Light Lines Jul/Aug 22

LIGHT LINES

RAYS OF HOPE

New president on the pivotal role of lighting

A STAR IS BORN Pulsars, pop and the Trotter Paterson Lecture

SECRETARY

Brendan Keely FSLL bkeely@cibse.org

EDITOR

Jill Entwistle jillentwistle@yahoo.com

COMMUNICATIONS

COMMITTEE:

Eliot Horsman MSLL (chair)

James Buck

Iain Carlile FSLL

Jill Entwistle

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 2022 IS 8 JULY

Anyone who has been involved in lighting for a fair number of years would probably agree that getting other people to understand its importance – or even what it involves – has been a bit of an uphill struggle. More than one lighting designer has experienced that sinking feeling at a social occasion when someone has asked what it is they do.

Professionally, of course, it's rather more vital that the essential importance of lighting beyond being able to see stuff is appreciated by design and engineering colleagues, and clients. Architects, engineers, developers, contractors of one stripe or another proved – and in some cases continue to prove – remarkably impervious to persuasion. Low budget priority and spec busting continue to bedevil lighting.

But things have changed over the years and certainly increasingly less proselytising is required. Clients and architects – many of whom were already on board theoretically – have grasped

that it is crucial commercially, aesthetically and for the wellbeing of workplace occupants. And talk of body clocks and biophilia in design circles has further allowed lighting, Trojan-horse-like, to take a more central role.

Incoming president Andrew Bissell was certainly optimistic in his address in May (see p5). 'I feel the time is now right, and the stars have aligned in such a way,' he said, 'that light and lighting can, and will, play a pivotal role in conserving the planet, benefiting society and improving the lives of every individual.'

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 (2006)

SLL Lighting Guide 5: Lighting for Education (2011)

SLL Lighting Guide 6: The Exterior Environment (2016)

SLL Lighting Guide 7: Office Lighting (2015)

SLL Lighting Guide 8: Lighting for Museums and Galleries (2021)

SLL Lighting Guide 9: Lighting for Communal Residential Buildings (2013)

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 (2016)

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)

Guide to Limiting Obtrusive Light (2012)

Code for Lighting (2012)

Commissioning Code L (2018)

SLL Lighting Handbook (2018)

CIBSE TM66: Creating a Circular Economy in the Lighting Industry (2021)

FROM THE SECRETARY

It was a real pleasure to be able to host the SLL AGM, Awards and Presidential Address in-person after two years of online events (see p5) and we look forward to more of the same from now on.

Thank you to those that joined us in the Engine Hall of the People’s History Museum, Manchester, as well as online. It was a great opportunity to thank outgoing president Ruth Kelly Waskett and welcome incoming president Andrew Bissell. And as usual, it was also an occasion to celebrate the SLL award winners and their achievements for the society and industry at large.

The Responsible Outdoor Lighting at Night (ROLAN 2022) online conference took place on 12-13 May. The event had 310 registrations with attendees located in North and South America, Australia and everywhere in between.

The Founding Partners – the International Association of Lighting Designers, International Dark-Sky Association, Illuminating Engineering Society, Illume, Institution of Lighting Professionals, Lighting Industry Association and the SLL – all played an important part in promoting the event, and the feedback on the day was excellent. The sponsors were Thorn Lighting (Diamond), Filix Lighting (Gold), and Selux and GL Optic (Silver). We really appreciated their support. We also thank the many eminent speakers for their contribution on this important and relevant topic.

Final thanks go to our conference partner Karolina Zielinska-Dabkowska who did an amazing job in bringing more than 30 speakers together and delivering a very highquality and informative event. We hope to arrange the recordings from the conference to watch on demand in the near future and will inform everyone when they are available.

The rewrite of SLL LG12: Emergency Lighting was published at the end of April (see Light Lines March/April 2022). The guide has been written not only for use when design work is to be undertaken but also to assist engineers in evaluating existing premises against current standards and legislative requirements. This guide gives information on how to comply with the relevant standards, and produce documentation so that the operator of the building can demonstrate compliance with safety legislation.

• To download LG12: Emergency Lighting, go to: www.cibse.org/knowledge/ knowledge-items/detail?id=a 0q3Y00000KytADQAZecscard. org.uk

• For details about the Sustaining Members programme and the company benefits it involves, go to: www.cibse.org/societyof-light-and-lighting-sll/ sponsorship

• Both the Responsible Lighting at Night (ROLAN) conference and the Trotter Paterson Lecture will be available to view online in the near future

Our thanks go to the lead author of the guide, David Mooney, and the committee, which included Kristina Allison, John Fitzpatrick, Stewart Langdown, Iain Macrae, Sophie Parry, Simon Robinson, Paul Ruffles and Peter Thorns. The publication can be downloaded from the Publications and Guidance section of the SLL website (see box above).

We are pleased to welcome two new supporters to the SLL Sustaining Member programme: Philip Payne and William Sugg and Co. More information about the programme is available from the SLL website (again, see above).

