Light Lines July/August

The Society of Light and Lighting

LIGHT LINES

VOLUME 14 ISSUE 4 JULY/AUGUST 2021

WELL AWARE Enlightening the public

NON-VISUAL LIGHT The expert consensus

Editorial

July/August 2021

FROM THE EDITOR SECRETARY Brendan Keely FSLL bkeely@cibse.org SLL COMMUNICATIONS MANAGER Juliet Rennie Tel: 020 8772 3685 jrennie@cibse.org EDITOR Jill Entwistle jillentwistle@yahoo.com COMMUNICATIONS COMMITTEE: Linda Salamoun MSLL (chair) James Buck Iain Carlile FSLL Jill Entwistle Chris Fordham MSLL Rebecca Hodge Eliot Horsman MSLL Stewart Langdown FSLL Luke Locke-Wheaton Rory Marples 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 2021 IS 9 JULY PUBLISHED BY The Society of Light and Lighting 222 Balham High Road London SW12 9BS www.sll.org.uk ISSN 2632-2838 © 2021 THE SOCIETY OF LIGHT AND LIGHTING The Society of Light and Lighting is part of the Chartered Institution of Building Services Engineers, 222 Balham High Road, London SW12 9BS. Charity registration no 278104

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Conveying health messages to the public has never been easy. Aside from the fact that you can't legislate for idiocy and boggling irrationality (witness the Covid deniers and the anti-vaxers convinced of conspiratorial microchipping), even telling sensible people that the things they like are bad for them is problematic.

If it's difficult to get people to eat more greens and less Green and Black's, then explaining the complexities of blue light before bedtime or the niceties of daylight deprivation is something of a challenge. Light, as we know, is complicated and there is a danger of a four-legs-good, two-legs-bad reductiveness, a need for a balance between the simple and the simplistic.

It is a challenge that new SLL president Ruth Kelly Waskett acknowledged in her presidential address (see p5), but one which is vital to address, she said.

'Our understanding of the role of light in human health has grown significantly

over the past 10 years alone, and we have now reached a point where we can make recommendations about what light people need, and when, in order to stay healthy,' she contended. A point confirmed by the recent release of a paper from international experts outlining recommended exposure levels for non-visual light (Measured response, p7).

Crucially, however, the SLL must take the lead in promoting the message, she said. 'As the foremost source of lighting knowledge, we need to be at the forefront of this, not running to keep up.'

As she pointed out, if not the SLL, then who?

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 (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 (2015) 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 Design Guide (2015) 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) Guide to Limiting Obtrusive Light (2012) Code for Lighting (2012) Commissioning Code L (2018) SLL Lighting Handbook (2018)

sll.org.uk

Secretary’s column/Contents

July/August 2021

Contents

FROM THE SECRETARY

Twitter: @sll100

• Ruth Kelly Waskett's

presidential address and the awards: www.cibse.org/newsand-policy/may-2021/unitedby-light,-new-sll-presidentcalls-for-incre • Jeevun Grewal, Jean Heap Bursary video: www.cibse.org/ society-of-light-and-lightingsll/education/the-jean-heapbursary • For more details of Lighting Research and Technology: https://journals.sagepub.com/ home/lrt issue aims to support their work by clarifying the publication process and by making an explicit effort to ensure particularly constructive feedback to authors.

We will also host the presentation of the best papers via a webinar and details of this will be confirmed in due course. We thank Dr Kynthia Chamilothori, assistant professor at Eindhoven University of Technology, and Dr Eleonora Brembilla, assistant professor at Delft University of Technology, for organising this initiative.

I am pleased to confirm that we have received many entries for the SLL Young Lighter 2021 competition. These are now with the Young Lighter review panel and soon we hope to announce the entrants who will move forward to the second round of the competition. This year the Young Lighter final will be hosted via an SLL webinar.

Finally, congratulations to Juliet Rennie.

Since joining the SLL seven years ago as SLL coordinator, Juliet has expanded her original role to the point where her job description no longer reflected her day-to-day activity.

We are therefore delighted to report that she now has the well-deserved new title of SLL communications manager.

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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LEADING LIGHT The SLL must spearhead the message about the relationship between light, health and wellbeing, says new president Ruth Kelly Waskett

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MEASURED RESPONSE The expert consensus on the recommended exposure levels for non-visual light

11 THE ROAD LESS TRAVELLED

Juliet Rennie examines what research has to say about how lighting affects perceptions after dark

14 COME TO TERMS

John O’Hagan reports on the CIE's recent activities including the latest edition of the International Lighting Vocabulary

15 STREET WISE

Iain Carlile looks at three recent LR&T papers focusing on street lighting and human health

16 EVENTS COVER: Apple Store Fifth Avenue, New York, by Foster + Partners. Retail Project of the Year; Integration Project of the Year, and highly commended in Daylight Project of the Year at the 2020/21 Lighting Design Awards

© Aaron Hargreaves/Foster + Partners

Thank you to everyone who joined us back in May at the SLL AGM, Awards and Presidential Address. The event allowed us to say thank you to Bob Bohannon, the immediate SLL past president, who had an incredibly busy year in office. We also welcomed the new president, Ruth Kelly Waskett, whom we look forward to working with. Her presidential address (see p5) and the awards can be viewed on the website (see box).

Congratulations go to Jeevun Grewal, the recipient of the Jean Heap Bursary 2021. Jeevun is currently a masters student at the University of Oxford. He will receive £4000 (payable in four instalments) in funding for his research, which centres on non-visual responses to light, specifically wellbeing and sleep/wake cycles. We look forward to posting updates from his research in due course. (See box for the link to Jeevun’s video entry.)

Once more we were unable to stage Ready Steady Light this year but we have still given people the opportunity to be creative with light. Launched by the SLL on the International Day of Light and hosted from 16-28 May, the first OurLight event was a brand-new social media initiative. The theme of this edition was film, and encouraged people to create scenes and celebrate the art and science of light using what they have around the home. They then posted images of their light scenes to Instagram and/or Twitter.

We had a great deal of fun with the event and some amazing images were created.

Prior to the summer we put a call out for papers for a Lighting Research and Technology special issue. This will focus on early-career researchers in lighting.

