Light Lines July/August 25

The Society of Light and Lighting

VOLUME 18 ISSUE 4 JULY/AUGUST 25

SCHOOL OF THOUGHT

Focus on the young, says new president

VIRTUOUS CIRCLE

The CE in action in Crown Estate scheme

Editorial

July/August 2025

FROM THE EDITOR SECRETARY Brendan Keely FSLL bkeely@cibse.org MEMBERSHIP EXECUTIVE Fiona Fanning ffanning@cibse.org EDITOR Jill Entwistle jillentwistle@yahoo.com COMMUNICATIONS COMMITTEE: Andrew Bissell FSLL James Buck Iain Carlile FSLL Jill Entwistle Fiona Fanning Debbie-Sue Farrell Chris Fordham MSLL Rebecca Hodge Stewart Langdown FSLL Luke Locke-Wheaton Rory Marples MSLL Linda Salamoun MSLL 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 LL5 2025 IS 14 JULY PUBLISHED BY The Society of Light and Lighting 91-94 Saffron Hill London EC1N 8QP www.sll.org.uk ISSN 2632-2838 © 2025 THE SOCIETY OF LIGHT AND LIGHTING The Society of Light and Lighting is part of the Chartered Institution of Building Services Engineers, 91-94 Saffron Hill, London EC1N 8QP. Charity registration no 278104 Designed and printed in the UK George Eason Graphic Design www.georgeeason.design hello@georgeeason.design

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It is one of life's ironies that for an element that governs our lives and gives us life, light does rather seem to escape people's attention as something to think about. Whether natural or artificial, it is either there or not there according to time of day or a switch, and has really rather been taken for granted.

Natural phenomena such as sunsets, rainbows and auroras clearly captivate people, and the absence of light can disturb, depress and annoy them – rainy days and power cuts.

But it's somehow something that just is rather than something that can be analysed, modelled, calculated, shaped to improve our environment on many different levels.

This, coupled with the fact that architectural lighting design is a relatively new profession, means that it really hasn't registered as a potential career. It is still famously a metier arrived at by circuitous routes that have begun in architecture, theatre lighting design, product design, engineering and

other tangential but tangible spheres. It seems to require some Damascene revelation to inspire people to step into the specialism.

It is something that new SLL president Kristina Allison would like to change. 'I want lighting to become an industry that young people choose to follow not just fall into,' she said in her presidential address in May. 'Let’s inspire children to want to learn about our magical subject, to "be curious" about how light works in all its facets, from physics to art to technology. Let’s change the status quo of we "fell into lighting" to "lighting found me".'

JILL ENTWISTLE JILLENTWISTLE @YAHOO.COM

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)

sll.org.uk

July/August 2025

Secretary’s column/Contents

Contents

FROM THE SECRETARY The Illuminating the Future: Balancing Light and Dark Nightscapes follow-up webinar took place in mid-May. The delegate numbers were high and comparable to the conference, and the Q&A was very active. Our thanks to Urbis Schréder, the webinar sponsor (see box for links to the webinar, conference presentations and notes.)

A big thank you to everyone who attended the SLL AGM, Awards and Presidential Address at the Barbican in May. It was a great evening to celebrate the award recipients and we appreciate all those who came to help make it a very enjoyable evening.

We thanked Dan Lister for his work during his presidential year and welcomed Kristina Allison, the new SLL president, who during her address launched the STEAM ‘Get Curious’ lighting programme (see p5). We look forward to seeing the programme’s progress over the next 12 months.

Congratulations to this year’s SLL Award recipients (see p7): the Leon Gaster Award went to Myriam Aries and Femke Beute et al for their two-part papers on the relationship of light exposure to sleep outcomes among office workers, while the Walsh Weston Award was given to Belal Abboushi et al, for their paper on predicting discomfort from glare with pedestrian scale lighting.

The Regional Award went to Giorgos Kourtelis, the Lighting Award to Tony Ownsworth, honorary fellowships to Paul Littlefair and Professor Debra J Skene, and the President’s Medal to Bob Venning. Our thanks to the citation providers: Ross Munro, Helen Loomes, Cosmin Ticleanu and Jeff Shaw.

The shortlist for the SLL Young Lighter 2025 has been announced (see p4). Congratulations to all those who reached this stage. The finalists of the competition are scheduled to be confirmed during the week starting 15 September.

Meanwhile, the SLL Jean Heap Bursary 2025 received six entries and we hope to confirm the recipient of the bursary soon.

As previously reported, the SLL will partner with LIA’s TECH-X on 10 September and the ICEL Conference on 11 September. SLL will also partner with the Recolight Circularity Live Conference on 25 September.

SLL Ready Steady Light, in association with Rose Bruford College and the IALD, will return on 14 October for its 30th year. We are very

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Illuminating the Future: Balancing Light and Dark Nightscapes follow-up webinar: Illuminating the Future Recording Conference presentations: Illuminating the Future Presentations Notes from the webinar: Illuminating the Future Notes More details of the STEAM Get Curious lighting programme: STEAM 'Get Curious' Lighting Programme To register teams for Ready Steady Light CIBSE Event Search

excited to be celebrating the 30th anniversary of the competition and welcome the teams to the college in Sidcup for what promises to be a great day and evening (see box for the link to register teams).

The SLL will join the Society of Public Health Engineers (SoPHE) and CIBSE Healthcare Group at the Healthcare Estates conference and exhibition from 21-22 October at Manchester Central. We enjoyed our first experience of the event in 2024 and we look forward to returning with our CIBSE colleagues and friends.

SLL will also partner with LiGHT 25 from 19-20 November at the Business Design Centre, Islington, London. We are excited to be exhibiting, and the SLL will also be represented by speakers in the conference programmes. We are also looking forward to seeing the newly introduced Tech Zone.

