Natural Ventilation of Buildings: THEORY, MEASUREMENT AND DESIGN -- Contents -- Preface -- Acknowledgements -- Principal Notation -- 1 Introduction and Overview of Natural Ventilation Design -- 1.1 Aims and Scope of the Book -- 1.1.1 Aims -- 1.1.2 Scope -- 1.2 Natural Ventilation in Context -- 1.2.1 Hierarchy of Ventilation Systems -- 1.2.2 Advantages and Disadvantages of Natural Ventilation -- 1.2.3 Differences between Natural and Mechanical Ventilation -- 1.3 Overview of Design -- 1.3.1 Overall Design Process -- 1.3.2 Stage 1: Assessing Feasibility -- 1.3.3 Stage 2: Choosing a Ventilation Strategy -- 1.3.4 Stage 3: Achieving the Ventilation Strategy -- 1.3.5 Stage 4: Internal Air Motion and Related Phenomena -- 1.3.6 Stage 5: Commissioning -- 1.4 Notes on Sources -- 1.4.1 Coverage of Recent and Past Developments -- 1.4.2 Natural Ventilation and Safety -- References -- 2 Physical Processes in Natural Ventilation -- 2.1 Introduction -- 2.1.1 Fundamental Principles of Fluid Mechanics -- 2.1.2 Numerical Analysis and CFD -- 2.2 The Effect of Gravity on Ventilation Flows -- 2.2.1 Navier-Stokes Equations -- 2.2.2 Hydrostatic and Piezometric Pressures -- 2.2.3 Envelope Flows -- 2.2.4 Internal Air Motion -- 2.3 Types of Flow Encountered in Ventilation -- 2.3.1 Reynolds Number -- 2.3.2 Laminar Flow -- 2.3.3 Transitional Flow -- 2.3.4 Turbulent Flow -- 2.4 Fluid Mechanics - Other Important Concepts and Equations -- 2.4.1 A Fluid as a Continuum -- 2.4.2 Transport Mechanisms -- 2.4.3 Momentum Principle - Newton's Laws of Motion -- 2.4.4 Momentum Equations for a Defined Body of Fluid and a Control Volume -- 2.4.5 Hydrostatic Equation -- 2.4.6 Steady Flow -- 2.4.7 Mass Conservation for an Envelope -- 2.4.8 Bernoulli's Equation -- 2.4.9 Energy Equations for a System and a Fixed Control Volume -- 2.4.10 Loss Coefficient and Resistance Coefficient.

2.4.11 Still-air Discharge Coefficient and Resistance Coefficient -- 2.4.12 Flow Separation -- 2.4.13 Irrotational Flow -- 2.5 Steady and Unsteady Ventilation -- 2.6 Flow Through a Sudden Expansion -- 2.6.1 Momentum and Continuity Equations -- 2.6.2 Energy Equation -- 2.6.3 Diffusion (Molecular and Turbulent) -- 2.7 Dimensional Analysis -- 2.8 Heat Transfer between Air and Envelope -- 2.9 Definitions Relating to Ventilation Rate -- 2.9.1 Envelope Flows - Single Cell -- 2.9.2 Envelope Flows - Multi-cell Buildings -- 2.9.3 Measurement of Ventilation Rate -- 2.9.4 Effectiveness of Ventilation and Local Ventilation Rates -- 2.10 Errors and Uncertainties -- 2.11 Mathematical Models -- 2.11.1 Envelope Flow Models (Chapters 4 and 5) -- 2.11.2 Zonal Models (Chapter 6) -- 2.11.3 Dynamic Thermal Models -- 2.11.4 CFD -- 2.12 Boundary Conditions -- 2.12.1 Velocity -- 2.12.2 Temperature -- Bibliography -- References -- 3 Steady Flow Characteristics of Openings -- 3.1 Introduction -- 3.1.1 Still-air Discharge Coefficient -- 3.1.2 Installation Effects -- 3.2 Classification of Openings -- 3.2.1 Shapes of Openings -- 3.2.2 Sizes of Openings -- 3.2.3 Reynolds Numbers Encountered in Practice -- 3.2.4 Types of Opening -- 3.3 Still-air Discharge Coefficient -- 3.3.1 Sharp-edged Orifices and Air Vents (Type 2) -- 3.3.2 Long Openings - Adventitious (Type 1) -- 3.3.3 Long Openings - Ducts and Chimneys (Type 3) -- 3.3.4 Permeable (Porous) Materials - Dynamic Insulation (Type 1) -- 3.3.5 Summary of Cd Relations -- 3.4 Installation Effects on Cd -- 3.4.1 Expected Effects of Cross-flow -- 3.4.2 Observed Effects of Cross-flow -- 3.4.3 Surface Openings that are Not Flush -- 3.4.4 Installation Effects - Pressure Variations -- 3.5 Openings in Combination -- 3.5.1 Power Law and Quadratic Equation -- 3.5.2 Envelope Leakage -- 3.6 Determination of Cd.

