Light Lines September/ October 25

The Society of Light and Lighting

VOLUME 18 ISSUE 5 SEPTEMBER/OCTOBER 25

CULTURAL EVOLUTION

Reshaping the future of lighting design

MAKING NIGHT WORK The DarkSky UK Conference

September/October 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 LL6 2025 IS 15 SEPTEMBER 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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As any judge of lighting design awards will have observed, an inescapable fact over recent years has been the emergence of China as an exceptional source of creative, thoughtful and even poetic lighting design.

In his article China: Design of the Times (see p7), lighting consultant Martin Klaasen talks of lighting design as being 'in the middle of a remarkable transformation'. He points out that a key crucible for this lies in the melding of 'Western' experience with 'Eastern' talent, energy and eagerness to push boundaries.

'Western lighting designers bring a depth of knowledge with an emphasis on narrative and a legacy experience of detail refinement,' says Klaasen. 'Chinese counterparts, on the other hand, bring speed, technical agility and a hunger for transformation and change. When these elements meet, the results are very gratifying.'

Interestingly, wellbeing and the effect of lighting on the way people feel and behave is high on the agenda, with Chinese developers

September/October 2025

Secretary’s column/Contents

Contents

FROM THE SECRETARY and hotel brands 'rapidly leapfrogging from conventional systems to smart, data-driven lighting strategies that encompass health, behaviour and experience'.

Klaasen believes that we stand at a pivotal moment where lighting will become an 'interactive, intuitive, emotional and even conversational interface'. The impetus will no longer reside with lux levels, glare ratings or standard compliance, he contends. 'It will be about what lighting says to you – how we communicate and interact with lighting.'

For lighting design these are interesting times – and not necessarily in the Chinese sense.

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

We are happy to confirm that the 2025 SLL Jean Heap Bursary recipient is Nicholas Witton.

Nicholas’s bursary project is titled, ‘The effects of near infrared on sleep outcomes via mitochondrial pathways: A comparative study on the impact of near infrared exposure on human performance, sleep metrics and circadian responses in workplace settings’.

We look forward to receiving Nicholas’s project updates in due course and we will share them with you via the SLL website. Nicholas’s bursary application recording can be viewed on the SLL website (for this, and links to all events mentioned here, see box).

Andrew Bissell, SLL past president and chair of the SLL marketing and communications committee, will be presenting at the DarkSky Conference 2025 on 9 September at Newcastle University, an event the society will be supporting (see p5).

As previously reported, the SLL will also partner with the LIA’s TECH-X conference which takes place on 10 September at Convene 133 Houndsditch, and then with the ICEL Conference on 11 September at the Cavendish Conference Centre, London. The SLL is also partnering with the Recolight Circular Lighting Live Conference on 25 September at the Minster Building, again in London.

In mid-September we also hope to be able to confirm the SLL Young Lighter 2025 finalists, as well as details of the final itself.

Giorgos Kourtelis, SLL and CIBSE North West regional lighting representative, will host an evening of interactive CPD and networking focused on lighting controls on 18 September.

It will be hosted in collaboration with Studiotech, at Revolution, Oxford Road, Manchester. This practical session is primarily aimed at designers, engineers and specifiers who want to better understand how lighting control systems work in real-world applications.

Team registration for SLL Ready Steady Light 2025 is now open. Ready Steady Light returns on 14 October for its 30th Year in association with Rose Bruford College and the IALD. This is a real milestone for the competition and we look forward to welcoming the teams to the college in Sidcup for what promises to be a memorable day and evening.

SLL will join the Society of Public Health Engineers (SoPHE) and CIBSE Healthcare Group at the Healthcare Estates conference and

X: @sll100

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To view Nicholas Witton's bursary application: www.cibse.org/policy-insight/ news/nicholas-witton-is-therecipient-of-the-jean-heapbursary-in-2025/ For details of DarkSky Conference 2025: www.cibse.org/whats-on/ search-events/darkskyconference-2025/ To register for TECH-EX: www.cibse.org/whats-on/ search-events/technicalexcellence-conference/ To register for ICEL: www.cibse.org/whats-on/ search-events/icel-emergencylighting-conference To register for Recolight Circular Lighting Live Conference: www.recolight.co.uk/circularlighting-live/ More details and registration for regional lighting controls event: www.cibse.org/whats-on/ search-events/light-logicunderstand-the-language-ofcontrol/ To register for Ready Steady Light: www.cibse.org/get-involved/ societies/society-of-light-andlighting-sll/whats-happening/sllready-steady-light/ To register for the Healthcare Estates conference and exhibition: www.healthcare-estates.com/ For more details and registration for Light25: www.lightexpo.london/

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, London. We are excited to be exhibiting in the Associations' Lounge with SLL speakers included in the conference programmes. The 2024 exhibition and conference were excellent and such a success the organisers have opened up a new Tech Zone.

