All contributions are the responsibility of the author, and do not necessarily reflect the views of the society. All contributions are personal, except where attributed to an organisation represented by the author.
COPY DATE FOR LL3 2025 IS 10 MARCH
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George Eason
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FROM THE EDITOR
As has been said before, there is no doubt that lighting has become a deal more complex in many respects than it was a few decades ago. We are very much not in Kansas any more.
In the physics sphere it always has been somewhat impenetrable (see p4 for a visualisation of a photon), but the apparently straightforward business of lighting a space has become much more fraught with possibilities and considerations. Which is on the whole a good thing because we are increasingly learning about the effects and implications of light.
Beyond basic functional and energy needs, lighting affects people’s comfort, safety, health, wellbeing, sense of place and orientation. It has impacts on social behaviour, and affects local ecology and dark skies. All, and more, to be negotiated alongside new and frequently changing legislation (see Safe in the Knowledge, p8) and digital change.
With so many things to consider, it is not surprising that those who are not specialists
resort to an overreliance on standards as a way of navigating what seems like an illumination minefield.
But as Jeff Shaw points out in his summary of a forthcoming SLL lighting guide on creative architectural lighting design (A Creative Leap, p5), that simply won't cut it. As specialist lighting designers have known for years. Shaw puts it more succinctly: 'Compliance should not be confused with good design.' With all due caution and provisos, the guide will ideally give the non-specialist the confidence and knowledge to think a little less of conformity and more of creativity.
CURRENT SLL LIGHTING GUIDES
SLL Lighting Guide 0: Introduction to Light and Lighting (2017)
SLL Lighting Guide 1: The Industrial Environment (2018)
SLL Lighting Guide 2: Lighting for Healthcare Premises (2019)
SLL Lighting Guide 4: Sports Lighting (2023)
SLL Lighting Guide 5: Lighting for Education (2011)
SLL Lighting Guide 6: The Exterior Environment (2016)
SLL Lighting Guide 7: Office Lighting (2023)
SLL Lighting Guide 8: Lighting for Museums and Galleries (2021)
SLL Lighting Guide 9: Lighting for Communal Residential Buildings (2022)
SLL Lighting Guide 10: Daylighting – a guide for designers (2014)
SLL Lighting Guide 11: Surface Reflectance and Colour (2001)
SLL Lighting Guide 12: Emergency Lighting (2022)
SLL Lighting Guide 13: Places of Worship (2018)
SLL Lighting Guide 14: Control of Electric Lighting (2023)
SLL Lighting Guide 15: Transport Buildings (2017)
SLL Lighting Guide 16: Lighting for Stairs (2017)
SLL Lighting Guide 17: Lighting for Retail Premises (2018)
SLL Lighting Guide 18: Lighting for Licensed Premises (2018)
SLL Lighting Guide 19: Lighting for Extreme Conditions (2019)
SLL Lighting Guide 20: Lighting and Facilities Management (2020)
SLL Lighting Guide 21: Protecting the Night-time Environment (2021)
SLL Lighting Guide 22: Lighting for Control Rooms (2022) Guide to Limiting Obtrusive Light (2012) Code for Lighting (2022)
Commissioning Code L (2018)
SLL Lighting Handbook (2018)
CIBSE TM66: Creating a Circular Economy in the Lighting Industry (2021)
CIBSE TM65.2: Embodied Carbon in Building Services – Lighting (2023)
FROM THE SECRETARY
For this issue, Secretary Brendan Keely hands over his column to former SLL president Helen Loomes to announce a major SLL conference this month
In March the SLL will be holding an important conference in London: Illuminating the Future –Balancing light and dark nightscapes. The event was born from an idea I shared during my presidential address.
My aim was to spread knowledge, research and best practices not only to those in the lighting industry and profession, but also to professionals in different disciplines. As well as that being an intrinsically important aim, think we need the rest of the world to understand just how much we know.
A further objective was to foster the sharing of knowledge within the sphere of lighting –between researchers, designers and end users. Lighting encompasses many aspects, including various application sectors, levels of complexity and, of course, different financial constraints. Lighting our night-time environments is a key area of discussion. It is an issue that we need other disciplines to understand, but we also need to better understand their concerns. We want to share knowledge, explore different perspectives, and understand the consequences of making one decision over another.
I am delighted that, after much work, we have created such a magnificent, exciting and informative programme, featuring an impressive array of experts, a balance of academics, practitioners and individuals with extensive experience. It will provide an illuminating exploration of how night-time lighting shapes our cities, communities and ecosystems.
The day will be divided into three sessions covering such topics as:
• Impact on nocturnal species
• Crime reduction and public safety
• Social interaction and community wellbeing
• Design considerations for women
The first session will provide a high-level overview looking at the pros and cons of lighting, understanding the consequences and how to navigate the information.
The second session will focus on research, giving a balance of diverse and opposing
• Illuminating the Future –Balancing light and dark nightscapes will be held on 27 March at Senate House, UCL, London WC1. For more details: www.cibse.org/get-involved/ societies/society-of-lightand-lighting-sll/whatshappening/illuminating-thefuture-balancing-light-anddark-nightscapes/
viewpoints, while the third session will look at practical applications, case studies and a view to the future.
Key to the day is an open debate to allow the audience to challenge the speakers, and form part of all subsequent follow-up events.
Florence Lam will chair the discussion which hopefully will reveal many other perspectives.
This has all been packaged into an unmissable day and evening event, to be held at Senate House, UoL, in London. The venue will certainly add to the occasion, which will culminate in a reception. I look forward to meeting with many of you there – and, most importantly, continuing the discussions which the day will undoubtedly provoke.