If you were lucky enough to join us at the Trotter Paterson Lecture presented by Professor Jocelyn Bell Burnell DBE FRS, you will know what a special event it was (see p11). Thank you to the Institute of Physics for hosting the event and the SLL events committee for planning and delivering it. A special thanks goes to Peter Phillipson for his work in making this such an incredible occasion, and we hope to share the event online with you in the near future.

EDITORIAL

SECRETARY'S COLUMN NEWS

DARKNESS TO DAYLIGHT

The time is right for lighting to play a pivotal role for both people and the planet, says new SLL president Andrew Bissell

NORTHERN LIGHTS

Members gather in Manchester for the first in-person AGM and Awards in three years

HELIOS AND HEALING

Do we need to change the design of rooms in healthcare facilities?

Maria Englezou, Young Lighter 2021, summarises her winning paper on the topic

STELLAR LINE-UP

Peter Phillipson on the conjunction of the pulsar discoverer Dame Jocelyn Bell Burnell and a member of the band Joy Division for the 2022 Trotter Paterson Lecture

MATERIAL EVIDENCE

Iain Carlile looks at four recent LR&T papers which investigate the impact of materials and MRSE

EVENTS

INDUSTRY BACKS CIRCULAR ECONOMY ASSURANCE SCHEME

Industry leaders have backed a new circular economy assurance scheme set up by CIBSE/SLL and the Lighting Industry Association (LIA). Designed to support the accuracy of circular economy claims from lighting manufacturers and specifiers, the TM66 Circular Economy Assured scheme will provide a quality mark for the design and manufacture of lighting products.

Supporting the recently published TM66 Creating a circular economy in the lighting industry, and accompanying Circular Economy Assessment Methods (CEAM), the scheme forms part of a tool kit for manufacturers and specifiers to assess the circular economy credentials of products.

Published in 2021, the award-winning TM66 Creating a circular economy in the lighting industry was the result of cross-industry collaboration, providing practical guidance and tools to enable the sector to deliver a circular, sustainable approach to lighting and building services engineering more broadly. Major specifiers and organisations have already adopted this metric and the intention is to develop it beyond lighting products, for application in other areas of building services engineering. Manufacturers are already rating their luminaires, while others are seeking help to do so, according to CIBSE.

'Anything that helps to drive greater knowledge of the environmental benefits of a circular economy approach is a positive step forwards,' said David Barnwell, managing director of Holophane Europe. 'The TM66 scheme allows participating manufacturers to demonstrate their sustainability and provides a clear differentiation from unsubstantiated greenwash.'

This scheme combines CIBSE’s sustainability knowledge and UKAS-accredited certification expertise with the LIA’s Quality Assurance systems and independent UKAS-accredited laboratory.

'Our focus is now shifting from energy efficiency in use towards whole life carbon and the life cycle of materials,' said SLL past president Ruth Kelly Waskett. 'TM66 and CEAM have already given us a framework within which to evaluate products and equip us to make the right specification decisions. TM66 Circular Economy Assured takes us one step further.'

Fittingly in the wake of the successful ROLAN conference, the Dutch city of Leiden is the latest to agree to turn all its lights off on one night so that its citizens can see the stars.

The Seeing Stars initiative has been created by social lab Studio Roosegaarde, led by artist and innovator Daan Roosegaarde, with Unesco, and follows a similar experiment in the Dutch city of Franeker.

The event will take place on 25 September as part of the Leiden European City of Science 2022. Roosegaarde hopes to repeat the experiment in other cities, including Sydney, Venice, Stockholm and Reykjavik.

'Every night, there is an amazing light

performance hidden up high in our sky,' said Kathleen Ferrier, chair of the Netherlands Commission for Unesco. 'Seeing Stars brings the stars back to your own street.'

www.seeingstarsleiden.nl

www.studioroosegaarde.net/ project/seeing-stars

BLUE LIGHT AT THE END OF THE TUNNEL

Researchers at the Technical University of Munich (TUM) and the University of Turin have created electrochemical cells from copper complexes that emit effective blue and white light.

Light-emitting electrochemical cells (LECs) are the simplest and least expensive thin-film lighting devices to date, say the researchers. A single active layer, they are used as electroluminescent inks and stickers.

As with the development of LEDs as white light sources, the goal has been to first produce blue light.

'The development of inexpensive devices that emit white and blue light is highly desired and holds many benefits,' explained Rubén D Costa, professor of biogenic functional materials at TUM.

'However, the previous lack of blue emitters has hindered the transition from the laboratory to the real market. Accordingly, the creation of blue emitters is a general milestone in thin-film lighting.'

After extensive data evaluation of various known approaches, a new design emerged for blue LECs which provide excellent performance compared to devices with conventional emitters.

'With the new high-performance blue LECs, copper(l) based single-layer white LECs with high quality white light and a CRI of 90 can be realised,' said Professor Claudia Barolo of Turin University. Read the paper at: https://onlinelibrary. wiley.com/doi/10.1002/adma.202109228

NEW START DATE FOR LET

The start date for the next LET Diploma in Lighting Design course has been moved to September, following requests that the timing should reflect the regular academic year. The number of students at each intake is limited to 25.

https://lightingeducationtrust.org/diploma/ about-the-course.html

DARKNESS TO DAYLIGHT

The time is right for lighting to play a pivotal role for both people and the planet, says new SLL president Andrew Bissell

Throughout his career lighting design has played much less of a role within the built environment than it should have, said incoming SLL president Andrew Bissell in his presidential address. The reasons have been numerous, he said, from a failure to use an experienced lighting designer and a focus on energy targets to the exclusion of other factors, through to 'other certification systems that drove the solution away from the optimum and indeed what is possible'.