Finally, a reminder that the new MSLL application enables early career lighters to apply for MSLL via a set of competencies and no longer relies on the years of experience, or lighting education with years of experience.

Please take a look at the new application process, which is completely online. If you would like to discuss your application further or have any queries, please do contact us at sll@cibse.

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EDITORIAL

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SECRETARY'S COLUMN

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NEWS

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A VIEW TO THE FUTURE

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HONOURS BRIGHT

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IN WITH THE OLD

Young people need to see lighting as a viable profession rather than an accidental career, says new SLL president Kristina Allison The SLL awarded leading lights of the profession and academia at this year's AGM at the Barbican Paul Beale explains how lighting consultancy 18 Degrees used refurbished luminaires and wireless technology to create a future-ready lighting scheme for the Crown Estate

12 TALES OF THE UNEXPECTED

An unconventional, eclectic and fascinating journey through the art, science and history of illumination: Alan Tulla reviews a new book, Stories with Light

EYEBROWS 14 RAISING Alan Tulla discovers a broad spectrum of studies in the latest online LR&T papers

OF GENIUS 15 FLASHES Top 5: Peter Raynham looks at five key scientific discoveries that revealed the properties of light

16 EVENTS COVER: Seen at this year's Venice Biennale, the concept for the Periscope House by Belgian-based Claerhout-Van Biervliet Architects is a radical solution to subterranean living. Moveable, solar-powered double-mirror structures, set at a 45-degree angle, can be independently raised to optimise light and views for underground levels.

BRENDAN KEELY BKEELY @CIBSE.ORG

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News

July/August 2025

THE LATEST NEWS AND STORIES

News

SHORTLIST OF CANDIDATES FOR SLL YOUNG LIGHTER RELEASED Five contenders have been shortlisted for this year's SLL Young Lighter Award, now in its 31st year.

Their topics range from tunnel lighting to how neurodiverse individuals perceive environments in relation to the use of colour in light.

Among the shortlisted candidates are Katerina Xynogala (pictured left), a lighting engineer at WSP, who will look at optimising maintenance factors in tunnel lighting, and Lucie Koháková, visual and product designer, who examines the impact of light on human circadian rhythms, especially in early childhood, and how design can support healthier sleep through biologically appropriate lighting.

Santiago Navarro Castro (pictured right), lighting designer and director at Casual Lighting, will focus on how lighting design in museums and private gallery settings can enhance the perception of paintings. Ruoxi Yin will look at perception in the neurodiverse while Shivani Manhas has taken the video game Stellaris as her focus.

Each finalist will receive a cash prize, with the winner awarded £1000. The competition is open to anyone under 30 who is interested in light and lighting, regardless of background or education. There is no requirement to write an academic paper to participate. All that is needed is an original and creative idea about any aspect of light.

The list of finalists will be available in September: www.cibse.org/get-involved/societies/ society-of-light-and-lighting-sll/whats-happening/sll-young-lighter/

ON THE LIGHTER SIDE… Aside from the fact that they look like something from the original 1960s Star Trek set, and might possibly lean over unexpectedly and do you a mischief, the Corallite collection of luminaires is actually very good for the planet.

Made of 80 per cent recycled material, with almost no water or electricity used in their production, they apparently have an almost zero carbon footprint.

Designed by Sanjay Puri Architects, they are inspired by the forms and textures of the coral reef. As well as emitting light in a single direction, the

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uplighters and pendants glow all over, highlighting the texture of the foam concrete (FEFS board) from which they are made.

DAYLIGHT AWARD OPENS FOR NOMINATIONS Nominations for the Daylight Award 2026 are officially open.

Presented by the Daylight Academy, the awards recognise individuals or teams whose innovative work with natural light has significantly advanced quality of life, human health, and the built environment.

There are two categories: Daylight Research and Daylight in Architecture.

Nominations are open globally to scientists, researchers, architects, journalists, editors, curators, and other professionals who know of outstanding individuals or teams working innovatively with daylight. Nominations are anonymous, and self-nominations are not accepted.

Previous laureates include architects Jørn Utzon (the first winner) and Steven Holl, and academics such as Prof Russell Foster.

Nominations, which close on 15 September, can be made at: https:// thedaylightaward.com/award/

BLUE LIGHT BAD FOR THE KIDNEYS? Researchers at Shanghai Jiao Tong University School of Medicine have found a potential link between blue light exposure (from artificial lighting and digital screens) and an increased risk of forming kidney stones.

While a common condition, the incidence of kidney stones has been growing, due to factors including environment, diet and metabolic diseases.

The team hypothesised that as recent studies have shown that blue light may have potential effects on human physiological functions, particularly metabolic regulation mechanisms, 'blue light may exert an impact on the kidneys through the brainkidney axis by regulating brain function'.

Results showed that blue light-exposed rats developed more kidney stones, specifically, higher levels of calcium oxalate crystals – the most common component of human kidney stones – compared to those not exposed to blue light.

For full details: www.nature.com/articles/ s41598-025-85586-y

sll.org.uk

July/August 2025

SLL AGM: President's address

A VIEW TO THE FUTURE We need to inspire young people to see lighting as a viable profession rather than just an accidental career, says new SLL president Kristina Allison

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key aim in her presidential year is to inspire and educate children about lighting, said

Kristina Allison in her presidential address.

'I want lighting to become an industry that young people choose to follow not just fall

into,' she said, citing the fact that her own informal 'poll' had revealed that around three quarters of the lighting profession, including herself, had 'fallen into' their lighting career.

'Let’s inspire children to want to learn about our magical subject, to "be curious" about how light works in all its facets, from physics to art to technology. 'Let’s change the status quo of we "fell into lighting" to "lighting found me".'