Lighting research – and that published in scientific journals – encompasses a variety of different topics, ranging from advancements in lighting technology and measurement, to human responses to light and lighting.

Original research across this wide range of topics is published and shared with the lighting community after a rigorous peerreview process. This can be daunting, especially for early-career researchers with limited experience in publishing their work in a scientific journal. This special

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News

July/August 2021

THE LATEST NEWS AND STORIES

SLL HONOURS THREE LEADING LIGHTERS AT 2021 AGM

John Aston, Florence Lam and Geoff Cook were this year's recipients of the highest accolades from the SLL, presented with the Lighting Award, the President's Medal and an Honorary Fellowship respectively at the 20 May 2021 online AGM. SLL president from 2014-15 and current chair of the membership committee, John Aston began his career in lighting in 1979 with Energy Conservation Systems (ECS), eventually acquired by Philips. His expertise in control systems has led him to contribute widely to the SLL and other organisations, including advising The Office of the Deputy Prime Minister (now DCLG) on Part L of the Building Regulations c1991. 'He has made a huge contribution and continues to move our industry forward with the work he still does for the SLL,' said Kristina Allison, who gave the citation.

Florence Lam, global lighting design leader at Arup, began there while studying engineering at Cambridge University and joined full-time in 1989, gaining her MSc in Light and Lighting. SLL Young Lighter 1991, she co-founded the Arup lighting team, growing it from four members in London to a global practice of 120 designers. Among many awards, in 2013 she was named Lighting Designer of the Year, the first woman to receive the honour. In the following year, she received the SLL Lighting Award.

'Her creative and holistic design vision and novel approach, backed by technical knowhow and rigour, have been pivotal in her ability to turn her authentic concepts into exemplary solutions,' said her colleague Arfon Davies in his citation.

Former SLL president Dr Geoff Cook is a senior lecturer in the School of Construction Management and Engineering at Reading University. Leaving school at 15 with no qualifications, he went on to gain a first-class honours in building science at Aston University.

Former chair of the LR&T editorial board and extremely active in the SLL, CIE and BSI, his research has always been focused on having a beneficial impact, particularly on lighting for the visually impaired. He is even responsible for doors on trains being a different colour to the rest of the carriage. His research has 'had a massive impact,' said the NPL's Teresa Goodman in her citation, 'and has made life better for millions of people.'

A more diverse profession is essential to help us build resilience against future crises and better respond to the pandemic and climate change, said new CIBSE president Kevin Kelly in his presidential address.

The former SLL president pointed to the 'warning shots' of the SARS, MERS and Ebola outbreaks that should have spurred an international effort to prepare for a pandemic. Instead, lulled into a false sense of security by the containment of these warning shots, the world was woefully unprepared to deal with the arrival of Covid 19, he said.

Outlining the central role being taken by CIBSE experts in analysing and responding to the threats posed by climate change, Kelly warned that the industry needed to take a lead in building the strongest possible defence.

That included positive action to improve inclusivity and diversity within the field of building services engineering, he said.

He warned that challenging the status quo would require a willingness 'to have the awkward and difficult conversations ahead and lean into them in order to change our industry for the better by making it more inclusive and welcoming to all.'

Kelly, emeritus professor at the Technological University of Dublin, succeeds Stuart McPherson as president.

The presidential address was delivered on 6 May and is available to watch at www.cibse.org/president

To see all the awards in full, go to www.gotostage.com/ channel/99978c30d5d347 486d85f02f912d1bc/recording/ c2cb1bc7ca8a44b5912 2b80205fc7067/watch

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sll.org.uk

AGM: President's address

July/August 2021

LEADING LIGHT The SLL must be at the forefront in communicating the message about lighting, health and wellbeing, says incoming president Ruth Kelly Waskett romoting the message about the relationship between light and health has to be a key mission for the SLL, said incoming president Ruth Kelly Waskett. 'Our understanding of the role of light in human health has grown significantly over the past 10 years alone, and we have now reached a point where we can make recommendations about what light people need, and when, in order to stay healthy,' she said. 'I firmly believe that it is our job, as the SLL, to spread this message. We have been talking among ourselves about this for long enough, now we need to engage with the

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wider construction industry and the public.'

She cited the recent webinar organised by SLL vice president Helen Loomes, featuring some of the authors of new recommendations for healthy light exposure (see p8). It was attended by 198 people from all over the world, she said, and since then the recording has been downloaded 160 times at last count.

'Clearly, there is a huge appetite for this subject. It really is a very exciting moment to be in lighting.'

Over the past year or so, several initiatives have emerged in response to this need, she continued, and the SLL was supportive of

many of the people behind these projects.

'But what is important is that, whether or not we agree with all of these approaches, this is happening. As the foremost source of lighting knowledge, we need to be at the forefront of this, not running to keep up.'

In order to achieve this, the society 'needs to disseminate digestible and useful information that non-technical, or at least non-lighting, people can engage with,' said Kelly Waskett.

'This can be difficult, as it can result in the need to simplify what is quite complex science.

However, if we don’t do it, who will? There are few commercial drivers for this, it is about public benefit.'

The example of other wider health initiatives, such as five-a-day and 10,000 stepsa-day, showed that others had grappled with this issue, she said. 'Despite the fact that these are gross oversimplifications of the science, they have been hugely successful in increasing awareness of the need to eat a healthy diet and the need to move as much as possible,' she said. 'This is about raising awareness above all, and signposting people to where they can find more detailed information.'

A further crucial mission for the SLL was the promotion of daylighting, said Kelly Waskett, a specialist in this area. 'The fact is, daylight cannot be commodified in the way that artificial lighting can. That is why there needs to be a voice for daylight, and the impartiality of the SLL is one of its biggest strengths here.

'One of its key roles is to ensure that the importance of daylight in buildings is kept high on the agenda of any design guidance in the built environment,' she continued, 'The SLL, being part of a professional institution, is in a unique position to be able to talk about daylight and artificial light as part of the same continuum.'

One of the great virtues of the SLL, said Kelly Waskett, is that it represents a very broad range of people who work with light: lighting designers, engineers, manufacturers and those in academic roles. 'One thing that is particularly special to me is that this has always included daylight,' she said. 'This ties into one of my core beliefs about lighting, which is that if we work with light, we need to embrace it in all its forms.'