BRENDAN KEELY BKEELY @CIBSE.ORG

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EDITORIAL

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SECRETARY'S COLUMN

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NEWS

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NIGHT WATCH

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CHINA: DESIGN OF THE TIMES

Andrew Bissell outlines this month's Dark Sky UK Conference – and stresses the need for young lighting professionals to attend

Lighting designer Martin Klaasen looks at how China – and the fusion of 'Eastern' and 'Western' ideas – is helping reshape the future of lighting design

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SOLAR FLAIR

Olafur Eliasson's new light art installation follows the path of the sun – and provides a beacon of regeneration

12 STAR TURN

The newly refurbished Prague Planetarium boasts the largest LED screen of its kind in the world and the first LED dome in Europe

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Iain Carlile finds three recent papers in LR&T that focus on the impact of directionality, source size and diffuser colour on performance and wellbeing

15 TREADING LIGHTLY

Top 5: Irene Mazzei on five key steps to sustainability

16 EVENTS COVER: Long daylight pavilion, by world-renowned Icelandic-Danish artist Olafur Eliasson, is a site-specific light artwork that traces the sun’s path above Helsinki on the summer solstice. Curated by HAM Helsinki Art Museum, it is Eliasson's first public artwork in Finland.

HAM/Maija Toivanen

Editorial

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News

September/October 2025

September/October 2025

Events

THE LATEST NEWS AND STORIES

News

GREEN LIGHT FOR RED LIGHT

INDUSTRY BODY FLAGS LIGHTING'S ABSENCE FROM EU STRATEGY Lighting is a critical, yet overlooked, technology in the EU green transition, according to a statement recently issued by industry body Lighting Europe. It calls for lighting to figure more strongly in key EU strategies and legislation.

'Despite its potential, lighting is almost absent from the recent key EU strategies – such as the Clean Industrial Deal and the Action Plan for Affordable Energy – and risks remaining absent in upcoming legislative proposals,' it says.

The organisation, which represents 32 companies and national associations, including the LIA, lists a dozen considerations it views as necessary if measures are to harness the potential of lighting.

Among them are a call for the clear political recognition of lighting as an essential technology for the green transition across all industrial and energy policies, and the ambitious implementation at national level of the Energy Efficiency Directive (EED) and the Energy Performance of Buildings Directive (EPBD), including the provision mandating the use of automatic lighting control systems in non-residential buildings.

It also asks for EU legislation on the built environment and building renovations, if reviewed, to always include clear requirements for high indoor environmental quality, including better lighting.

A further aim is the introduction, in the current EU legislative framework, of a harmonised set of rules regarding light at night (replacing fragmented national regulations), to support quality outdoor lighting and address potential adverse effects on the environment.

'Too often, lighting is seen as a simple utility – something we turn on without a second thought,' says the statement. 'But lighting is far more than that. Lighting, when done right, has the power to improve life for everyone, everywhere... and to transform indoor and outdoor environments. It is also a cornerstone of energy efficiency and should be better recognised as such in EU legislation.'

Full details are available at www.lightingeurope.org

ON THE LIGHTER SIDE… Soli, a protoype lamp by Mexican designer Milú Brunell, is literally rooted in nature – it's planted in the ground and powered by soil.

It features a microbial fuel cell (MFC), a system that generates electricity through the natural metabolic processes of microbes in the soil. As these microorganisms break down organic matter, they release electrons. These are captured by an anode and flow through a circuit to a cathode, a small but steady current that's sufficient to power the lamp. It's also a useful indicator: the

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healthier and more biologically active the soil, the brighter the Soli lamp glows.

'It turns energy from the earth into a visual reflection of its own wellbeing, inviting us to see the ground not just as something we use, but as something we care for, and that, in turn, cares for us,' says Brunelli. www.milubrunell.com

The increased focus on the benefits of infrared light are reflected in a prototype device by Dutch tech start-up SunLED Life Science that attaches to computer monitors and laptops to deliver near-infrared light to users while they work.

