EBOOK - Underfloor Air Distribution (UFAD) - Design Guide (ASHRAE)




EBOOK - Phân phối không khí dưới sàn (UFAD) - Hướng dẫn thiết kế (ASHRAE)



Contents

Acknowledgments xi

Chapter 1—Introduction 1

1.1 Purpose of Guide 1

1.2 System Description 2

1.3 Background 7

1.4 Benefits 11

1.4.1 Improved thermal comfort 11

1.4.2 Improved ventilation efficiency

and indoor air quality 12

1.4.3 Reduced energy use 12

1.4.4 Reduced life-cycle building costs 13

1.4.5 Reduced floor-to-floor height

in new construction 14

1.4.6 Improved productivity and health 14

1.5 Technology Needs 14

1.5.1 New and unfamiliar technology 15

1.5.2 Lack of information and

design guidelines 15

1.5.3 Gaps in fundamental understanding 15

1.5.4 Perceived higher costs 16

1.5.5 Limited applicability to retrofit

construction 16

1.5.6 Problems with applicable

standards and codes 17

1.5.7 Cold feet and draft discomfort 17

1.5.8 Problems with spillage and dirt entering

UFAD systems 18

Copyright ASHRAE

Provided by IHS under license with ASHRAE Licensee=Australia/5940240024

Not for Resale, 09/28/2010 02:18:33 MDT No reproduction or networking permitted without license from IHS

--`,`,`,,,`,`,,,```,,``,,`,`,`,-`-`,,`,,`,`,,`---

CONTENTS

vi

1.5.9 Condensation problems and

dehumidification in UFAD systems 18

1.6 Applications 19

1.7 Organization of Guide 20

Chapter 2—Room Air Distribution 23

2.1 Conventional Overhead Mixing Systems 23

2.2 Displacement Ventilation and

Conditioning Systems 24

2.3 UFAD Systems 31

2.3.1 UFAD Room Air Distribution Model 31

2.3.2 Temperature Near the Floor 35

2.3.3 Stratification Height 36

2.3.4 Controlling Stratification 37

Chapter 3—Thermal Comfort and Indoor Air Quality 41

3.1 Thermal Comfort Standards 43

3.2 Personal Control 44

3.3 Thermal Stratification 49

3.4 Ventilation Performance 49

3.5 Productivity 50

Chapter 4—Underfloor Air Supply Plenums 53

4.1 Description 53

4.1.1 Pressurized Plenum 56

4.1.2 Zero-Pressure Plenum 56

4.2 Airflow Performance in Pressurized Plenums 57

4.2.1 Dimensional Constraints of the Plenum 57

4.2.2 Plenum Inlets 59

4.2.3 Horizontal Ducting within the Plenum 59

4.2.4 Obstructions within the Plenum 59

4.3 Air Leakage 60

4.3.1 Leakage Due to Construction Quality 60

4.3.2 Leakage Between Floor Panels 61

4.4 Thermal Performance 63

4.4.1 Thermal Decay 63

4.4.2 Ductwork and Air Highways 66

Chapter 5—Underfloor Air Distribution

(UFAD) Equipment 69

5.1 Supply Units and Outlets 69

Copyright ASHRAE

Provided by IHS under license with ASHRAE Licensee=Australia/5940240024

Not for Resale, 09/28/2010 02:18:33 MDT No reproduction or networking permitted without license from IHS