She recalled former president Liz Peck’s address in 2015, when she referred to the SLL as a lighting family tree, comprising people from a range of backgrounds and professional roles.

'Liz recognised that the strength of the SLL lies in this diversity,' she said. 'I would like to honour my friend by carrying forward her wish that the SLL should be truly representative of all who work with light and lighting.

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AGM: President's address

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So who does the SLL represent? she asked.

'Lighting is at the intersection of so many adjacent fields, and we are not even limited to the built environment. We have people from creative backgrounds, scientific backgrounds, as well as engineering and manufacturing. From that perspective, we are a diverse group of people. But what unites us is light.

'We recognise its transformational power,' she continued, 'that is why we choose to work with light, and why so many of us see our job as much more than just a job. The society therefore has a very important role, to be the place that we can all get together, to share ideas, to formulate standards, and to harness that passion that so many of us have, to benefit people everywhere.'

One thing the SLL had to ensure, said Kelly Waskett, was that it truly reflected the lighting profession in terms of gender. A 2019 survey of people working in lighting internationally, the Lighting Family Tree, carried out by Light Collective, revealed a balanced gender split, both universally and in the UK, she said. The survey additionally showed gender split by age, demonstrating a clear distinction between the age groups above and below 40. 'What these data are telling us is that the future of lighting is female,' said Kelly Waskett. 'So if we want to represent all who work in lighting, we need to have at least a balance of genders in our membership.' However, she continued, as things stood, more than three quarters of SLL members are male. 'This does not reflect the lighting industry', she said.

To redress this, one of the first things the society

'As the foremost source of lighting knowledge, the SLL needs to be at the forefront not running to keep up'

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July/August 2021

needed to do was connect with the wider industry, increasing its visibility to everyone who works in lighting, said Kelly Waskett, citing the example of Women in Lighting and its success in increasing the visibility of women in the industry across the world. One of its main aims has been to work with lighting event and conference organisers to ensure a 50/50 gender balance among speakers and panellists.

'This is something that we ourselves need to follow if we want to help women working in the industry to see people like themselves speaking and participating in events,' she said.

'Thanks to the Women in Lighting initiative, I have seen a huge improvement in the gender balance of speakers at events over the past two years, but we need to keep going. I would like to use my presidential platform to highlight to women across the industry that SLL membership could be for them, too.'

Now a co-opted member of the CIBSE Board, Kelly Waskett said she was looking forward to working closely with the institution during the coming year to build on common goals and develop new ones, especially as former SLL president Kevin Kelly is now CIBSE president. (Both are Dubliners, and both have links with the Technological University of Dublin, from where Kelly Waskett graduated and Kelly is emeritus professor). 'Through this role I will build closer ties with other parts of CIBSE and find opportunities to strengthen our collective voice.'

In conclusion, Kelly Waskett referred to the unprecedented year that the world had experienced. 'We have endured the most challenging period of our generation, she said. 'My wish is that we, the Society of Light and Lighting, can be a source of hope for the industry and for our members.

'During the past year, we have provided an unparalleled programme of online events, which has been hugely enriching to our members, the wider industry and the public.

It is more important than ever that we go forward with the same spirit, providing events and initiatives that are a source of stimulation and inspiration to those who attend them.

Let’s go forward together in hope of a brighter year ahead,' she concluded.

The SLL AGM, Awards and Presidential Address took place online on 20 May. To watch in full, go to: www.gotostage.com/channel/99978c 30d5d3478486d85f02f912d1bc/recording/ c2cb1bc7ca8a44b59122b80205fc7067/watch

Former SLL Young Lighter (2006) and chartered engineer, Ruth Kelly Waskett is a senior associate in the specialist lighting team at Hoare Lea. She previously worked at Atkins, Max Fordham and BakerHicks.

With a first-class degree in building services engineering from TU Dublin, she subsequently gained her MSc in light and lighting at UCL in 2005. She became a highly skilled daylight specialist, gaining her PhD in daylighting at De Montfort University in 2016, working alongside Prof John Mardaljevic.

She is a visiting lecturer at UCL, contributing to both the MSc in light and lighting, and the MEng in architectural engineering.

She also developed the daylight module of the LET diploma course. She chaired the SLL task group responsible for the revision of LG 10: Daylighting (2014).

'Exposure to daylight is vital for human health,' she says. 'Daylight is the ultimate “human-centric” light source.'

The Neolithic Unesco world heritage site of Newgrange (above) in the Boyne Valley, north west of Dublin, which she visited when at school, was what sparked her love of light, she says. Older than Stonehenge and the pyramids at Giza by several thousand years, it features a specially constructed geometry that at the winter solstice allows a beam of light to penetrate an opening above the main entrance, travelling up the 19m passage to dramatically illuminate the inner chamber. 'It was a profound experience,' she says. 'It is rich with symbolism: the shortest day of the year gives way to such beauty and warmth, death giving way to new life, and the fertility of the land for these Neolithic farmers. A spark was ignited in me that day that made me want to know more about the power of light in buildings.'

sll.org.uk

Guidance: non-visual light

July/August 2021

MEASURED RESPONSE In answer to a newly developed, SI-compliant measurement standard quantifying the influence of non-visual light, a group of international specialists set out to produce the following consensus-based recommendations for lighting design cular light exposure has important influences on human health and wellbeing through modulation of circadian rhythms and sleep, as well as neuroendocrine and cognitive functions. Advances in our understanding of the underpinning mechanisms and emerging lighting technologies now present opportunities to adjust lighting to promote optimal physical and mental health and performance.

A newly developed, SI-compliant standard provides a way of quantifying the influence of light on the intrinsically photosensitive, melanopsin-expressing, retinal neurons that mediate these effects. The present report provides recommendations for lighting, based on an expert-scientific consensus and expressed according to this new measurement standard.

These recommendations are supported by a comprehensive analysis of the sensitivity of human ‘non-visual’ responses to ocular light, are centred on an easily measured quantity –

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melanopic equivalent daylight (D65) illuminance – and will provide a straightforward framework to inform lighting design and practice.