Near-infrared light (NIR) is an invisible part of the solar spectrum that makes up 50 per cent of sunlight. Unlike SAD lamps, the company's SunBooster uses LEDs to deliver targeted near-infrared light with a wavelength of 850nm. Wavelengths higher than 750nm are considered to be able to reach deep into skin cells.

Research has indicated that a variety of medical benefits can be ascribed to both deep red light (650-750nm) and near infrared (see Unseen Benefits, LL May/ June). SunLED has focused on the energy and sense of wellbeing it promotes.

'Today's modern lifestyle lacks exposure to natural sunlight,' says Dr Anne Berends, a nanomaterials scientist and co-founder of the company.

'Near-infrared light... plays a vital role in helping humans feel happier, healthier and more energised,' adds Berends, who spent more than five years researching the subject before partnering with lighting industry specialist Ayhan Siriner to launch the SunLED device.

Having produced a proof-of-concept computer clip-on for MWC 2025 tech fair in Barcelona, the company is now seeking to partner with brands and manufacturers to incorporate the technology, which can be applied to a wide range of contexts and products, including light fittings, electronic devices, screens and car dashboards.

NIGHT WATCH Andrew Bissell outlines this month's SLL-supported conference on dark skies – and stresses the need for young lighting professionals to attend

sll.org.uk

X: @sll100

he importance of designing for dark skies has always existed to both restore the night sky in areas of excessive brightness and to protect those areas which still enjoy pristine night

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Events

September/October 2025

skies. Over the past five years or so the subject of designing for dark skies, and the need to improve what we do, has become more prominent in the lighting industry.

This was highlighted through the collection of evidence by the House of Lords examining the impact on health and wellbeing of light and noise pollution. While designing for dark skies has historically been about seeing the stars, wildlife and energy, the House of Lords approach has rightly adjusted the focus to people and health.

Ultimately the recent emphasis on people now means that there is an even stronger case that every project should be designed to protect or restore the pristine sky.

The DarkSky UK Conference is designed to provide an update on what has been achieved and what is planned. It will also provide attendees with the opportunity to shape future policies, standards and education. Throughout the day there will be plenty of time to network, share experiences, knowledge and ideas.

The conference is aimed at everyone involved, or potentially involved, in dark skies, including lighting designers, lighting manufacturers, researchers, local authorities and end users. Key professional bodies are involved (see box), which further demonstrates how the subject of dark and pristine skies has captured the attention of the lighting industry.

The conference has collated talks from a wide range of industry professionals whose work and experience will be shared with the attendees. The sessions and talks provide a great balance between design, products, policies, standards and delivery.

Over the years more and more design guides, how-to booklets and supplementary design guides have been produced in relation to designing for dark skies.

There have also been many more conferences and educational sessions on the subject. Equally with the House of Lords enquiry and the publication of the Dark Skies All-Party Parliamentary Group report, there has been more talk about

policies and legislation. This has all been very positive to get the subject to where we are today. However, what do we need to do next? The discussion in the afternoon will allow all attendees to contribute to how this subject moves forward and, importantly, moves forward with a more refined, powerful and single voice.

One thing that is vital is that the next generation participates in the conference, and we are keen to help our early careers members feel they can attend and contribute to events such as this. It is critical that the next generation is helping to drive this subject forward, as quite frankly the problem will not be solved before I and others who are speaking or chairing sessions retire.

Having been an early career professional many, many years ago, and feeling as if I would be imposing if I attended, or that I wouldn’t know enough to say anything, I understand how some people may feel daunted and as a result perhaps might not register or attend.

If that is you do not worry, you are not alone in many ways. Others will feel the same and the older folk there will have been in your shoes at some point.

Therefore, if you want help getting to know people when you get to the event or you need a friendly face to hang around with, drop Brendan at the SLL an email (bkeely@cibse.org) and he will ensure we meet and greet you, and introduce you to key people.

