INFLUENCE OF DESIGN PARAMETERS ON THE INDOOR ENVIRONMENTAL QUALITY AND THERMAL COMFORT IN PRIMARY SCHOOLS IN HO CHI MINH CITY, VIETNAM Le Thi Ho Vi BArch, MArch Thesis submitted to the University of Nottingham for the Degree of Doctor of Philosophy October 2019 ABSTRACT Indoor environmental quality significantly impacts on comfort levels which affect students’ performance and productivity Currently in Vietnam, very few studies have dealt with the issue, and the current trend is to install energy-intensive air-conditioning in primary schools as this is perceived as more comfortable In this study, indoor comfort and users’ perceptions were investigated in three primary schools in Ho Chi Minh City during the mid-season (September 2015), the hottest season (April 2016) and the coldest season (December 2016 – January 2017) to provide a good overview In-situ spot and long-term measurements were recorded Questionnaires were completed by 4411 children (age range from to 11 years) and 116 teachers to inform the study about their experiences and the extent of their interaction with the buildings in 124 classrooms The results were analysed by correlating the conditions measured and the comfort votes on a seven-point scale In free-running schools, more than 90% of children were satisfied with the overall indoor conditions, although the classrooms were found to be out of thermal comfort for more than 20% of the school time Furthermore, the classrooms were usually in noisy and dim conditions The conflict between the quantitative and qualitative results shows that the current standards not reflect the current expectation in the free running classrooms In the air-conditioned classrooms, the CO2 concentration levels were over 2000ppm and affected children’s alertness The calculated neutral temperature in the free running classrooms was 31.3oC with the relative humidity of 60% to 70% and an average air velocity of 0.56m/s; and a benchmark of 33°C for overheating calculations was suggested The adjusted neutral temperature with a normal air speed was 29.4oC In this study, an adaptive thermal comfort model for Vietnamese children in primary schools was proposed The thermal comfort criteria of design parameters for renovation projects and new-built buildings were recommended through parametric and optimisation studies The findings suggested that air conditioning all year round may be unnecessary from a comfort perspective These findings could help and encourage architects and engineers to design and deliver schools that provide thermal comfort and minimise the use of air conditioning systems The results of this work could inform design standards to deliver high quality, low-energy indoor environmental classrooms in primary schools in Ho Chi Minh City, Vietnam i PUBLICATIONS VI LE, T H., GILLOTT, M C & RODRIGUES, L T 2016 The case for hybrid ventilated primary schools in Ho Chi Minh City in Vietnam 36th International Conference on Passive and Low Energy Architecture Cities, Buildings, People: Towards Regenerative Environments (PLEA 2016) Los Angeles, USA LE, T H V., GILLOTT, M C & RODRIGUES, L T 2017 An analysis of thermal comfort in primary schools in Vietnam 16th International Conference on Sustainable Energy Technologies (SET2017) Bologna, Italy LE, T H V., GILLOTT, M C & RODRIGUES, L T 2017 Children thermal comfort in primary schools in Ho Chi Minh City in Vietnam Passive Low Energy Architecture Design to Thrive (PLEA 2017) Edinburgh, Scotland, UK Under preparation: LE, T H V., GILLOTT, M C & RODRIGUES, L T - expected 2021- The impact of indoor environmental quality on children’s productivity in primary schools in Vietnam ii ACKNOWLEDGEMENTS I would like to express my deepest gratitude to my supervisors, Professor Mark Gillott and Dr Lucelia Rodrigues, for their excellent guidance and supervision throughout this research project Without their support, this thesis would not have been possible The research depends very much on the field study data from various case studies I would like to thank to Mr To Huu Cuong (the headmaster