Bad experiences with construction quality, the energy crises of 1973 and 1979, complaints about "sick buildings", thermal, acoustical, visual and olfactory discomfort, the need for good air quality, the move towards energy efficiency, decarbonization and sustainability ? all these have accelerated the development of a discipline that, for a long time, was hardly more than an academic exercise: building physics. The discipline embraces domains such as heat and mass transfer, building acoustics, lighting, indoor environmental quality, energy efficiency, and, in some countries, fire safety. Through the application of physical knowledge and its combination with information coming from other disciplines, building physics helps to under-stand the physical phenomena governing building parts, building envelope, whole building and built environment performance ? called urban physics. Today, building physics has be-come a key player on the road to highly performing new buildings and renovations. This book deals with heat, air and moisture transport in building parts or assemblies and whole buildings with emphasis on the building engineering applications. Compared to the third edition, this fourth edition has been expanded in chapter 1 to include the physical determination of the thermal conductivity of materials, together with an in-depth discussion of all the effects of thicker insulation layers. In chapter 2, additional information has been added on wind pressure and the evaluation of condensation inside the building com-ponents, while a new chapter 4 on material properties has been included. The whole book, including the figures, has been revised and restructured where necessary.

Table of Contents:
Preface xv About the Author xix List of Units and Symbols xxi 0 Introduction 1 0.1 Subject of the Book 1 0.2 Building Physics? 1 0.2.1 Definition 1 0.2.2 Constraints 2 0.2.2.1 Comfort 2 0.2.2.2 Health andWell-being 3 0.2.2.3 Architecture and Materials 3 0.2.2.4 Economy 3 0.2.2.5 Sustainability 3 0.3 Importance? 4 0.4 History 5 0.4.1 In General 5 0.4.2 Applied Physics 5 0.4.2.1 Heat, Air, Moisture 5 0.4.2.2 Acoustics 8 0.4.2.3 Lighting 9 0.4.3 Indoor Air Quality and Thermal Comfort 9 0.4.4 Building Services 11 0.4.5 Building Design and Construction 11 0.4.6 Hall of Fame 12 0.4.7 Building Physics at the KULeuven and Other Universities in the Low Countries 13 Further Reading 15 1 Heat Transfer 17 1.1 In General 17 1.1.1 Heat 17 1.1.1.1 What? 17 1.1.1.2 Sensible Heat 17 1.1.1.3 Latent Heat 18 1.1.2 Temperature 18 1.1.3 Why are Heat and Temperature so Compelling? 18 1.1.4 Some Definitions 19 1.2 Conduction 19 1.2.1 Conservation of Energy 19 1.2.2 Conduction Laws 20 1.2.2.1 First Law 20 1.2.2.2 Second Law 22 1.2.3 Thermal Conductivity 22 1.2.3.1 In General 22 1.2.3.2 Heat Transfer Modes Fixing the Property 22 1.2.4 Steady-State 26 1.2.4.1 What? 26 1.2.4.2 One Dimension, Flat Assemblies 27 1.2.4.3 Two Dimensions, Cylinder Symmetric 33 1.2.4.4 Two and Three Dimensions: Thermal Bridges 35 1.2.5 Non-steady-state 38 1.2.5.1 In General 38 1.2.5.2 Periodic Boundary Conditions, Flat Assemblies 39 1.2.5.3 Any Boundary Conditions, Flat Assemblies 48 1.2.5.4 Two and Three Dimensions: Thermal Bridges 52 1.3 Heat Exchange at Surfaces by Convection and Radiation 52 1.3.1 What? 52 1.3.2 Convection 53 1.3.2.1 In General 53 1.3.2.2 Typology 55 1.3.2.3 Quantifying the Convective Surface Film Coefficient 55 1.3.2.4 Values for the Convective