3.6.1 Laboratory Measurement at Full Scale -- 3.6.2 Wind Tunnel Measurement at Model Scale -- 3.6.3 Application of Loss Coefficients -- 3.6.4 CFD Calculations and Analytic Solutions -- 3.7 Uncertainties in Design Calculations -- 3.8 Other Definitions of Discharge Coefficient -- 3.9 Large (and Very Large) Openings -- 3.9.1 Large External Opening in an Otherwise Sealed Room -- 3.9.2 Large Internal Opening Separating Two Spaces with Small Openings -- 3.10 Relevance to Design -- References -- 4 Steady Envelope Flow Models -- 4.1 Introduction -- 4.1.1 Conventional Envelope Flow Models -- 4.2 Basic Theory -- 4.2.1 Piezometric Pressure Difference -- 4.2.2 Flow Equations -- 4.2.3 Conservation of Mass for the Envelope -- 4.2.4 Assumptions in Basic Theory -- 4.3 Single- and Multi-cell Models -- 4.3.1 Single-cell Models -- 4.3.2 Multi-cell Models -- 4.3.3 Uniqueness of Solutions -- 4.3.4 Steady Envelope Models and Slowly Varying Boundary Conditions -- 4.4 Simple Analytic Solutions -- 4.4.1 Analysis for Wind and Buoyancy -- 4.4.2 Wind Alone -- 4.4.3 Buoyancy Alone -- 4.4.4 Wind and Buoyancy Combined -- 4.5 Non-uniform Density -- 4.5.1 Buoyancy and Vertical Openings -- 4.6 Turbulent Diffusion -- 4.7 Large Openings -- 4.8 Adventitious Openings -- 4.9 Explicit Method of Solution -- 4.9.1 Effect of Wind with Upward Ventilation -- 4.9.2 Effect of Wind with Top-down Ventilation -- 4.9.3 Inclusion of Fans -- 4.10 Uncertainties in Envelope Flow Models -- 4.10.1 Purpose-provided Openings -- 4.10.2 Adventitious Openings -- 4.10.3 External and Internal Temperatures -- 4.10.4 Wind Pressures -- 4.10.5 Relative Importance of Wind and Buoyancy - Flow Patterns -- 4.11 Combined Envelope Models and Thermal Models -- 4.11.1 Simple Thermal Equilibrium Models -- 4.11.2 Simple Dynamic Thermal Models -- 4.11.3 General Dynamic Thermal Models -- 4.11.4 Combined Envelope Models and CFD.