Speakers
Andrew Bissell, past president SLL, Ridge and Partners
Dr Elettra Bordanaro, senior research fellow LSE and Light Follows Behaviour
Ryan Carroll, past chair of YLP, DFL-UK
Chiara Carucci, Noctua
Professor Steve Fotios, University of Sheffield
Florence Lam, Arup fellow, visiting professor at UCL Bartlett IEDE
Dan Lister, president SLL, director Arup
Mark Major, Speirs Major
Professor Peter Raynham, formerly UCL, past president SLL
Benz Roos, Speirs Major Alistair Scott, past president ILP, chairman DFL-UK
Mike Simpson, past president SLL, CIBSE and ILP, Signify
COVER: Dichroic desk at the Plus Company Campus and Cossette Offices, Montreal, lighting by LAAB Architecture.
See p5 for Jeff Shaw's outline of the SLL's new guide to creative lighting design
A team of physicists at the University of Birmingham has created the first direct visualisation of a photon’s shape, providing new insights into the fundamental nature of light and how it interacts with matter.
According to research published in Physical Review Letters, the team has now calculated the wave function of photons (individual particles of light) to produce an accurate image of a single photon as it’s emitted. The visualisation represents an intensity distribution, showing where a photon is likely to be found at a specific moment. The research team has explored the nature of photons to show how they are emitted by atoms or molecules and shaped by their environment. The nature of this interaction 'leads to infinite possibilities for light to exist and propagate, or travel, through its surrounding environment'. However, this makes the interactions very hard to model, a problem that quantum physicists have been trying to solve for decades.
By grouping the possibilities into distinct sets, the researchers were able to produce a model that describes not only the interactions between the photon and the emitter, but also how the energy from that interaction travels into the distant ‘far field’. Their calculations also enabled them to produce a visualisation of the photon itself.
'Our calculations enabled us to convert a seemingly insolvable problem into something that can be computed,' explained first author Dr Benjamin Yuen of the university’s School of Physics and Astronomy. 'And, almost as a bi-product of the model, we were able to produce this image of a photon, something that hasn’t been seen before in physics.'
The work is important, say researchers, because it opens up new avenues of research for quantum physicists and material science. 'This work helps us to increase our understanding of the energy exchange between light and matter, and secondly to better understand how light radiates into its nearby and distant surroundings,' said Dr Yuen. 'By understanding this, we set the foundations to be able to engineer light-matter interactions for future applications, such as improved photovoltaic energy cells.'
Working with Polynesian artisans, biodesigner and engineer Christopher Bellamy has combined biotechnology with craft to create a series of objects made from bioluminescent algae.
Pictured is a swim suit, which like the other Lucid Life objects, a drum and necklace, lights up in response to touch or movement.
The algae live within a gel that is encapsulated in a permeable membrane, which Bellamy likens to a Gore-Tex for algae. The Lucid Life objects retain their
bioluminescence for over six months. 'They need about eight hours of sleep and 12 hours of daylight,' explains Bellamy. 'They need regular movement and exercise. They kind of need the same things as me.' https://biocrafted.com/
The project builds on Turrell's work at Roden Crater in the desert of Northern Arizona where for the past five decades he has been reshaping an extinct volcano with light.
An exhibition featuring Turrell's work and insight into the project will run in AlUla until 19 April: www.experiencealula. com/en/things-to-do/experiences/jamesturrell-exhibition
BURSARY OPEN FOR APPLICATIONS
The SLL Jean Heap Research Bursary, worth up to £4000, is now open for 2025 applicants. It can be awarded to anyone with an interest in light and lighting.
A panel of expert judges is looking for a specific piece of lighting study or research designed for the benefit of SLL members and the industry as a whole. Applicants are asked to put forward their research proposal by 6 May 2025. For more information and to apply:sll@cibse.org
A CREATIVE LEAP
The SLL's forthcoming new lighting guide, LG23, on creative architectural lighting design, is something of a departure. Jeff Shaw elucidates
esign is to design a design to produce a design,' observed John Heskett, academic and writer on industrial design history and thinking.
The word ‘design’ can mean different things at different times and in different contexts. It can be a noun referring to the professional field of design, or it can be a verb describing the activity and process of designing – thus creating a design, another noun that is the actual outcome of a design process.
The field of design is concerned with making things how they should be (whether from scratch or by modification). This means that design is about improvement, taking a thing from its current state to a preferred state. The process usually involves
solving a problem (which is how engineers may typically view the process of design), but it could involve a number of other nuances, such as adding luxury, reducing cost, simplifying processes, changing use, even simply the removal or replacement of a previous design.
In the case of lighting design, it may be about improving the quality of a space or changing its use in a renovation or taking a new space and using light to make it comfortable, inviting, sustainable, all while supporting its function. This goes well beyond the meeting of a given lux level on a specified surface based on a range of assumptions.
Renowned American architect Frank Lloyd Wright once said, 'More and more, so it seems to me, light is the beautifier of the building'. Lighting, both natural and artificial, plays an intrinsic role in architecture, well beyond the functional role of facilitating the task.
Depending on the individual project, the role of designing the lighting in the built environment can fall on a wide range of different practitioners. Given this, and the complexity of the topic, the SLL concluded that there was a role for a new lighting guide on the topic of creative architectural lighting design, which will be the upcoming Lighting Guide 23 (LG23). There is already an extensive range of guidance and standards covering lighting, published by the SLL and others, such as the British Standards Institute (BSI). Standards generally
� Sanxingdui Museum New Hall, Guanghan, Sichuan (lighting by Puri Lighting Design), IALD Merit Award 2024: lighting, both natural and artificial, plays an intrinsic role in architecture. 'As Frank Lloyd Wright once said, "More and more, so it seems to me, light is the beautifier of the building"'
focus on targets and design parameters to ensure functional lighting requirements are met, and that lighting installations are safe and fit-for-purpose.