With the support of the profession, education at a young age – 'when we are at our most creative' – was essential to inspire the next generation of lighters to actively want to join this community, said Allison. 'It also means that we can embed best practice principles right at the beginning of the journey into lighting,' she added.

'Lighting has the potential to solve and resolve so many things not just in terms of

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SLL AGM: President's address

'I want to give school-age pupils the opportunity to come into our industry through work-experience placements'

the climate emergency, but also health and wellbeing, medical applications, food production – and many more global problems we may face in the future too,' she continued. 'Imagine we use our position, time and knowledge as lighters to give the opportunity for the workforce of the future to resolve the challenges in their future world.'

Allison said that in this respect she aimed to take forward the 'great work' of past presidents Liz Peck, Jeff Shaw, Iain Carlile, Richard Capel and Dan Lister. 'What I learnt from reading past presidential addresses was the strong theme for education in lighting and school engagement through STEM, or science, technology, engineering and maths.

'I remember listening to Jeff Shaw’s presidential address reflecting on the late Liz Peck’s achievements with Night of Heritage Light and STEM through Pockets of Light. At the time I was a member of the education committee and was inspired to give a lesson in lighting design myself.'

A class on lighting as part of a design and technology lesson at her former secondary

school in 2018 led to her being invited back the following year. Last year Allison arranged a Pockets of Light event in her local village, Abbots Langley in Hertfordshire, working with three local schools. Sponsored by the nearby Warner Brother’s film studios and involving the local community, the event, which inolved illuminating the local church, was again very successful.

Reflecting the multifaceted nature of lighting, Allison also emphasised that the exercise should not just be about STEM but STEAM – the addition of arts to science, technology, engineering and maths. It was also about taking a practical approach, she said.

'I want to give school-age pupils the

'I, like many, began my career in lighting not long after I finished my masters degree, studying in a different area of design. Like 74 per cent of us – yes, I did a poll – I ‘fell into lighting’. But once I began learning about lamps and energy-saving technologies, I was hooked. This was during what I’d later describe as an old-fashioned apprenticeship in energy-effective lighting design working with David Matyus-Flynn, a highly knowledgeable consultant and lecturer in the subject of sustainable lighting.

Looking back, I realise how lucky I was to have a mentor to guide me both in lighting and business. Unfortunately David was unable to travel here to join us tonight, but I would like to give him a very special thanks for his time, guidance, patience, and the sharing of his knowledge.

These are the traits I do my best to embody now as a lighting professional.

One evening David and I travelled into London to an SLL event hosted by iGuzzini at Southwark Cathedral. The event was a blend of CPD and a mini Ready Steady Light. It was at this event that I met SLL past president Stephen Lisk, and he encouraged me to sign up as an SLL member and to join the communications committee. So you see from pretty much day one I was already getting very involved.

It was around this same time I also met SLL past president John Aston.

John and David had played rugby together in their youth, and it was John who introduced me to an emerging technology called ‘LED’, and this, just as I’d memorised all the lengths, wattages and lumen outputs for fluorescent tubes. In the months and years that followed, I became more and more involved with the society, through attending events and delivering the occasional CPD, and even writing the odd TM – and well, 14 years later, here I am.'

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opportunity to come into our industry through work-experience placements. To achieve this, I will work closely with our SLL regional lighting representatives across the UK to spread news about this important strategy, and to go into schools as STEM or STEAM ambassadors, working collaboratively with our industry partners, and friends at the ILP too.'

'It was Sir Issac Newton who talked of "standing on the shoulders of giants",' concluded Allison. 'Let’s lift up the next generation of lighters because the future belongs to the curious.'

Kristina Allison, CEng MCIBSE FSLL, is an associate environmental, sustainability and netzero lighting capability lead at WSP. A former chair of the SLL education committee, she has project managed and co-authored the industry leading documents CIBSE/SLL TM66 ‘Creating a Circular Economy in the Lighting Industry’ and CIBSE TM65.2 ‘Embodied Carbon in Building Services: Lighting’, both award-winning publications.

All attendees at the AGM received a card with a QR code (see below) for those who might be interested in the STEAM ‘Get Curious’ Lighting Programme. If you would like to participate please scan the QR code and complete the short registration form.

sll.org.uk

July/August 2025

AGM: Awards

HONOURS BRIGHT The SLL recognised leading lights of the profession and academia following the annual AGM at the Barbican his year's SLL Awards moved south again, held at London's Barbican, the once controversial Brutalist residential development and now Grade II listed landmark.

The first major accolade, the SLL Lighting Award, went to Tony Ownsworth, whose 'career has left a lasting mark on our industry – and on all of us,' said citation-giver Ross Munro, who has recently taken over from Ownsworth as the SLL regional lighting representative for Scotland.

Ownsworth, born in Glasgow in 1944, left school at 16 to begin an engineering apprenticeship at Ramsay and Primrose Consulting Engineers. His part-time studies over time included electrical and electronic engineering, industrial engineering, as well as accountancy and financial management, at institutions including Stow College of Technology, Glasgow College of Technology and the Open University.

Munro conveyed the measure of the man in his contribution to a major hospital development. 'He used what he called "schoolboy physics" to design a modular fluorescent fitting for operating theatres,' recounted Munro. 'Solving a problem where others had come up short, his design was ultimately adopted, manufactured by Troughton and Young, and used across Europe.'

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� Tony Ownsworth receives the Lighting Award from SLL president elect Carolina Florian

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Ownsworth joined the IES (becoming CIBSE in 1985) in 1971, ultimately earning a fellowship.

Also awarded a fellowship of the SLL in 2005, he served as president in 2007.

