Developing an Adaptive Model of Thermal Comfort and Preference FINAL REPORT ASHRAE RP- 884 March 1997 Richard de DearÀ, Gail BragerÁ, Donna CooperÀ À Macquarie Research Ltd., Macquarie University, Sydney, NSW 2109 AUSTRALIA Á Center for Environmental Design Research, University of California, Berkeley, CA 94720 USA “Results of Cooperative Research between the American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc., and Macquarie Research, Ltd.” i ii i TABLE OF CONTENTS iii ACKNOWLEDGMENTS vii EXECUTIVE SUMMARY ix CHAPTER 1 - INTRODUCTION & BACKGROUND 1 1.1. Introduction 1 1.2. Defining the adaptive process 3 1.2.1. The dialectic of contemporary thermal comfort theory 3 1.2.2. The “adaptive” hypothesis 4 1.3. A conceptual model of adaptation -- feedback loops 6 1.3.1. Behavioral feedback - adjustment 8 1.3.2. Physiological feedback -- acclimatization 10 1.3.3. Psychological feedback -- habituation and expectation 12 1.4. Literature review 13 1.4.1. Climate chamber evidence for adaptation to climate 13 1.4.2. Field evidence for adaptation 15 1.4.2.1. The earlier field evidence for adaptation 16 1.4.2.2. Analysis of neutral temperatures using recent field experiments 18 1.4.2.3. Evidence for behavioral adaptation - personal/environmental adjustment 22 1.4.2.4. Evidence for psychological adaptation - expectation and context 23 1.5. Implications for RP-884 26 1.5.1. Lessons from static heat balance models 26 1.5.2. Time scales of thermal adaptation 29 1.6. Aims 31 CHAPTER 2 - METHODS 33 2.1. Overview of the RP-884 approach 33 2.2. Establishing the database for RP-884 36 2.2.1. Sourcing the raw data 36 2.2.2. Ratings of raw data submitted to RP-884 40 2.3. Raw data standardisation 41 2.3.1. Creation of a standard data template 41 2.3.2. Consistent mean radiant temperatures within the database. 42 2.3.3. Consistent comfort index calculations within the database 42 2.3.4. Predicted draft risk index (PD) 43 2.3.5. Clothing insulation in the ASHRAE RP-884 database 44 2.3.5.1. Discrepancies between field estimation methods for clo. 45 2.3.5.2. The chair insulation effect 49 2.4. Developing an index for perceived thermal control 49 iii 2.5. Thermal acceptability issues within the RP-884 database 51 2.5.1. Developing a proxy variable for thermal acceptability based on thermal sensation votes. 51 2.5.2. Rating buildings in terms of their compliance with ASHRAE Standard 55 acceptable indoor climate guidelines 52 2.6. Outdoor meteorological/climatological data for the data base 52 2.6.1. Appending outdoor weather observations to each row of data 52 2.6.2. Climate classification applied to RP-884 raw data 53 2.7. Subdivision of the standardized field experiments 54 2.8. The meta-analysis 54 2.8.1. The unit of analysis for the RP-884 meta-analysis 54 2.8.2. Meta-file’s structure and coding conventions 55 2.8.3. General assumptions within the statistical meta-analysis 55 2.8.4. Statistical treatments on the various subjective thermal ratings 56 2.8.5. Preferred temperatures 59 2.9. The RP-884 database in the public domain and disseminated via the world wide web 60 2.10. Summary of the methods used in RP-884 64 CHAPTER 3 - BASIC RESULTS 67 3.1. Interactions with indoor climate 67 3.1.1. Thermal sensation 67 3.1.1.1. Dependence of thermal sensation on indoor operative temperature 68 3.1.1.2. Dependence of thermal sensation on indoor ET 69 3.1.1.3. Dependence of thermal sensation on PMV 70 3.1.1.4. Dependence of thermal sensation on indoor SET 71 3.1.2. Thermal neutrality 72 3.1.2.1. Neutral operative temperatures (neut_top) 72 3.1.2.2. Neutral effective temperatures (neut_et) 74 3.1.2.3. Neutral predicted mean votes (neut_pmv) 74 3.1.2.4. Predicted neutralities with the PMV heat balance model 75 3.1.2.5. Neutral standard effective temperatures (neut_set) 77 3.1.3. Thermal acceptability and indoor climate 78 3.1.3.1. Relationship between direct and inferred thermal acceptability 78 3.1.3.2. Directly determined thermal acceptability 80 3.1.3.3. Thermal acceptability inferred from thermal sensation 83 3.1.3.4. Thermal sensitivity and the range of thermally acceptable temperatures. 84 3.1.4. Thermal preferences and indoor climate 89 3.1.5. Comparisons between neutral and preferred temperatures indoors. 