Guidance, such as the SLL’s series of lighting guides, tends to focus on specific aspects of lighting design or building types, in many cases touching on design techniques and approaches, as well as setting out technical targets and design considerations, and other relevant requirements.
This newest guide in the series, LG23, is framed differently. Rather than focusing on a specific aspect of lighting, it addresses the overall architectural lighting design process, giving guidance on approaches to creative design and delivery, and appropriate to any lighting design project.
Professional lighting designers only design the lighting for a fraction of our buildings; those responsible for the lighting design can come from a wide range of backgrounds. The purpose of LG23 is to give all those who may develop lighting schemes robust guidance on a creative approach to lighting design.
The guide is aimed therefore at anyone who bears responsibility for the design of the lighting on a project, such as lighting designers, architects, interior designers, landscape architects, electrical engineers, manufacturers and contractors. The guide aims to support the improvement of the quality of lighting design carried out throughout the built environment by all involved.
DEFINING A GOOD LIGHTING SCHEME
Good lighting design is not only about displaying a high degree of creative flair. A wide range of skills, talents and simple common sense contribute to creating high-quality outcomes for projects. While reading standards may lead some to believe that there is a 'right answer' to a design problem, there is generally no single solution, and it is the role of the designer to best apply his or her abilities to work with the project team to develop a solution that fits the requirements and stakeholders’ aspirations.
Good lighting design also goes beyond just minimising the carbon footprint; an extremely lowenergy scheme that is technically compliant with standards, if not considered more holistically may be deemed inadequate by users and they may not use the space or be comfortable in it. A truly sustainable lighting scheme is ‘energy effective’ – delivering a useful, comfortable space that people will use, which can require a little more energy use than the absolute minimum, but that therefore has longevity.
Overall, good lighting design is about balancing the meeting of functional and energy requirements with lighting’s effect on people’s comfort, safety, health, wellbeing, sense of place and orientation; and potentially there can also be wider social impacts and implications for the local ecology and dark skies. All design is about compromise, and responsible design is about balancing all requirements in order
to maximise the effectiveness of the result. The guide outlines the design process, drawing on models such as the consideration of design as a 'Wicked Problem' (as defined by Rittel, Horst and Webber in 1973 in Dilemmas in a General Theory of Planning), and the process of orderly and informed decision-making depicted by the Double Diamond, developed by the Design Council. The Double Diamond divides the design process into four distinct stages:
Discover: Understand the requirements, explore the challenge and identify the user needs for the design
Define: Make sense of these findings, align the user needs with the design challenge and develop a clearly-defined design brief and narrative Develop: Using this as a basis, develop, test and refine potential solutions – many options may be explored, expanded or rejected during this stage Deliver: The final phase is to select the most optimal single solution and prepare this solution for delivery
LG23 is broadly structured around the considerations and approaches needed for each of these four stages, and covers the principles of lighting design, including:
• The human relationship with light, and the intrinsic relationship between light and architecture
visual interest, can be uncomfortable, and is wasting energy. Or lighting the concourse of a transport hub to a strict uniformity target, with no consideration of how the other surfaces in the space appear, is likely to create an unwelcoming environment which can be confusing to navigate and that may even feel unsafe.
The guide outlines the sorts of situations where a designer may justifiably choose to depart from the standards, with due care and consideration (as well as with a risk assessment).
WHY NOW?
• The fundamentals of lighting design in terms of elements such as visual perception, contrast, visibility, shadow, adaptation, lighting the task, emphasis, mood, atmosphere, style, suitability, spatial expression and decoration
• The importance of considering all the requirements of the people using the space being designed
• Consideration of the place – the context, materials and architecture
• Lighting regulations, standards and guidance, the difference between these and how to interpret these
• Other considerations including daylight, sustainability, circular economy, safety and security, inclusive design, wellbeing, dark skies, ecology, CDM, access and maintenance, and lighting control
• The key objectives a lighting designer has and the choices that he or she must make in their approach to a scheme
• The lighting design process, from gathering the information needed, through creating the design narrative, to developing the detailed design
• Fundamentals of project delivery, such as outlining the various roles in the project design team, project design stages (RIBA Plan of Work), BIM, lighting analysis software and communication of the design
BEYOND COMPLIANCE
The guide outlines how compliance should not be confused with good design. Clearly lighting standards do provide a framework to set design targets for a lighting scheme and are generally viewed as providing mandatory targets (in some cases they are a legal requirement, such as for emergency lighting).
However, delivering a scheme focused only on compliance to these targets does not necessarily deliver a good design. An office lit to a blanket uniform 500 lux on the working plane can lack
This guide is timely in the sense that the lighting profession has been subject to significant change over recent years, including an ever-growing recognition of the importance of lighting in the built environment. Over the past two decades we have seen the takeover of LEDs as the primary source which, by their nature, opens a much wider range of design possibilities than we had in the past. We are also subject to more significant pressure than ever in the drive for sustainability. And there is a greater awareness that our designs need to be inclusive, along with more understanding of the fact that lighting impacts the health and wellbeing of building occupants.
All of this must be navigated alongside new and frequently changing legislation and on the wave of digital change affecting all industries. This puts a greater degree of opportunity and responsibility than ever before on the practitioner carrying out the lighting design. LG23 aims to capture as much of this change as possible, and to prepare practitioners for the current and future direction of lighting design practice.
The guide is not intended to provide solutions, but it goes into detail on a wide range of possible design considerations and approaches for every stage of a project. The overall intent is for it to inform and assist lighting designers with design and to ensure that they are aware of the potential issues involved when undertaking a lighting design project, as well as to enable them to know when to ask questions and seek advice.
