Heating and cooling of buildings : principles and practice of … · 2016. 12. 20. · THIRD...
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THIRD EDITION HEATING AND COOLING OF BUILDINGS Principles and Practice of Energy Efficient Design
Transcript of Heating and cooling of buildings : principles and practice of … · 2016. 12. 20. · THIRD...
THIRD EDITION
HEATING AND
COOLING
OF BUILDINGS
Principles and Practice
of Energy Efficient Design
Contents
Preface to the Third Edition xxiii
Preface to the Revised Second Edition xxv
Acknowledgments to the Third Edition xxvii
Acknowledgments to the Revised Second Edition xxix
Authors xxxi
Some Useful Constants xxxiii
Conversion Factors xxxv
1. Background of the Building Sector and Energy Use Patterns 1
Nomenclature 1
1.1 A Bit of History 1
1.2 Importance of Buildings in the U.S. Economy and Other Countries 2
1.3 Energy Use Patterns by Building Type and End Use 5
1.3.1 Residential Buildings 5
1.3.2 Commercial Buildings 6
1.3.3 End Use 6
1.4 Roles of Building Energy Professionals and HVAC Design Engineers 9
1.5 Basic Concepts in Economics of Energy Efficiency 12
1.6 Units and Conversions 13
1.7 Orders of Magnitude Calculations 15
Problems 16
References 18
2. Basic Thermal Science 19
Nomenclature 19
2.1 Fluid and Thermodynamic Properties 20
2.2 Determining Property Values 24
2.2.1 Gibbs Phase Rule 24
2.2.2 Ideal Gas Law 24
2.2.3 Tabular Data for Perfect Gases 25
2.2.4 Mixtures of Perfect Gases 25
2.3 Types of Flow Regimes 26
2.4 Conservation of Mass and Momentum 27
2.5 First Law of Thermodynamics 28
2.5.1 Applied to Closed Systems 28
2.5.2 Applied to Open Systems 29
2.6 Second Law of Thermodynamics 31
2.7 Modes of Heat Transfer 31
2.8 Conduction Heat Transfer 32
2.8.1 Fourier's Law of Heat Conduction 32
2.8.2 Steady-State Conduction in Plane Walls 32
2.8.3 Steady-State Conduction in Cylindrical Coordinates 36
2.8.4 Steady-State Conduction in Other Geometries 37
2.8.5 Thermal Conductivity of Materials 39
2.9 Convection Heat Transfer 39
2.9.1 Defining Equation for hcon 39
2.9.2 Convection Thermal Resistance and R Value 40
2.9.3 Relevant External Flow Equations 41
2.9.4 Relevant Internal Flow Equations 43
ix
x Contents
2.9.5 Tables and Graphs of Convection Coefficients 44
2.9.6 Combined Conduction and Convection 45
2.10 Radiation Heat Transfer 47
2.10.1 Thermal Radiation Spectrum and the Stefan-Boltzmann Law 47
2.10.2 Gray Surfaces 47
2.10.3 Radiation Properties: Absorptivity, Transmissivity, and Reflectivity 49
2.10.4 Shape Factors 49
2.10.5 Radiative Exchange 51
2.10.6 Combined Convection and Radiation 52
2.10.7 Thermal Bridges 55
2.11 Evaporation and Moisture Transfer 55
2.12 Closure 59
Problems 59
References 64
3. Human Thermal Comfort and Indoor Air Quality 67
Nomenclature 67
3.1 Indoor Environmental Quality 68
3.2 Thermal Comfort 68
3.2.1 Thermal Balance of the Human Body 68
3.2.2 Operative Temperature 70
3.2.3 Clothing Insulation 71
3.2.4 Humidity Effects 72
3.3 Perception of Comfort 74
3.3.1 ASHRAE Comfort Chart 74
3.3.2 Corrections to ASHRAE Comfort Chart 77
3.3.3 Adaptive Model 80
3.3.4 Other Considerations 81
3.4 Air Quality and Indoor Contaminants 83
3.5 Control of Indoor Air Quality 86
3.5.1 General Methods 86
3.5.2 Ventilation of Fully Mixed Spaces 87
3.5.3 ASHRAE Standard 62.1 88
3.5.4 Air Distribution Efficiency 90
3.5.5 Filtration Cleaning of Air 92
3.6 Closure 95
Problems 95
References 97
4. Solar Radiation 99