91 3.1.6. Behavioural adjustments to indoor climate 93 3.1.6.1. Thermal insulation adjustments indoors 94 3.1.6.2. Metabolic rate adjustments indoors 97 3.1.6.3. Air speed adjustments indoors 99 iv 3.2. Interactions with outdoor weather and climate 102 3.2.1. Thermal neutrality and outdoor climate 102 3.2.1.1. Seasonal comparisons 103 3.2.1.2. Dependence of observed neutrality on outdoor climate 104 3.2.1.3. Analysis of predicted neutralities with respect to mean outdoor temperature 106 3.2.2. Thermal acceptability and outdoor climate 108 3.2.3. Thermal preference and outdoor climate 110 3.2.4. Behavioral responses to outdoor climate 113 3.2.4.1. Indoor clothing and outdoor climate 114 3.2.4.2. Metabolic rate indoors related to outdoor climate 115 3.2.4.3. Indoor air speeds in relation to outdoor climate 116 3.3. Influence of building characteristics on thermal comfort 118 3.3.1. HVAC versus natural ventilation 118 3.3.1.1. Thermal sensation and sensitivity in HVAC versus naturally ventilated buildings 119 3.3.1.2. Thermal acceptability in HVAC versus naturally ventilated buildings 121 3.3.1.3. Thermal preferences in HVAC versus naturally ventilated buildings. 122 3.3.2. Personal environmental control 124 3.3.3. Building occupancy types - offices, residential and industrial 127 3.4. Summary of basic results 130 3.4.1. Summary of thermal sensation, acceptability and preference 131 3.4.2. Summary of thermal sensitivity and behavioral thermoregulation 133 3.4.3. Summary of the effects of outdoor climate on thermal perception indoors 134 3.4.4. Summary of the effects of contextual factors and perceived control 135 CHAPTER 4 - TOWARDS ADAPTIVE MODELS 139 4.1. The semantics of thermal comfort 139 4.2. Comparison of RP-884 models with earlier adaptive model publications 141 4.3. Comparison of RP-884 models with the PMV “static model” 145 4.3.1. Comparisons within the centrally conditioned building sample 146 4.3.2. Comparisons within the naturally ventilated building sample 150 4.4. Adaptive models for acceptable ranges of indoor temperatures 152 CHAPTER 5 - VARIABLE TEMPERATURE STANDARDS 155 5.1. A variable temperature standard for application in buildings with centrally controlled HVAC 155 5.1.1. Purpose 155 5.1.2. Scope 156 5.1.3. Definitions 156 5.1.4. Conditions for an acceptable thermal environment. 161 5.1.4.1. Analytic PMV method 161 5.1.4.2. Adaptive PMV method 161 5.1.4.3. Prescriptive method 163 5.2. A variable temperature standard for application in naturaly ventilated buildings 165 v 5.2.1. Purpose 165 5.2.2. Scope 165 5.2.3. Definitions 166 5.2.4. Conditions for an acceptable thermal environment. 168 BIBLIOGRAPHY 171 APPENDIX A - THERMAL SENSATION AND NEUTRALITY FOR EACH BUILDING IN THE RP-884 DATABASE 185 APPENDIX B - PREFERRED TEMPERATURE FOR EACH BUILDING IN THE RP-884 DATABASE 227 APPENDIX C - SUMMARY OF THE ORIGINAL FIELD EXPERIMENTS COMPRISING THE ASHRAE RP-884 DATABASE 235 C.1. Project Title - ASHRAE TC 2.1 sponsored RP-702 236 C.2. Project Title - Thermal comfort studies in modern industrial buildings. 239 C.3. Project Title - Doctoral dissertation. From comfort to kilowatts: An integrated assessment of electricity conservation in Thailand’s commercial sector. 242 C.4. Project Title - The CSAA, Antioch (1995) component of the Advanced Customer Technology Test (ACT2) project. 245 C.5. Project Title - Higher PMV causes higher energy consumption in air- conditioned buildings: a case study in Jakarta, Indonesia. 248 C.6. Project Title - Montreal ASHRAE RP-821. 250 C.7. Project Title - Richard de Dear’s PhD research project in Australia. 253 C.8. Project Title - A field study of thermal comfort using questionnaire software. 256 C.9. Project Title - “Thermal comfort in Pakistan.” 258 C.10. Project Title - Comfort criteria for passively cooled buildings. a PASCOOL task. 262 C.11. Project Title - Developing indoor temperatures for naturally ventilated buildings. 264 C.12. Project Title - Mixed mode climate control: some hands-on experience. 267 C.13. Project Title - ASHRAE sponsored RP-462. San Francisco area. 269 C.14. Project Title - A field investigation of thermal comfort environmental satisfaction and perceived control levels in UK office buildings, University of Liverpool. 272 C.15. Project Title - Thermal comfort in the humid tropics: field experiments in air conditioned and naturally ventilated buildings in Singapore. 275 C.16. Project Title - The Steelcase building. Grand Rapids Michigan, US 277 C.17. Project Title - Sunset building: a study of occupant thermal comfort in support of PG&E’s Advanced Customer Technology Test (ACT2) for maximum energy efficiency 279 C.18. Project Title - The Verifone building, a component of the Advanced Customer Technology Test (ACT2) Project. 282 APPENDIX D - CLIMATE CLASSIFICATION 285 APPENDIX E - CODEBOOK FOR RAW DATA IN RP-884 DATABASE 287 vi APPENDIX F - CODEBOOK FOR THE RP-884 META-ANALYSIS 291 APPENDIX G - AULICIEMS’ ADAPTIVE MODEL DATABASE 295 ACKNOWLEDGMENTS The successful completion of this project depended very heavily on the willingness of field researchers to make available their raw data for re-analysis and incorporation into the RP- 884 database.