Lighting Guide 23 (LG23) is due to be published this year. For more details of all SLL publications go to: www.cibse.org/get-involved/societies/society-oflight-and-lighting-sll/knowledge-resources/sllpublications-and-guidance/
Jeff Shaw, FSLL, lead author of LG23, is associate director lighting design at Arup and former SLL president
� The guide draws on models such as the 'Wicked Problem' (defined by Rittel, Horst and Webber in 1973 in Dilemmas in a General Theory of Planning), and the process of orderly, informed decision-making depicted by the Double Diamond, developed by the Design Council
� Farringdon Elizabeth Line Station: good lighting design goes way beyond conformity to standards: 'responsible design is about balancing all requirements to maximise the effectiveness of the result'
� ... and showing key lighting design decisions that were made
By now everyone should know about the Building Safety Act and its implications. The Act aims to ensure best practice in the management of building design and operation, improving standards and safety by ensuring that there is a 'Golden Thread' of information throughout the whole design, build and maintenance process –showing what decisions were made, why they were made and how they were implemented.
But for this to be effective it is important to understand what decisions should be made.
This is where the concept of a competent person comes into play, defined as 'Any person carrying out any building or design work [shall] have the skills, knowledge, experience and behaviours necessary'.
This means not only having skills and knowledge but also a professional approach in applying these in practice.
It is important to understand that the Building Safety Act currently applies to a limited set of buildings, termed higher-risk buildings (although it is good practice for all buildings). These are buildings that are at least 18m in height or have at least seven stories and
• contain at least two residential units, or
• are a care home, or
• are a hospital
So for lighting, what are the requirements? The definition means that a range of building types are in scope as a high-rise building containing non-residential and residential units is covered.
For residential spaces there are little to no requirements for lighting within the domestic unit apart from existing requirements in 'wet' areas such as kitchens and bathrooms. However, communal areas are generally covered within workplace requirements, as well as plant rooms and so on within the building.
Non-residential spaces, care homes and hospitals are covered by workplace regulations.
For this, key legislation is contained in the Workplace (Health, Safety and Welfare) Regulations and the fire safety orders/acts in the countries of the UK. SI 1992 No 3004 Health and Safety The Workplace (Health, Safety and Welfare) Regulations 1992 states:
Lighting
8 – (1) Every workplace shall have suitable and sufficient lighting (2) The lighting mentioned in paragraph (1) shall, so far as is
reasonably practicable, be by natural light (3) Without prejudice to the generality of paragraph (1), suitable and sufficient emergency lighting shall be provided in any room in circumstances in which persons at work are specially exposed to danger in the event of failure of artificial lighting
So to start with, what is 'suitable and sufficient lighting'? Standards and codes of practice are good places to begin: BS EN 12464-1, BS EN 12464-2 and the SLL Code for Lighting give requirements and advice, but these should always be starting points.
Competence implies an understanding of what requirements mean and how they should be applied. Just using default values does not show competence and it does not guarantee suitable and sufficient as standard design values ignore who is in the space and concentrates on what they are doing.
Requirements assume a standard person of a specific age with good eyesight, and real world occupants may differ significantly from these assumptions, depending on age, visual capability, physical ability and so on. Thinking about how a space is lit as well as to what lighting level is important. A person with good eyesight but poor processing capability will need help to understand what they can see. Visibility is not a solution in itself.
Clause 8(3) moves the discussion towards emergency lighting, a legal requirement that has its own regulations. The requirements across the countries of the UK are essentially the same, and clauses within the Regulatory Reform (Fire Safety) Order 2005 state:
13 – (1) Where necessary (whether due to the features of the premises, the activity carried on there, any hazard present or any other relevant circumstances) in order to safeguard the safety of relevant persons, the responsible person must ensure that:
(b) any non-automatic fire-fighting equipment so provided is easily accessible, simple to use and indicated by signs
14 (g) emergency routes and exits must be indicated by signs
14 (h) emergency routes and exits requiring illumination must be provided with emergency lighting of adequate intensity in the case
� Hospitals and care homes fall into the 'higher-risk building' category
of failure of their normal lighting. The responsible person must: a. ensure that the premises are designed, constructed and maintained so as to reduce risk
So before a designer can start they need to understand a lot of information. This should include a risk assessment as this will reveal any additional risks or special considerations that may require more or different lighting. Consider the viewpoint of a person in a wheelchair, for example, and whether signage will be visible to direct people to suitable evacuation routes, or a location where occupants may have consumed quantities of alcohol, or perhaps a place where occupants have an older age profile. These are not uncommon occurrences in residential buildings.
And the text uses the
'The
Building Safety Act is a key piece of legislation which should not intimidate professional practitioners'
wording 'adequate intensity'. As mentioned, standards and codes of practice such as BS 5266-1, BS EN 1838 and BS EN 50172 are a good starting point but a competent designer needs to take this information and apply it in the real world conditions.
The text also states that a responsible person must ensure that lighting is maintained. This implies that full information is supplied to allow someone to perform this task. A standard fire and emergency file would contain all assumptions in the design of the fire safety systems which would include risk assessments, and details of fire safety signage and emergency lighting. It should also include information that identifies the responsible person, and details of
what they have done and how they operate.
In design, compliance can never be a boxticking exercise; it requires competence which itself requires a professional approach, knowledge and experience. And once a design has been produced and signed off, any changes affecting the design mean that responsibility could pass from the original designer to the person who made the changes.
Design, however, is not purely providing the correct lit environment. It needs to be provided using suitable equipment, such as the luminaires installed in the space. Again, changing the equipment could change the design, invalidating the original design responsibility. Equal and approved very rarely is, and as Dame Judith Hackett stated, 'Value engineering has nothing to do with value and nothing to do with engineering'.
Any equipment must be UKCA/CE marked (currently both marks are valid although this may change in future). This requires a fairly high level of testing and every product should have a product file detailing all testing that has occurred. This has implications for conversions or luminaires that are remanufactured. Unless this involves an approved upgrade kit that has been tested for use in a particular product, the luminaire will probably need retesting and certifying, as it is no longer the luminaire supplied by the original manufacturer. Remanufacturing is an important part of a designer's toolbox, but it should be used responsibly.