Nomenclature 99
4.1 Introduction 100
4.2 Solar Movement and Basic Angles 100
4.2.1 Earth's Orbit 100
4.2.2 Solar Declination 102
4.2.3 Basic Sun-Earth Angles 102
4.2.4 Solar Time 102
4.3 Solar Geometry with respect to Local Observer 104
4.3.1 Solar Zenith and Azimuth Angles 104
4.3.2 Sun-Path Diagrams 105
4.3.3 Daylength 107
4.3.4 Incidence Angle on Planes of Arbitrary Tilt and Orientation 108
4.3.5 Shading from Far Objects 109
Contents xi
4.4 Extraterrestrial Insolation 110
4.4.1 Hourly Values Normal to Solar 110
4.4.2 Daily Values on Horizontal Surface Ill
4.5 Effect of Atmosphere 112
4.5.1 Air Mass Ratio 112
4.5.2 Components of Solar Radiation 113
4.6 ASHRAE Clear-Sky Irradiance Model 114
4.7 Transposition Models for Tilted and Vertical Surfaces 116
4.7.1 Isotropic Sky Model 116
4.7.2 ASHRAE Anisotropic Sky Model 117
4.8 Measured Solar Radiation Data Worldwide 118
4.9 Statistical Correlation Models 119
4.9.1 Monthly Mean Daily Diffuse from Daily Global Insolation 119
4.9.2 Monthly Mean Hourly from Monthly Mean Daily Insolation 120
4.9.3 Monthly Mean Insolation on Vertical Surfaces 121
4.9.4 Hourly Diffuse from Hourly Global Horizontal Insolation 122
Problems 124
References 126
5. Heat Gains through Windows 127
Nomenclature 127
5.1 Importance and Design Considerations 128
5.2 Optical Properties 130
5.3 Thermal Properties 134
5.3.1 Center-Glass U Values 134
5.3.2 U Values for Entire Windows 137
5.3.3 Surface Temperature of Glazing 138
5.4 Solar Heat Gains 140
5.4.1 Calculation Procedure 140
5.4.2 SHGC Derivation 142
5.5 External and Internal Shading 143
5.5.1 Overhangs and Recessed Windows 143
5.5.2 Internal Shading Devices 146
5.6 High-Performance Glazing 147
5.6.1 Promising Improvements 147
5.6.2 Smart Windows 149
Problems 149
References 150
6. Infiltration and Natural Ventilation 153
Nomenclature 153
6.1 Importance and Basic Definitions 154
6.2 Infiltration Rates across Building Stock 155
6.3 Basic Flow Equations 156
6.3.1 Introduction and Types of Airflow Models 156
6.3.2 Crack Flow Equation 158
6.4 Induced Pressure Differences 159
6.4.1 Wind Effect 159
6.4.2 Stack Effect 163
6.4.3 Combining Wind, Stack, and Mechanical Ventilation Effects 165
6.5 Engineering Component Models for Air Infiltration 167
xii Contents
6.6 Simplified Physical Models for Single-Zone Air Infiltration 174
6.6.1 Basic Lawrence Berkeley National Laboratory Model 174
6.6.2 Air Change Method 176
6.7 Multizone Models 177
6.8 Natural Ventilation Airflow through Large Openings 178
6.8.1 Background 178
6.8.2 Simplified Correlation 179
6.8.3 Computer Programs 181
6.9 Measuring Air Infiltration and Interzone Flows 181
6.9.1 Blower Door Tests 181
6.9.2 Building Component Tests 183
6.9.3 Tracer Gas Methods 183
6.10 Infiltration Heat Recovery 184
Problems 184
References 185
7. Steady-State Heat Flows 187
Nomenclature 187
7.1 Load Calculations 188
7.2 Sol-Air Temperature and Instantaneous Conduction Heat Gain 189
7.3 Below-Grade Heat Conduction 190
7.3.1 Soil Conductivities 191
7.3.2 Soil Temperature Profiles 191
7.3.3 ASHRAE Method for Basement Heat Losses 192
7.3.4 ASHRAE Method for Slab on Grade Heat Losses 195
7.3.5 True 2-D Methods for Ground Coupling Losses 196
7.4 Internal Heat Gains 197
7.4.1 Heat Gains from Occupants 197
7.4.2 Heat Gains from Lights 197
7.4.3 Heat Gains from Equipment 198
7.5 Treatment of One Zone Spaces 200
7.5.1 Overall Conductive Heat Transmission Coefficient 200