However, continued Bissell, this situation is now changing. 'I feel the time is now right, and the stars have aligned in such a way, that light and lighting can, and will, play a pivotal role in conserving the planet, benefiting society and improving the lives of every individual.'

Bissell cited examples of the progress in knowledge, research and awareness that was leading to a better universal understanding of how lighting – and its absence – can contribute to both human and planetary wellbeing, beginning with the importance of daylighting.

'There is an ever-growing library of evidence to show the benefits of daylight and in particular, when it is managed, to deliver the light our circadian system needs.' Over the past few years, he observed, people have experienced long periods of working from home where generally they had better access to daylight, better quality views and the type of blind they wanted rather than what the building operator wanted them to have. 'Most of us chose our own lighting at home and also chose when to use it, even preferring to work in lower lighting levels if it meant we were lighting our spaces with daylight,' he said.

Coupled to having access to light, continued Bissell, was appreciating the benefits to ourselves and the planet's ecosystem of limiting the light we use at night, and in particular being careful about when and where it is used. He commended the SLL's new document, LG21 Protecting the Night-time Environment, written by Liz Peck. 'This is also a passion of my own and we will be adding to LG21 in the next 12 to 18 months to take forward significant change on how we light at night.'

Sitting between delivering daylight and darkness are the products we use, and E

the importance of the circular economy, he said, pointing out that we were highly fortunate to have the 'world-leading' TM66 Creating a circular economy in the lighting industry, a document written by Bob Bohannon and Kristina Allison. 'The TM66 CE Assured independent accreditation initiative is being taken forward by CIBSE, the SLL and the LIA,' he said.

A further positive development was client awareness, he said. 'They have embraced net zero carbon and are ready to listen to genuine solutions which take them towards, and hopefully beyond, net zero. Again, lighting delivered by competent lighting designers will make the difference.'

In fact, whether the issue was daylighting, localised lighting, views, personal control, repairable products, ultra-low lighting solutions or the safeguarding of darkness, said Bissell, the expertise of lighting designers was key. 'As lighters we have the knowledge, ability, products and passion for design which can improve people's lives.'

'How do we make this happen?' he asked. He advocated following the lead set by TM66, BSEN 12464-1 and LG5 Lighting for Education. When SLL lighting guides were written or updated, it was important to provide a safe approach, but also to provide and promote a more ambitious and more beneficial approach, he said.

'The SLL already provides a forum for open discussion to push boundaries and highlight issues. To do this we need to empower the lighting guide authors and reviewers to be bold and brave, to challenge the ordinary and demand the optimum.'

While making step changes, and doing so more quickly, it was important to bring the next generation of lighters into the society, he said, 'so that the baton can be handed over and the society can remain relevant, ambitious and ready for the next chapter in its history. This needs careful management but is an incredibly exciting prospect.'

Summary of aims

• The pace of change in our industry is faster than it has ever been. I want to explore ways of ensuring that clients and our built-environment colleagues understand the depth of knowledge lighters have and that we are key to the design and construction process. One of the strengths of TM66 is that we engaged with end users, other professional bodies and clients. This same approach could also be used in many other SLL TMs, guides and Fact Files

• We need to bring the next generation of lighters into the society so that it remains relevant, ambitious and ready for the next chapter in its history. I want to explore how we make it more appealing, comfortable and desirable for the younger generation to take that first step towards the running of the SLL

• We have collected together a diverse group of people to enhance LG21: Protecting the Night-time Environment. The aim is to add advice and the principles of solutions to the guide so that we move towards delivering pristine skies in both city and urban environments

Andrew Bissell has spent more than 15 years as director of Light4 at Cundall, and has just joined property and construction consultant Ridge as a partner. He started his working life as an apprentice electrician 'and by chance found myself installing a lot of light fittings'. Thorn Pop Packs, Philips floodlights, Staff track lights among others. 'I found myself asking a lot of questions about the colour difference of the lamps among other things, but even then I still didn’t know lighting was a career.'

A college lecturer suggested that with the recession of the 1990s looming that he should go to university 'and ride it out while also doing some learning'. He began studying engineering at the University of Manchester Institute of Science and Technology (UMIST).

On graduating he got job at a large consulting engineering company. 'What stood out in their brochure was their openness to new ideas, the desire to explore, challenge the norm and push the boundaries of technology and materials. As a society I believe we have a responsibility to also do that while having the appropriate measure of checks and balances.'

One of his first projects was a museum in Bradford. 'I was lucky in that the senior engineer had me complete all of the lighting calculations, collect the lighting data and produce the drawings (on tracing paper). For the first time I felt this was something I wanted to be involved with as a career.'

Bissell read widely and enthusiatically. 'For every document I read on the office microfiche system, there were five more references at the end I wanted to follow up on. Thanks have to go to all of the authors of the SLL and CIBSE guides at that time and the many papers from LR&T.'