Similar to the requirements contained within application standards it is important to understand what the requirements for products mean, and how they apply. For example, legally the requirement for the use of thermoplastic materials in products recessed into a ceiling is that they should resist the spread of flame over their surfaces.
In England this is considered within Part B of the building regulations approved documents, and test method 508A from BS 2782-0 is quoted to classify a product as TP(a) or TP(b). In the 2011 version of this standard Method 508A is detailed in Annex B, and clearly states that, 'The method has been declared obsolescent but is made available here because it is referred to in the Approved Document B Building Regulations'. Method 508A was originally defined within BS 2782-5:1970 and was withdrawn by BSI in 1992.
It dates from when light sources were generally discharge lamps and optics were single-piece plastic controllers. However, current methods of optical control are generally via a sandwich of
materials with dissimilar burning properties and varying thicknesses. Method 508A as used historically is not suitable for testing this type of composite construction. It should be noted that the introduction to Part B includes the wording, 'Complying with the guidance in the approved documents does not guarantee that building work complies with the requirements of the regulations'. The test should consider the materials as present in the luminaire, so the stack of materials, rather than just a single one of them in isolation.
So when choosing a luminaire it is important to consider whether it is suitable for the application, based on knowledge and experience and not based on assumptions.
The Building Safety Act is a key piece of legislation which should not intimidate professional practitioners. It confirms good practice in the interests of safety through thoughtful design by competent people.
BS EN 1838 Lighting applications. Emergency lighting
BS 2782-0 Methods of testing plastic – Introduction
BS 5266-1 Emergency lighting.
Code of Practice for the Emergency Lighting of Premises
BS EN 12464 – 1 Lighting of work places. Part 1 Light and lighting. Lighting of work places.
Indoor work places
BS EN 12464 – 2 Lighting of work places. Part 2 Lighting of work places. Outdoor work places
BS EN 50172 Emergency escape lighting systems
DARK THOUGHTS AND BRIGHT IDEAS
application centre. Two tour parties were invited into warehouse, retail, supermarket and office layouts displaying numerous lighting solutions. A great deal of thought and engineering had gone into being able to show the differing appearances of various lighting designs.
The Building SafetyAct became anAct of Parliament on 28April, 2022. It was introduced in response to the Dame Judith Hackitt report on Building Regulations and Fire Safety following the tragic events at Grenfell Tower on 17 June, 2017. TheAct created a Building Safety Regulator and brought some major changes to all controlled building work, statutory registration of all building inspectors and the creation of the category of 'higher-risk buildings'.
he central themes of the conference were predictably diverse: the measurement and impact of TLM; light pollution and the importance of darkness for humans as well as ecosystems; the need to extend lighting education for those in the industry as well as the public, and the definition of the right light.
TThe meeting was preceded by the annual ILIAD event organised by the Intelligent Lighting Institute of the university, which opened with a wide-ranging review of what makes healthy buildings by Sywert Bongersma, director of strategic partnerships at imec, nano and digital technologies specialist. Lighting certainly plays an important role, ideally with indistinguishable combinations of natural and artificial light, he said. However, it is essential to strike the appropriate balance of lighting, ventilation, noise and the thermal environment to make a building comfortable for its occupants. Reliable, energy efficient sensors are vital to ensure healthy buildings are also economically affordable to run.
Yvonne de Kort, professor of environmental psychology at EUT, in her presentation ‘Could there be more to light than lux and mEDI?’ (mEDI = melanopic equivalent daylight illuminance) stressed the links between light, mood and mental health. Substitution of natural light by artificial light does not always produce the same health benefits, she said, perhaps because the latter usually lacks contributions from UV-B and near-IR. Many in the audience were surprised to learn that radiation between 810nm and 830nm penetrates the skin and the skull.
After an introduction from Georges Zissis, chair of the IEEE Smart Lighting steering committee, LS2024 began with three fascinating contributions. Marilyne Andersen, professor of sustainable construction technologies at EPFL, Lausanne, reviewed the importance of both the variability in intensity and SPD in natural light, advocating that these changes should ideally be reflected in indoor
lighting. Our ‘spectral diet’ should be close to that we would experience outdoors.
John Mardaljevic, professor of building daylight modelling at Loughborough University, followed with an account of the history of the measurement of daylight from Socrates to modern day satellites.
Peter Thorns, head of strategic lighting applications at Thorn, went into great detail about the derivations of the candela, one of the seven SI base units and the only one that depends on a human response. He also surveyed the measurements that led to the current value of V(λ). The value most commonly used is that for a twodegree observer but there is a growing view that for many applications, especially driving, the 10-degree values would be more suitable.
One of the limitations of V(λ) is that it disregards the impact of age on vision perception. The future will almost certainly see V(λ) and all photometry based on cone fundamentals (for example, see Cone fundamentals and CIE standards by Andrew Stockman, Current Opinion in Behavioural Sciences, Vol 30, p. 87-89, 2019).
The late afternoon sessions were either the ‘Play with light workshop’ (TU/e Innovation Space) or a visit to the Signify Lighting Application Centre. Signify was very generous in accepting 70 guests into their
Professor Anne Skeldon from the University of Surrey gave a detailed account of her research into the impact of light-dark cycles on human sleep and circadian timings. Sleep timing is determined by physiology but is strongly influenced by light exposure and social constraints.