of Binh Quoi Tay Primary School), Ms Pham Thi Thanh Hao (the headmistress of Phu Dong Primary School), Ms Vo Thi Kim Lien (the headmistress of Ha Huy Tap Primary School) and all of teachers and children in three primary schools for their support during the data collection of the project I am also grateful to my assistance team during the surveys I also wish to acknowledge the financial support from the Ministry of Education and Training of Vietnam, the University of Nottingham and the Newton Fund (British Council) Without their funding, this research could not have reached its goal I am heartily thankful to my colleagues in Ho Chi Minh City University of Architecture for their help and introduction to the case studies Many thanks to all of my friends in SRB, Mark Group House and Nottingham House, as well as in the UK, for spending their invaluable time with me Thanks also go to Mrs Chau Lam, my closest friend, and her family for their kind-hearted host during my time in the UK Special thanks to Mr and Mrs Peters for their love and care to me Last but not the least, I would like to express my deepest appreciation to my family: my parents, my parents in law, my husband, my sister and especially my son - Benz, for their understanding, encouragement and support throughout the research iii TABLE OF CONTENTS ABSTRACT i PUBLICATIONS ii ACKNOWLEDGEMENTS iii TABLE OF CONTENTS iv LIST OF FIGURES LIST OF TABLES 18 INTRODUCTION 22 THE CONTEXT OF HO CHI MINH CITY – VIETNAM 27 1.1 1.1.1 Climate classification 29 1.1.2 Climate for building design in Ho Chi Minh City 30 1.1.3 Summary 36 1.2 The socio-economic and urban environmental contexts 36 1.2.1 Socio-economic context 36 1.2.2 Urban environmental context 39 1.2.3 Summary 43 1.3 The context of primary education in Ho Chi Minh City 44 1.3.1 Funding and management of education 45 1.3.2 The architecture of primary schools 48 1.3.3 Summary 54 1.4 The climate context 28 Conclusion and discussion 55 INDOOR ENVIRONMENTAL QUALITY IN PRIMARY SCHOOLS 57 2.1 Thermal Comfort 58 Heat balance model 58 The adaptive thermal comfort model 61 Vietnamese standards 64 Thermal comfort studies in naturally ventilated primary schools 64 Conclusion 69 iv 2.2 Indoor Air Quality 69 Standards 70 Research 72 2.3 Visual Comfort 74 Maintained illuminance 74 Uniformity 76 Vietnamese standards 76 Research 77 2.4 Acoustic Comfort 77 Standards 78 Research 80 2.5 Indoor environmental quality 81 Standards 81 Research 83 2.6 PILOT STUDY BINH QUOI TAY PRIMARY SCHOOL 87 3.1 Description 87 3.2 Scope and Method 89 3.3 Results and discussion 92 3.3.1 Spot measurements 93 3.3.2 Long-term monitoring 95 3.4 Conclusions 84 Conclusions 97 CASE STUDY BINH QUOI TAY PRIMARY SCHOOL 99 4.1 Scope and Method 100 4.1.1 Long-term recording 101 4.1.2 Spot measurement 101 4.1.3 Questionnaire survey 102 4.1.4 International and Vietnamese Standards for indoor environmental quality 103 4.2 4.2.1 Results and discussion 103 Thermal comfort 108 v 4.2.2 Indoor air quality 122 4.2.3 Visual Comfort 124 4.2.4 Acoustic comfort 126 4.2.5 Indoor environmental quality 129 4.2.6 Occupants’ behaviour 131 4.3 CASE STUDY PHU DONG PRIMARY SCHOOL 135 5.1 Description 136 5.2 Scope and Method 140 5.2.1 Long-term recording 141 5.2.2 Spot measurement 142 5.2.3 Questionnaire survey 142 5.3 Results and Discussion 143 5.3.1 Thermal comfort 147 5.3.2 Indoor air quality 160 5.3.3 Visual Comfort 163 5.3.4 Acoustic comfort 165 5.3.5 Indoor environmental quality 168 5.3.6 Occupants’ behaviour 169 5.4 Conclusions 133 Conclusions 173 CASE STUDY HA HUY TAP PRIMARY SCHOOL 175 6.1 Description 176 6.2 Scope and Method 179 6.2.1 Long-term recording 180 6.2.2 Spot measurement 180 6.2.3 Questionnaire survey 181 6.3 Results and Discussion 181 6.3.1 Thermal comfort 187 6.3.2 Indoor air quality 196 6.3.3 Visual Comfort 198 vi 6.3.4 Acoustic comfort 200 6.3.5 Indoor environmental quality 202 6.3.6 Occupants’ behaviour 203 6.4 AN ADAPTIVE THERMAL COMFORT MODEL FOR CHILDREN 207 7.1 Case studies 208 7.2 Scope and Method 208 7.2.1 Environmental data collection 209 7.2.2 