The DarkSky UK Conference 2025: Good Lighting – from Pollution to Solution takes place at Newcastle University on 9 September

'We are keen to help our early careers members feel they can attend and contribute to events such as this – it’s critical the next generation help to drive this subject forward'

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September/October 2025

Opinion

MORNING: PRESENTATIONS These will be followed by Q&As and are grouped into the following topics: • Light Pollution Benefits No One: chaired by Andrew Bissell, past president of the SLL, and partner, lighting design, at Ridge and Partners • Less is More, New Approaches to Lighting Design: chaired by Amy Rennie, lighting lead at Buro Happold • Policy to Practice: Settlement Wide: chaired by Nick Dunn, professor of urban design, and executive director of Imagination at Lancaster University • Policy to Practice: Community and Business Projects: chaired by Guy Harding, ILP AFTERNOON: DISCUSSIONS The following three discussion groups will be encouraged to offer input into how to develop the subject of dark sky lighting: • National policy and regulatory changes: chaired

by Jack Ellerby, FLD • New standards: chaired by Dan Oakley, Darkscape Consulting • Engagement, education and training: chaired by Paul Gregory, Dark Sky Lighting

Professional bodies supporting the event: • Society of Light and Lighting (SLL) – cibse.org • Institution of Lighting Professionals – theilp.org.uk • International Association of Lighting Designers (IALD) – iald.org • The Lighting Industry Association – thelia.org.uk • ECA (Electrical Contractors’ Association) – eca.co.uk • Dark Sky Discovery – darkskydiscovery.org.uk

sll.org.uk

� Alila Hotel, Shanghai, 'where cultural sensitivity, nature integration and smart technology came together through knowledge exchange and close collaboration'

CHINA: DESIGN OF THE TIMES Lighting designer Martin Klaasen looks at how China – and the fusion of 'Eastern' and 'Western' ideas – is helping to reshape the future of lighting design X: @sll100

f you had asked me three decades ago what lighting design was all about, I would have told you that it was a balance of function and form: task lighting to see by, ambient lighting to set the mood, with the 'Western' world at the centre of lighting design. And that would have been true… then.

But today, lighting design is in the middle of a remarkable transformation. Reminiscent of how mobile phones evolved from simple communication tools to smart, interactive devices embedded into nearly every aspect of our lives, lighting too has outgrown its original role. It has now evolved into a globally applied, dynamic, data-integrated interface with our built environment.

And if there is one place in the world that epitomises this evolution, it is China.

Working on projects and organising lighting events in China over the past 30-odd years has been one of the most eye-opening and

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Opinion

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September/October 2025

Sugarhouse Hotel, Yangshuo: 'the design weaves together history, texture and landscape through carefully curated layers of light'

rewarding experiences of my professional journey. Not only because of the scale or speed at which things move (my first trip to China was in 1995), but specifically because of the mindset, the cultural readiness to embrace change, innovation and experimentation, mostly driven by the desire to prove to the 'West' that China is not just a nation that follows, but one that leads.

Unlike many of the more conservative markets in the West, where cost, risk-aversion (think quality and safety compliance) or traditional procurement processes often stifle creative ambition, clients in China are curious, bold and open to new ways of thinking.

Take, for example, my work on the Sugarhouse Hotel in Yangshuo, in southern China, a project that transformed an old sugar mill into a luxury destination. Here, lighting was not so much about visibility or decoration, it was more about storytelling and the quality of the experience. The design weaves together history, texture and landscape through carefully curated layers of light.

While that may not sound revolutionary, what stood out was the willingness of the client to go beyond expectation, welcoming sitetested mock-ups and facade lighting experiments involving a huge bamboo artwork to assure the highest quality guest experience.

In the Naera Hotel in Xitang, we took things a step further, integrating art, sculptures and a light show as

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part of the guest journey, day or night, creating magical and unexpected experiences throughout the resort, moments to remember, moments of introspection. The client’s keenness to include a museum-like environment, together with a curated nightly lightshow, as part of the hotel experience (a unicum to my knowledge) showed his forward thinking and openness to exploring new forms of hospitality. The hotel has now become more than just a place to stay; it is now a 'must visit' destination shaped by light.

China’s lighting evolution didn’t come out of nowhere. Many of the world’s latest innovations (electric cars, smart phones, robotics, health care and so on) are now originating in China. We just have to look at the evolution of electric car technology to see how brands such as BYD are overtaking and now even leading Tesla in terms of innovation.

The same with the lighting technology. The latest smart and sensor-driven innovations are

'Today, lighting design is in the middle of a remarkable transformation'

born in China, and manufactured, prototyped and refined in factories across the Shenzhen, Zhongshan and Guangzhou area.