Among Ownsworth's proudest achievements, said Munro, was co-organising the iconic CIBSE Centenary Conference in Scotland with Dr Laurie McElroy and 'playing a pivotal role alongside others in the formation of the Society of Light and Lighting we see today.'

Two honorary fellowships were awarded, in recognition of significant contributions not only of services to the society but to the wider lighting profession. The first was given to Professor Debra J Skene, distinguished professor of neuroendocrinology and section lead of chronobiology at the University of Surrey. She is widely recognised as one of the leading pioneers in the field, particularly for her research on circadian rhythms, sleep and the effects of melatonin and light on human physiology.

'With over 40 years of dedicated scientific research, Professor Skene’s contributions have left an indelible mark on our understanding of how light influences our biological clocks,' said Helen Loomes in her citation.

Born and educated in South Africa, Professor Skene is particularly renowned for her pioneering investigations into the spectral sensitivity of human circadian photoreception.

Her seminal work revealed in 2001 the

� Professor Debra Skene, one of two recipients of an honorary fellowship

sensitivity of the human circadian system to short-wavelength blue light, a discovery that also led to the identification of a novel photoreceptor system, distinct from the known rod and cone photoreceptors.

Professor Skene’s work has also focused on the effects of ageing on circadian regulation. Her team made critical discoveries regarding the diminished responsiveness of older adults to the acute effects of blue light, providing insights into how light therapy might potentially be tailored for different age groups.

'Her work continues to shape the way we understand and manage the intricate relationship between light, sleep and human health,' said Loomes.

'Prof Skene’s contributions have left an indelible mark on our understanding of how light influences our biological clocks' The second honorary fellowship was awarded to Dr Paul Littlefair, who spent more than four decades at the Building Research Establishment, with nearly 20 years as head of the lighting team.

'His contributions have profoundly shaped the world of lighting design, daylighting research and sustainable building practices,' said Cosmin Ticleanu in his citation.

Littlefair gained an MA in natural sciences (physics), followed by a PhD on daylighting design and energy conservation, a topic that would become the cornerstone of his career. 'From the

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AGM: Awards

very beginning, Paul demonstrated a rare combination of scientific rigour and creative vision,' said Ticleanu.

Over his 40-year career at the BRE, Littlefair became the go-to expert for everything from daylight design and solar shading to glare control, electric lighting, lighting controls, and even site microclimate and solar radiation availability.

One of his most enduring contributions, said Ticleanu, came in the 1995 edition of the UK Building Regulations, where he helped introduce the first-ever lighting requirement – a minimum lamp efficacy of 50lm per circuit-watt. 'This was a pivotal moment in the journey towards energy-efficient lighting, and it laid the groundwork for the standards we now take for granted,' he said.

A longstanding member of the SLL technical and publications committee, Littlefair was the lead author of LG10 Daylight and window design, and later TM37 Design for improved solar shading control, which further cemented his influence on how daylight can be integrated into the built environment.

Littlefair's work has informed not only design practice, said Ticleanu, but also planning policy and environmental assessment.

He wrote the BRE Digest on lighting controls, which remains a key reference in Part L of the Building Regulations.

'Paul’s legacy is not only in the documents he authored or the standards he helped define, but in the generations of lighting professionals he has mentored and inspired, myself included,' said Ticleanu. 'His work has illuminated more than buildings – it has illuminated minds.'

The President’s Medal, which recognises a significant and lifetime contribution to lighting, this year went to Bob Venning. Jeff Shaw, whom Venning had employed nearly 30 years ago as a 'fresh-faced graduate', gave the citation.

Venning joined Arup in 1972, when Ove Arup himself still led the firm, and stayed for 36 years, retiring in 2008. Always passionate about lighting, in 1988 he founded Arup’s Lighting Engineering Group, although as Shaw pointed out, 'for the next several years, he was the group'. In 2000, this formally became Arup’s lighting design practice – 'and we have since grown to more than 100 designers in 23 cities around the globe,' continued Shaw.

Venning's projects demonstrate a wide repertoire, said Shaw, from King’s Cross Station to Dublin Airport; from Deutsche Bank’s HQ in Tokyo to Inland Revenue’s HQ in Nottingham, and cultural milestones such as the 1990s Royal

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� Paul Littlefair was made an honorary fellow: 'His work has illuminated more than buildings'

� Bob Venning, awarded the President's Medal: 'He has helped shape our industry'

Opera House renovation. 'From his carefully integrated lighting solutions in heritage spaces, through striking colour-changing "light trees", to acoustic "Mexican hats", Bob’s lighting solutions were always highly thoughtful, creative and practical,' said Shaw.

He also brought the best out in the team, he added. 'When he attacked your work with a red pen, it was not just about correction – his goal was to sharpen ideas and refine visions, empowering those who worked with him and pushing us to strive for the highest standards with confidence and clarity.'

More widely, as one of the legendary ‘Three Musketeers’ of lighting (with Barrie Wilde and Eric Maddock), 'Venning's influence has helped shape our industry, with his contributions to guidance, research, education and thought leadership,' said Shaw. As chair of CIBSE’s Lighting Division in 1999 and the first president of the Society of Light and Lighting in 2000, it was under his leadership that the Lighting Division transformed into the SLL. As chair of the Lighting Education Trust, since 2013, he has worked to enhance the LET Diploma in Lighting Design and to pursue opportunities to create lighting undergraduate courses.

'Bob's wisdom and unwavering commitment to excellence have been a beacon for many across the industry, and this award is richly deserved. I’ll finish with some words from Florence Lam, Arup's former global lighting design director and current Arup fellow, that reflect my own feelings: “Bob’s influence is woven into so much of what we do at Arup and beyond... I feel incredibly grateful to have benefited from his wisdom.”'