--`,`,`,,,`,`,,,```,,``,,`,`,`,-`-`,,`,,`,`,,`---

UNDERFLOORAIRDISTRIBUTIONDESIGNGUIDE

vii

5.1.1 Types of UFAD and TAC Diffusers 69

5.1.2 Passive Swirl Floor Diffusers 71

5.1.3 Passive VAV Floor Diffusers 73

5.1.4 Linear Floor Grilles 75

5.1.5 Active TAC Diffusers 77

5.2 Underfloor Fan Terminals 81

5.3 Raised Floor Systems 85

Chapter 6—Controls, Operation, and Maintenance 89

6.1 Control Strategies in Pressurized Plenums 89

6.1.1 Supply Air Temperature (SAT) 89

6.1.2 Constant Pressure 90

6.1.3 Variable-Air-Volume (VAV) 91

6.1.4 Controlling Stratification 91

6.1.5 Humidity Control 93

6.2 Control Strategies in Zero-Pressure Plenums 94

6.3 Individual Outlet Controls 95

6.4 Operation and Maintenance 96

6.4.1 Cleaning Considerations in

Underfloor Plenums 96

6.4.2 Reconfiguring Building Services 97

6.4.3 Acoustic Performance 97

Chapter 7—Energy Use 99

7.1 Air Distribution Energy 99

7.2 Air-Side Economizers 102

7.2.1 Extended 100% Free Cooling 105

7.2.2 Extended Integrated-Economizer

Free Cooling 105

7.2.3 Climate Factors 105

7.3 Cooling-System Efficiency 106

7.4 Occupant Thermal Comfort 106

7.5 Pre-Cooling Strategies 107

Chapter 8—Design, Construction,

and Commissioning 109

8.1 Design Phase 109

8.2 Construction 110

8.3 Retrofit Projects 115

8.4 Space Planning 115

8.5 Commissioning 116

Copyright ASHRAE

Provided by IHS under license with ASHRAE Licensee=Australia/5940240024

Not for Resale, 09/28/2010 02:18:33 MDT No reproduction or networking permitted without license from IHS

--`,`,`,,,`,`,,,```,,``,,`,`,`,-`-`,,`,,`,`,,`---

CONTENTS

viii

Chapter 9—Perimeter and Special Systems 119

9.1 Perimeter System Definition 119

9.2 Perimeter System Options 120

9.2.1 Two- or Four-Pipe Constant-Speed

Fan Coils 120

9.2.2 Hydronic Heat Pumps 122

9.2.3 VAV or Fan-Powered VAV with Reheat 122

9.2.4 Cooling from VAV Diffusers, Heating

from Heating-Only Fan Coil 122

9.2.5 Fan-Powered Outlets 123

9.2.6 Convector or Baseboard Heating

Coupled with Central UFAD

System Cooling 123

9.2.7 Variable-Speed Fan Coils 125

9.2.8 VAV Change-Over Air Handlers 127

9.3 Conference Rooms or Other Special Systems 130

9.4 Issues to consider in the Design of Perimeter

and Special Systems 132

Chapter 10—Cost Considerations 133

10.1 Standard First Cost Components 137

10.1.1 Raised Floor System 137

10.1.2 Slab Modification and Preparation 137

10.1.3 Cleaning and Sealing the Plenum 138

10.1.4 Fire Detection and Sprinkler Systems 138

10.2 Design-Dependent First Cost Components 138

10.2.1 UFAD System Design 138

10.2.2 Cable Management Systems 139

10.2.3 Floor-to-Floor Heights 140

10.2.4 Ceiling Finishes and Acoustical

Treatment 140

10.3 Life-Cycle Cost Components 141

10.3.1 Churn (Reconfiguration) 141

10.3.2 Operation and Maintenance 141

10.3.3 Tax Savings 142

10.3.4 Increased Property Value and Rents 142

10.3.5 Productivity and Health 142

Copyright ASHRAE

Provided by IHS under license with ASHRAE Licensee=Australia/5940240024

Not for Resale, 09/28/2010 02:18:33 MDT No reproduction or networking permitted without license from IHS