He also emphasises the importance of the support and help of lighting companies in his early years, and the many talks and events at the time, notably Love Light. 'What all this highlights is how as an industry we are willing to share knowledge, help one another and therefore how many people there are to thank for all of the learning we do.'

While interested in the SLL for many years, he recalls 'looking at the wealth of talent and knowledge of the people who were on the committees and council and thinking I am a million miles away from knowing what they know, and therefore I kept my distance'. Prompted by former president Liz Peck, he finally joined in 2015. 'Looking back I wish I had found a way to be more involved sooner and if there is anything I can do to help others make that choice I would be delighted to help.'

The AGM took place on 26 May at the People's History Museum in Manchester, breaking the tradition to hold the event in London

NORTHERN LIGHTS

Members gather at Manchester's People's History Museum for the first in-person AGM and Awards in three years

The 2022 SLL Presidential Address, AGM and Awards was the first to be held face-to-face in three years, a development that was clearly welcomed by participants. It was also notable for being held outside London, taking place on 26 May in the Engine Hall of the People’s History Museum, Manchester, as well as streaming live online.

The three major awards acknowledged the contributions of individuals representing three spheres of lighting: professional lighting design, manufacturing and academia.

David Mooney (pictured top right), associate at Atkins, received the Lighting Award for his outstanding service to the society. A representative of the CIBSE South/ West region and regular conference speaker, he sits on the technical and publications committee, most recently leading and authoring LG12 on emergency lighting.

With a degree in building services engineering, he began specialising in lighting design after he joined BDP in 1985. ‘Even as a young electrical engineer, it was clear he was destined to become a lighting designer of considerable technical skills and imaginative talents,' said former colleague Barrie Wilde. He has 'an unquenchable passion for getting lighting right, down to the last detail,' said his Atkins colleague Matthew Beard. 'For David, lighting perfection is a minimum requirement.' 'David is a joy to work with and the industry is lucky to have benefited from his

passion in lighting throughout his career,' said Kristina Allison who gave the citation.

Peter Hunt (top left), recently retired COO of the LIA, was given an Honorary Fellowship, in recognition not only of services to the SLL but the significant contribution he has made to the wider lighting profession.

Passionate about product design, he became managing director of family business David Hunt Lighting. The company joined the Lighting Association in 1979 and Peter joined the council in 1987, eventually becoming president in 1992.

He became joint CEO of the LA in 2008 and in 2012 he oversaw the merger of the Lighting Association with the Lighting Industry Federation. In the same year he helped forge the merger of CELMA – the group of European lighting associations – with ELC, the European lamp manufacturers' group, to create Lighting Europe of which he became president in 2016.

'Peter Hunt’s work has been behind the scenes, hidden, not on our radar. But for others, especially those in manufacturing, the decades of his work have been invaluable and important,' said Bob Bohannon in his citation. 'When you specify a luminaire or buy a light for your child’s bedroom, you can thank him for helping create some of the institutions that ensure you are safe.'

Recognising a significant and lifetime contribution to lighting, the president's medal was awarded to Peter Raynham (top centre),

currently professor of the lit environment at UCL. He studied chemical physics at Sussex University, going on to work at Osram before joining Philips in 1978. After 22 years there in a number of technical roles, he joined UCL as a research fellow, moving on to become a senior lecturer.

He was SLL president in 2011, and until recently was the principal author of the Code for Lighting. A seasoned speaker, he has also led many research studies and contributed to numerous committees, the CIE among them, especially on standards.

'His ability to come up with simple practical solutions to complex problems is recognised internationally,' said Jemima Unwin Teji in her citation. 'Not only students and staff at UCL who go to him for advice, but also CEN (European standards) and ISO (world standards) turn to him for his ability to break up complex problems into manageable bitesize portions which can be addressed.'

The SLL's Regional Award was given to lighting designer Bonnie Brooks, director of Lighting Bee and representative of the CIBSE/ SLL South West region.

The Leon Gaster award for the best paper concerned with lighting applications went to Christopher Kyba, Andreas Ruby, Helga Kuechly, Bruce Kinzey, Naomi Miller, Jessie Sanders, John Barentine, Ralph Kleinodt and Brian Espey. Their paper – Direct measurement of the contribution of street lighting to satellite observations of night-time light emissions from urban areas – can be found in LR&T 2021;53(3):189-211.

The Walsh Weston award for the best paper covering more fundamental lighting matters was given to Ayesha Batool, Peter Rutherford, Paul McGraw, Timothy Ledgeway and Sergio Altomonte for their paper, View preference in urban environments (LR&T 2021; 53[7]: 613-636).

HELIOS AND HEALING

Do we need to change the design of rooms in healthcare facilities?

Maria Englezou, SLL Young Lighter 2021, summarises her winning paper

Many people in different disciplines have researched light, but how can we fully appreciate that something we cannot truly see is the source of life?

In his book, The Healing Sun, Richard Hobday asserts that 'in the right hands, sunlight is a medicine'. In the 1930s, diseases such as tuberculosis and rickets were believed to be prevented and even cured by exposing the patient to sunlight. Florence Nightingale contends in 1863 that direct sunlight, not only daylight, can help to speed up the recovery of patients in hospitals.