THE NEED FOR GUIDANCE Industrialisation and urbanisation have progressively and dramatically altered individuals’ light exposures, resulting in less light, including natural light, during the daytime and less darkness during the night, due to spending more time indoors where electrical lighting provides the dominant source of illumination.

Substantial evidence shows that such altered light exposure patterns have negative impacts on health and productivity. Therefore, there is an urgent need for evidence-led recommendations to help inform the design and application of light-emission technologies and human exposures.

To date, a key challenge to optimising light exposure for promoting human health, wellbeing and performance has been the

The 2nd International Workshop on Circadian and Neurophysiological Photometry in 2019 brought together experts in lighting, neurophysiological photometry, and sleep and circadian research (all authors of this paper). The workshop was chaired by Brown and Wright who provided workshop participants with goals and key questions to address prior to a structured faceto-face meeting. The primary focus of the meeting was to develop expert consensus recommendations for healthy daytime and evening/night-time light environments tentatively based on the new SI-compliant measurement system (CIE S 026:2018).

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Fig 1: differences in visual and non-visual spectral sensitivity formalised in the SI-compliant system for quantifying ipRGCinfluenced responses to light

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lack of an accepted scientific framework on which to quantify the propensity for light to elicit the relevant responses and from which to base recommendations for lighting design and practice. Fortunately, as a result of several decades of scientific advances, research-based recommendations are now possible.

Building on initial observations that nonvisual responses to ocular light can persist even in people who are totally visually blind, convergent evidence from studies of humans and animals has shown that such physiological responses originate via a specialised class of retinal neurons, the intrinsically photosensitive retinal ganglion cells (ipRGCs). The light-sensing photopigment within the ipRGCs is melanopsin which, in humans, is maximally sensitive to photons in a distinct portion of the visible spectrum (λmax ≈ 480nm prior to accounting for filtering through the lens and ocular media) to the cone photopigments. As a result, the established photometric quantities used to describe brightness and luminous sensation as perceived by humans do not adequately reflect the spectral sensitivity of any melanopsindependent responses to light.

Rather, measures such as photopic (il)luminance, which primarily reflect the spectral sensitivity of long and mediumwavelength sensitive cones, place substantially greater weight on longer wavelengths than those to which melanopsin is most sensitive, and are therefore inappropriate to quantify light with respect to non-visual responses (Figure 1A).

While the potential value of a melanopsinbased photometric quantity has been recognised for some time, there has also been

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uncertainty as to whether this provides a sufficiently detailed model of the spectral sensitivity of human non-visual responses to ocular light. Hence, while the spectral sensitivity of physiological responses to light in visually blind people and animals matches that expected for melanopsin, in the fully intact retina, ipRGCs can also receive signals originating from rods and/or cones. Moreover, available data indicate that the relative contributions of melanopsin and rod/cone photoreception to non-visual ocular light responses, and consequently their apparent sensitivity, may vary as a function of exposure duration, light intensity, and perhaps time of day and/or prior light exposure.

As an initial response to the absence of a suitable metric for quantifying ipRGCdependent ocular light responses, in 2013 an expert working group proposed a system that weighted irradiance according to the effective in vivo spectral sensitivity of the five known human retinal opsin proteins (melanopsin, rhodopsin, S-, M- and L-cone opsin).

This framework has now been formalised as an SI-compliant system of metrology (Commission Internationale de l’Eclairage; CIE S 026)28, where the photopic properties (for example, illuminance) of standard daylight (D65) that match the effective rates of photon capture for each opsin are reported as α-opic equivalent daylight illuminance (α-opic EDI, Figure 1B).

The adoption of such approaches has facilitated a number of large-scale retrospective evaluations of historical data and informed new hypothesis-driven investigations on the photoreceptive

physiology for circadian, neuroendocrine and neurobehavioural responses in humans.

The evidence from such studies supports the view that, under most practically relevant situations (extended exposures to polychromatic light in the absence of pharmacological pupil dilation), light-sensitivity of human physiological responses can be reliably approximated by the α-opic irradiance for melanopsin or the corresponding EDI (melanopic EDI). Moreover, based on the consistency of melanopic irradianceresponse relationships across studies, it is now possible to define realistic, evidencebased recommendations for light exposures that target non-visual responses. Therefore, there now exists an easily measured and internationally accepted SI-compliant system of metrology to inform lighting design and associated policy.

EXPERT CONSENSUS-BASED RECOMMENDATIONS Here we describe expert consensus-based recommendations for daytime, evening and night-time light exposure. The initial questions for review and discussion were as follows: 1.

2.

3.

What range of melanopic EDI can be reasonably considered to provide minimal and maximal impacts on non-visual ocular light responses in humans?

Do signals from rods and/or cones also play a major role and, if so, what relevant guideline levels could be recommended to account for such actions?

Do the answers to (1) and/or (2) vary across different non-visual forming responses (for example, circadian entrainment/resetting, sleep/arousal, effects on hormone secretion, mood) and, if so, what is the most appropriate general recommendation that can be provided?

The recommendations, described below, are intended to provide realistic targets that will result in appropriate non-visual responses to ocular light exposure in humans.

Daytime light recommendations for indoor environments Throughout the daytime, the recommended minimum melanopic EDI is 250 lux at the eye measured in the vertical plane at ~ 1.2 m height (in other words, vertical illuminance at eye

sll.org.uk

Guidance: non-visual light

July/August 2021

level when seated). If available, daylight should be used in the first instance to meet these levels.

If additional electrical lighting is required, the polychromatic white light should ideally have a spectrum that, like natural daylight, is enriched in shorter wavelengths close to the peak of the melanopic action spectrum (Figure 1A).

Fig 2: recommendations for melanopic light exposures in relation to the sensitivity of melatonin suppression, circadian phase resetting and subjective alerting responses

Evening light recommendations for residential and other indoor environments During the evening, starting at least three hours before bedtime, the recommended maximum melanopic EDI is 10 lux measured at the eye in the vertical plane ~ 1.2 m height. To help achieve this, where possible, the white light should have a spectrum depleted in short wavelengths close to the peak of the melanopic action spectrum.

Night-time light recommendations for the sleep environment The sleep environment should be as dark as possible. The recommended maximum ambient melanopic EDI is 1 lux measured at the eye.