Dr Christophe Martinsons, light and health specialist at the Université de Reims Champagne Ardennes, gave an overview of the International Energy Agency's recently published report, SolidState Lighting: Review of Health Effects. This is an update of the report published in 2014. The effects of temporal light modulation (TLM) were highlighted as these are not always consciously felt but nonetheless are detected by the human brain. Glare was the commonest cause of complaints about solid state lighting installations. The importance of accurate and repeatable measurements of temporal light modulation were further emphasised by Yoshi Ohno, fellow of the US National Institute of Standards and Technology, in describing the interlaboratory comparison study for short term flicker (Pstlm) and stroboscopic effect visibility measure (SVM). It was reassuring to learn that the results from 18 laboratories were in close agreement.
Elena Scaroni, secretary general of Lighting Europe, gave a brief but fascinating insight into life in ‘The Brussels Bubble’ before reviewing some of the challenges facing the lighting industry in Europe. Among these concerns are use of the EPREL database and the interpretation of energy labelling. Lighting Europe has recently released a video to promote smart lighting (see below for link).
Ingrid Heynderickx, professor in Applied Visual
� The conference coincided with Eindhoven's GLOW festival with installations throughout much of the city centre
Perception at EUT, chaired the panel discussion
‘Should access to the right light be a human right?’, which stimulated thought about the most appropriate definition of the term ‘right light’. This could have eventually given right light the same status as the UN human rights to water and sanitation.
There was unanimous agreement that everyone has a right to daylight and artificial light, but the consensus was that right light was predominantly a concept extended to the privileged in the first world. There was also agreement that the use of artificial light should include the needs of the natural world. Although sunlight could be viewed as the right light, members of the panel stressed that the characteristics of sunlight depend on latitude and this is reflected in the geographical variation in the perception of natural light. The right light is also something individual – what is right for one person is not necessarily right for another, and is almost certainly age dependent.
The need for the lighting industry to improve the public’s understanding about light, lighting and the importance of darkness was clear. A particularly poignant comment was that outdoor light changed seemingly for ever in the 1950s when the emphasis switched from people to cars. Thus, the agreement was that the lighting community is not ready to formulate a widely applicable definition of the right light and the world is not yet in a position to address the right to the right light.
The impacts on ecological systems of the worldwide increase in light pollution were stressed by Annika Jagerbrand, assistant professor in environmental science at Halmstad University, Sweden. There is a pressing need for changes to international obtrusive light thresholds. This is in part being addressed by CIE Technical Committee 2-95 Measurement of Obtrusive Light and Sky Glow.
Norman Bardsley, chief analyst for the International Solid-State Lighting Alliance, outlined his team’s vision of how to secure additional energy savings from solid state lighting. They estimate that the current average efficacy of commercially available LED-based light sources is around 83 lm/W, a rise from from ~48 lm/W in recent years. However, the higher efficacy has been offset by greater demand and so the electric power consumed per annum remains at approximately 2900 TWh.
Reducing the total energy consumption for lighting will require involvement from governments.
A target of an average efficacy of ~140 lm/W by 2030 seems to be achievable but the more ambitious longer term target of 300 lm/W requires major improvements in phosphors, control of
� The festival encourages the promotion of light artworks where artists, businesses, residents and students can work together, combining technology with creativity
light distribution and manufacturing processes. Erkki Ikonen, professor of measurement science and technology at Aalto University, described detailed TLM measurements on 60 LED lamps with E27 bases, 40 of which were purchased prior to 2017 with the remainder from 2021. Between these dates EU regulations for TLM limits had changed to P st lm >1 and SVM <0.4. All lamps satisfied the Pst lm limit but half of the pre-2017 lamps did not meet the new SVM limits. All of the newer lamps were within both limits, a good example of manufacturers following the regulations. Lighting Research and Technology Vol 56 (7), published in November 2024, is devoted to TLM.
Melissa Handa, programme director within technical activities at the IEEE, introduced attendees to the IEEE DataPort (see below for link), a research data platform designed to make scientific data openly accessible to all, and help researchers and institutions share research, manage their data, and collaborate with peers. IEEE membership is not required to use this tool, there is no charge for uploading datasets, but access to some datasets is chargeable.
The conference closed with two contrasting presentations, the first by Sylvia Pont (professor of human information communication design at the Technical University of Delft) on the ‘Interaction of light with materials – lighting materials and materialising light’, the second by Christian Tenhumberg (Signify), ‘Manage, monitor and control lighting with connected and integrated solutions’. The former concentrated on the human perception of light reflected by materials and the way various spectra appear to change the visual appearance of objects. One telling comment was that, ‘perception is not physics’.
Tenhumberg highlighted that turning lights off is not a realistic solution for reducing energy consumption, and that a far better approach is the extensive use of sensors and controls. The increase in the number of lighting-related connected nodes is staggering, from ~80,000 in 2012 to ~139m in 2023.
The conference coincided with the GLOW festival which is a free-to-attend event with displays stretching throughout much of the city centre. The festival encourages the promotion of light artworks where artists, businesses, residents and students can work together by combining technology with creativity to generate fascinating displays. GLOW attracts thousands of visitors to the city each of the eight days of the event. Students kindly led tours of the displays for the LS2024 participants.
Stuart Mucklejohn is secretary of the LS2024 International Scientific Committee
The IEEE Sustainable Smart Lighting Conference, also known as LS2024, was held from 12-14 November at the Eindhoven University of Technology. The meeting was preceded by the annual ILIAD event organised by the Intelligent Lighting Institute of the university. The programme can be downloaded (see link below) and papers from the conference are available via IEEE Xplore.
The next conference will be held in Monastir, Tunisia, during early December 2025. This will mark the 50th anniversary of the first symposium in the LS series which began as the Symposium on Incoherent Light Sources held at Loughborough in April 1975.
Lighting Europe video on smart lighting: www.youtube.com/watch? v=VDWKj1PHctQ
IEEE DataPort a research data platform: https://ieee-dataport.org/
Programme for LS2024: www.ssleindhoven.com/program
At the end of 2024, BSI published the new code of practice for the remanufacture of luminaires. It lays out the step-by-step procedures that a producer should follow to ensure that remanufactured luminaires are compliant and suitable for their intended use. That should give producers, specifiers and end users the confidence to make, install and use remanufactured products.