4.12 Models for Very Large Openings -- 4.12.1 Basic Theoretical Problems -- 4.12.2 Purely Empirical Approach -- 4.12.3 Semi-empirical Approach -- 4.12.4 CFD -- 4.13 Relevance to Design -- References -- 5 Unsteady Envelope Flow Models -- 5.1 Introduction -- 5.2 Flow Equation -- 5.2.1 Principle of Linear Momentum -- 5.2.2 Quasi-steady Temporal Inertia Theory -- 5.2.3 Support for the Assumptions -- 5.2.4 Specification of Inertia Length le -- 5.3 Pressure Difference across Openings -- 5.4 Mass Conservation Equation -- 5.5 Envelope Flow Models -- 5.5.1 QT Model -- 5.5.2 Non-Dimensional Form of QT Model -- 5.5.3 Important Non-dimensional Parameters -- 5.5.4 Other Models -- 5.6 Comparisons with Measurement -- 5.6.1 Two Openings -- 5.6.2 Multiple Openings -- 5.7 Mean Flow Rates -- 5.7.1 Single Opening in a Sealed Room -- 5.7.2 Two Openings with Wind and Buoyancy -- 5.8 Instantaneous Flow Rates -- 5.9 Unsteady Flow Models in Design -- 5.9.1 Mean Flow Rates -- 5.9.2 Instantaneous Flow Rates -- 5.9.3 Multiple Openings -- 5.10 Relevance to Design -- References -- 6 Internal Air Motion, Zonal Models and Stratification -- 6.1 Introduction -- 6.1.1 Cases of Interest -- 6.1.2 Comparison with Mechanical Ventilation Design -- 6.1.3 Importance of Stratification -- 6.1.4 Well-mixed Spaces and Uniform Temperature -- 6.2 Governing Equations -- 6.2.1 Mathematical Models -- 6.2.2 Dimensional Analysis -- 6.3 Primary and Secondary Flows -- 6.3.1 Jets -- 6.3.2 Plumes -- 6.3.3 Flow through Internal Doors -- 6.3.4 Flows in Bounded Spaces -- 6.4 Zonal Models -- 6.4.1 Primary Flow Models -- 6.4.2 Secondary Flow Models -- 6.4.3 Performance of Zonal Models (Secondary Type) -- 6.4.4 Relevance of Zonal Models to Design -- 6.5 Coarse-grid CFD -- 6.6 Integrated Zonal and Envelope Flow Models -- 6.6.1 Buoyancy Alone -- 6.6.2 Wind and Buoyancy -- 6.6.3 Relevance to Design.

6.7 Stratification -- 6.7.1 Occurrence and Nature of Stratification -- 6.7.2 Purely Empirical Relations -- 6.8 Relevance to Design -- References -- 7 Contaminant Transport and Indoor Air Quality -- 7.1 Introduction -- 7.1.1 Scope of Chapter -- 7.1.2 Conservation Principle for Passive Contaminant -- 7.1.3 Conservation Equation for Finite Control Volume -- 7.2 Concentration at a Point -- 7.2.1 Transport Equations for Concentration at a Point -- 7.3 Conservation Equations for Bounded Spaces, Envelope Models -- 7.3.1 Multi-cell Building, Uniform Concentration -- 7.3.2 Single-cell Building, Uniform Concentration -- 7.3.3 Single-cell Building, Non-uniform Concentration -- 7.4 Conservation Equations for Large Unbounded Volumes as Used in Zonal Models -- 7.4.1 Secondary Flow Models -- 7.4.2 Primary Flow Models -- 7.5 Analytic Relations for Concentration at a Point -- 7.5.1 Constant Emission at Inlet -- 7.5.2 Pulse Emission at Inlet -- 7.5.3 Emission within the Space -- 7.6 Analytic Relations for Uniform Concentration -- 7.6.1 Multi-chamber Theory -- 7.6.2 Single-cell Building, Uniform Concentration -- 7.6.3 Tracer Gas Techniques -- 7.7 Analytic Relations for Non-uniform Concentration -- 7.8 Calculations with CFD, Coarse-grid CFD and Zonal Models -- 7.9 Definitions Relating to Contaminant Removal -- 7.10 Relevance to Design -- References -- 8 Age of Air and Ventilation Efficiency -- 8.1 Introduction -- 8.1.1 Nature of the Problem -- 8.1.2 Meaning of Age at a Point and its Frequency Distribution -- 8.1.3 Relation between Concentration and Frequency Distribution -- 8.1.4 Illustrative Examples of Frequency Distributions -- 8.1.5 Parameters of Practical Interest -- 8.1.6 Air Change Rate -- 8.2 Theoretical Modelling of Age Properties at a Point -- 8.2.1 Transport Equations for Age Distribution and Age at a Point -- 8.2.2 Transport Equations for Turbulent Flow.

8.2.3 Examples of CFD Calculations with Natural Ventilation.