More recently, a study by Bauschemin and Hays (1996) indicated that patients in sunny rooms had a reduced length of stay compared to patients staying in dull rooms. Benedetti et al (2000) addressed the importance of timing by focusing on the impact of morning and afternoon sunlight exposure. Their study showed that patients in east-facing rooms (morning sunlight exposure) stayed around three days less than patients in west-facing rooms.

Another important study carried out by Walch et al (2005) researched the impact of sunlight on the psychological health of patients and the medication used after surgery. They suggested that patients in bright rooms (increased intensity of sunlight) experienced less perceived stress and less pain; they took less analgesic medication, therefore reducing medication costs. Sunlight exposure can have an impact on people, but how does that happen?

In the 21st century, people

are spending around 90 per cent of their time in indoor environments. Because of that, there is an increased interest in studying how buildings affect human physiology and psychology. A large part of that research focuses on how daylight and sunlight exposure affect mammals' circadian rhythm since light is the main 'zeitgeber'.

Two decades ago, it was discovered that the mammalian retina has the so-called intrinsically photosensitive retinal ganglion cells (ipRGCs) which are directly connected to the suprachiasmatic nuclei (SCN), the central 'circadian clock'. The ipRGCs contain the photopigment 'melanopsin' which is spectrally sensitive to the shortwavelength part of the visible spectrum. Based on this knowledge, new metrics were developed to allow architects and lighting designers to research the non-visual effects

'It is widely accepted that humans need bright days and dark nights'

of lighting. The CIE S 026:2018 standard proposes using α-opic metrics for the rods, each type of cone, and the ipGRCs.

Many studies in neuroscience focused on finding correlations between light exposure and melatonin response, pupil constriction, and circadian phase shifts. It is widely accepted that humans need bright days and dark nights. Brown et al (2020) have proposed recommendations for providing proper light at the proper time. More specifically, based on the metrics proposed by the CIE, they recommend having a melanopic EDI of at least 250 lux throughout the day. For evening hours, the recommendation is to have a melanopic EDI of 10 lux for at least three hours before bedtime and a melanopic EDI of no more than 1 lux during the sleeping period. Moreover, the certification scheme WELL Building Standard proposes guidelines for circadian lighting for daylight and electric lighting. The standard mentions that lighting could impact the endocrine, muscular, nervous, cardiovascular, digestive, immune, reproductive and skeletal systems.

When studying the nonvisual effects of lighting in

p Patient placement in a double room and the three gaze directions

p Me lanopic DER and EDI results for both locations, with three window-to-wall ratios, eight orientations, patient placements and gaze directions

indoor spaces, it is essential to evaluate environmental factors such as the location, weather conditions, timing during the day, and seasonality. For an interior space, the orientation, window size, geometry of the space, and the spectral reflectance of surfaces play a significant role. Other essential parameters are based on the light source, such as intensity, spectral

properties, and duration of exposure. Finally, person-related parameters are the chronotype, eye photosensitivities, age, and photic history of a person.

To this day, daylight assessments for buildings focus on using static and dynamic metrics to understand how building parameters affect indoor lighting levels. The main scope is to find ways to increase acceptable lighting levels while reducing the effect of glare and the use of electric lighting. This paper focused on investigating various parameters using climate-based daylight metrics and the CIE S 026 melanopic metrics. The main question was whether there are any intersections between those metrics, and if we can find ways to provide optimum design strategies without compromising each other.

The study evaluated natural lighting performance in a typical hospital patient room (3.5m x 5.5m), with three windowto-wall ratios (W1: 23 per cent, W2: 34 per cent, W3: 68 per cent), and eight orientations (south, north, east, west, south-east, south-west, north-east, northwest). In addition, the analysis included an investigation of two locations: Brussels, Belgium (lat 50.85 degrees N, long 4.36 degrees E) and Paralimni, Cyprus (lat 35.05 degrees N, long 33.99 degrees E).

Computer simulations were carried out using climate-based daylight metrics for the visual effects and CIE S 026 melanopic metrics for the non-visual effects. The climate-based daylight metrics used are the Useful Daylight Illuminance (UDI) in four categories, the Spatial Daylight Autonomy (sDA), and the Annual Sunlight Exposure

(ASE). To assess non-visual effects, the melanopic DER and melanopic EDI metrics were used.

Since the simulation for the melanopic metrics is static, the research included the investigation of clear and overcast skies, three seasons (March, June, December) and five timings during each day (7:00, 9:00, 12:00, 15:00, 17:00). Moreover, the evaluation included four patient positions in the double room and, for each position, three vertical gaze directions at the height of 1.3m, the height of a sitting person's eyes on a hospital bed. The software used was Climate Studio version 1.7.8 and ALFA version 0.5.7, both implemented in Rhinoceros 7.