Questionnaire 209 7.2.3 Analysis 210 7.3 Results and discussion 212 7.3.1 Neutral temperature 214 7.3.2 The relationship between comfort temperature and outdoor climate 222 7.3.3 Overheating occurrence 224 7.3.4 Teachers’ thermal comfort and occupant’s behaviour 227 7.4 Indoor thermal conditions and building elements 227 7.4.1 Shape 228 7.4.2 Fabric 229 7.4.3 Fenestration 230 7.4.4 Ventilation 232 7.4.5 Summary 232 7.5 Conclusions 205 Conclusion 233 SENSITIVITY ANALYSIS OF DESIGN PARAMETERS AND THERMAL COMFORT 235 8.1 Simulation basis 236 8.1.1 Simulation software 236 8.1.2 Simulation model 237 8.1.3 Model calibration 240 8.1.4 Weather data file 242 8.1.5 Base Case 243 8.2 Parametric study 246 vii 8.2.1 Floor-to-ceiling height 246 8.2.2 Window area 248 8.2.3 Window type 250 8.2.4 Exhaust opening area 252 8.2.5 Overhang projection 254 8.2.6 Orientation 256 8.2.7 External wall material 258 8.2.8 Roof system 261 8.2.9 Infiltration 264 8.2.10 Additional natural ventilation 266 8.2.11 Summary 268 8.3 8.3.1 Method 270 8.3.2 Results and discussion 271 8.4 Optimisation study 269 Conclusion 274 CONCLUSIONS 277 9.1 Significance and impact of the study 281 9.2 Originality and contribution to knowledge 281 9.3 Recommendations for further work 282 REFERENCES 283 APPENDIX A 295 APPENDIX B 298 APPENDIX C 302 viii LIST OF FIGURES Figure 1-1 Ho Chi Minh City at (a) daytime and (b) night time (Long T Nguyen, 2019) 27 Figure 1-2 Administrative map of Socialist Republic of Vietnam (Center of Survey and Mapping Data, 2020) 28 Figure 1-3 Koppen-Geiger map of Asia showing climate type (Aw) of Ho Chi Minh City (Peel et al., 2007) 29 Figure 1-4 Building climate zones in Vietnam (Ministry of Construction, 2009) 30 Figure 1-5 Urban districts (bright shaded) and rural districts (dark shaded) (Google, 2020) 30 Figure 1-6 Monthly mean precipitation of Ho Chi Minh City 31 Figure 1-7 Monthly mean air temperature of Ho Chi Minh City 32 Figure 1-8 Air temperature during typical days of the hottest month (April) and the coldest month (December) in Ho Chi Minh City 32 Figure 1-9 Monthly average relative humidity of Ho Chi Minh City 33 Figure 1-10 Relative humidity during typical days of the hottest month (April) and the coldest month (December) in Ho Chi Minh City 33 Figure 1-11 Wind velocity and main wind direction of Ho Chi Minh City 34 Figure 1-12 Stereographic Diagram of Ho Chi Minh City (Andrew Marsh, 2014) 34 Figure 1-13 Total sunshine hours during a year in Ho Chi Minh City 35 Figure 1-14 Monthly mean global solar radiation on horizontal surfaces in Ho Chi Minh City 35 Figure 1-15 The density of (a) an urban area (District 5) and (b) a rural area (Binh Chanh District) (Google, 2020) 37 Figure 1-16 Population pyramid of Ho Chi Minh City in 2014 (General Statistics Office, 2016a) 38 Figure 1-17 Urban environmental threats from both climate change impacts and urban development patterns (Gravert, 2011) 39 Figure 1-18 Rankings of the most PM2.5 levels across South East Asian countries (IQAir AirVisual, 2018) 42 Figure 1-19 Hourly AQI level in the first quarter during recent years in Ho Chi Minh City 42 Figure 1-20 The national education system in Vietnam (Ministry of Education and Training, 2016) 44 Figure 1-21 State funding for school constructions and the number of new classrooms put into use (Ho Chi Minh City People’s Committee, 2017) 47 Figure 1-22 Timeline of Saigon – Ho Chi Minh City history of development and relationship to Modern Architecture (Truong and Vu, 2018) 49 ... conditions of investigated classrooms in School in the mid-season (continued) 105 Table 4-7 Environmental parameters and indoor conditions of investigated classrooms in School in the hottest... and indoor conditions of investigated classrooms in School in the coldest season 107 Table 4-10 Environmental parameters and indoor conditions of investigated classrooms in School in. .. indoor conditions of investigated classrooms in School in the hottest season 144 Table 5-5 Environmental parameters and indoor conditions of investigated classrooms in School in the hottest