7.5.2 Heat Balance 202
7.5.3 Treatment of Unconditioned Attached Spaces 204
7.6 Multizoning in Buildings 205
7.6.1 Need for Zoning 205
7.6.2 Practical Issues 206
Problems 207
References 209
8. Transient Heat Flow through Building Elements 211
Nomenclature 211
8.1 Basic Concepts 212
8.1.1 Storage Effects and Limits of Static Analysis 212
8.1.2 One-Dimensional Transient Heat Flow Equation 214
8.1.3 Properties of Linear Systems 216
8.1.4 Classes of Analysis Methods 216
8.2 Numerical Methods: Finite Differences 217
8.3 Time-Series Methods for Conduction Heat Gains 219
8.3.1 Basis 219
8.3.2 CTF Model 221
8.3.3 Conduction Time-Series Model 225
Contents xiii
8.4 Thermal Networks Models 227
8.4.1 Network Diagrams and Modeling Equations 227
8.4.1.1 Single-Pane Glass 228
8.4.1.2 Homogeneous Wall 228
8.4.1.3 Heterogeneous Building Elements 229
8.4.1.4 One-Zone Building 230
8.4.2 1R1C Network and Time Constant 231
8.4.3 A Network with Two Nodes 233
8.4.4 Connection with Transient Heat Conduction Equation 234
8.4.5 Deducing Transfer Function Coefficients 235
8.5 Frequency-Domain Methods 236
8.5.1 Basis 236
8.5.2 Admittance Method 236
Problems 237
References 239
9. Heating and Cooling Design Load Calculations 241
Nomenclature 241
9.1 Introduction 242
9.2 Winter and Summer Design Conditions 242
9.3 Design Heating Load Calculation Procedure 246
9.4 Subtleties with Cooling Load Calculations 247
9.4.1 Calculation of Design-Day Sol-Air Temperatures 247
9.4.2 Need to Consider Storage Effects 248
9.4.3 Extensions to Multiple Zones 250
9.5 Transfer Function Method for Cooling Load Calculations 250
9.5.1 Basis of the Method 250
9.5.2 Cooling Load at Constant Temperature 251
9.5.3 Variable Indoor Temperature and Heat Extraction Rate 255
9.6 Heat Balance Method 260
9.7 Radiant Time-Series Method 261
Problems 267
References 270
10. Simplified Annual Energy Estimation Methods and Inverse Modeling 271
Nomenclature 271
10.1 General Approaches 272
10.2 Degree-Day Method 273
10.2.1 Balance-Point Temperature 273
10.2.2 Heating Degree-Day Method 273
10.2.3 Cooling Degree-Day Method 276
10.3 Models for Estimating Degree-Days under Different Base Temperatures 280
10.3.1 Erbs et al. Method 280
10.3.2 Schoenau and Kehrig Method 281
10.3.3 Parametric Analysis 282
10.4 Bin Method 285
10.4.1 Basic Approach 285
10.4.2 Model for Generating Bin Data 288
10.4.3 Diurnal Temperature Distribution 289
10.4.4 Inclusion of Solar Gains 290
10.4.5 Inclusion of Dynamic Effects 290
10.5 Advantages and Limitations 292
xiv Contents
10.6 Inverse Modeling 29210.6.1 Background 292
10.6.2 Single-Variate Models for Monthly Data 294
10.6.2.1 Variable-Base Degree-Day Model 294
10.6.2.2 Monthly Mean Temperature Model 295
10.6.2.3 Discussion 296
10.6.3 Single- and Multivariate Models for Daily and Hourly Data 298
10.6.4 Dynamic Models 300
10.6.5 Calibrated Simulation Models 300
10.6.6 Summary of Methods 301
Problems 302
References 305
11. Description of Typical Building HVAC Systems and Components 30711.1 Primary and Secondary HVAC Systems 307
11.2 Types of Secondary Systems 309
11.3 Broad Classification of HVAC Systems 310
11.4 Unitary Systems 310
11.5 Centralized Systems 311
11.6 District Systems 316
Problems 318
References 319
12. Thermal Principles Relevant to Equipment and Systems 321
Nomenclature 321
12.1 First Law: Heat and Work Interactions 322
12.1.1 Recap 322
12.1.2 Important Steady-State Processes 322