For unavoidable activities where vision is required during the night-time, the recommended maximum melanopic EDI is 10 lux measured at the eye in the vertical plane at ~ 1.2 m height.

Additional considerations • Exposure to a stable and regular daily lightdark cycle is also likely to reinforce good alignment of circadian rhythms, which may further benefit sleep, cognition and health.

These recommendations should therefore be applied at the same time each day, so far as possible.

• These recommendations are not intended to supersede existing guidelines relating to visual function and safety. The non-visual ocular light responses covered here should be an additional level of consideration provided that relevant visual standards can still be met.

• These recommendations are intended to apply to adults with regular daytime schedules. Special considerations may apply to specific populations (children, the elderly, shift workers).

SCIENTIFIC RATIONALE Evidence from laboratory studies The rationale for basing these recommendations on melanopic EDI is provided by a comprehensive analysis of data aggregated from controlled laboratory studies that have evaluated

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the two best understood neuroendocrine and circadian light responses in humans: acute suppression of nocturnal pineal melatonin production and circadian phase resetting by evening or night-time light exposure.

In sum, most of the available laboratory data suggest that melanopic EDI provides a reliable index that, in most commonly encountered scenarios, provides a good approximation of the apparent spectral sensitivity of human circadian and acute nonvisual responses to ocular light. In particular, for the extended exposures to polychromatic light that are of most relevance to the real world, existing evidence indicates that any additional contributions from cones (or rods, whose spectral sensitivity is relatively close to melanopsin) do not compromise the predictive value of melanopic EDI. Evidence from real-world settings While our current understanding of the spectral sensitivity and dynamic range of circadian, neuroendocrine and neurobehavioural light responses in humans is most directly informed by laboratory studies, our recommendations are also supported by field evaluations of the impact of environmental lighting.

Access to electric lighting is associated with reduced daytime and increased night-time light exposure and altered sleep timing, with many individuals in modern society routinely experiencing melanopic EDI <250 lux during the day, especially those with delayed sleep schedules. Accordingly, there have been a number of real-world studies implementing daytime high melanopic lighting interventions

in workplaces, schools, and care homes that provide practical corroboration for the recommendations outlined above.

Collectively, increasing melanopic light exposure during the day in line with our recommendations has been shown to benefit alertness, performance and sleep in a wide range of real-world settings, even in the presence of daylight or stimulants such as caffeine. Also of importance, at this time, there is minimal evidence for negative effects of increased daytime melanopic light exposures.

FUTURE DIRECTIONS The recommendations outlined here are derived from a synthesis of several decades of research into the biology regulating circadian, sleep, physiological and cognitive responses to light and their practical implications. There is, without question, evidence that the use of melanopic irradiance as a model for the spectral sensitivity of such responses represents a simplification of the underlying biology. Although, as an aside, we note that this is true also for the established and widely used, photometric quantities (luminance and illuminance) that are currently applied to quantify conventional ‘brightness’.

Nevertheless, we leave open the possibility that a deeper understanding of rod and/or cone contributions to physiological responses will reveal multi-photoreceptor models of spectral sensitivity that may allow a more accurate prediction of circadian, sleep, neuroendocrine and cognitive responses.

The contribution of rods to such responses is clearly an important topic for research in its own right. Including rods in any future metric is, however, unlikely to materially improve its

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Guidance: non-visual light

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Authors

p Fig 3: impact of divergent spectral composition of electrical white light sources on melanopic efficiency

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accuracy since rods and melanopsin have rather similar spectral sensitivity.

Conversely, cone spectral sensitivity is quite distinct from melanopsin and has the potential to substantially refine metrics for circadian and neurophysiological responses. In particular, future work may reveal specific lighting conditions that maximise cone influence to produce practically relevant modulations in nonvisual responses to light.

At present, however, existing evidence indicates that the use of melanopic irradiance would not lead one to substantially over or underestimate biological and behavioural effects for the types of light exposure that are typically encountered across daily life.

The current recommendations are intended to inform lighting design considerations for typical, real-world environments such as offices and other workplaces, schools and colleges, residences, care homes, and both in and outpatient settings. A final point for

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consideration relates to applications of light therapy for clinical conditions such as affective and circadian rhythm sleep disorders, or for purposes such as improving circadian regulation and alertness in night and shift workers or transmeridian travellers experiencing jet lag. The current recommendations are not intended for such uses, but the existing applications of ocular light therapy likely involve the same or similar biological underpinnings as discussed above.

Perhaps widespread adoption of the recommendations described here will contribute to a reduction in the prevalence of affective and sleep disorders. More significantly, we expect the scientific framework which informs these recommendations to provide a concrete basis on which to generate hypotheses to test for the subsequent establishment of optimal light treatment recommendations for clinical and travel applications.

Timothy M Brown and Robert J Lucas, Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester; George C Brainard and John P Hanifin, Dept of Neurology, Thomas Jefferson University, Philadelphia; Christian Cajochen, Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel; Charles A Czeisler and *Steven W Lockley, Division of Sleep and Circadian Disorders, Depts of Medicine and Neurology, Brigham and Women's Hospital, Boston, MA, and Division of Sleep Medicine, Harvard Medical School, Boston, MA, and *Surrey Sleep Research Centre, Faculty of Health and Medical Sciences, University of Surrey; Mirjam Münch, Sleep/ Wake Research Centre, Massey University, Wellington, New Zealand; John B O’Hagan and Luke LA Price, Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, Didcot; Stuart N Peirson, Sleep and Circadian Neuroscience Institute, Nuffield Dept of Clinical Neurosciences, University of Oxford; Till Roenneberg, Institute for Medical Psychology, Medical Faculty, LudwigMaximilians University (LMU), Munich; Luc JM Schlangen, Intelligent Lighting Institute, Dept of Human Technology Interaction, Eindhoven University of Technology; Debra J Skene, Surrey Sleep Research Centre, Faculty of Health and Medical Sciences, University of Surrey; Manuel Spitschan, Department of Experimental Psychology, University of Oxford; Céline Vetter, Circadian and Sleep Epidemiology Laboratory, Dept of Integrative Physiology, University of Colorado Boulder; Phyllis C Zee, Dept of Neurology, Northwestern University, Chicago, and Center for Circadian and Sleep Medicine, Northwestern University, Chicago; Kenneth P Wright Jr, Sleep and Chronobiology Laboratory, Dept of Integrative Physiology, University of Colorado Boulder