Interestingly, we are seeing design-led innovation coming from China with the boundary between technology and design dissolving. China has now truly moved from a nation of cheap copiers to a nation of high-end innovation and design leadership.

That’s the critical difference. Chinese developers and hotel brands are rapidly leapfrogging from conventional systems to smart, data-driven lighting strategies that encompass health, behaviour and experience. Where Western clients might still be approaching lighting design in a more conventional way, fixated on LED efficacy, energy or standard compliance, many Chinese clients seem to be one step ahead focusing on improving the customer comfort and experience using the latest innovations and technologies.

This cultural openness is not a one-way street.

What I’ve found most rewarding in my China experience is the willingness to exchange ideas.

Western lighting designers bring a depth of knowledge with an emphasis on narrative and a legacy experience of detail refinement. Chinese counterparts, on the other hand, bring speed, technical agility and a hunger for transformation and change. When these elements meet, the results are very gratifying.

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September/October 2025

I was proud to co-host the 'East Meets West' event at GILE (Guangzhou International Lighting Exhibition) not long ago, where we focused on Health and Wellbeing in Lighting Design. This event was not just a promotion of knowledge from either hemisphere, it was designed as an immersive platform where the thought leaders could exchange their knowledge of Eastern philosophies and approaches with typical Western compliance approaches and strategies.

The event was a cultural exchange, attended by a melting pot of designers, manufacturers and academics with different backgrounds, engaged in real-time dialogue, exploring how lighting could be redefined for the future.

In cities such as Shenzhen and Hangzhou, smart lighting infrastructures are already in place, networked, adaptive and responsive to people flow, weather and events. In Western cities it feels like they are still debating pilot programmes (though catching up). This technological momentum in China gives designers a playground to test, prototype and learn.

Over the years, I’ve had the privilege of working with Chinese clients who were not only deeply respectful of our design knowledge but also challenged us to push the envelope, often in combination with new architectural or interior design explorations. Projects such as the Alila Hotel in Shanghai, the Banyan Tree hotel in Dongguan and the Andaz hotel in Nanjing are examples where cultural sensitivity, nature integration and smart technology came together through knowledge exchange and close

Opinion

collaboration. These weren’t projects that imposed a Western design model on to a Chinese context – if anything it was the other way around.

Sometimes that collaboration meant learning how to translate visual comfort or technical lighting qualities into a common language that expresses the experience, feeling or mood, rather than pure engineering specifications.

At other times, it meant embracing Chinese materials, symbolism or local urban conditions in the lighting narratives.

But the result always ends up being better with both sides open, transparent and united in pursuit of something that goes beyond traditional expectation, ultimately forming a shared design philosophy where East and West genuinely meet.

That’s the bridge we need to continue building. With more Chinese designers studying abroad and more international designers working in China, the cross-pollination is well and truly happening. But we need to deepen that exchange: not just in conferences or project design meetings, but also in training programmes, design incubators or collaborative research. The next big thing in lighting undoubtedly will be AI and its integration in the design process will hopefully come from shared wisdom, not isolated expertise.

I believe we are standing at a pivotal moment where lighting will become an interactive, intuitive, emotional and even conversational interface. The push is no longer just about lux

levels, glare ratings or standard compliance, it will be about what lighting says to you, how we communicate and interact with lighting.

From my perspective, China is uniquely positioned to lead in this space. With 5G connectivity, a fast-growing AI infrastructure, the high level of mobile device adaptation and an ambitious design community, the country is turning its cities, hotels, museums and retail environments into 'experience centres'. The Western design community should embrace the opportunity to learn from this current momentum by both contributing and balancing it with their own deep-rooted expertise and sensibilities, and not to forget their heritage.

As someone who has travelled the world, educated in the West, yet deeply embedded in the Asian culture, I see the lighting design profession no longer as a 'Western' invention exported to the 'East'. It is now a global dialogue with unique opportunities for our future.

'Clients in China are curious, bold and open to new ways of thinking'

Singapore-based Martin Klaasen is managing partner of Nulty Lighting and founder of Klaasen Lighting Design. He is also co-founder of the Virtual Lighting Design Community (www.vld.community), founder of Light Talk (www.lighttalk. space), and founder of Lighting Design of Things (www.lightingdesignofthings.com) �

The Naera Hotel, Xitang, is 'now a "must visit" destination shaped by light'

X: @sll100

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Light art

September/October 2025

September/October 2025

Light art

SOLAR FLAIR

integrate contemporary art into the urban fabric.