12.2 Second Law Applied to Ideal Carnot Cycles 324
12.2.1 Power Cycle 324
12.2.2 Refrigeration Cycle 325
12.2.3 Heat Pump Cycles 326
12.2.4 Combined Carnot Heat Engine and Refrigerator 326
12.3 Pure Substances 327
12.3.1 Phase Diagrams of Water Vapor and Steam 327
12.3.2 Determining Property Values 329
12.3.3 Refrigerants 330
12.4 Homogeneous Binary Mixtures 333
12.5 Convective Heat Transfer Correlations 334
12.6 Heat Exchangers 337
12.6.1 Background 337
12.6.2 LMTD Approach 338
12.6.3 Effectiveness-NTU Approach 341
12.6.4 Comparison of Methods 344
Problems 344
References 347
13. Psychrometric Properties and Processes 349
Nomenclature 349
13.1 Definition and Importance of Psychrometrics 350
13.2 Composition and Pressure of Atmospheric Air 350
13.3 Psychrometric Properties of Moist Air 351
13.3.1 Ideal Gas Assumption 351
13.3.2 Important Moist-Air Properties and Tables 351
Contents xv
13.4 Analytical Approach to Determining Moist-Air Properties 352
13.4.1 Saturated Moist-Air Tables 352
13.4.2 Humidity Ratio from Relative Humidity and Dry-Bulb Temperature 354
13.4.3 Adiabatic Saturation and Thermodynamic Wet-Bulb Temperatures 355
13.4.4 Relative Humidity from Wet-Bulb and Dry-Bulb Temperatures 357
13.4.5 Dew Point Temperature from Partial Water Vapor Pressure 358
13.4.6 Moist-Air Enthalpy and Specific Heat 359
13.5 Psychrometric Chart 360
13.6 Basic Psychrometric Processes 363
13.6.1 Underlying Conservation Equations 364
13.6.2 Adiabatic Mixing of Airstreams 364
13.6.3 Sensible Heating and Cooling 366
13.6.4 Adiabatic Saturation and Evaporative Cooling 368
13.6.5 Cooling and Dehumidification 370
13.6.6 Heating and Humidification 374
13.7 Closure 376
Problems 378
References 382
14. Chillers and Heat Pump Cycles and Systems 383
Nomenclature 383
14.1 Standard Vapor Compression Cycle 384
14.1.1 Description 384
14.1.2 Analysis Equations 385
14.2 Modified and Actual VC Cycles 387
14.2.1 Modified VC Cycle 387
14.2.2 Actual Single-Stage Cycle 390
14.2.3 Multistage Cycles 390
14.3 Absorption Cooling 390
14.3.1 Absorption Cycle 390
14.3.2 Analysis of Lithium Bromide Cycle 392
14.4 Chiller Systems 394
14.4.1 System Analysis 394
14.4.2 Chiller Performance Maps 397
14.5 Air Source Heat Pumps 400
14.5.1 General Description 400
14.5.2 Operational Considerations 401
14.5.3 Heat Pump Manufacturer Performance Data 403
14.5.4 Control and Other Considerations 404
14.5.5 Electric Resistance Heating 405
14.6 Rating Standards 405
14.6.1 AHRI Standards 405
14.6.2 IPLV Rating 406
14.7 Part-Load Performance 407
14.7.1 Unitary Chillers: Degradation Coefficient Method 407
14.7.2 Medium to Large Chillers: Simplified Part-Load Model 411
14.7.3 Medium to Large Chillers: DOE Model 412
14.8 Ground Source Heat Pumps 414
14.9 Decentralized Water Loop Heat Pumps 416
14.10 Theoretical Performance Indices for Heating and Cooling 417
14.10.1 Limit for Ideal Heat Pumps 417
14.10.2 Finite Airflow Rates in Building 418
14.10.3 AT of Heat Exchangers 419
14.10.4 Actual Heat Pumps 420
xvi Contents
14.11 Refrigerants 420
14.11.1 Background 420
14.11.2 Classification and Method of Designation 421
14.11.3 Thermodynamic Properties 422
14.11.4 Physical and Chemical Characteristics and Health Safety 423
14.11.5 Environmental Concerns 424
Problems 425
References 428
15. Combustion Heating Equipment and Systems 431
Nomenclature 431
15.1 Principles of Combustion 432
15.1.1 Introduction 432
