CONTENTS Preface xi 1 Introduction 1 1.1 Energy flowpaths and causal effects 4 1.2 The need for accuracy and flexibility 14 1.3 Energy modelling techniques 17 1.4 The issue of integrity in building energy modelling 22 2 Advanced modelling techniques 24 2.1 Response function methods 24 2.2 Time-domain response functions 28 2.2.1 Multi-layered constructions 31 2.2.2 Zone energy balance 36 2.2.3 Response function application 43 2.3 Frequency-domain response functions 44 2.3.1 Multi-layered constructions 45 2.3.2 Zone energy balance . 51 2.3.3 Response function applications 51 2.4 Numerical methods 56 2.4.1 Finite differencing by Toy lor series expansion 57 2.4.2 The control volume heat balance method 61 2.4.3 Numerical solution techniques 63 2.5 Which method? 67 3 Numerical simulation by finite differences 71 3.1 System discretisation 72 3.2 Finite difference energy flow equations 77 3.2.1 Energy balance: capacity/insulation systems 79 3.2.2 Energy balance: exposed surface layers 91 3.2.3 Energy balance: fluid volumes 97 3.3 Structuring the equations for multi-component simulation 102 4 Matrix processing of energy flow equation sets 114 4.1 Establishing the equation set for solution 115 4.1.1 Single zone formulation 115 4.1.2 Zone contents and plant interaction 125 4.1.3 Multi-zone systems 128 4.1.4 Treatment of time-dependent properties 130 4.2 Fast simultaneous solution by matrix processing 130 4.2.1 Single zone solution 131 4.2.2 Multi-zone solution 141 4.2.3 Solution on the basis of sensing element characteristics or comfort criteria 142 4.2.4 Treatment of non-linear processes 144 4.3 Mixed frequency inversion 144 5 Energy related subsystems 146 5.1 Geometrical considerations 146 5.2 Insolation of exposed building surfaces 150 5.2.1 Insolation transformation equations 151 5.2.2 The complete translation, rotation and projection equations 156 5.2.3 An insolation algorithm 157 5.3 Shortwave radiation processes 159 5.3.1 Solar position 161 5.3.2 Intensity of direct and diffuse radiation on inclined surfaces 163 5.3.3 Reflection, absorption and transmission within transparent media 165 5.3.4 Intra-zone shortwave distribution 172 5.4 Longwave radiation processes 173 5.4.1 Exchange between internal surfaces 174 5.4.2 View factor determination 184 5.4.3 Linearised longwave radiation coefficients 192 5.4.4 Exchange between external surfaces 193 5.5 Surface convection 195 5.5.7 Natural convection at internal surfaces 196 5.5.2 Forced convection at internal and external surfaces 198 5.6 Air flow 200 5.6.1 The mass balance approach 201 5.6.2 Iterative solution procedure 205 5.6.3 Simultaneous energy/air flow simulation 207 5.7 Casual heat sources 207 5.7.7 Lighting heat gain control on the basis of natural lighting levels 208 5.8 Climate 215 5.8.1 Availability of climatic collections 215 5.8.2 Climatic severity assessment 217 5.8.3 Solar radiation prediction 224 6 Plant simulation 234 6.1 Sequential versus simultaneous approaches 235 6.2 Air conditioning systems 237 6.3 Active solar systems 250 6.4 Wet central heating systems 260 6.5 Simultaneous building/plant modelling 268 6.6 Control system simulation 269 6.7 Future developments in systems simulation 272 7 Software development 275 7.1 Structuring the overall system 276 7.2 Software requirements 281 7.2.7 Input data management 282 7.2.2 Permanent databases and related software 287 7.2.3 System utilities and temporary databases 291 7.2.4 Energy simulation 296 7.2.5 Results recovery 309 7.3 Indicative performance data 311 7.4 Development environment 315 8 Validation and implementation in practice 318 8.1 Model validation 318 8.2 Implementation in practice 326 Appendix A Fourier heat equation 333 Appendix B Thermophysical properties of building materials 336 Appendix C Alternative discretisation schemes 339 Appendix D Nomenclature 342 Appendix E Description of the ESP system 346 Appendix F Data structures of the ESP system 353 Appendix G ESP system output examples 373 Index 383