Contents

Water Freedom System

Survive Global Water Shortages

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Preface xiii

1 Introduction 1

1.1 Use of guidance 4

1.2 General definitions applicable to L1 and L2 4

1.3 Testing 7

2 The Conservation of Fuel and Power in Dwellings 9

2.1 The legal requirement for the conservation of fuel and power in dwellings 9

2.2 AD L1 - Section 0 General Guidance 10

2.3 AD L1 - Section 1 Design and Construction 11

2.3.1 Specific guidance 11

2.3.2 The elemental method for dwellings 13

2.3.2.1 Adjustments allowed by the elemental method 15

2.3.2.2 The elemental method applied to extensions to dwellings 16

2.3.3 The target U-value method for dwellings 17

2.3.4 The carbon index method for dwellings 19

2.3.5 Constraints applicable to all three methods of demonstrating compliance 20

2.3.5.1 Area of glazing 20

2.3.5.2 Poorest acceptable U-values 20

2.3.6 Additional requirements for fabric thermal performance 21

2.3.6.1 Thermal bridging 21

2.3.6.2 Air leakage 22

2.3.7 Heating and hot water systems for dwellings 22

2.3.7.1 Controls for space heating 22

2.3.7.2 The provision of hot water systems in dwellings 23

2.3.7.3 Alternative approach for space heating and the controls for hot water systems 24

2.3.7.4 Commissioning, operating and maintenance instructions for heating and hot water systems 24

2.3.7.5 Insulation of pipes and ducts 25

2.3.8 Lighting systems for dwellings 26

2.3.8.1 Internal lighting 26

2.3.8.2 External lighting 27

2.3.9 Conservatories 27

2.3.9.1 A conservatory attached to and built as part of a new dwelling 28

2.3.9.2 A conservatory attached to an existing dwelling 28

2.4 AD L1 - Section 2 Work on Existing Dwellings 28

2.4.1 Replacement of controlled services or fittings 28

2.4.1.1 Windows doors and rooflights 29

2.4.1.2 Heating boilers 30

2.4.1.3 Hot water vessels 30

2.4.1.4 Boiler and hot water controls 30

2.4.1.5 Alternative approach using the carbon index 30

2.4.1.6 Commissioning, and operating and maintenance instructions 31

2.4.2 Material alterations 31

2.4.2.1 Roof insulation 32

2.4.2.2 Floor insulation 32

2.4.2.3 Wall insulation 32

2.4.2.4 Sealing measures 32

2.4.2.5 Controlled services or fittings 32

2.4.3 Material changes of use 32

2.4.3.1 Accessible lofts 33

2.4.3.2 Roof insulation 33

2.4.3.3 Floor insulation 33

2.4.3.4 Wall insulation 33

2.4.3.5 Sealing measures 34

2.4.3.6 Lighting 34

2.4.3.7 Controlled services or fittings 34

2.4.4 Historic buildings 34

3 The Conservation of Fuel and Power in Buildings other than Dwellings 36

3.1 The legal requirement for the conservation of fuel and power in buildings other than dwellings 36

3.2 AD L2 - Section 0 General Guidance 37

3.2.1 Carbon and carbon dioxide indices 38

3.2.2 Special cases 38

3.2.2.1 Exemptions 38

3.2.2.2 Historic buildings 39

3.2.2.3 Buildings constructed from sub-assemblies 39

3.2.2.4 Mixed use development 40

3.3 AD L2 - Section 1 Design 40

3.3.1 Specific guidance 40

3.3.2 The elemental method for buildings other than dwellings 44

3.3.2.1 Adjustments allowed by the elemental method 46

3.3.2.2 Additional requirements for fabric thermal performance 46

3.3.2.3 Heating systems 49

3.3.2.4 The carbon intensity of heating plant 49

3.3.2.5 The carbon intensity of combined heat and power systems 51

3.3.2.6 The carbon intensity of community heating and other heating methods 52

3.3.2.7 Trade-off between construction elements and heating system efficiency 53

3.3.2.8 Space heating controls 53

3.3.2.9 Hot water systems and their controls 54

3.3.2.10 Insulation of pipes and ducts 54

3.3.2.11 Lighting efficiency standards 55

3.3.2.12 Lighting controls 58

3.3.2.13 Air conditioning and mechanical ventilation

3.3.3 The whole-building method 62

3.3.3.1 Office buildings 62

3.3.3.2 Schools 64

3.3.3.3 Hospitals 64

3.3.4 The carbon emissions calculation method 64

3.3.5 Other matters - conservatories, atria, sun-spaces, etc. 65

3.3.5.1 Definitions 65

3.3.5.2 A sun-space attached to and built as part of a new building 65

3.3.5.3 A sun-space attached to an existing building 66

3.4 AD L2 - Section 2 Construction 66

3.4.1 Building fabric 66

3.4.1.1 Continuity of insulation 66

3.4.1.2 Airtightness 67

3.4.1.3 Certificates and testing 67

3.4.2 Inspection and commissioning of building services systems 67

3.4.2.1 Inspection of building services systems 67

3.4.2.2 Commissioning of building services systems 67

3.4.2.3 Reports and testing 68

3.5 AD L2 - Section 3 Providing Information 69

3.5.1 Building log-book 69

3.5.2 Installation of energy meters 70

3.5.2.1 Reasonable provision for energy metering 70

3.5.2.2 Reasonable provision of energy meters and sub-meters 71

3.6 AD L2 - Section 4 Work on Existing Buildings 72

3.6.1 Replacement of a controlled service or fitting 72

3.6.1.1 Windows, doors and rooflights 72

3.6.1.2 Heating systems 73

3.6.1.3 Hot water systems 73

3.6.1.4 Lighting systems 73