The recipient of this year’s Regional Award, presented in recognition of the work undertaken by an individual on behalf of the society in the

regions, was Giorgos Kourtelis, principal lighting designer at WSP, who represents the North-West.

The Leon Gaster and Walsh Weston Awards are awarded annually for the best published papers in Lighting Research and Technology.

The Leon Gaster award is for the best paper concerned with lighting applications, and recognises the role that Leon Gaster played as the founder of the Illuminating Engineering Society (forerunner of the SLL) in 1909. The award was first made in 1929.

This year it went to Myriam Aries, Géza Fischl, Arne Lowden and Femke Beute for their paper, The relationship of light exposure to sleep outcomes among office workers, Part 1: Working in the office versus at home before and during the Covid pandemic. The paper can be found in LR&T Vol 56 issue 2.

A second Leon Gaster Award has been given to Femke Beute, Arne Lowden and Myriam Aries for the follow-up paper, The relationship of light exposure to sleep outcomes among office workers, Part 2: Comparison of days with and without social constraints. This can also be found in LR&T, Vol 56 issue 2.

The Walsh Weston award is for the best paper on more fundamental lighting matters. It recognises the roles of JWT Walsh, who was instrumental in laying down the systems of photometry we use today, and HC Weston who worked in the area of illumination and work, which led to the first IES task illuminance recommendations, in other words the first Lighting Code in the UK. The Walsh Weston Award has been given to Belal Abboushi, Steve Fotios and Naomi Miller for their paper, Predicting discomfort from glare with pedestrian scale lighting: A comparison of candidate models using four independent datasets.

The paper can be found in LR&T Vol 56, issue 3.

sll.org.uk

July/August 2025

Circular economy

Nacho Rivera

'At a time when sustainability claims are cheap, this project proves what the reality and capability is'

IN WITH THE OLD Paul Beale explains how lighting consultancy 18 Degrees used refurbished luminaires and wireless technology to create a low-carbon, future-ready lighting scheme

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Alongside the reuse strategy, a smart wireless Casambi control system was installed, enabling daylight linking, occupancy sensing and flexible scene-setting to drive down operational energy use.

The project stands as an example of how thoughtful design and technical innovation can deliver genuinely sustainable outcomes.

It shows that the future of lighting lies not just in what is built, but also in what is preserved and enhanced.

EMBRACING CIRCULAR DESIGN Circular economy principles – designing out waste, keeping products and materials in use,

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and regenerating natural systems – are becoming increasingly more critical to the built environment, and lighting design clearly has a key role to play in this. In traditional practice, luminaires are still often replaced wholesale during refurbishments, regardless of their remaining lifespan or material value.

We firmly believe that lighting design must evolve beyond this conventional linear mindset of 'take-make-dispose'.

The environmental and economic costs of manufacturing new luminaires – in terms of raw material extraction, energy use and transportation – are significant. By rethinking how product life cycles are approached, designers can dramatically reduce embodied carbon and contribute meaningfully to client sustainability targets. The scheme at 7 Air Street offered an ideal opportunity to demonstrate this philosophy in action. At a time when sustainability claims are cheap, it proves what the reality and capability is.

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Nacho Rivera

Circular economy

� Lighting tiles were installed in the work spaces, one of three types of luminaires used across the scheme all salvaged from other commercial projects in the Crown Estate portfolio

PROJECT OVERVIEW The Crown Estate has set ambitious net zero carbon targets across its developments, aiming not only to reduce operational emissions but also to minimise embodied carbon within refurbishment and construction activities. Within this framework, the team at 18 Degrees was tasked with delivering a lighting scheme for levels six and seven at 7 Air Street that met the functional, aesthetic, and sustainability aspirations of the project.

'Our brief was deliberately challenging,' says Danny Hall, the Crown Estate's head of engineering. 'We wanted the project team to explore every opportunity to reduce carbon impact, from embodied to operation. 18 Degrees responded with a creative, futurefocused approach to lighting that matches our sustainability goals.'

The unequivocal and ambitious brief set the tone for an innovative approach based on reuse, refurbishment and intelligent control, ensuring that sustainability was embedded at every stage of the design.

SOURCING AND REFURBISHING LUMINAIRES One of the most exciting aspects of the project was the opportunity to implement circular principles in a real, commercially

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driven environment. To show that a crisp, high-performance lighting scheme could feel as good as it looked, sustainability and style hand in hand.

Early in the design process, we proposed that rather than specify entirely new fittings, existing luminaires would be sourced from other commercial projects within the Crown Estate's wider portfolio. Carefully selected for their quality and compatibility, the fittings –including linear LED systems, downlights and wall-mounted fixtures – were recovered during strip-outs and decommissions.

Three types of lighting were used throughout to minimise variation and create a cohesive lighting aesthetic, with each type tailored to the specific function of the space: • Lighting tiles (600 x 600mm) were installed in workspaces to provide the high level of illumination needed for screen-based tasks, with efficiency and flexibility in mind • Recessed downlights were positioned in circulation areas, touchdown points and tea points to provide softer, ambient lighting • Linear extrusions (3m) were used in the lounge and cafeteria areas to define these social spacesz

Each luminaire underwent a detailed inspection and refurbishment process at the 18 Degrees workshop, including full electrical testing, cleaning and, where necessary, upgrading of components such as LED boards and drivers to meet modern efficiency and performance standards. Housings and optics were retained wherever possible, preserving both the material and embodied carbon value of the originals. All refurbished luminaires were fully re-certified to comply with current regulations, ensuring safety and reliability for long-term use.