Kruunuvuorenranta, rehabilitated from former oil depot into a residential zone, is being shaped into Helsinki’s district of light art, and Eliasson's installation establishes a focal point along the shoreline. It is the first public artwork in Finland by the Icelandic-Danish artist.

Olafur Eliasson's new light art installation follows the path of the sun – and provides a beacon of regeneration nspired by time, the sun and the geographical location of Helsinki, Long daylight pavilion by Olafur Eliasson is a site-specific light artwork that traces the sun’s path above the Finnish capital on the summer solstice.

Curated by HAM Helsinki Art Museum and located on the rocky waterfront of eastern Helsinki's Kruunuvuorenranta district, the artwork comprises 24 poles, embedded directly into the bedrock. The poles form an open, spacious ring that extends from the land into the water.

The height of the poles was determined by tracking the path of the sun as it appears from

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All Images courtesy of HAM/Maija Toivanen

'The artwork appears in the city like a lighthouse shining across the dark water'

sll.org.uk

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the site on 21 June, the longest day of sunlight during the year. The shortest pole, which indicates the lowest point of the sun on the solstice, is situated at the north side of the circle, and the tallest – reflecting the location of the sun at its zenith – is in the south.

Their varying heights allow the viewer to read the solstice’s geometry through the structure itself, using the work as a compass to orient themselves to their surroundings and in relation to the Earth. As the sun shifts overhead, shadows travel across the circular formation, introducing a quiet sense of movement.

After night falls, the lanterns shine out of the poles through diamond-shaped apertures that become increasingly open towards the top.

Here, they culminate in single points of bright light. Together, these points of light produce an angled ring that matches the sun’s path.

For residents of Kruunuvuorenranta, the artwork appears as a softly glowing beacon within an attractive waterfront park. As the bright lights at the top of the poles are oriented towards central Helsinki, to the west, the artwork appears in the city like a lighthouse shining across the dark water. People approaching from the bridge glimpse the lights foreshortened into changing ellipses, whereas from particular angles, they may appear as a single luminescent ring hovering in the distance.

The project is part of the City of Helsinki and HAM Helsinki Art Museum’s ongoing efforts to

Born in 1967, Eliasson grew up in Iceland and Denmark, where he studied at the Royal Danish Academy of Fine Arts. In 1995, he moved to Berlin and founded Studio Olafur Eliasson, which today comprises a vast team of craftspeople, architects, archivists, researchers, administrators, cooks, programmers, art historians and specialised technicians.

His work has featured in leading international galleries, including Tate Modern and the Guggenheim Bilbao. Among his well-known public art installations around the world are The weather project, an enormous artificial sun shrouded in mist, installed in the Turbine Hall of Tate Modern, London, in 2003, and Your rainbow panorama, a circular coloured-glass walkway on top of the ARoS Museum, Aarhus, Denmark, which opened in 2011.

In 2012 Eliasson founded Little Sun together with engineer Frederik Ottesen. The social business continues to work with off-grid communities in sub-Saharan Africa and spreads awareness about the need to expand access to clean, sustainable energy. In 2019 Eliasson was appointed Goodwill Ambassador for renewable energy and climate action by the United Nations Development Programme. https://olafureliasson.net/ www.littlesun.com

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LED technology

September/October 2025

September/October 2025

LED technology

STAR TURN

Boys Play Nice

Boys Play Nice

The newly refurbished Prague Planetarium boasts the largest LED screen of its kind in the world and the first LED dome in Europe

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sll.org.uk

he largest LED screen of its kind in the world, and the first LED dome in Europe, has been installed at the newly refurbished Prague Planetarium. The protected building, designed by architect Jaroslav Frágner in the 1950s, has been renovated by Czech architectural studio collcoll. The project centres on a new 22mdiameter, hemispherical screen created by US company Cosm, specialist in immersive experiences. Its 45 million pixels will allow visitors an extraordinary depth of colour and realism.

The installation of the revolutionary LED projection technology involved the removal of layers of interventions from recent decades.

The central Zeiss Jena projector was moved outside the main hall, freeing space for a new auditorium design. Architects from collcoll studio designed a stepped geometric layout that visually lifts the audience above the horizon, increasing capacity by 20 per cent to 277 seats in the process.