Surface Film Coefficient 58 1.3.3 Radiation 63 1.3.3.1 In General 63 1.3.3.2 Definitions 63 1.3.3.3 Reflection, Absorption and Transmission 64 1.3.3.4 Radiant Surfaces 66 1.3.3.5 Simple Formulae 74 1.4 Building-related Applications 76 1.4.1 Surface Film Coefficients and Reference Temperatures 76 1.4.1.1 Methodology 76 1.4.1.2 Indoors 76 1.4.1.3 Outdoors 78 1.4.2 Steady-state, Flat Assemblies 80 1.4.2.1 Thermal Transmittance of Envelope Assemblies, Partitions and PartyWalls 80 1.4.2.2 Average Thermal Transmittance of Envelope Parts in Parallel 83 1.4.2.3 Electrical Analogy 84 1.4.2.4 Thermal Resistance of Non-ventilated Cavities 84 1.4.2.5 Interface Temperatures 86 1.4.2.6 Effect of Ever Thicker Insulation Layers on the Thermal Transmittance 87 1.4.2.7 Solar Transmittance 88 1.4.3 Local Inside Surface Film Coefficients 91 1.4.4 Steady-state: Two and Three Dimensions 92 1.4.4.1 Pipes 92 1.4.4.2 Floors on Grade 93 1.4.4.3 Thermal Bridges 94 1.4.4.4 Windows 98 1.4.4.5 Building Envelopes 99 1.4.5 Heat Balances 100 1.4.6 Non-steady-state 101 1.4.6.1 Periodic Boundary Conditions: Flat Assemblies 101 1.4.6.2 Periodic Boundary Conditions: Spaces 101 1.4.6.3 Any Boundary Conditions: Thermal Bridges 105 Problems and Solutions 106 Further Reading 118 2 Mass Transfer 121 2.1 In General 121 2.1.1 Facts 121 2.1.2 Definitions 122 2.1.3 Saturation Degree Scale 123 2.1.4 Air and Moisture Transfer 123 2.1.5 Moisture Sources 125 2.1.6 Air and Moisture in Relation to Durability 127 2.1.7 Links with Energy Transfer 127 2.1.8 Conservation of Mass 128 2.2 Air 129 2.2.1 In General 129 2.2.2 Air Pressure Differentials 130 2.2.2.1 Wind 130 2.2.2.2 Stack Effect 130 2.2.2.3 Fans 133 2.2.3 Air Permeability and Air Permeances 133 2.2.4 Airflow in Open-porous Materials 135 2.2.4.1 The Conservation Law Adapted 135 2.2.4.2 One Dimension: Flat Assemblies 138 2.2.4.3 Two and Three Dimensions 139 2.2.5 Airflow Through Assemblies with Air-open Layers, Leaky Joints, Leaks, Cavities, etc. 140 2.2.6 Airflow at the Building Level 141 2.2.6.1 Definitions 141 2.2.6.2 Thermal Stack 142 2.2.6.3 Large Openings 142 2.2.6.4 The Conservation Law Applied 143 2.2.6.5 Applications 145 2.2.7 Combined Heat and Airflow Through Assemblies Composed of Open-porous Layers 148 2.2.7.1 Heat Balance 148 2.2.7.2 Steady-state: Flat Assemblies 148 2.2.7.3 Steady-state, Two and Three Dimensions 152 2.2.7.4 Non-steady-state, Flat Assemblies 152 2.2.7.5 Non-steady-state, Two and Three Dimensions 153 2.2.7.6 Air-permeable Layers, Joints and Leaks 153 2.2.7.7 Vented Cavities 153 2.3 Water Vapour 156 2.3.1 Water Vapour in the Air 156 2.3.1.1 In General 156 2.3.1.2 Quantities 156 2.3.1.3 Vapour Saturation Pressure 157 2.3.1.4 Relative Humidity 157 2.3.1.5 Changes of State in Humid Air 161 2.3.1.6 Enthalpy of Humid Air 162 2.3.1.7 Measuring Air Humidity 162 2.3.2 Vapour Balance in Spaces 163 2.3.3 Relative Humidity On Inside Surfaces 165 2.3.4 Vapour in Open-porous Materials 168 2.3.4.1 Different from Air? 168 2.3.4.2 Sorption/Desorption Isotherm 168 2.3.5 Vapour Transfer in the Air 172 2.3.6 Vapour Flow by Diffusion in Open-porous Materials and Building Assemblies 174 2.3.6.1 Flow Equation 174 2.3.6.2 Vapour Resistance Factor μ 175 2.3.6.3 Mass Conservation 176 2.3.6.4 Applicability of the Diffusion Concept 177 2.3.6.5 Steady State: Flat Assemblies 177 2.3.6.6 Steady State: Two and Three Dimensions 186 2.3.6.7 Non-steady State 187 2.3.7 Vapour Flow by Diffusion and Moist