Applied Building Physics

Dr. Ir. Hugo S.L.C. Hens is an emeritus professor of the University of Leuven (KULeuven), Belgium. Until 1972, he worked as a structural engineer and site supervisor at a mid-sized architectural office. After the sudden death of his predecessor and promotor Professor A. de Grave in 1975 and after defending his PhD thesis, he stepwise built up the Department of Building Physics at the Department of Civil Engineering. He taught Building Physics from 1975 to 2003, performance based building design from 1975 to 2005 and building services from 1975 to 1977 and 1990 to 2008. He authored and co-authored 68 peer reviewed journal papers and 174 conference papers about the research done, has helped to manage hundreds of building damage cases and acted as coordinator of the CIB W40 working group on Heat and Mass Transfer in Buildings from 1983 to 1993. Between 1986 and 2008, he was operating agent of the Annexes 14, 24, 32 and 41 of the IEA EXCO on Energy in Buildings and Communities. He is a fellow of the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE).

• Preface xvAbout the Author xviiList of Units and Symbols Introduction 1Subject of the Book 1Further Reading 21 Ambient Conditions Out- and Indoors 31.1 Overview 31.2 Outdoors 51.2.1 In General 51.2.2 Air Temperature 61.2.3 Solar Radiation 91.2.3.1 In General 91.2.3.2 Beam Radiation 111.2.3.3 Diffuse Radiation 131.2.3.4 Reflected Radiation 151.2.3.5 Total Radiation 151.2.4 Clear Sky Long Wave Radiation 151.2.5 Relative Humidity (RH) and (Partial Water) Vapour Pressure 181.2.6 Wind 201.2.6.1 Impact 201.2.6.2 Wind Speed 211.2.6.3 Wind Pressure 221.2.7 Rain 231.2.7.1 Impact 231.2.7.2 Precipitation 231.2.7.3 Wind-driven Rain 251.2.8 Microclimate Around Buildings 281.2.9 Standardized Outside Climate Data 281.2.9.1 Design Temperature 281.2.9.2 Very Hot Summer, Very Cold Winter Day 301.2.9.3 Moisture Reference Year 301.2.9.4 Equivalent Temperature for Condensation and Drying 321.2.9.5 Monthly Mean Vapour Pressure Outdoors 351.3 Indoors 351.3.1 In General 351.3.2 Air Temperature 351.3.2.1 In General 351.3.2.2 Measured Data 361.3.3 Relative Humidity (RH) and Vapour Pressure 371.3.3.1 In General 371.3.3.2 Vapour Release Indoors 381.3.3.3 Measured Data 381.3.3.4 Indoor Climate Classes 451.3.4 Indoor to Outdoor Air Pressure Differentials 47Annex: Solar Radiation at Uccle, Belgium (50 ∘ 51 ′ N, 4 ∘ 21 ′ E) 48Further Reading 592 Performance Metrics and Arrays 632.1 Definitions 632.2 Functional Demands 632.3 Performance Requirements 642.4 A Short History 642.5 Performance Arrays 662.5.1 Overview 662.5.1.1 The Built Environment 662.5.1.2 Whole Buildings and Building Assemblies 662.5.2 Some Demands More in Detail 702.5.2.1 Functionality 702.5.2.2 Structural Adequacy 702.5.2.3 Building Physics-Related Requirements 712.5.2.4 Fire Safety 712.5.2.5 Durability 722.5.2.6 Sustainability 732.5.2.7 Maintenance 73Further Reading 733 Performance Demands at the Whole Building Level 753.1 In Brief 753.2 Thermal, Acoustical, Visual and Olfactory Comfort 753.2.1 In General 753.2.2 Thermal Comfort 763.2.2.1 Physiological Basis 763.2.2.2 The Autonomous Control System 773.2.2.3 Steady State Thermal Comfort, A Physiological Approach 783.2.2.4 Comfort Parameters and Variables 813.2.2.5 Steady State Thermal Comfort, the Adaptive Model 853.2.2.6 Thermal Comfort Under Non-uniform, Non-steady-state Conditions 863.2.2.7 Local Discomfort 873.2.2.8 Standard-based Comfort Requirements 893.2.2.9 Consequences for the Enclosure Performance 923.2.3 Acoustical Comfort 933.2.3.1 Anatomy of the Ears 933.2.3.2 Physiological Facts 943.2.3.3 Effects of Unacceptable Noise 943.2.3.4 Comfort Values 973.2.4 Visual Comfort 993.2.4.1 