3.6.1.5 Air conditioning or mechanical ventilation systems 73

3.6.1.6 Commissioning, etc 73

3.6.2 Material alterations 74

3.6.2.1 Roof insulation 74

3.6.2.2 Floor insulation 74

3.6.2.3 Wall insulation 74

3.6.2.4 Sealing measures 75

3.6.2.5 Controlled services or fittings 75

3.6.3 Material changes of use 75

3.6.3.1 Accessible lofts 75

3.6.3.2 Roof insulation 75

3.6.3.3 Floor insulation 75

3.6.3.4 Wall insulation 75

3.6.3.5 Sealing measures 76

3.6.3.6 Controlled services or fittings 76

3.6.4 Historic buildings 76

4 Tables of U-values 78

4.1 Windows, doors and rooflights 78

4.1.1 Minimum specifications for windows 80

4.2 Roofs, walls and floors 80

4.2.1 Determining the thickness of insulation for roofs 82

4.2.1.1 Example calculations for roofs 85

4.2.2 Determining the thickness of insulation for walls 88

4.2.2.1 Example calculations for walls 90

4.2.3 Determining the thickness of insulation for floors 95

4.2.3.1 Solid floor in contact with the ground 95

4.2.3.2 Suspended timber ground floor 96

4.2.3.3 Suspended concrete ground floor 97

4.2.3.4 Determining the thickness of insulation for upper floors 98

4.2.3.5 Example calculations for floors 99

4.3 Thermal conductivity and density of building materials 101

5 The Calculation of U-values for Walls 103

5.1 Background theory 103

5.1.1 Corrections to calculated U-values 105

5.1.1.1 Correction for air gaps 105

5.1.1.2 Correction for mechanical fasteners 106

5.1.1.3 Correction for inverted roofs 106

5.1.2 The U-value via an unheated space 106

5.2 Example calculations 108

6 The Calculation of U-values for Ground Floors 117

6.1 Introduction 117

6.2 Solid ground floors 118

6.2.1 Solid ground floors with edge insulation 118

6.2.2 Ground floors with both all-over insulation and edge insulation 120

6.3 Suspended floors 120

6.3.1 Uninsulated suspended ground floors 120

6.3.2 Insulated suspended floors 121

6.4 Example calculations 121

7 Compensation Calculations for Glazing 124

7.1 Introduction 124

7.2 Example calculations 124

8 Target U-value Examples 129

8.1 Semi-detached dwelling 129

8.2 Detached dwelling 132

9 SAP Ratings and the Carbon Index 137

9.1 SAP 137

9.2 Carbon factor and carbon index 137

9.3 Relationship between SAP and CI 138

10 Example of Trade-off Calculations 139

10.1 Residential and conference centre 139

11 Methods of Meeting the Lighting Standards 144

11.1 Lamp and luminaire efficiency 144

11.2 Lighting controls 146

11.3 Example calculations 146

12 CPR Calculations - Methods for Office Buildings 151

12.1 Origins of the CPR method for office buildings 151

12.2 The carbon performance rating for mechanical ventilation, CPR(mv) 151

12.3 The carbon performance rating for air conditioning and mechanical ventilation, CPR(acmv) 152

12.3.2 Values for FD 153 12.3.2.1 Plant management features for FD 153

12.3.3 Values for FR 154 12.3.3.1 Plant management features for FR 155

12.4 The carbon performance rating and the whole-building method, CPR(hlac) 156

12.5 Example calculations 159

13 Solar Overheating Calculations 165

13.1 Definitions 165

13.1.1 Perimeter zones 165

13.1.2 Interior zones 165

13.1.3 Parameters and equations 165

13.2 Sources of data for the parameters 166

13.2.1 Values of qsw and qsr 166

13.2.2 Values of fc 166

13.2.3 Values of frw and frr 168

13.3 Example calculation 168

14 Airtightness and Air Leakage Testing 172

14.1 The importance of airtightness 172

14.2 The mechanisms of air infiltration 172

14.2.1 Basic equations 173

14.2.1.1 Cracks or small openings with a typical dimension less than 1mm 173

14.2.1.2 Openings greater than 1 mm 173

14.2.1.3 Ducts and chimneys 174

14.2.2 Driving forces 174

14.2.2.1 Wind induced pressure difference 174

14.2.2.2 Stack effect pressure difference 175

14.2.3 Openings and the leakage area 175

14.3 The measurement of air leakage 176

14.3.1 Fan pressurisation measurement 177

14.3.2 Preparation for a fan pressurisation test 178

14.4 The air leakage criterion 179

14.4.1 The Part L standard 179

14.4.2 Comparison with other standards 180

14.4.3 Meeting the Part L standard 181

14.5 Air leakage paths 181

14.5.1 Wall, roof and floor components 182

14.5.2 Windows, doors and rooflights 182

14.5.3 Joints and sealing 182

14.5.4 Penetration of the external fabric 183

14.6 Alternative test methods 184

14.6.1 Air permeability and infiltration rate 184

14.6.2 Tracer gas measurement 186

15 Thermal Bridges 188

15.1 The importance of thermal bridges 188

15.2 Thermal bridging, causes and avoidance 189

15.3 Calculation methods 190

15.3.1 Inclusion in the U-value 190

15.3.2 Linear thermal bridges 191

15.3.3 Complex thermal bridges 193

15.4 Compliance with Part L 193

15.5 Condensation and mould growth 196

15.6 Testing 197

15.6.1 Infrared radiation 197

15.6.2 Infrared thermography 198

References

Other Sources of Information

199 202

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