--`,`,`,,,`,`,,,```,,``,,`,`,`,-`-`,,`,,`,`,,`---

UNDERFLOORAIRDISTRIBUTIONDESIGNGUIDE

ix

Chapter 11—Standards, Codes, and Ratings 143

11.1 ANSI/ASHRAE Standard 55-1992:

Thermal Environmental Conditions

for Human Occupancy 143

11.2 ANSI/ASHRAE Standard 62-2001:

Ventilation for Acceptable Indoor Air Quality 145

11.3 ANSI/ASHRAE/IESNA Standard 90.1-2001:

Energy Standard for Buildings

Except Low-Rise Residential Buildings 146

11.4 ANSI/ASHRAE Standard 113-1990:

Method of Testing for Room Air Diffusion 146

11.5 ASHRAE Standard 129-1997:

Measuring Air Change Effectiveness 147

11.6 Title-24: CEC Second Generation

Nonresidential Standards 147

11.7 NFPA 90A: Standard for the Installation

of Air-Conditioning and Ventilating Systems 148

11.8 Uniform Building and Other Applicable Codes 150

11.9 LEED (Leadership in Energy &

Environmental Design) Rating System 150

Chapter 12—Design Methodology 153

12.1 UFAD vs. Conventional Overhead System Design 153

12.2 Building Structure Considerations 153

12.2.1 Building Plan 153

12.2.2 New Construction 154

12.2.3 Retrofit Applications 157

12.3 Determination of Space Cooling

and Heating Loads 158

12.3.1 Space Cooling Load Calculation 158

12.3.2 Space Heating Load Calculation 159

12.4 Determine Ventilation Air Requirements 164

12.5 Temperature Control and Zoning 165

12.5.1 Interior Zones 165

12.5.2 Perimeter Zones 166

12.5.3 Other Special Areas 166

12.6 Air Distribution System Configuration 167

12.6.1 Plenum Configuration 167

12.6.2 Duct Requirements 170

12.7 Determine Zone Supply Air Temperature

and Air Flow Requirements 172

Copyright ASHRAE

Provided by IHS under license with ASHRAE Licensee=Australia/5940240024

Not for Resale, 09/28/2010 02:18:33 MDT No reproduction or networking permitted without license from IHS

--`,`,`,,,`,`,,,```,,``,,`,`,`,-`-`,,`,,`,`,,`---

CONTENTS

x

12.8 Select and Locate Diffusers 174

12.9 Determine Return Air Configuration 176

12.10 Select and Size Primary HVAC Equipment 177

12.11 Thermal Storage Opportunities 178

Chapter 13—UFAD Project Examples 181

Chapter 14—Future Directions 185

14.1 Research 186

14.1.1 Room Air Stratification 186

14.1.2 Underfloor Air Supply Plenums 186

14.1.3 Whole-Building Energy

Simulation Model 186

14.1.4 Thermal Comfort 186

14.1.5 Ventilation Performance 186

14.1.6 Field Studies 187

14.1.7 Productivity Studies 187

14.1.8 Cost Studies 187

14.2 Design Tools 187

14.3 Standards and Codes 188

14.4 Building Industry Developments 188

14.5 Technology Transfer 188

Glossary 189

References and Annotated Bibliography 207

Index 237








EBOOK - Phân phối không khí dưới sàn (UFAD) - Hướng dẫn thiết kế (ASHRAE)



Contents

Acknowledgments xi

Chapter 1—Introduction 1

1.1 Purpose of Guide 1

1.2 System Description 2

1.3 Background 7

1.4 Benefits 11

1.4.1 Improved thermal comfort 11

1.4.2 Improved ventilation efficiency

and indoor air quality 12

1.4.3 Reduced energy use 12

1.4.4 Reduced life-cycle building costs 13

1.4.5 Reduced floor-to-floor height

in new construction 14

1.4.6 Improved productivity and health 14

1.5 Technology Needs 14

1.5.1 New and unfamiliar technology 15

1.5.2 Lack of information and

design guidelines 15

1.5.3 Gaps in fundamental understanding 15

1.5.4 Perceived higher costs 16

1.5.5 Limited applicability to retrofit

construction 16

1.5.6 Problems with applicable

standards and codes 17

1.5.7 Cold feet and draft discomfort 17

1.5.8 Problems with spillage and dirt entering

UFAD systems 18

Copyright ASHRAE

Provided by IHS under license with ASHRAE Licensee=Australia/5940240024

Not for Resale, 09/28/2010 02:18:33 MDT No reproduction or networking permitted without license from IHS