Anatomy of the Eyes 993.2.4.2 Physiological Facts 993.2.4.3 Comfort Values 1003.2.5 Olfactory Comfort 1023.2.5.1 Anatomy of the Nose 1023.2.5.2 Physiological Facts 1023.2.5.3 Comfort Values 1023.3 Health and Indoor Environmental Quality (IEQ) 1033.3.1 In General 1033.3.2 Health 1043.3.3 Definitions 1043.3.4 Relation Between Pollution Out- and Indoors 1053.3.5 Process-related Contaminants, Some Coming from Outdoors 1053.3.5.1 Dust, Vapours, Smoke, Mist and Gaseous Clouds 1053.3.5.2 Fibres 1063.3.5.3 Ozone 1073.3.6 Contaminants Emitted by Materials and Other Sources 1073.3.6.1 (Semi) Volatile Organic Compounds ((S)VOCs) 1073.3.6.2 Formaldehyde (HCHO) 1083.3.6.3 Phthalates 1083.3.6.4 Pentachlorophenol 1093.3.7 Soil Linked Radon 1093.3.8 Combustion Linked Contaminants 1103.3.8.1 In General 1103.3.8.2 Carbon Monoxide (CO) 1113.3.8.3 Nitrous Dioxide (NO 2) 1113.3.9 Bio-germs 1113.3.9.1 Viruses 1113.3.9.2 Bacteria 1113.3.9.3 Moulds 1123.3.9.4 Dust Mites 1143.3.9.5 Insects 1153.3.9.6 Rodents 1153.3.9.7 Pets 1153.3.10 Human Related Contaminants 1153.3.10.1 In General 1153.3.10.2 Carbon Dioxide (CO 2) 1163.3.10.3 Water Vapour 1163.3.10.4 Bio-odours 1163.3.10.5 Tobacco Smoke 1163.3.11 Perceived Indoor Air Quality 1183.3.11.1 Odour 1183.3.11.2 Indoor Air Enthalpy 1193.3.12 Sick Building Syndrome 1203.3.13 Contaminant Control 1213.3.13.1 In General 1213.3.13.2 Minimizing the Emissions 1213.3.13.3 Ventilation 1213.3.13.4 Air Cleaning and Personal Protective Measures 1303.4 Energy Efficiency 1313.4.1 The Problem 1313.4.2 Some Statistics 1323.4.3 End Energy Use in Buildings 1323.4.3.1 In General 1323.4.3.2 Lighting and Appliances 1333.4.3.3 Domestic Hot Water 1353.4.3.4 Space Heating, Cooling and Air Conditioning 1363.4.4 Space Heating, Steady-state 1363.4.4.1 Terminology 1363.4.4.2 Steady State Heat Balance at Zone Level 1383.4.4.3 Whole Building Net Heating Balance 1433.4.4.4 Annual End Energy Use for Heating 1443.4.4.5 Protected Volume Seen as One Zone at Given Temperature 1453.4.5 Simple Methods to Guess the Annual End Energy Use for Heating 1453.4.5.1 When Predesigning Single-family Houses 1453.4.5.2 Using Degree-days 1453.4.6 Space Conditioning and Overheating, Non-steady-state Evaluation 1463.4.6.2 Methodologies 1463.4.6.3 Harmonic Analysis in Detail 1483.4.6.4 Lines of Influence in Detail 1543.4.6.5 Control Volumes in Detail (CVM) 1563.4.7 Residential Buildings, Factors Shaping the Net Heating Demand 1573.4.7.1 Overview 1573.4.7.2 Outdoor Climate 1573.4.7.3 Building Use 1583.4.7.4 Building Design and Construction 1663.4.8 Residential Buildings, Factors Fixing the Net Cooling Demand 1753.4.9 Residential Buildings, Gross Energy Demand and End Use for Heating and Cooling 1753.4.10 Residential Buildings Ranked in Terms of Energy Efficiency 1773.4.10.1 Insulated 1773.4.10.2 Energy Efficient 1773.4.10.3 Low Energy 1773.4.10.4 Passive 1773.4.10.5 Nearly Net Zero (nZEB) 1773.4.10.6 Net Zero (ZEB) 1783.4.10.7 Net Plus 1783.4.10.8 Energy Autarkic 1783.4.10.9 Zero Carbon 1783.4.11 Non-residential Buildings, From Net Demand to Primary Energy Use 1793.4.11.1 In General 1793.4.11.2 School Renovation as Exemplary Case 1793.5 Durability 1823.5.1 In General 1823.5.2 Loads 1833.5.3 Damage Patterns 1843.5.3.1 Decrease in Thermal Insulation Performance 1843.5.3.2 Decrease in Strength and Stiffness 1853.5.3.3 Stress, Strain, Deformation and Cracking Induced 1853.5.3.4 Biological Attack 1883.5.3.5 Frost 1903.5.3.6 Salt Attack 1943.5.3.7 Chemical Attack 1983.5.3.8 Corrosion 1993.6 Economics 2013.6.1 In General 2013.6.2 Total and Net Present Value 2013.6.3 Optimal Insulation Thickness 2023.6.4 Whole Building Optimum 2033.6.4.1 Methodology 2033.6.4.2 Application 2043.7 