This is a heavily edited extract of the original pre-print, pre-peer-review paper Recommendations for Healthy Daytime, Evening, and Night-time indoor Light Exposure. To read the original paper, including full references (redacted in this version for space reasons), go to: www. preprints.org/manuscript/202012.0037/v1 The SLL webinar Melanopic Lux Recommendations, held on 5 May and featuring some of the authors, is now available at: www.gotostage. com/channel/99978c30d5d3478 486d85f02f912d1bc/recording/ f6e24413bf2c4279bf3b8e746714eda5/watch

sll.org.uk

Urban lighting

July/August 2021

THE ROAD LESS TRAVELLED Juliet Rennie, SLL communications manager, examines what existing research has to say about the role of lighting in perceptions of safety after dark

he SLL publishes guidance on protecting the night-time environment, and lighting for the exterior environment (LG6). Undoubtedly the protection of the environment and ecology is of utmost importance, not only in the face of a climate emergency but as a general principle.

However, another major consideration relating to the night-time environment is perceptions of safety.

Following the widely publicised murder of Sarah Everard in March, the government announced that it would be taking immediate steps to improve the safety of women and girls in England and Wales, including £25m for better lighting and CCTV. This led to a discussion with our immediate past president, Bob Bohannon, as to the role of the SLL in this respect and what information it had relating to the role of lighting in providing safer streets.

Within this article, I will be looking at examples of research and work that have been carried out to understand

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the relationship between lighting and perceptions of safety in the night-time environment. Several entries for the SLL Young Lighter competition, for example, have examined the role of lighting in the urban environment, many specifically looking at the potential for lighting to be used as an intervention in areas perceived to be unsafe. There have also been a number of papers featured in Lighting Research and Technology which seek to address the same topics, providing an insight into the extent to which lighting can impact perceptions of safety after dark and the challenges that arise when trying to measure this.

I began by focusing on two SLL Young Lighter finalists. Sophia Klees, a 2012 entrant, produced a paper entitled Catching the Light: Lighting for Humans in Urban Context, based on research carried out for her master’s thesis. It focused on Görlitzer Park, Berlin, and the potential for lighting to address a feeling of unease created by taking a shortcut through the park.

In starting her research, Sophia was

surprised by the findings of an earlier study, The Influence of Street Lighting on Crime and Fear of Crime (S Atkins, S Husain, A Storey, 1991). Focusing on an inner London borough with a high crime rate relative to the national average, this study was designed to test whether ‘area-wide improvement of street lighting reduces reported crimes after dark'. The study concluded that there was no evidence to support this hypothesis.

However, there was evidence to show that there had been an improvement in women’s perception of safety when walking after dark in the area that had been relit. 'It is clear that a very much larger social survey would be necessary to trace with any statistical confidence more subtle changes in social and attitudinal effects arising from relighting,' concluded the authors.

Returning to Görlitzer Park, the shortcut through the centre of the park was identified as a more direct route, but the perceived threat of danger acted as a barrier to using the space after a certain time. Sophia’s research sought to identify the additional

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Urban lighting

July/August 2021

p Story Wall in Eskilstuna, Sweden, an award-winning scheme by ÅF Lighting (now Light Bureau), part of an urban trend to transform tunnels and subways with light

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elements which contribute to the perception of safety in the urban environment. She concluded that alongside the lighting, the following factors had to be considered: uses and activities, access, comfort, and design and sociability.

With the defined objective of reducing a feeling of unease while travelling from points A to B through the park, Sophia’s research led her to the concept of an intervention point that would embody all these attributes, so challenging the threat of danger. It took the form of an interactive lighting installation. Using additive colour mixing, passers-by were invited to play with light and interact with the space. Her Catching the Light concept was designed to address the common elements that contribute to a perception of safety, with lighting as an integral element, but not in isolation. It encouraged people to gather and to interact with the space after dark, to play with light.

In her 2019 SLL Young Lighter entry, Outdoor Lighting and Perception of Safety from a Female Perspective, Fatima Dastgheib expanded on the importance of social participation, as well as lighting, in making urban areas feel safer. Fatima’s project aimed to define the parameters of visibility which influence a perception of safety, including '…visual orientation, obstacle detection, facial recognition, awareness of surrounding environment, glare avoidance, high colour rendering index and lighting distribution.'

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She used the Women’s Safety Audit tool, originally developed in Canada in 1989 and further developed by UN-Habitat, designed to enable ‘a critical evaluation of the urban environment’ in respect to women’s safety and the impact of poor urban design and management of public spaces. This was then adapted to create an analytical tool which focused on these visibility parameters. A participating group of women were asked to determine unsafe areas during an exploratory night walk and, using this developed tool, Fatima was able to assess whether the lighting in these particular areas supported the visual parameters previously outlined.

The second, more social aspect of Fatima’s study invited participants to engage with the spaces, seeking to ‘reclaim’ the locations that were perceived as unsafe, with a view to raising awareness of the possibilities for better lighting to enhance visibility and improve safety perception.

Turning to papers published in LR&T, Evaluation of pedestrian reassurance gained by higher illuminances in residential streets using the day-dark approach (S Fotios, A Liachenko Monteiro, J Uttley, Vol 51, Issue 4, 2019), identifies that lighting is often expected to alleviate other risks, as it improves our ability to see them coming.

However, it also identifies the influence of other methodological and physical factors on the extent to which someone feels

and evaluates their level of reassurance.

By asking participants to evaluate their level of reassurance in the same locations during the day and at night (the dark-day method pioneered by Boyce et al), and summarising responses to a number of questions, the researchers were able to gain a more intricate understanding of the factors that inform someone’s perception of safety or, in this case, reassurance.

Additionally, identifying the complexity and subjectivity involved in perceptions of reassurance, the study sought to understand the extent to which the mode of evaluation might influence participant’s responses. Previous research had centred around one evaluative question, which was subject to the participants' differences in interpretation. Participants were therefore asked different but related questions.

'Reassurance is a complex concept that may include behavioural, emotional and cognitive factors,' say the authors, 'and may be better represented by responses to a series of questions, rather than a single question.'