'A study in 2000 showed that patients in east-facing rooms stayed around three days less than patients in westfacing rooms'

p Four categories of useful daylight illuminance (UDI) for Brussels and Paralimni, the three window-to-wall ratios and eight orientations

EOverall, the results for UDI show that Brussels and Paralimni have more than 58 per cent for the category UDI 3003000 lux for all the cases presented. The fluctuations in this category are due to the orientation of the room. For example, the north orientation in Brussels for W1 has 58 per cent UDI 300- 3000 lux, while the south orientation has 63 per cent. On the other hand, when the window-to-wall ratio is bigger, such as W3, the north orientation has 76 per cent UDI 300-3000 lux while the south orientation has 58 per cent. This is because when the window-to-wall ratio is small, the north orientation has more room area with illuminance levels of less than 300 lux, meaning that electric lighting is needed.

By comparison, with a higher windowto-wall ratio, the south orientation is more susceptible to direct sunlight; hence the larger area near the window will have more than 3000 lux. Finally, it should be noted that the hours analysed are only the hours from sunrise until sunset for each location, a total of 4373 hours for Paralimni and 4388 for Brussels.

The results for melanopic DER and melanopic EDI show (with a red dashed line) the equivalent melanopic DER for the CIE standard illuminant D65 with a CCT of 6500K, and (with a grey dashed line) the minimum recommendation for a proper

light during the daytime for comparison purposes (see graph previous page).

It is clear that there is a great variability for occasions with a clear sky with a melanopic DER ranging from 0.45 up to 1.22 and a melanopic EDI ranging from 10 lux up to 40,000 lux depending on the time of the day, orientation, and more. On the other hand, the cases with an overcast sky have a melanopic DER ranging from 0.8 up to 1.0 and melanopic EDI from 50 lux up to 10,000 lux.

When looking at the data for Paralimni for each orientation and window size, there is mainly a difference in melanopic EDI. The window-to-wall ratio only affects south, south-west and south-east orientations, which have direct sunlight exposure. However, all the occasions with direct sunlight exposure seem to have a melanopic DER less than 1.0.

In conclusion, it is impossible to directly correlate the climate-based and melanopic metrics to find the best optimisation techniques for improved visual and nonvisual effects. However, this study shows that a comprehensive investigation of all those metrics can provide insights for achieving good results for visual and nonvisual effects on patients.

To see the YL final, go to: www. youtube.com/watch?v=aPOBsn5lt-A

Insights from the study:

• Building parameters such as window size significantly affect interior lighting levels

• Orientation and timing (season, time of day) are the most critical parameters since these are related to the sun's position

• Direct exposure to sunlight increases the melanopic EDI (intensity) but at the same time reduces the melanopic DER (spectrum)

• The north, north-east and north-west orientations seem to have better results than the other orientations for visual and non-visual effects

• Based on the findings, we can try different design options to provide the optimum quality and quantity of natural lighting for patients. In addition, more attention should be given to the needs of patients when designing healthcare facilities

STELLAR LINE-UP

Peter Phillipson on the science-meets-art image that inspired the conjunction of the pulsar discoverer Dame Jocelyn Bell Burnell and a member of the band Joy Division for the 2022 Trotter Paterson Lecture

The Society of Light and Lighting is self-evidently concerned with the applications of light. However, lighting is a fluid and multifaceted field, and the SLL has always been concerned to demonstrate a broad vision and definition of lighting, to examine what has been discovered using light itself, for example, or exploring other aspects of the electromagnetic spectrum.

The idea for the 2022 Trotter Paterson Lecture started in 1997 when I went to see, what was to me at the time, one of the most well-researched art exhibitions that I had ever been to. It was held at the National Gallery in London and entitled Seurat and the Bathers. Always at exhibitions, I read avidly all the captions and notes, and what impressed me deeply was how much detail had been

'Crucially the front cover had no words on it, only the image. Its impact has been far reaching and the image has become iconic'

discovered as to how Georges Seurat had come to paint Bathers at Asnières in 1884. It is a very agreeable painting and can be appreciated purely as just that, a beautiful, well-executed aesthetic masterpiece, but this insight into his artistic approach was enlightening on another level.

In his all-too-brief lifetime Seurat

experimented with different techniques. He was fascinated by colour perception, and studied the works of James Clark Maxwell whose three-colour theory of how we perceive colour using three receptors in the eye intrigued him. He studied the works of French chemist Eugene Chevreul and German physicist and physician Hermann von Helmholtz, both multifaceted scientists, along with the theories of US physicist Ogden Rood whose book, Modern Chromatics, had a profound effect on Seurat.

From these influences he developed his pointillism or chromoluminarism technique where small dots or fine strokes

© National Gallery

Previous page: image from Unknown Pleasures by Joy Division Above: Bathers at Asnières (1884) by Georges Seurat

An alogue and digital equipment used at Arecibo Observatory

of differing colours, often complementary colours, are painted very closely together and consequently, from a distance, blend and can invoke completely different colours in the eye-brain mechanism. Thus, it is a science-meets-art image.

What does this have to do with the lecture? The story goes even further back to 1967, when Jocelyn Bell Burnell made an original discovery, observed as a pen recorder trace when she was a postgraduate student. She had been looking for quasars, but noticed the most subtle pulse of data with an exact periodicity of 1.33730 seconds among miles of recorded data. Was it a signal from an extra-terrestrial being or interference from a manmade device here on Earth? What she had in fact discovered was the first known pulsar, CP1919: she had identified a new type of star.