The new technology also

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needed new energy and technical facilities, which were integrated into the building while conserving its protected structures. The planetarium’s location in the heart of the city's Stromovka Park was exploited for cooling and heat recovery. Heat from the screen is stored in six deep wells (each 200m deep) in summer and then used to heat the building in winter. The dome itself has a thermal output comparable to three family houses, so the retained heat is reused within the building.

The installation uses the CX System, Cosm’s end-to-end immersive technology solution. It includes Digistar 7, which Cosm bills as the world’s most advanced planetarium system, a Shared Reality software platform, as well as a deep integration of Unreal Engine, a 3D computer graphics game engine. The result is a viewing experience with a brightness that is more than 100 times that in most projection domes, which visibly eliminates the cross-reflection typically seen in traditional projection systems.

It will give the planetarium the capability not only to feature the most immersive, high-quality astronomy simulations and scientific visualisations, but also to develop in-house experiences, such as multimedia presentations, immersive events and experiential fundraisers.

'The viewing experience is more than 100 times brighter than in most projection domes'

HVAC

SPACE FRAME DOME STRUCTURE

LED DOME STEEL SUPPORT BRACKETS RECLINING SEATS

AUDITORIUM SHELL

STEEL SUPPORT STRUCTURE

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ACOUSTICS

Key features: • Extended 22m CX System LED dome, the first in Europe and largest in any planetarium worldwide • 8K+ resolution and 45+ million pixels • A true-black LED dome surface that enhances contrast, depth and dimensionality, while eliminating cross-reflection • Increased brightness, outputting more than 100 times the brightness of most projection domes • Digistar advanced planetarium software • Integration with Unreal Engine for custom, inhouse productions • Industry-leading calibration and blending capable of addressing each LED for seamless, uniform visuals across the dome

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visual and non-visual effects, besides the main direction of light, another aspect of the spatial distribution of light is the perceived size of the light source. The study investigates the effect of frontal light exposure with two different solid angles and luminance settings, and their effect on sleepiness and visual comfort.

Two different settings were used for the early afternoon laboratory study, in which the vertically measured illuminance was similar resulting in an EDI of 580 lux (6400K, CRI >80).

The 24 male and 16 female participants (20-37 years) took part in a two-hour session consisting of cognitive tasks and subjective assessments of visual comfort and sleepiness.

The authors found mixed results, with light exposure from the source with higher luminance and smaller solid angle leading to decreased subjective sleepiness, at the cost of decreased reaction speed in a cognitive task. The authors also observe that perceived visual comfort was not significantly different between the conditions, despite the difference in objectively quantified glare rating. Therefore a direct link between glare and cognitive performance and subjective alertness was not confirmed.

The emotional and physiological response to lampshade colours in combination with CCT and illuminance is the subject of a study by Ding et al. This considered varying light source CCT values (3000K, 4000K, 6500K) and resultant illuminance levels (150 lux, 250 lux, 500 lux) on

Iain Carlile, FSLL, is a past president of the SLL and a senior associate at dpa lighting consultants 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) The effect of light directionality on creative performance and subjective sleepiness in the early afternoon N Derengowski, M Knoop and S Völker A controlled lab experiment on the effect of light exposure of different source sizes on subjective alertness and cognitive performance during the post-lunch dip N Derengowski, M Knoop and S Völker

� Fish-eye luminance images of the lighting scenes, taken from the position of eye height between two sitting participants (The effect of light directionality, Derengowski et al)

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Emotional and physiological responses to correlated colour temperature and lamp shade colour M Ding, Z Liu, X Chen and J Cho

sll.org.uk

Irene Mazzei on five key steps to sustainability ighting shapes the way we experience spaces, but the way we use it has a profound impact on the environment around us. From the energy consumed by light fittings to the invisible impacts of light on human and wildlife health, sustainable lighting can assume several different meanings, all connected to the concept that artificial lighting should be used to enhance our experience of the world without damaging it.

The lighting industry has recently experienced a rapid increase of interest in topics related to sustainability: the systematic reporting of product environmental information, implementation of circular economy-aligned approaches and the efforts to tailor our lights to minimise unintended consequences on our health and environment.

Here are five key steps that the lighting industry has recently taken towards sustainability.

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1 LED technology Since 2009, several types of non-LED light sources have been phased out across Europe.

Providing up to 80 per cent energy saving over incandescent bulbs – plus longer lifespans and much lower heat output – LED lighting has delivered a revolution. They are also flexible, can be tailored to wide ranges of colour temperatures, and can be accurately directed to illuminate only a specific space. The technology is constantly improving, with pioneering designs and the integration of smart and digital features.