To quantify the environmental benefit of the reuse strategy, 18 Degrees undertook an embodied carbon assessment following the CIBSE/SLL TM65.2 guidance (Embodied carbon in building services: Lighting). The assessment compared the impact of installing refurbished luminaires against that of specifying new equivalents, considering the whole-life carbon stages A1–A4 (product and supply chain emissions), C2–C4 (end-of-life impacts), and D (benefits beyond system boundary such as recycling potential). Figures were based on typical values found in manufacturers' Environmental Product Declarations (EPDs), ensuring a realistic, industry-standard comparison.

In total, 130 luminaires were recovered and refurbished for use at 7 Air Street, representing 100 per cent of the total lighting installed.

Based on the TM65.2 framework and EPDderived figures, it is estimated that the reuse strategy saved around 800kg of CO2e – the equivalent of driving around 5700 kilometres in an average petrol car.

The scheme highlights the potential for lighting refurbishment to deliver significant embodied carbon savings, even on complex

� Linear extrusions were used to define social spaces

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July/August 2025

commercial projects, and reinforces the role of circular economy thinking in mainstream architectural design.

SMART LIGHTING: THE ROLE OF WIRELESS CONTROLS While the reuse of existing luminaires significantly reduced embodied carbon, achieving meaningful operational energy savings required a different kind of innovation.

To complement the circular design strategy, we integrated a Casambi wireless control system throughout the refurbished floors.

This combination of hardware reuse and smart digital control allowed the lighting to perform not just sustainably at the point of installation, but intelligently throughout its operational life.

The Casambi system enabled a highly responsive, decentralised lighting control network without the need for extensive new cabling – an important consideration in a retrofit project like this one. Luminaires were grouped into zones that respond dynamically to both occupancy and available daylight.

This approach embodied our ethos of ensuring spaces are appropriately lit for comfort, function and wellbeing, but never overlit or wasteful. The flexibility of Casambi's app-based interface also allowed bespoke scenes to be programmed for different tenant needs, with adjustments possible postoccupancy without invasive works. All refurbished luminaires were upgraded with Casambi-enabled drivers or control modules as part of the refurbishment process, which meant that both reuse and smart control were fully integrated.

Post-occupancy data suggests a reduction in operational lighting energy use of around 59 per cent compared to the previous lighting control arrangement.

REFLECTIONS AND LOOKING AHEAD The success of this project has shown that circular lighting design can move beyond pilot schemes and into the mainstream of commercial projects. By valuing existing assets, combining them with smart technologies, and putting user experience at the heart of the solution, 18 Degrees delivered a lighting scheme that meets both environmental and operational goals. The project reinforces the belief that sustainability

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Circular economy

must be embedded from the very first design conversations — not treated as an afterthought.

Looking ahead, 7 Air Street serves as a blueprint for how lighting designers, contractors and clients can work together to drive real change. Circularity in lighting is no longer an ideal – it is an achievable, exciting reality, and one that offers tangible environmental benefits while delivering beautiful, effective spaces for people to enjoy.

Paul Beale, MSLL, is the cofounding director of London-based lighting design consultancy 18 degrees

Strategic recommendations for the Crown Estate: • Prioritise the use of refurbished luminaires where possible to reduce embodied carbon • Prioritise the use of UK, or Europe-based luminaires to reduce embodied carbon • Encourage embodied and operational carbron analysis to support best sustainable practice • Collaborate with manufacturers to develop circular supply chains, such as take-back schemes and leasing models. Ensure that lighting schemes are designed to suit the specific requirements of each space and avoid a ‘one-size-fits-all’ approach • Use energy-efficient luminaires • Implement smart controls such as presence detection, daylight linking and automatic time-based controls in all lighting schemes to reduce operational energy consumption

Key findings from the analysis for 7 Air Street Total carbon reduction The circular design approach reduces total carbon emissions by 60 per cent compared to a standard approach, through the reuse of refurbished luminaires and lighting controls. This is equivalent to a reduction of 60 tCO2e, with a 1.3x buffer factor applied as per TM65 framework guidelines to account for potential uncertainties.

Lower embodied carbon The circular approach generates up to 85 per cent less embodied carbon compared to a standard approach by reusing refurbished luminaires and sourcing locally.

The circular approach enables fittings to be reused or refurbished for a ‘third-life’, reducing the production of ewaste. This is equivalent to a reduction of 3 tCO2e.

Reduced operational energy use By integrating smart lighting controls, the circular approach achieves a 59 per cent reduction in operational energy emissions over 12 years. This is equivalent to a reduction of 44 tCO2e.

Lower costs Based on the design for 7 Air Street, the circular approach costs 33 per cent less than standard design practice. This is equivalent to a saving of around £7871 in luminaire costs.

Further operational energy savings are anticipated from the reduction of energy usage due to automatic lighting controls.

While embodied carbon might appear minimal compared to operational energy, it offers an immediate, short-term benefit, whereas operational carbon savings accumulate over a 12year period. Although the current project on levels six and seven at 7 Air Street is small in scale, it serves as a case study to explore the potential impact of circular lighting design if implemented across the Crown Estate’s commercial portfolio.

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Book review

July/August 2025

TALES OF THE UNEXPECTED Alan Tulla finds Stories with Light an unconventional, eclectic and fascinating journey through the art, science and history of illumination

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ver the years, I have reviewed many books by top rank lighting designers such as Howard

Brandston, Sally Storey, Mark Major and Jonathan Speirs, to name just a few. All of these books have included many of the

best examples of their author’s work.

But this book by Michael Grubb, coauthored by journalist Francis Pearce, is surprising in that it doesn’t include any of his own award-winning designs. When asked, Grubb said he did not want to write a 'howto' book or an academic text on light. The book’s cover describes it as an anecdotal exploration of light, lighting and illumination. I would also describe it as a history of light since time began.

The short stories can be read in any order and it is intended to be a bit random, and include bizarre or unexpected stories.

