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SLL Code for Lighting (2022)
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SLL Code for Lighting (2022)

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The SLL Code for Lighting establishes the fundamentals required by lighting designers and anyone responsible for the application of light and lighting within the built environment.

The 2022 update reflects the rapid development in lighting technologies and research. Advances in LED lighting technology over the last decade have seen it become the dominant light source. Amongst other developments, this has led to extensive lighting research around the non-visual effects of LED light, and the potential for artificial lighting to disrupt and/or support human circadian rhythms.

It is understood that lighting conditions can affect visual performance, and in some cases, cause visual discomfort. The dominance of LED lighting has contributed to discussions relating to lighting metrics, colour rendering, and the spectral content of LED light sources. The possibility that exposure to light can have significant effects on human health and functioning beyond the obvious visual effect implies another basis for lighting recommendations. However, more knowledge is required before non-visual effects can be applied with confidence, particularly about the effects on healthy people exposed to light by day.

Lighting is vital in the modern world, enabling the 24-hour society to exist. It is used for many different purposes, from enabling people to work accurately and safely, to visually enhancing our environment and improving accessibility and security.

The new edition of the Code considers the cost of lighting in relation to the health and wellbeing of an occupant and the environment. The recommendations included in the Code aim to strike a balance between the benefits and the costs. The basis of energy efficient lighting is to provide the right amount of light, in the right place, at the right time, with the right lighting equipment.

Split over twenty chapters, the Code covers definitions for the various units of measurement and the interrelationships between them; calculation methodologies for a range of applications; photometric data; colour metrics; and maintenance factors for LED light sources and luminaires.

Most lighting calculations are carried out using software tools based on the fundamental calculations that are listing within the Code for Lighting. The Code specifies the quantitative lighting requirements for a wide range of applications, along with guidance on how these might be achieved. By understanding these fundamentals, the designer, engineer, or facilities manager is equipped with the information they might need to verify automated calculations.

The Code sits alongside the SLL Lighting Handbook, which is more aligned to project-based lighting design, technology, and applications.lications. 

Note: A corrigendum was issued on 25th July 2023 to make changes to chapters 3, 9 and 17. Purchasers of the hard copy can view the corrigendum here.

Please note: The PDF available for download has been updated accordingly.

Chapter 1: The balance of lighting

1.1 Lighting quality

1.2 The place of lighting in the modern world

1.3 Lighting and safety

1.4 Lighting costs

Chapter 2: Light and human performance

2.1 An overview of the effects of light on human performance

2.2 Lighting and visual task performance

2.3 Lighting and behaviour

2.4 Lighting and perception

Chapter 3: Indoor workplaces

3.1 Lighting design criteria

3.2 Schedule of lighting requirements

Chapter 4: Outdoor workplaces

4.1 Lighting design criteria

4.2 Schedule of lighting requirements

4.3 Verification procedures

Chapter 5: Road lighting

5.1 Introduction

5.2 Standards and guidance

5.3 Sustainability

5.4 Classification of roads

Chapter 6: Daylight

6.1 Introduction: why we need daylight in buildings

6.2 Daylight recommendations

6.3 Sunlight exposure

6.4 Glare

6.5 View

6.6 Integration with artificial lighting

Chapter 7: Energy and electric lighting

7.1 Simple guidance for energy efficient lighting

7.2 Energy regulations and standards

7.3 Optional certification schemes

Chapter 8: Construction (Design and Management) Regulations

8.1 Introduction

8.2 Client duties

8.3 Duties and roles

8.4 Duties relating to health and safety on construction sites

Chapter 9: Basic energy and light

9.1 Properties of electromagnetic waves

9.2 Evaluating energy as light

9.3 The non-visual impacts of light

Chapter 10: Luminous flux, intensity, illuminance, luminance and their interrelationships

10.1 Definitions of the units

10.2 Interrelationships between the units

Chapter 11: Direct lighting

11.1 Illuminance from point sources

11.2 Non-point sources

Chapter 12: Indirect lighting

12.1 Introduction

12.2 Sumpner’s method

12.3 Transfer factors

Chapter 13: Photometric datasheets

13.1 Photometric measurement

13.2 Elements of a datasheet

13.3 Calculations for datasheets

Chapter 14: Indoor lighting calculations

14.1 Introduction

14.2 The illumination vector

14.3 Cubic illuminance

14.4 Derived values

Chapter 15: Outdoor lighting calculations

15.1 Calculation of intensity towards a point

15.2 The reflective properties of road surfaces

15.3 Calculation of illuminance and luminance

15.4 Calculation of glare

15.5 Calculations in other outdoor areas

Chapter 16: Measurement of lighting installations and interpretation of results

16.1 Light measuring equipment

16.2 Field measurements

Chapter 17: Colour

17.1 Introduction

17.2 Colour properties of light sources

17.3 Colour rendering

17.4 Colour properties of surfaces

Chapter 18: Predicting maintenance factor

18.1 Determination of maintenance factor

18.2 Lamp lumen maintenance factor and lamp survival factor

18.3 Luminaire maintenance factor

18.4 Room surface maintenance factor (RSMF)

18.5 Ingress protection (IP) classes

Project manager and editor-in chief: Sophie Parry

Chapter authors and principal contributors: Allan Howard BEng (Hons) FLIP FSLL (Group Technical Director (Lighting), WSP) Professor Peter Raynham CEng MSc MCIBSE FILP FSLL (UCL Institute for Environmental Design and Engineering), Sophie Parry CEng MIET FSLL (Technical Applications and Education Consultant, Zumtobel Group Lighting), Peter Thorns CEng BSc (Hons) FCIBSE FSLL (Zumtobel Group Lighting), Ruth Kelly-Waskett PhD CEng MCIBSE FSLL (Hoare Lea LLP)

Contributors and reviewers: Professor Steve Fotios PhD CEng MEI MILP FSLL (University of Sheffield), Nigel Monaghan FSLL (Senior Lighting consultant, Luminous Solutions), Professor Peter Raynham CEng MSc MCIBSE FILP FSLL (UCL Institute for Environmental Design and Engineering Peter Thorns CEng BSc (Hons) FCIBSE FSLL (Zumtobel Group Lighting)

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