The study determined that ‘mean horizontal illuminance did not correlate with after-dark ratings of reassurance’, but that the mean illuminance did correlate with the difference between evaluations of reassurance during the day and after dark, which was shown to be better predicted by minimum illuminance.

'What may be useful is

'Inequality is spatially reinforced by design, from our systems all the way down to individual public spaces'

sll.org.uk

July/August 2021

for lighting guidance to specify the minimum illuminance and uniformity rather than the mean and minimum as in the current standards,' concluded the authors.

By considering how participants evaluate a complex, subjective concept such as reassurance, and outlining other non-lighting factors that might impact their evaluation, this study illustrates the challenges faced by planners in addressing perceptions of safety in the night-time environment. The paper clearly defines the limitations of the study and the requirement for further research.

For example, the study was conducted in one urban area within a UK city and would need to be validated by similar studies in a range of locations. The group of 24 participants were aged between 18-38, whereas older participants would be more likely to have poorer vision, which may in turn lead to a lower level of reassurance. The daydark method may offset this, if the difference between older and younger participants correlated in both daytime and after-dark responses, but this would need to be tested.

Additionally, alternative methods could be introduced to validate the subjective evaluations, for example, monitoring physical responses such as eye movement and heart rate, and considering behavioural measures.

The effect of lighting might be different depending on a range of factors – the time of day, the purpose for taking that route and choosing to walk, and the weather.

As with the conversation relating to the effects of light on health and wellbeing, there are myriad factors to be considered, which may contribute to someone’s overall sense of safety or reassurance while navigating an urban environment after dark.

Considering measures taken to try and detach the non-lighting mitigating factors and gain an understanding of how lighting can best support levels of reassurance, it is immediately apparent that there is no default pedestrian. And as was implied by the government initiative referred to at the start of this article, perceptions of safety are also clearly differentiated by gender.

Jennifer Gardner, a US-based urban planner, and Larissa Begault, a design researcher, examine this aspect in their article How Better Urban Planning can Improve Gender Equality (www.behavioralscientist. org). As with Caroline Criado Perez’s book, Invisible Women: Exploring Data Bias in

Twitter: @sll100

Urban lighting

p Catching the Light, an interactive intervention proposed by 2012 Young Lighter finalist Sophia Klees to address a feeling of unease created by taking a shortcut through a Berlin park

This approach contributes to marginalisation. a World Designed for Men, this piece Fair representation, consultation and lived investigates the shortcomings of current experience must inform the planning process. and historical approaches to urban planning.

An article such as this can do no more It references initiatives introduced in early than barely scratch the surface regarding 1990s Vienna to ‘…introduce strategic plans the work that has been done to better and initiatives to support the explicit inclusion understand these topics. However, its main of needs, concerns, and lived experiences purpose is to highlight the fact that research of women to shape more equitable policy and evidence is available to support a more outcomes for residents of all genders'. proactive, explorative and representative They draw attention to the fact that approach to lighting in the context of designing to reduce interaction between planning for urban environments. Of course, genders may contribute to women feeling lighting does not and cannot stand in safer in certain spaces, but it does not isolation when it comes to creating a safer address the root cause of the problem. The environment for all. It is not lighting that will piece also emphasises the importance of a decrease certain types of violent crime, this representative, consultative process in urban is a much broader societal issue. However, planning and design. lighting can demonstrably help to create an 'Because the typical user of urban space environment where people feel safer, and has, since the advent of modernism, been this in turn may impact the way people use the young, professional, white male, this and interact with a space and each other. baseline informs every other user group's experience of the city,' say the authors. 'This If anyone is interested in finding out also means… the practice of urban planning more about research on lighting and and design and its outcomes are not gender perceptions of safety in the night-time neutral. Inequality is spatially reinforced by environment, please contact Juliet Rennie at the SLL (jrennie@cibse. design, from our systems all the way down to org) for access to relevant papers and individual public spaces.' direction to members of the lighting Working to create solutions for the Durdle Door in Dorset, lit by Michael Grubb Studiocommunity for NoHL with in-depth academic ‘average’ human being is always problematic. knowledge of this area

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CIE-UK report

July/August 2021

COME TO TERMS John O’Hagan, chair of CIE-UK, reports on the global lighting body's recent activities including the latest edition of the International Lighting Vocabulary significant recent publication from the CIE has been the latest edition of the International Lighting Vocabulary (ILV). In developing technical publications, terminology is where it all begins. It provides a set of agreed definitions and terms for concepts common to a field, reducing the level of ambiguity associated with words and sentences. Before starting work on technical documents, experts first must agree on the terminology, so that everyone understands the concepts which are referred to. This is particularly important when disciplines come together to discuss topics that overlap their fields.

In the CIE, terminology has always been a key subject. A century ago, in 1921, attendees at the Fifth Session of the CIE began to discuss the publication of a lighting vocabulary. The first edition of the ILV was published in 1938. Further editions followed and the 1987 edition was adopted by the International Electrotechnical Commission (IEC) for integration into their International Electrotechnical Vocabulary (IEV).

In 2011 CIE published a new, completely revised edition, the first time as an International Standard, CIE S 017 ILV: International Lighting Vocabulary. The second edition was published in late 2020 with many new terms, reflecting advances in LED lighting and imaging technologies.

The goal is to promote international standardisation in the use of quantities, units, symbols and terminology related to the science and art of light and lighting, colour and vision, metrology of optical radiation over the ultraviolet, visible and infrared region, photobiology and photochemistry, and image technology. The terms and definitions from CIE

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S 017:2020 have also been made available online through the e-ILV. There have also been two other new publications: Photometry of curved and flexible OLED and LED sources (CIE 242: 2000). The trend for high-tech products is towards the capability of flexibility: flexible lighting, displays, memory, solar cells and so on. Flexible products can be light, thin, break-resistant, and offer more creative freedom for the designer and lighting designer. It is not only for fun and fashion, but also because flexible products are practical – rollable displays can reduce the limitations of space and add further convenience for portable digital electronic products. As it is thin and light, flexible lighting can be integrated with clothes to increase safety at night. As flexible products become more common, measurement research is needed to support the industry.