--`,`,`,,,`,`,,,```,,``,,`,`,`,-`-`,,`,,`,`,,`---

CONTENTS

vi

1.5.9 Condensation problems and

dehumidification in UFAD systems 18

1.6 Applications 19

1.7 Organization of Guide 20

Chapter 2—Room Air Distribution 23

2.1 Conventional Overhead Mixing Systems 23

2.2 Displacement Ventilation and

Conditioning Systems 24

2.3 UFAD Systems 31

2.3.1 UFAD Room Air Distribution Model 31

2.3.2 Temperature Near the Floor 35

2.3.3 Stratification Height 36

2.3.4 Controlling Stratification 37

Chapter 3—Thermal Comfort and Indoor Air Quality 41

3.1 Thermal Comfort Standards 43

3.2 Personal Control 44

3.3 Thermal Stratification 49

3.4 Ventilation Performance 49

3.5 Productivity 50

Chapter 4—Underfloor Air Supply Plenums 53

4.1 Description 53

4.1.1 Pressurized Plenum 56

4.1.2 Zero-Pressure Plenum 56

4.2 Airflow Performance in Pressurized Plenums 57

4.2.1 Dimensional Constraints of the Plenum 57

4.2.2 Plenum Inlets 59

4.2.3 Horizontal Ducting within the Plenum 59

4.2.4 Obstructions within the Plenum 59

4.3 Air Leakage 60

4.3.1 Leakage Due to Construction Quality 60

4.3.2 Leakage Between Floor Panels 61

4.4 Thermal Performance 63

4.4.1 Thermal Decay 63

4.4.2 Ductwork and Air Highways 66

Chapter 5—Underfloor Air Distribution

(UFAD) Equipment 69

5.1 Supply Units and Outlets 69

Copyright ASHRAE

Provided by IHS under license with ASHRAE Licensee=Australia/5940240024

Not for Resale, 09/28/2010 02:18:33 MDT No reproduction or networking permitted without license from IHS

--`,`,`,,,`,`,,,```,,``,,`,`,`,-`-`,,`,,`,`,,`---

UNDERFLOORAIRDISTRIBUTIONDESIGNGUIDE

vii

5.1.1 Types of UFAD and TAC Diffusers 69

5.1.2 Passive Swirl Floor Diffusers 71

5.1.3 Passive VAV Floor Diffusers 73

5.1.4 Linear Floor Grilles 75

5.1.5 Active TAC Diffusers 77

5.2 Underfloor Fan Terminals 81

5.3 Raised Floor Systems 85

Chapter 6—Controls, Operation, and Maintenance 89

6.1 Control Strategies in Pressurized Plenums 89

6.1.1 Supply Air Temperature (SAT) 89

6.1.2 Constant Pressure 90

6.1.3 Variable-Air-Volume (VAV) 91

6.1.4 Controlling Stratification 91

6.1.5 Humidity Control 93

6.2 Control Strategies in Zero-Pressure Plenums 94

6.3 Individual Outlet Controls 95

6.4 Operation and Maintenance 96

6.4.1 Cleaning Considerations in

Underfloor Plenums 96

6.4.2 Reconfiguring Building Services 97

6.4.3 Acoustic Performance 97

Chapter 7—Energy Use 99

7.1 Air Distribution Energy 99

7.2 Air-Side Economizers 102

7.2.1 Extended 100% Free Cooling 105

7.2.2 Extended Integrated-Economizer

Free Cooling 105

7.2.3 Climate Factors 105

7.3 Cooling-System Efficiency 106

7.4 Occupant Thermal Comfort 106

7.5 Pre-Cooling Strategies 107

Chapter 8—Design, Construction,

and Commissioning 109

8.1 Design Phase 109

8.2 Construction 110

8.3 Retrofit Projects 115

8.4 Space Planning 115

8.5 Commissioning 116

Copyright ASHRAE

Provided by IHS under license with ASHRAE Licensee=Australia/5940240024

Not for Resale, 09/28/2010 02:18:33 MDT No reproduction or networking permitted without license from IHS