Air Moving Through Open-porous Assemblies 189 2.3.7.1 In General 189 2.3.7.2 Isothermal, Single- and Multi-layered Assemblies 190 2.3.7.3 Non-isothermal, Single- and Multi-layered Assemblies 191 2.3.8 Surface Film Coefficients for Diffusion 195 2.3.8.1 Derivation 195 2.3.8.2 Applications 198 2.3.9 Evaluating Interstitial Condensation in Practice 201 2.3.9.1 Boundary Conditions Used 201 2.3.9.2 Calculation Sequence 203 2.3.9.3 Example 204 2.4 Moisture 209 2.4.1 In General 209 2.4.2 Water Flow in a Pore 209 2.4.2.1 Capillarity 209 2.4.2.2 Poiseuille’s Law 211 2.4.2.3 IsothermalWater Flow in a Pore ContactingWater 212 2.4.2.4 IsothermalWater Flow in a Pore AfterWater Contact 218 2.4.2.5 Non-isothermalWater Transfer in a Pore AfterWater Contact 218 2.4.2.6 Remark 219 2.4.3 Vapour Flow in a Pore ContainingWater Isles with Air Inclusions in Between 219 2.4.3.1 A Short Description 219 2.4.3.2 Isothermal 219 2.4.3.3 Non-isothermal 220 2.4.4 Moisture Flow in and Through Materials and Assemblies 221 2.4.4.1 Transport Equations 221 2.4.4.2 Moisture Permeability 223 2.4.4.3 Mass Conservation 223 2.4.4.4 Starting, Boundary and Contact Conditions 224 2.4.4.5 Remarks 224 2.4.5 Simple Moisture Flow Model 225 2.4.5.1 How to Do? 225 2.4.5.2 Applying the Simple Model 227 Problems and Solutions 240 Further Reading 261 3 Heat, Air and Moisture Combined 265 3.1 Why? 265 3.2 Material and Assembly Level 265 3.2.1 Assumptions 265 3.2.2 Solution 266 3.2.3 Conservation of Mass 266 3.2.4 Conservation of Energy 267 3.2.5 Flux Equations 270 3.2.5.1 Heat 270 3.2.5.2 Mass, Air 270 3.2.5.3 Mass, Moisture 270 3.2.5.4 Remark 271 3.2.6 Equations of State 271 3.2.6.1 Enthalpy and Vapour Saturation Pressure in Relation to Temperature 271 3.2.6.2 Relative Humidity in Relation to Moisture Content 271 3.2.6.3 Suction in Relation to Moisture Content 271 3.2.7 Start, Boundary and Contact Conditions 271 3.2.8 Two Examples of Simplified Models 272 3.2.8.1 Assemblies Composed of Non-Hygroscopic, Non-Capillary Materials 272 3.2.8.2 Assemblies Composed of Fine Porous, Hygroscopic Materials 274 3.3 Whole Building Level 274 3.3.1 In General 274 3.3.2 Balance Equations 275 3.3.2.1 Vapour 275 3.3.2.2 Air 276 3.3.2.3 Heat 276 3.3.2.4 Closing the Loop 278 3.3.3 Sorption Active Surfaces and Hygric Inertia 279 3.3.3.1 In General 279 3.3.3.2 Sorption-Active Thickness 280 3.3.3.3 Zone with One Sorption-Active Surface 282 3.3.3.4 Zone with Several Sorption-Active Surfaces 283 3.3.3.5 Harmonic Analysis 284 3.3.4 Consequences 284 Problems and Solutions 287 Further Reading 300 4 Heat, Air and Moisture Material Property Values 303 4.1 In General 303 4.2 Dry Air andWater 304 4.3 Thermal Properties 305 4.3.1 Definitions 305 4.3.2 Standard Values 305 4.3.2.1 Regardless of Being on the In- or on the Outside of the Thermal Insulation 305 4.3.2.2 Depending on Being on the In- or on the Outside of the Thermal Insulation 309 4.3.3 Surfaces, Radiant Properties 316 4.3.4 Measured Values 317 4.3.4.1 Thermal Conductivity, Test Methods 317 4.3.4.2 Test Results 318 4.4 Air Properties 325 4.4.1 Standard Values 325 4.4.2 Measured Values 325 4.4.2.1 Air Permeance, Test Method 325 4.4.2.2 Test Results 327 4.5 Moisture Properties 336 4.5.1 Standard Values 336 4.5.1.1 Building and Finishing Materials 336 4.5.1.2 Insulation Materials 340 4.5.2 Measured Values 340 4.5.2.1 Diffusion Resistance Factor (μ), Test Method 340 4.5.2.2 Test Results 342 Further Reading 357 Postscript 359 Index 361