Currently, the proportion of luminaires that is remanufactured in the UK is tiny compared to the supply of new products. And when new products are installed, this frequently means that used, but useable or upgradeable products are removed, and either recycled as e-waste or scrap metal, or landfilled. Recycling products that could be reused is not a good environmental outcome.
Remanufacturing, repair and product upgrade are at the heart of a circular economy: the key principle is to keep existing products in service for as long as possible. It can yield very significant circular economy outcomes, including typical embodied carbon savings of 50-80 per cent, and waste avoidance of 60-90 per cent. Clearly products also need to be energy efficient, and to meet end user
needs, and that means remanufacture is not always possible or desirable.
The Ellen MacArthur Foundation has shown that a fully circular economy is essential if we are to meet net zero targets: moving to renewables can only address 55 per cent of current emissions. So greater material efficiency – more reuse, remanufacture and repair – is vital in tackling the climate crisis.
THE NEW CODE OF PRACTICE
Enter BS8887:221 2024. This game-changing code of practice can provide the assurance that remanufacture and upgrade is managed in a consistent manner to produce compliant luminaires meeting agreed performance requirements. It provides a structured approach covering the entire process of remanufacture:
Preliminary assessment This is required to assess the electrical and mechanical condition of incoming products, and any need for surface treatments.
Scope of works This defines the expected work to be undertaken, the required specification and outcomes, and any modifications that may be
� Remanufacturing process flowchart, based on BS8887
necessary. It should also determine testing requirements.
Electrical and mechanical remanufacture
The next stage of the process concerns the requirement for an engineering plan to include identification of any hazardous materials and alignment with the requirements of the BSEN50598. For circularity, it is important to maximise the reuse of existing components, and also to design with further remanufacture in mind. Assessing components This is an important part of the process, by gathering evidence of performance, compliance, safety and suitability. They should be reused, or harvested for other reuse where possible.
Defining markings and instructions Also important, remanufacturer labelling must be applied, and the original manufacturer markings should preferably be removed, or at least be distinguishable from the remanufacturer markings. Testing and validation Both are clearly a vital part of the process. The remanufacturer is responsible for the compliance of the remanufactured products, including a technical file. It is important to note that BS8887:221 is not a safety standard, and all the requirements for a new product, including the relevant parts of BSEN605981, are applicable to remanufactured products.
The code of practice was developed over two years by around a dozen individuals drawn from across the lighting industry. It is hoped that it will make a significant contribution to 'mainstreaming' the remanufacture of light fittings.
The Code of Practice BS 8887-221:2024 Design for manufacture, assembly, disassembly and endof-life processing (MADE) – Remanufacture of luminaires was published in December 2024. To download go to: https://knowledge.bsigroup.com/products/designfor-manufacture-assembly-disassembly-and-endof-life-processing-made-remanufacture-ofluminaires-code-of-practice?version=standard
Nigel Harvey is chief executive of Recolight, which offers a one-day training workshop in luminaire remanufacture
CIBSE/SLL's TM66 CEAM-Make guides manufacturers through CE requirements for lighting equipment and helps specifiers understand what they need to look for: www.cibse.org/knowledge-research/knowledgeportal/tm66-creating-a-circular-economy-in-thelighting-industry/
LR&T attracts wide international interest and December's issue publishes three papers from afar on the theme of photosynthesis. Photosynthesis has importance for space exploration to support astronaut'slives for long journeys in space, for polar regions with little daylightfor large parts of the year, and regions with extreme weather conditions. Food can also be grown indoors without the use of chemicals, more easily than outdoors.Interior horticulturalists need expert advice on optimum lighting based on sound research findings.
The first paper in this issue is a joint publication from the Russian Federation and China (S Turanov et al). It examines dynamic irradiation where different LED light sources are applied for 35 days to see how this affects the growth and development of lettuce plants.
The results of the study show the effects of photoregulation on the growth and development of the plants. The optimal outcome for this case was with a dynamic regime using two colour components, white 2700K and red (660nm)
LEDs. By optimising the ratio of different parts of the lighting spectrum, it was possible to influence the content of nitrates, and the functional and structural characteristicsof plants. This has the potential toregulate yields, control quality and reduce energy costs.
The second paper, from Iran, investigates flowering and vegetative growth (L Ahamadi et al). The experiment examined the flowering and vegetativetraits of the African violet over six months, 12 hours a day, using four spectra of artificiallight, LED monochromatic red, LED monochromatic blue, LED mixed 75 per cent red and 25 per cent blue and cool white fluorescent lamps. The number of days of flowering was significantly influenced by irradiance.
The blue illuminated cases affected the plants positively. The plants appeared smaller and more compact but were superior in their flowering qualities in terms of earliness, uniformity, consistency, the number of flowers and the percentage of the canopy covered with the flowers. Plantsgrown under the red and fluorescent lamps, however, produced leaves with
the highest area. They conclude that LEDs can be used as an effective tool in plant growth and without the need for chemicals.
On a closely related theme, the food industry is interested in extending food preservation time while maintaining food safety and health aspects.
The third paper is from China (Y-Y Zhu et al) and documents a novel light source based on the chlorophyllabsorption spectrum. Chlorophyll is responsible for the green colour of many plants, in this case lettuces. Although temperature and humidity are also significant factors in this respect, it was found that lighting reduced the colour difference by 23.5 per cent and delayedthe degradation of chlorophyll compared with the dark. However, weight loss of the lettuce did occur under the lighting.
As vegetables are normally stored in the dark this may have implications for food suppliers, although itwas a limited study.