15.1.2 Types of Fuels and Their Properties 432
15.1.3 Combustion Analysis 433
15.1.4 Excess Air 434
15.2 Furnaces 435
15.2.1 Classification and Description 435
15.2.2 Furnace Design and Selection 437
15.2.3 Furnace Controls 437
15.2.4 Furnace Efficiency and Energy Calculations 439
15.3 Boilers 441
15.3.1 Classification and Description 441
15.3.2 Boiler Design and Selection 441
15.3.3 Boiler Controls 443
15.3.4 Boiler Efficiency 445
15.3.5 Factors Affecting Boiler Efficiency 445
15.4 Seasonal Energy Calculations 446
15.4.1 Part-Load Models 446
15.4.2 Bin Method Calculation 447
15.5 Improving and Monitoring Thermal Performance 448
15.5.1 Direct Method of Efficiency Determination 448
15.5.2 Indirect Method: Flue Gas Analysis 449
15.6 Combined Heating and Power Systems 451
15.6.1 Introduction 451
15.6.2 Available Technologies 451
15.6.3 Definitions of Different Thermodynamic Efficiency Metrics 452
15.6.3.1 First Law Efficiency of Individual Equipment 453
15.6.3.2 Ideal System Efficiencies 453
15.6.3.3 System Efficiencies 454
15.6.4 Designing CHP Systems for Buildings 456
Problems 457
References 459
16. Pumps, Fans, and System Interactions 461
Nomenclature 461
16.1 Modified Equation of Motion 462
16.2 Pressure Losses in Liquid and Air Systems 463
16.2.1 Pressure Losses in Straight Piping 463
16.2.2 Pressure Losses in Pipe Fittings 468
16.2.3 Pressure Losses in Ducts and Duct Fittings 474
16.2.4 System Characteristic Curves 478
16.3 Prime Movers 478
16.3.1 Fans 478
16.3.2 Pumps 479
Contents xvii
16.3.3 Expressions for Power 481
16.3.4 Fan Laws 482
16.3.5 Pump Affinity Laws 483
16.4 System and Prime Mover Interactions 483
16.4.1 Relationship between Pressure and Velocity in a Duct or Pipe 483
16.4.2 Combined Prime Mover and System Behavior 485
16.4.3 Elements in Parallel and in Series 486
16.5 Types of Fans and Their Control 488
16.5.1 Fixed-Speed Operation 488
16.5.2 Variable-Volume Operation 489
16.6 Duct Design Methods 492
16.6.1 Background 492
16.6.2 Different Classes and Types of Methods 493
16.6.3 Equal Friction Method 495
16.6.4 Static Regain Method 497
16.7 Fluid Flow Measurement 498
16.7.1 Venturi Meter 498
16.7.2 Orifice Plate 498
16.7.3 PitotTube 498
16.7.4 Turbine Flow Meters 499
16.7.5 Hot-Wire Anemometers 500
16.8 Closure 501
Problems 501
References 508
17. Cooling System Equipment 509
Nomenclature 509
17.1 Introduction 510
17.2 Compressors 510
17.2.1 Categories of Chillers 510
17.2.2 Generic Compressor Power 510
17.2.3 Reciprocating Compressors 511
17.2.4 Rotary Compressor 513
17.2.5 Scroll Compressors 514
17.2.6 Screw Compressors 515
17.2.7 Centrifugal Compressors 515
17.2.8 Intercomparison 517
17.3 Expansion Devices 518
17.4 Evaporators and Condensers 520
17.4.1 Evaporators 521
17.4.2 Condensers 523
17.5 Heating Air Coils 525
17.6 Wet Cooling Air Coils 527
17.7 Cooling Towers 530
Problems 536
References 537
18. Hydronic Distribution Equipment and Systems 539
Nomenclature 539
18.1 Hydronic System Classification 540
18.2 Types of Hydronic Distribution Circuits 541
18.3 Traditional Terminal Units 543
18.3.1 For Heating Applications 543
18.3.2 For Heating/Cooling Applications 544
18.3.3 Terminal Unit Manufacturer Ratings 545
xviii Contents
18.4 Low-Temperature Radiant Panels 546
18.4.1 Description 546
18.4.2 Performance Equations 549
18.4.3 Design Suggestions 550
18.5 Auxiliary Heating Equipment 553
18.5.1 Service Hot Water 553
18.5.2 Steam Systems and Equipment 556