As such, this book will appeal to a much wider audience than conventional books about lighting.

When I first started my career in lighting, one of its appeals was that it was

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Book review

'Why does everyone love a rainbow?And was the light bulb such a bright idea after all?'

– Stories with Light

so interesting. If you know any sciency kids, or even grown-up kids, this book is a dream.

There’s an interesting fact, or more, on every one of its 200-plus pages.

The book is also, pardon another pun, chock-full of illuminating quotations. Building services engineers would certainly find themselves in agreement with the Russian philosopher and anarchist Peter Kropotkin: 'For the worker, a room, properly heated and lighted, is as much an instrument of production as the tool or the machine.'

A physicist once described a rainbow as a bridge between two disciplines. By this, they meant that both poets and scientists have described this wonderful phenomenon in their own particular way. There are many more examples of what you might call ways of seeing light (apologies to art critic and novelist John Berger) in the book.

Turning to the actual structure, it has three sections: Light, Lighting, Illumination.

The first section looks at the science of

'This book will appeal to a much wider audience than conventional books about lighting'

light, especially the biology. There is also a lot of astronomy where you will learn that when comparing the surface temperatures of the nearest 200,000 galaxies (as you do), the astronomers found that the universe isn’t white but more a pinky beige which they called cosmic latte.

The second section, Lighting, is about all the different ways that we create artificial light. It starts with a discussion of firelight used to illuminate cave paintings, as opposed to solely being a source of warmth. The caves at Lascaux in the Dordogne and others show that artificial illumination dates back at least 17,000 years. There’s also an argument for saying artificial illumination goes back more than 100,000 years.

The section then moves on to the invention of gas lamps and electric lighting. The book provides a lot of evidence to suggest that much of the technology was driven as much by ego and greed as by pure scientific enquiry.

The third section, Illumination, looks at our changing relationship with light and lighting.

This era really starts around 200 years ago when the cost of lighting, measured as the number of hours a human would have to work to produce a given quantity of light, really plummeted. Researchers at UCL calculated that the cost of lighting in real terms dropped to one three-thousandth of its value between 1800 and 2000. It is what the book frequently refers to as the Great Illumination.

Our cities and whole way of life have been transformed enormously by the Great Illumination. Many of the stories in the book are about industrialisation and what you might call the mechanisation of lighting, and

people. As you might expect, the effect of artificial light on the work of artists from Caravaggio to Edward Hopper features heavily. The history of modern cinema also crops up in many of the stories.

While there is a great deal in the book about the impact on the night sky, there is much less on the ecology and natural environment.

In conclusion, I cannot improve on the Epilogue which states: 'Our relationship with light continues to evolve, influenced not only by technological advances but also by growing knowledge and reflection. We hope that Stories with Light will, in its modest way, contribute to this process.'

Finally, I should mention that I greatly enjoyed the playful design and illustrations by Jane Davies. Their eclecticism is a perfect match for the book’s style.

Stories with Light

By Michael Grubb and Francis Pearce, illustrations

by Jane Davies Price: £25 Light Read (ISBN 978-10684060-0-3) www.waterstones.com

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LR&T essentials

July/August 2025

RAISING EYEBROWS Alan Tulla finds a highly diverse selection of studies in the latest Lighting Research and Technology he latest issue of Lighting Research and Technology features a very eclectic range of topics, ranging from eyebrow glare and Columbian energy labels through to the best lighting for an aromatherapy salon.

We usually think of glare as being caused by strong contrasts arising, for example, from a large array of luminaires in the field of view. However, much less studied is what some people call eyebrow glare, the subject of a paper by Abboushi et al. It is produced by the luminaires which are more directly above your head. The degree of glare partly depends on how far deep in your head your pupils are.

Previous studies by Luckiesh and Guth, and Boyce et al showed that the portion of the face illuminated had an effect on the degree of glare.

For example, when an overhead source with a luminance of 31,000 cd/sqm was positioned 75 degrees above the line of sight, the mean discomfort rating increased from noticeable when the nose and cheek were exposed to just uncomfortable when the eye was also exposed.

Boyce et al also showed that applying black grease to exposed cheeks reduced glare from overhead sunlight – less is reflected upwards towards your eyes.

This paper takes the previous work further and describes an experiment comparing pupil obscuration with the perception of glare. Here, the light source is positioned 60 degrees above the line of sight and a comparison made

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with the depth that the pupil is recessed.

The results are in line with that of previous work and suggest that people with unshaded pupils were more sensitive to an overhead glare source located 60 degrees above the line of sight.

I wonder how many Light Lines readers have ever been asked to illuminate an aromatherapy salon. A paper by HC Li will give you a solid foundation for your design.

The experiment included many variables such as luminance of the source and CCT. These were combined with five essential oils (lavender, tea tree, geranium, peppermint and sweet orange). The differences in emotional response (distressed, hostile, alert, inspired, nervous and active emotions) were recorded.

The results indicate that white light sources of varying luminance, and chromatic light sources with changes in lightness significantly affect all emotional perceptions. The blackbody locus, CCT, hue, chroma and essential oils also have notable influence. CCT significantly affects determination and attentiveness, whereas different hues impact all feelings apart from distress, alertness and fear.

It’s well worth reading the whole of this paper in depth as this summary cannot include all the background research on olfaction and emotional response. Who among us realised that smelling grapefruit reduces men’s anxiety?

Energy efficiency policies (EEPs), including minimum energy performance standards (MEPS) and energy labels serve as crucial instruments to

drive countries towards enhancing the energy efficiency of end-use products. The majority of globally established EEPs target luminous efficacy.

A paper from Columbia by LA Cardenas et al argues that the labelling should also include the circadian impact of the products. The work presents a labelling model for indoor LED lighting products incorporating not only energy performance but also visual and circadian performance.