Sustainability 2103.7.1 In General 2103.7.2 Life Cycle Inventory and Analysis (LCIA) 2113.7.2.1 Definition 2113.7.2.2 Some Criteria 2123.7.2.3 Total Energy Use 2153.7.2.4 Recycling 2163.8 High-performance Buildings 2163.8.1 In General 2163.8.2 Rationale Developed for Governmental Office Building 217Further Reading 2204 Heat, Air, Moisture (HAM) Metrics at the Building Assembly Level 2294.1 Introduction 2294.2 Airtightness 2294.2.1 Airflow Patterns 2294.2.2 Performance Requirements 2314.2.2.1 Air In- and Exfiltration 2314.2.2.2 Indoor Air Washing, Wind Washing and Air Looping 2324.3 Thermal Transmittance 2334.3.1 Definitions 2334.3.1.1 Opaque Envelope Assemblies Above Grade 2334.3.1.2 Floors on Grade as Three Dimensional Case 2334.3.1.3 Other Three Dimensional Cases 2354.3.1.4 Transparent Parts 2354.3.1.5 Whole Envelopes 2374.3.2 Basis for Requirements 2384.3.2.1 Envelope Parts 2384.3.2.2 Whole Envelopes 2384.3.3 Examples of Requirements 2384.3.3.1 Remark 2384.3.3.2 Envelope Parts 2384.3.3.3 Whole Envelopes 2384.4 Transient Thermal Response 2424.4.1 Properties of Importance 2424.4.2 Performance Requirements 2434.4.3 Consequences for the Building Fabric 2444.5 Moisture Tolerance 2454.5.1 In General 2454.5.2 Construction Moisture 2454.5.2.1 Definition 2454.5.2.2 Performance Requirements 2464.5.2.3 Consequences for the Building Fabric 2464.5.3 Rain 2484.5.3.1 In General 2484.5.3.2 Performance Requirements 2504.5.3.3 Modelling 2504.5.3.4 Consequences for the Building Envelope 2524.5.4 Rising Damp 2564.5.4.1 Definition 2564.5.4.2 Performance Requirements 2564.5.4.3 Modelling 2574.5.4.4 Avoiding or Curing Rising Damp 2594.5.5 Pressure Heads 2614.5.5.1 Definition 2614.5.5.2 Performance Requirements 2614.5.5.3 Modelling 2624.5.5.4 Protecting the Building Fabric 2624.5.6 Accidental Leakages 2634.5.7 Hygroscopicity 2634.5.7.1 Definition 2634.5.7.2 Performance Requirements 2644.5.7.3 Modelling 2644.5.7.4 Consequences for the Building Fabric 2654.5.8 Surface Condensation 2654.5.8.1 Definition 2654.5.8.2 Performance Requirements 2654.5.8.3 Modelling 2654.5.8.4 How to Avoid? 2674.5.9 Interstitial Condensation 2674.5.9.1 Definition 2674.5.9.2 Modelling 2674.5.9.3 Performance Requirements 2754.5.9.4 How to avoid? 2764.5.9.5 Remark 2764.5.10 Heat, Air, Moisture (HAM) Modelling, All Moisture Sources Combined 2774.5.10.1 Modelling 2774.5.10.2 Performance Requirements 2784.5.10.3 Why Full Models Still Have Limitations 2794.5.10.4 Usability of Full HAM Tools 2834.6 Thermal Bridging 2874.6.1 Definition 2874.6.2 Performance Requirements 2884.6.3 Consequences for the Envelope 2884.7 Contact Coefficients 2884.8 Hygrothermal Stress and Strain 2884.9 Transparent Parts: Solar Transmittance 2894.9.1 Definition 2894.9.2 Performance Requirements 2904.9.3 Consequences for the Envelope 290Further Reading 2905 The Envelope Parts Heat Air Moisture (HAM) Performances applied to Timber-Frame 2955.1 In General 2955.2 Assembly 2955.3 Performance Evaluation 2965.3.1 In General 2965.3.2 Airtightness 2965.3.3 Thermal Transmittance 2975.3.4 Transient Response 2995.3.5 Moisture Tolerance 3005.3.5.1 Construction Moisture 3005.3.5.2 Rain 3005.3.5.3 Rising Damp 3015.3.5.4 Hygroscopic Moisture and Surface Condensation 3025.3.5.5 Interstitial Condensation 3025.3.5.6 More Advanced Modelling 3085.3.6 Thermal Bridging 310Further Reading 310Appendix: Heat, Air, Moisture (HAM) Material Properties 311A.1 Heat Related, Standard Values; Applicable In- and Outside of the Thermal Insulation 311A.2 Heat Related, Standard Values; Differentiating Between In- and Outside of the Thermal Insulation 315A.3 Air-Related, Measured Values 323A.4 Water Vapour Related: Vapour Resistance Factor, Standard Values 331Index 337