18.5.3 Expansion Tanks 558
18.6 Piping Systems Design 560
18.6.1 Design Considerations 560
18.6.2 Design Methodology 561
18.7 Modulating Valves and Capacity Control 563
18.8 Large Cooling Systems 564
18.8.1 Distribution Piping Configurations 564
18.8.2 Rules for Chiller System Operation and Control 567
18.9 Cool Thermal Energy Storage 567
18.9.1 Purpose and Benefits 567
18.9.2 Storage Mediums 568
18.9.3 Design and Control Considerations 570
18.9.4 Ice Storage Designs 574
Problems 578
References 579
19. All-Air Systems 581
Nomenclature 581
19.1 Basic Principles 582
19.1.1 Introduction 582
19.1.2 Basic One-Zone AC System 582
19.1.3 Airstream Heating due to Fans 586
19.1.4 Fundamental Operational Difference between CAV and VAV Systems 587
19.2 Single-Zone Single-Duct CAV Systems 589
19.2.1 Description 589
19.2.2 Cooling Mode: Peak Design Conditions 590
19.2.3 Heating Mode: Peak Design Conditions 592
19.2.4 Part-Load Operating Conditions 593
19.3 Single-Zone Single-Duct VAV Systems 595
19.3.1 Description of the Basic System 595
19.3.2 Different Operating Modes 596
19.4 All-Air Systems for Multiple Zones 598
19.4.1 Basic Single-Duct Systems 598
19.4.2 Fan-Powered Single-Duct VAV Systems 598
19.4.3 Dual-Duct and Multizone Systems 603
19.5 Design Sizing and Energy Analysis 607
19.5.1 Sizing under Design Conditions 607
19.5.2 Performance under Part-Load Conditions 611
19.5.3 Energy Analysis Using the Bin Method 614
19.6 Energy Efficiency Design and Operation Practices 619
19.6.1 HVAC System Variants 619
19.6.2 Air-Side Economizer Cycle 620
19.6.3 Exhaust Air Energy Recovery Devices 622
19.6.4 Ways to Improve Energy Efficiency under Part-Load Conditions 624
19.7 Energy Penalties due to Mixing of Hot and Cold Streams 625
19.7.1 Multizone Efficiency Index 625
19.7.2 Energy Delivery Efficiency 627
Contents xix
19.8 Closure 628
Problems 629
References 631
20. Room Air Distribution and Hybrid Secondary Systems 633
Nomenclature 633
20.1 Introduction 634
20.2 Basic Air-Water Systems 634
20.3 Air Distribution in Rooms 638
20.3.1 Basic Considerations 638
20.3.2 Behavior of Air Jets 638
20.3.3 Classification of Air Diffusion Methods 639
20.4 Fully Mixed Room Distribution Systems 640
20.4.1 Qualitative Flow Patterns 640
20.4.2 Types of Diffusers 641
20.4.3 Noise and Pressure Drop 643
20.4.4 EDT, ADPL and AER 645
20.4.5 Air Distribution Systems Design Procedure 646
20.5 Other Types of Room Air Distribution Methods 648
20.5.1 UFAD 648
20.5.2 UFAD Design Calculation Procedure 651
20.5.3 Displacement Ventilation Distribution 653
20.6 Chilled Beams 656
20.6.1 Passive Chilled Beams 656
20.6.2 Active Chilled Beams 656
20.7 Hybrid Secondary Systems 659
20.7.1 Basic Principle 659
20.7.2 DOAS 660
20.8 Evaporative Cooling Equipment 664
20.8.1 Background 664
20.8.2 Direct Evaporative Coolers 664
20.8.3 Indirect Evaporative Coolers 667
20.8.4 Design Considerations 669
20.9 Desiccant Cooling Systems 671
20.9.1 Operational Principles 671
20.9.2 Description of Systems 672
20.9.3 Desiccant Materials 676
20.9.4 Miscellaneous Issues 676
Problems 677
References 679
21. HVAC Control Systems 681
Nomenclature 681
21.1 Introductory Concepts 682
21.1.1 Need for Control 682
21.1.2 Local versus Supervisory Control 682
21.1.3 Elements of a Control System 682
21.1.4 Duties of the Control Designer 684
21.2 Modes of Feedback Control 684
21.2.1 Two-Position 684
21.2.2 Proportional (P) 684
21.2.3 Proportional Integral 687