Dr Kevin Kelly is emeritus professor at the Technological University Dublin and a past president of the SLL
All papers were published in Lighting Research and Technology (LR&T), Vol 56, Issue 8, December 2024, and are also available at Lighting Research and Technology: OnlineFirst.
In advance of being published in the print version of LR&T, all papers accepted for publishing are available online. SLL members can gain access to these papers via the SLL website (www.sll.org.uk)
Influence of dynamic LED irradiation mode on the content of nitrates, structural and functional characteristics of lettuce plants
S Turanov, A Burenina, E Surnina, A Butenmova, TAstafurova and T Han
Light sources spectrum influences long term flowering cycles and visual appearancein African violet LAhamadi, M Matloobi and A Motallebi-Azar
A novel light source for postharvest lettuce preservation based on chlorophy; absorbtion spectrum
Y-Y Zhu, X Zhao, Y-d Kang, Y-Z Li, J-H Zhang and G-Y Cao
David Battersby celebrates city lighting festivals
Over the past 20 or so years there appears to have been an explosion in lighting festivals. But these types of events have been occurring for hundreds of years, with eastern lantern festivals dating back millennia. They celebrate a multitude of topics from honouring Buddha to paying tribute to the Virgin Mary.
Today's festivals are a far cry from lanterns with fire or candles, featuring spectacular large-scale projections, colour-change moving lights or lasers, backed up with expansive soundscapes. Others have more thought-provoking, quiet installations off the main spectator paths.
Some festivals attract more than 2m visitors every year so they can get extremely busy. For me, it is wonderful to see members of the general public seeing lighting in, well, a different light.
David Battersby, FSLL, is senior lighting designer at Gamma Illumination, SLL representative Yorkshire region, and winner of the SLL lighting award 2023
Lumiere, Durham, UK
This bi-annual festival, the UK's largest, takes place in the centre of Durham and has been a regular on the list of festivals since 2009. It has a mix of large and small scale installations, and usually includes the magnificent facade of Durham Cathedral and surrounding buildings turned into a fully immersive experience, or the word ‘light’ in sign language in a local church cemetery. The festival runs every two years in November.
Image: Durham Pulse Topology, Rafael LozanoHemmer.
Fête des Lumières, Lyons, France
This lighting festival dates back to 1852 when residents lit candles in their windows to illuminate the procession of the statue of the Virgin Mary through the city. The roots of the festival actually date back to 1653 when councillors promised to pay tribute to the Virgin Mary if the town was spared from the plague. This now large-scale festival is attended by millions of visitors every December and takes over the centre of Lyons for four days.
Vivid Sydney, Australia
Vivid is held annually in May and June, originally conceptualised in 2008 as a lowenergy lighting festival. It has evolved to include not only light but world-class projection, music, ideas and food. You can walk around the festival on a suggested route or take to the water to view the installations. During the festival there is music, dance and talks to encourage thought and answer those big questions. Sydney Opera House is the perfect canvas for extraordinary creative, colourful projections and animated narratives.
Berlin Festival of Lights, Germany
Given the backdrop of such recognisable landmarks as the Brandenburg Gate (shown), it’s not surprising Berlin puts on a lighting festival. Filled with large-scale projections and light artworks spread around the city centre in October, this festival has just celebrated its 20th anniversary with more than 3m spectators. The festival has a different theme or ‘motto’ every year adding a fresh perspective to its vibrant installations. For 2024 it was 'Celebrating Freedom'.
Amsterdam Light Festival, Netherlands Spread over the city and running throughout December and most of January every year since 2012/2013, this festival attracts artists and audiences from all over the world. The artworks are positioned along the canals and are designed to be viewed from either the footpaths or a boat. Each year has a different theme from Rituals to AI and Nature, allowing the artists great freedom with their inspiration and ideas for their designs.
Image: Light A Wish by Israeli artists' collective OGE Group, winner of the first Amsterdam Light Festival Public Choice Award (2018/9).
⊳ Climate chamber with LED-based systems
(S Turanov et al)
Events 2025
For details of all upcoming webinars, go to: www.cibse.org/societyof-light-and-lighting-sll/sll-events/upcoming-webinars-and-onlinecontent
For previously recorded CPD webinars (including regional webinars), go to: https://www.cibse.org/get-involved/societies/society-of-lightand-lighting-sll/sll-events/on-demand-webinars-past-presentations
EVENTS
SLL SCOTLAND CONFERENCE 2025: RETROFIT AND REMANUFACTURING
Date: 6 March
Venue: Technology and Innovation Centre, University of Strathclyde, Glasgow www.cibse.org/whats-on/search-events/sll-scotland-conference2025-retrofit-and-remanufacturing/
ILLUMINATING THE FUTURE: BALANCING LIGHT AND DARK NIGHTSCAPES
(Organised by the SLL)
Date: 27 March 2025
Venue: Senate House, University of London www.sll@cibse.org
EUROLUCE
Date: 8-13 April
Venue: Milan Fairgrounds www.salonemilano.it/en/exhibitions/euroluce
LUCI CITIES AND LIGHTING SUMMIT LONDON
Date: 23-25 April
Venues: Guildhall and Barbican Centre www.luciassociation.org/events/luci-cities-lighting-summit/lucicities-lighting-summit-london/
DARC AWARDS
Date: 24 April
Venue: Fireworks Factory, Woolwich Works, London SE18 https://darcawards.com/
NET ZERO LIGHTING CONFERENCE
Date: 29 April
Venue: Coin Street Conference Centre, London SE1 www.recolight.co.uk/net-zero-lighting/
CIE MID-TERM CONFERENCE
Date: 7-9 July
Location: Vienna https://vienna2025.cie.co.at/
LET DIPLOMA IN LIGHTING DESIGN
For details and registration: www.lightingeducationtrust.org