Dr Irene Mazzei is sustainability lead at Stoane Lighting

3 Assessing environmental impacts With manufacturers wanting to produce luminaires with lower impacts and designers wanting to minimise the impacts of their projects, the need for a consistent flow of product environmental information has become clear. It is now being requested by a significant number of practices, allowing for the sector to gather data and understanding. This is also supported by the development of luminairespecific assessment rules and current efforts to standardise reporting practices in compliance with policy requirements.

X: @sll100

4 The focus on lighting and human health We spend up to 90 per cent of our time indoors and are exposed to artificial lighting for most of our day. The effects of light quality on human health are becoming an extremely important consideration, causing evident (visual discomfort, glare, flicker) and less evident (circadian rhythm, mood and sleep quality) effects on wellbeing. The latter relate to the light wavelengths we receive but don’t see, now studied extensively to provide guidance for the design of light systems with less disruptive non-visual impacts.

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he first topic is how the directionality of light affects creative performance and sleepiness in the early afternoon. Derengowski et al note in their paper that while the spatial distribution of light has been documented in relation to its affect on alertness and cognitive performance on simple tasks, the effect of spatial distribution on more complex, creative performance remains largely unresearched.

The study was carried out in a simulated meeting room with two distinct lighting conditions, one having side-dominant lighting and the other upper dominant lighting. Both had a constant irradiance of 305 lux melanopic EDI (equivalent daylight illuminance) at the participants’ eye level, a CCT of 4068K and a CRI of >90. The 35 subjects (21 male/14 female, age range 21-35 years) took part in a two-hour study involving a number of tasks assessing aspects of creative thinking (including divergent, convergent and mental rotation).

For the other dependent variables no significant effects were found. Further, covariate analysis showed a significant correlation between an increase in creative task performance and time spent under interior daylit conditions.

Another paper by Derengowski et al also looks at cognitive performance and wellbeing, concentrating on the effect of light source size.

Noting that the spatial distribution of light within a person’s field of view can influence both

TREADING LIGHTLY 2 Circular economy-inspired schemes CE principles in lighting are reflected in product design choices (easy disassembly, repair and recycling), but also in alternative business models centred around remanufacturing, take-back schemes and giving new value to reused and repurposed luminaires. These approaches are less resource-heavy, promote innovation and life-cycle thinking, and align the industry with more sustainable choices. To promote their uptake, consistent collaboration and dialogue across stakeholders are a must. Everybody needs to be on board to shift current practices from a linear to a circular perspective.

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Iain Carlile finds three recent papers in Lighting Research and Technology that focus on how directionality, source size and diffuser colour affect performance and wellbeing

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LIGHTING EFFECTS

users’ emotional state and brain activity.

Experimental stimulus images of desk lamps were used, with varying combinations of 10 lampshades along with illuminance and CCT. Special software was used to vary these properties to minimise the variables and constants within the study.

The authors found that the yellow shade combined with a 3000K light source and a resultant 250 lux made the participants feel more relaxed, while a green shade made participants feel more nervous. An electroencephalogram (EEG) showed eventrelated potential components in all three types of brain regions. The authors note that while the EEG data offers insight into correlation between emotion and luminaire shade colour, the study only looked at a limited number of CCT and illuminance conditions. They suggest that future studies should explore a wider range of lighting parameters and real-world scenarios, and consider EDI as a better metric to provide a more comprehensive evaluation of the emotional and physiological effects of light.

September/October 2025

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September/October 2025

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LR&T essentials

5 Concern for the night sky The excessive and misdirected lighting of our cities causes light pollution. It disrupts natural cycles of nocturnal animals and humans, interferes with views of the night sky, and causes energy waste and unnecessary costs. Dark Skies protection initiatives include better light shielding, use of light only when and where necessary, alongside niche LED specifications (deep reds and ambers). Most important is a higher awareness from local governments and businesses. These topics are now making their way into policy discussions to regulate the use of artificial light in cities.

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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 DARKSKY UK CONFERENCE 2025: GOOD LIGHTING: FROM POLLUTION TO SOLUTION (supported by the SLL) Date: 9 September Time: 9.15am-4pm Venue: Newcastle University www.cibse.org/whats-on/search-events/darksky-conference-2025/ 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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