The results were published in scientific journals, along with other pulsars she had discovered. In science, it is always compelling when other scientists verify

CP 1919 Image In HDC Thesis (1970)

findings by repeating experiments using different apparatus in different institutions. In the late 1960s and early 1970s, Dr Harold D Craft at the Arecibo Observatory, Puerta Rico, measured the same pulsar many times producing traces not using a pen-recorder, but with (recently invented) digital equipment. The periodicity of the signals was exactly as had been measured initially in Cambridge.

He worked out a method to place the results one above the other, producing a stacked image. His findings were also published in journals including the Cambridge Encyclopaedia of Astronomy.

Several years later, in 1979, the Manchester band Joy Division was recording its first full album entitled Unknown Pleasures. The band's guitarist/ keyboardist, Bernard Sumner, saw the stacked image of the pulsar in a copy of the encyclopaedia in the library and suggested to Peter Saville, art director and co-founder of Factory Records, that it was adapted to be used as their cover art.

Crucially the front cover had no words on it, only the image. Its impact has been far reaching and the image has become iconic.

I asked Dame Jocelyn whether, after her talk, we could convey the story of the image through a live meeting of four diverse and remarkable people – Dr Harold D Craft, Peter Saville, Joy Division

A Pulsar

– from pulsating radio source –is a highly magnetised rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Earth, and is responsible for the pulsed appearance of emission.

– Wikipedia

Used with kind permission of Dr Harold D Craft Jr

Left: or iginal artwork for Joy Division's album Unknown Pleasures. Right: CP1919 taken from Harold D Craft's 1970 thesis

Events: Trotter Paterson Lecture

drummer Stephen Morris, and herself –brought together for a discussion about the unique science-meets-art image. She was not only receptive to the idea but enthusiastic.

Her talk, Flashes and Bangs from the Sky, was not about pulsars but the most up-todate cutting-edge research in astronomy, a cosmic round-up of phenomena that have been discovered only in the past 15 years or so. These included tidal disruption events, where recent detection techniques have shown rare evidence that super massive black holes can tear apart stars in their vicinity, and fast radio bursts which, here on Earth, are very weak as they have travelled so far. Having regular pulses of energy (around a fraction of a millisecond in length to a few milliseconds), they are incredibly powerful and are not fully understood, but might be produced by rotating neutron stars. She also described up-to-date research on super novae.

Following Dame Jocelyn's lecture, Dr Harold D Craft, Peter Saville and Stephen Morris were all present to discuss the provenance of this truly iconic sciencemeets-art image in an informative, amusing and entertaining discourse.

Wouldn’t it have been fascinating if Seurat, Chevreul, Maxwell and Helmholtz could have been put in the same room to discuss these cross-over influences on colour perception? Sadly nobody thought of it back in the 19th century.

The 2022 Trotter Paterson Lecture took place on 18 April at The Institute of Physics (IOP) in Caledonian Road, London. Later this year there will be an opportunity to see both the lecture in full and what followed afterwards as a live stream of the event

See also https://www.cam.ac.uk/stories/ journeysofdiscovery-pulsars

ABOUT THE TROTTER PATERSON LECTURE

The lecture was founded in 1951 as a biennial event to commemorate two distinguished past presidents of the Illuminating Engineering Society, Alexander Trotter (president 1917-1920) and Sir Clifford Paterson (1928). Both were founding members of the SLL in 1909 when Paterson was in charge of the Electrotechnical and Photometrical Department of the National Physical Laboratory and Trotter was electrical adviser to the Board of Trade

The Trotter Paterson

2022 participants

Dame Jocelyn Bell Burnell CBE FRS was a postgraduate working at the Mullard Radio Astronomy Observatory in Cambridge when she discovered the first known radio pulsar in 1967. Having obtained her PhD in Cambridge in 1969, between 1968 and 1973 she worked at the University of Southampton, and then at University College London from 1974 to 1982 as a tutor, examiner and lecturer at the Open University. She became the project manager at the James Clark Maxwell Telescope in Hawaii.

She has been visiting professor at Princeton University and president of the Royal Astronomical Society between 2002 and 2004. She is currently visiting professor of Astrophysics at the University of Oxford. She has continued to study the sky in almost every part of the electromagnetic spectrum.

In 2018 she was awarded the Special Breakthrough Prize for Fundamental Physics but chose, generously, to give the entire $3m (around £2.5m) prize money to fund women and under-represented ethnic minority and refugee students to become physics researchers.

In 2021 she was the winner of the Royal Society’s prestigious Copley Medal for her discovery of pulsars: it is the world’s oldest scientific prize. Past winners include Charles Darwin, Dorothy Hodgkin and Albert Einstein.

Dr Harold D Craft gained a BEE in electrical engineering at Cornell University in 1961 and an MEE at New York University in 1963. His PhD in radio astronomy, astrophysics and communications theory at Cornell featured the now celebrated stacked image. He is currently vice president emeritus, Cornell University.

Stephen Morris is a drummer, who also plays keyboard and synthesizer, and who is best known for his work with the rock band Joy Division and subsequently New Order.