--`,`,`,,,`,`,,,```,,``,,`,`,`,-`-`,,`,,`,`,,`---

CONTENTS

viii

Chapter 9—Perimeter and Special Systems 119

9.1 Perimeter System Definition 119

9.2 Perimeter System Options 120

9.2.1 Two- or Four-Pipe Constant-Speed

Fan Coils 120

9.2.2 Hydronic Heat Pumps 122

9.2.3 VAV or Fan-Powered VAV with Reheat 122

9.2.4 Cooling from VAV Diffusers, Heating

from Heating-Only Fan Coil 122

9.2.5 Fan-Powered Outlets 123

9.2.6 Convector or Baseboard Heating

Coupled with Central UFAD

System Cooling 123

9.2.7 Variable-Speed Fan Coils 125

9.2.8 VAV Change-Over Air Handlers 127

9.3 Conference Rooms or Other Special Systems 130

9.4 Issues to consider in the Design of Perimeter

and Special Systems 132

Chapter 10—Cost Considerations 133

10.1 Standard First Cost Components 137

10.1.1 Raised Floor System 137

10.1.2 Slab Modification and Preparation 137

10.1.3 Cleaning and Sealing the Plenum 138

10.1.4 Fire Detection and Sprinkler Systems 138

10.2 Design-Dependent First Cost Components 138

10.2.1 UFAD System Design 138

10.2.2 Cable Management Systems 139

10.2.3 Floor-to-Floor Heights 140

10.2.4 Ceiling Finishes and Acoustical

Treatment 140

10.3 Life-Cycle Cost Components 141

10.3.1 Churn (Reconfiguration) 141

10.3.2 Operation and Maintenance 141

10.3.3 Tax Savings 142

10.3.4 Increased Property Value and Rents 142

10.3.5 Productivity and Health 142

Copyright ASHRAE

Provided by IHS under license with ASHRAE Licensee=Australia/5940240024

Not for Resale, 09/28/2010 02:18:33 MDT No reproduction or networking permitted without license from IHS

--`,`,`,,,`,`,,,```,,``,,`,`,`,-`-`,,`,,`,`,,`---

UNDERFLOORAIRDISTRIBUTIONDESIGNGUIDE

ix

Chapter 11—Standards, Codes, and Ratings 143

11.1 ANSI/ASHRAE Standard 55-1992:

Thermal Environmental Conditions

for Human Occupancy 143

11.2 ANSI/ASHRAE Standard 62-2001:

Ventilation for Acceptable Indoor Air Quality 145

11.3 ANSI/ASHRAE/IESNA Standard 90.1-2001:

Energy Standard for Buildings

Except Low-Rise Residential Buildings 146

11.4 ANSI/ASHRAE Standard 113-1990:

Method of Testing for Room Air Diffusion 146

11.5 ASHRAE Standard 129-1997:

Measuring Air Change Effectiveness 147

11.6 Title-24: CEC Second Generation

Nonresidential Standards 147

11.7 NFPA 90A: Standard for the Installation

of Air-Conditioning and Ventilating Systems 148

11.8 Uniform Building and Other Applicable Codes 150

11.9 LEED (Leadership in Energy &

Environmental Design) Rating System 150

Chapter 12—Design Methodology 153

12.1 UFAD vs. Conventional Overhead System Design 153

12.2 Building Structure Considerations 153

12.2.1 Building Plan 153

12.2.2 New Construction 154

12.2.3 Retrofit Applications 157

12.3 Determination of Space Cooling

and Heating Loads 158

12.3.1 Space Cooling Load Calculation 158

12.3.2 Space Heating Load Calculation 159

12.4 Determine Ventilation Air Requirements 164

12.5 Temperature Control and Zoning 165

12.5.1 Interior Zones 165

12.5.2 Perimeter Zones 166

12.5.3 Other Special Areas 166

12.6 Air Distribution System Configuration 167

12.6.1 Plenum Configuration 167

12.6.2 Duct Requirements 170

12.7 Determine Zone Supply Air Temperature

and Air Flow Requirements 172

Copyright ASHRAE

Provided by IHS under license with ASHRAE Licensee=Australia/5940240024

Not for Resale, 09/28/2010 02:18:33 MDT No reproduction or networking permitted without license from IHS

--`,`,`,,,`,`,,,```,,``,,`,`,`,-`-`,,`,,`,`,,`---

CONTENTS

x

12.8 Select and Locate Diffusers 174

12.9 Determine Return Air Configuration 176

12.10 Select and Size Primary HVAC Equipment 177

12.11 Thermal Storage Opportunities 178

Chapter 13—UFAD Project Examples 181

Chapter 14—Future Directions 185

14.1 Research 186

14.1.1 Room Air Stratification 186

14.1.2 Underfloor Air Supply Plenums 186

14.1.3 Whole-Building Energy

Simulation Model 186

14.1.4 Thermal Comfort 186

14.1.5 Ventilation Performance 186

14.1.6 Field Studies 187

14.1.7 Productivity Studies 187

14.1.8 Cost Studies 187

14.2 Design Tools 187

14.3 Standards and Codes 188

14.4 Building Industry Developments 188

14.5 Technology Transfer 188

Glossary 189

References and Annotated Bibliography 207

Index 237





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