21.2.4 Proportional Integrative Differential 687
xx Contents
21.3 Basic Control Hardware 688
21.3.1 Pneumatic 688
21.3.2 Electric and Electronic 690
21.3.3 Direct Digital Controllers 691
21.4 Basic Control System Design Considerations 694
21.4.1 Sensors 694
21.4.2 Steam and Liquid Flow Control 695
21.4.3 Airflow Control 700
21.5 Examples of HVAC System Control Systems 701
21.5.1 Outside Air Control 701
21.5.2 Heating Control 702
21.5.3 Cooling Control 703
21.5.4 Complete Systems: CAV and VAV 704
21.5.5 Other Systems 707
21.6 Building Automation 709
21.6.1 Networking Architectures 709
21.6.2 BACnet Data Exchange Protocol 710
21.7 Topics in Advanced Control System Design 712
21.7.1 Laplace Transforms 712
21.7.2 Laplace Transforms for HVAC Equipment 713
21.7.3 Control System Stability 714
21.7.4 Selection of Control Constants: Control System Simulation 716
21.8 Summary 719
Problems 719
References 723
22. Lighting and Daylighting 725
Nomenclature 725
22.1 Principles of Lighting 725
22.2 Electric Lighting 726
22.3 Daylighting 729
22.3.1 Importance 729
22.3.2 Principles 729
22.4 Analysis of Daylighting 731
22.4.1 Daylight Data 731
22.4.2 Lumen Method for Toplighting 732
22.4.3 Lumen Method for Sidelighting 738
22.5 Design of Buildings for Daylighting 742
22.5.1 Windows 743
22.5.2 Roof Apertures (Skylights) 745
Problems 747
References 749
23. Costing and Economic Analysis 751
Nomenclature 751
23.1 Comparing Present and Future Costs 752
23.1.1 Effect of Time on the Value of Money 752
23.1.2 Discounting of Future Cash Flows 755
23.1.3 Equivalent Cash Flows and Levelizing 756
23.1.4 Discrete and Continuous Cash Flows 759
23.1.5 Rule of 70 for Doubling Times 761
23.2 Life Cycle Cost 761
23.2.1 Cost Components 761
23.2.2 Principal and Interest 762
23.2.3 Depreciation and Tax Credit 763
Contents xxi
23.2.4 Energy and Demand Charges 764
23.2.5 Complete Formula 765
23.2.6 Cost per Unit of Delivered Service 766
23.2.7 Constant Currency versus Inflating Currency 767
23.3 Economic Evaluation Criteria 767
23.3.1 Life Cycle Savings 767
23.3.2 Internal Rate of Return 768
23.3.3 Payback Time 769
23.4 Complications of the Decision Process 770
23.5 Cost Estimation 771
23.5.1 Capital Costs 771
23.5.2 Maintenance and Energy 772
23.6 Optimization 774
Problems 776
References 777
24. Design for Energy Efficiency 779
Nomenclature 779
24.1 Road to Efficiency 780
24.1.1 Introduction 780
24.1.2 Design Goal 781
24.1.3 Design Process 781
24.1.4 Role of Building Type and Utilization 781
24.2 Design Elements and Recommendations 782
24.2.1 Categories 782
24.2.2 Environment 782
24.2.3 Structure and Envelope 784
24.2.4 Equipment 787
24.2.5 System and Controls 787
24.2.6 Solar Energy 789
24.3 Residential Buildings 790
24.3.1 Lightweight Houses: Energy and Window U Values 790
24.3.2 Effects of Thermal Mass 794
24.3.3 Passive Solar Heating 796
24.4 Commercial Buildings: HVAC Systems 800
24.5 Alternative Energy Technologies 803
24.5.1 Solar Water Heating 803
24.5.2 Solar Preheated Air 804
24.5.3 Passive and Hybrid Cooling 804
24.5.4 Solar Photovoltaics 807
24.6 Uncertainties in Simulations 809
24.6.1 Sources 809
24.6.2 Validation 809
24.6.3 Comparison with Measured Data 810
24.7 Energy Benchmarking and Rating 811
24.8 Drivers for Efficiency 812
24.8.1 Codes and Standards 812
24.8.2 Design Guides 814
24.8.3 Green Building Movement 815
Problems 816
References 8^8
Appendix8^
Index 847