Peter Saville CBE is an art director and graphic designer. He came to prominence for the many record sleeves he designed for Factory Records, which he co-founded in 1978 alongside Tony Wilson and Alan Erasmus.

Robert Barker (Cornell University)

University of Dundee

Wolfgang Stahr

MATERIAL EVIDENCE

Iain Carlile looks at four recent Lighting Research and Technology papers which investigate the impact of materials and the proposed metric MRSE

The complex interactions between materials and illuminants, and the effect this has on the chromatic properties of inter-reflected light within a space, have been investigated by Yu et al. Examining materials which scatter light in a diffuse manner, it was found that the spectral properties vary as a function of the number of inter-reflections made.

Using a computational model, the spectral variations of the inter-reflected light were found to be systematic, corresponding with changes in brightness, saturation and hue. The computational model was tested and confirmed using computer renderings and cubic spectral illuminance measurements using two differently furnished mock-up rooms and with two different illuminants.

Also looking at how materials can affect the spectral composition of light, Villalba et al have studied the effect of woven fabric window shades on daylight experience in interior spaces. An analysis of horizontal illuminance and CCT was performed in a

daylit laboratory, examining the impact of the physical parameters of the woven fabric shades, such as fabric colour and opennessfactor (OF). Eleven different fabrics with different colours (white, grey and black) and varying OF were analysed.

It was found that the OF had most impact on illuminance values, with a larger OF value resulting in higher illuminances, and that the fabric colour impacted on the CCT with white and grey fabrics resulting in a lower CCT value than black fabrics.

Durante and Kelly have looked at lighting in an office space in relation to the Mean Room Surface Exitance (MRSE) metric.

MRSE is a proposed metric that focuses on ambient and target illumination. Using a test room furnished as an office, the experiment investigated the results of a previous study which showed that a linear relationship existed between Perceived Adequacy of Illumination (PAI) and MRSE.

It was found that the relationship diverges from linear when the scale of MRSE values

The (a) first and (b) second of a series of (inter-)reflections of colours plotted in the BGR coordinates under equal energy white lighting (Yu et al)

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)

Effects of inter-reflections on the chromatic structure of the light field

C Yu, E Eisemann and S Pont

The impact of woven shade fabrics on correlated colour temperature and illuminance with daylighting

A Villalba, J Yam´ın Garretón and A Pattini

Investigating mean room surface exitance values for office lighting

Durante and Kelly

A practical method for field measurement of mean room surface exitance

P Zhang, M Li, Y Huang and Q Dai

exceeds 100lm/sqm. The study also showed a relationship between spatial brightness and MRSE for MRSE values below 1400lm/sqm. The authors note that these findings provide a tentative range of MRSE values that may be suitable for use in an office environment.

Meanwhile Zhang et al suggest a novel method to measure MRSE in a rectangular cuboid space by using an illuminance meter at defined locations to measure the indirect light. Taking a weighted average of these values results in a value of MRSE. The weighting parameters used depend on the geometry of the space. The experimental values were verified using Radiance lighting simulation software showing an error of less than 10 per cent. From the results the authors conclude that it is possible to take measurements of MRSE in the field.

Iain Carlile, FSLL, is a past president of the SLL and a senior associate at dpa lighting consultants

Events 2022

For details of all upcoming webinars, go to: www.cibse.org/society-oflight-and-lighting-sll/sll-events/upcoming-webinars-and-online-content

For previously recorded CPD webinars (including regional webinars), go to: www.cibse.org/society-of-light-and-lighting-sll/sll-events/pastpresentations

EVENTS

IALD ENLIGHTEN AMERICAS

Date: 29 September-1 October

Venue: Westin Mission Hills Resort, Rancho Mirage, California www.iald.org

LIGHT + BUILDING 2022

Date: 2-6 October

Venue: Messe Frankfurt www.light-building.com

READY STEADY LIGHT (SLL)

Date: 18 October

Venue: Rose Bruford College, Sidcup www.sll.org.uk

LIGHT MIDDLE EAST 2022 (MESSE FRANKFURT MIDDLE EAST)

Date: 21-23 November

Venue: Dubai World Trade Centre www.lightme.net

AVAILABLE WEBINARS INCLUDE FINDING DARKNESS WITHIN THE LIGHT: THE ROLE OF RESPONSIBLE OUTDOOR LIGHTING DESIGN IN CONFRONTING THE GLOBAL LOSS OF THE NIGHT

(SLL & CIBSE East Midlands webinar)

Speaker: Dr John Barentine, astronomer, author and founder/ principal consultant of Dark Sky Consulting.

John Barentine reviews recent advances in our understanding of the causes and consequences of light pollution. He suggests that now is the time for a movement in outdoor lighting design that prioritises light pollution reduction as a core element

LIGHTING FOR 2050: NET ZERO CARBON (SLL & CIBSE Ireland webinar)

Speaker: Sophie Parry FSLL

Sophie Parry looks at approaches to lighting application with low carbon outcomes. Topics explored include considerations for luminaire specification, luminaire manufacturer credentials, Environmental Product Declarations (EPDs) and lighting energy vs lighting quality – getting the balance right