In essence, the proposed label looks the same as the familiar, coloured arrow ranking A-G but with some extra information.

The model is presented as a case study of 25 products (three samples of each) on the Columbian market. These products were categorised into two principal groups: tuneable white and standard LEDs. The study also categorised products into lamps and luminaires with directional and non-directional sources.

The study concludes that the AHP (analytic hierarchy process) Sort method is well-suited for evaluating the overall performance of LED lighting products.

Alan Tulla is a former president of the SLL and principal of the independent consultancy Alan Tulla Lighting Lighting Research and Technology: OnlineFirst In advance of being published in the print version of Lighting Research and Technology (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) Pupil obscuration mediates the impact of an overhead glare source Abboushi et al Investigation of suitable lighting conditions on emotions and perception models for beauty aromatherapy application HC Li Multi-criteria decision-making methods for labelling energy, visual and circadian performance of LED lighting products LA Cardenas, F Herrera, P Acuna

� A 3D facial model showing the pupil obscuration angle (Abboushi et al)

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Top five

FLASHES OF GENIUS

Peter Raynham looks at five key scientific discoveries that revealed the properties of light

here has been discussion about the properties of light at least since the time of the Ancient Greeks and while some obvious ones were known from observation – such as the fact that light appears to travel in straight lines – its true nature was not understood.

However, there were many misleading ideas about light that needed to be corrected, and as shown here some new incorrect ideas crept in along the way. These experiments have given rise to our modern understanding of light, which seems to support the way we use light, but may itself be fundamentally flawed.

They have given us a model of light that is good enough to explain what happens in all practical situations. However, this tells us very little about the way people and biological systems in general react to light, and it is the complexity of these interactions that keep researchers working today.

3 Light as wave Thomas Young had studied sound waves and ripples in water and believed that some properties of light could be better explained if it was considered to be a wave rather than a set of particles. In 1802 he demonstrated that a beam of light split by a card produced a fringe pattern, and later went on to develop the double-slit experiment that he is famous for. However, if light was a wave, classical physics implied that it needed a medium to propagate it. This gave rise to the concept of the aether (ether in Young’s publications) that pervaded space.

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Wikimedia

Former SLL president Peter Raynham is emeritus professor of the lit environment at the UCL Institute for Environmental Design and Engineering (IEDE)

4 The absence of aether During the 1870s Michelson and Morley ran an experiment comparing the speed of light along two paths at right angles to each other using interferometry. The Earth's motion around the sun implied that the experiment should be moving through the aether and so changes in the speed of light should have been noticed at different times of the year. After running the experiment for several years they came to the conclusion that aether did not exist. This work led in due course to the Theory of Relativity.

Bradley byThomas Hudson/Wikimedia

Speed of light In the 1720s astronomer James Bradley was trying to measure the position of some stars at different times of the year, hoping to work out how far away they were by assessing the change in their position due to parallax.

In fact most stars are so far away that this shift would be too small to measure using his apparatus.

However, his observations showed that the stars moved in the opposite direction to that expected due to parallax. Over time, he realised the shift was due to the Earth’s movement and the finite speed of light. He estimated the speed of light at 301,000,000m/s (the true value is 299,792,458m/s).

scienceready.com.au

Light spectrum We know from Newton’s experiment with a prism during the 1660s that white light can be split into coloured light. However, Newton's analysis of the topic is not perfect. He felt it necessary to use seven colour names to describe the spectrum, and he also asserted that light was a stream of particles without evidence to support this contention. The other point Newton missed, which was picked up by Goethe more than 100 years later, was that colour is as much to do with perception as it is to do with the physical properties of the radiation.

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Nobel Foundation

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Sarin Images/GRANGER

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5 Photoelectric effect This was not a simple one-off experiment but more a series of studies starting with Becquerel in 1839 making a chance observation, through to Lenard in 1902.

Lenard's key observation was that the energy of individual emitted electrons (voltage) was independent of light intensity but was a function of the wavelength of the light. In 1905 Einstein took these findings and, in conjunction with the mathematics that Planck had needed to model black-body radiation, was able to lay the foundations of the quantum nature of light.

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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 LIGHTING THE ELIZABETH LINE: FROM CONCEPT TO REALITY (organised by the SLL HCNE and Yen) Date: 9 July Time: 6.30pm Venue: XAL showroom, London EC2 www.cibse.org/whats-on/search-events/lighting-the-elizabethline-from-concept-to-reality/ TECH-X TECHNICAL EXCELLENCE CONFERENCE (organised by the LIA and supported by the SLL) Date: 10 September Venue: Convene 133 Houndsditch, London EC3 www.thelia.org.uk/member-services/events/tech-x.html ICEL CONFERENCE (organised by the LIA and supported by the SLL) Date: 11 September Venue: Cavendish Conference Centre, London W1 www.thelia.org.uk/member-services/events/icel-emergencylighting-conference.html CIRCULARITY LIVE CONFERENCE (organised by Recolight and supported by the SLL) Date: 25 September Venue: Minster Building, London EC3 www.recolight.co.uk/circular-lighting-live/ READY STEADY LIGHT (organised by the SLL with Rose Bruford College and the IALD) Date: 14 October Venue: Rose Bruford College, Sidcup, Kent www.cibse.org/ready-steady-light HEALTHCARE ESTATES CONFERENCE AND EXHIBITION (organised by the Society of Public Health Engineers (SoPHE) and CIBSE Healthcare Group, and supported by the SLL) Date: 21-22 October Venue: Manchester Central www.healthcare-estates.com/

LET DIPLOMA IN LIGHTING DESIGN For details and registration: www.lightingeducationtrust.org

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