The report describes the methods of measuring photometric and colorimetric quantities for curved sources and gives guidance for the determination of measurement uncertainties. The measurement quantities include luminance, luminous flux, colour, reflectance and viewing angle.

Discomfort glare in road lighting and vehicle lighting (CIE 243: 2021). This report provides an overview of the research methods, mathematical models and variables that are considered to influence discomfort glare, and describes the difficulties associated with its evaluation and measurement, and the variance in the models. The report aims to encourage

further research using methods recommended by the proposals it raises. Such research will generate a greater body of credible data, enabling the development of a more robust model. It is intended to update this report in due course with these additional data and a revised discomfort glare model.

CIE-UK is the UK national committee of the International Commission on Illumination or CIE (Commission Internationale de l´Éclairage). SLL is a Sponsoring Organisation member. If you are interested in joining, or want more details, contact Allan Howard at allan.howard@wsp.com

• The complete ILV can be purchased through the CIE Webshop. For more details on the e-ILV, go to:http://cie.co.at/e-ilv • UK members of SLL are eligible for the CIE-UK members’ discount for CIE publications, a two-thirds reduction on the list price. A discount is also available for some CIE events (including the CIE conference below). Please email sll@cibse.org for the discount code.

Publications can be purchased via the relevant link on the CIE website: http://cie.co.at/ • CIE is making one publication available free of charge to its national committees for a year (until February 2022), including to SLL UK members (email sll@cibse. org). The document is Lighting for older people and people with visual impairment in buildings (CIE 227:2017).

It summarises recommendations on lighting and the visual environment in interior spaces for healthy older people (defined as aged 50-plus) with normal vision, and people with low vision, and implements guidelines from CIE 196:2011 (CIE guide to increasing accessibility in light and lighting) into practical solutions. It provides (1) illuminance recommendations (2) state of art studies on how light helps people with low vision see objects and (3) guidelines for lighting practitioners on designing appropriate visual environments for people with low vision.

• The 2021 CIE Mid-Term three-day conference will be held online from 27-29 September 2021. The theme is Light for Life – Living with Light.

More details can be found at the conference website: https://malaysia2021.cie.co.at

sll.org.uk

LR&T essentials

July/August 2021

STREET WISE Iain Carlile looks at three recent Lighting Research and Technology papers focusing on road lighting and human health

skola et al investigate trafficaware dimming of LED street lights considering both potential operational energy savings and the impact on the lifetime of luminaires. To simulate the effects of long-term operational use, two batches of luminaires were aged under controlled conditions over a period of five years. One batch simulated continuous operation at full power, and the other operation in a dimmed state for part of its life subject to prevalent traffic conditions.

The authors identified that the dimmed luminaires showed additional stress to the LEDs, and occasional failure. However, the costs of the reduced operational lifetime of the LEDs was less than the energy savings made, a 25 per cent saving to the lifecycle cost. With LED street lighting becoming more prevalent, this study suggests the potential savings that can be made through dimming luminaires during low use and intermittent traffic conditions.

Looking at lighting for pedestrians, Mao and Fotios examined how multi-tasking affects their ability to undertake critical visual tasks such as obstacle detection and facial emotion recognition. Laboratory experiments were performed in which both object detection and facial recognition tasks were undertaken in parallel under different illuminances.

Results from the experiments were compared with previous studies where only one task was undertaken. The comparisons

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suggested that multi-tasking does impede performance on the peripheral detection task, but did not impact the on-axis facial emotion recognition task.

Boyce’s paper investigates the effects of light and lighting on human health. He summarises what is understood of the impacts of light on human health, via visual and non-visual systems originating in the retina of the eye, and optical radiation falling on the eye or skin.

From this he concludes that human health is undoubtedly influenced by lighting, but there are four conditions that need to be considered in this assertion: • • •

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The impact of lighting on human health can be either positive or negative Human health is affected by many factors other than lighting The severity of the effects of light exposure can vary widely from the short term and trivial to the long term and fatal The same lighting conditions can have very different health impacts for different individuals depending on their age and medical status

Taking these four conditions together implies that care is needed when judging the veracity and relevance of broad assertions about the benefits of lighting for human health.

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) Effect of adaptive control on the LED street luminaire lifetime and on the lifecycle costs of a lighting installation J Askola, P Kärhä, H Baumgartner, S Porrasmaa and E Ikonen Lighting for pedestrians: Does multi-tasking affect the performance of typical pedestrian tasks?

Y Mao and S Fotios Light, lighting and human health PR Boyce

p Examples of face models used to determine facial emotion recognition (Mao and Fotios)

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MOST READ PAPER (in the past six months): Road lighting research for drivers and pedestrians: The basis of luminance and illuminance recommendations S Fotios and R Gibbons

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Events 2021

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/sllevents/past-presentations

ONLINE EVENT ENGINEERING THE BUILT ENVIRONMENT FOR A NEW 'NORMAL' (ANNUAL CIBSE TECHNICAL SYMPOSIUM) Date: 13-14 July 2021 www.cibse.org/technical-symposium/about

AVAILABLE WEBINARS INCLUDE RECOMMENDATIONS AND PRACTICAL APPLICATIONS FOR MELANOPIC LIGHTING DESIGN Based on the paper (pre-print, awaiting peer review) Recommendations for Healthy Daytime, Evening, and NightTime Indoor Light Exposure which arose from the second International Workshop on Circadian and Neurophysical Photometry, 2019.

Speakers: Helen Loomes, FSLL, Innovation Akademie, Trilux Group; Prof Debra Skene, University of Surrey; Manuel Spitschan, University of Oxford; Prof Timothy Brown, University of Manchester; Steven Lockley, Harvard Medical School DELIVERING THE CIRCULAR ECONOMY FOR THE LIGHTING INDUSTRY SLL and CIBSE Home Counties South West Chair: Hakeem Makanju, CIBSE HCSW regional chair, and David Mooney, SLL representative for HCSW Speakers: Bob Bohannon FSLL, SLL president; Kristina Allison, CEng MCIBSE MSLL, chair of the SLL education and membership committee; Roger Sexton, FSLL, business development for Stoane Lighting; Tim Bowes, MSLL, head of lighting application for Whitecroft Lighting SLL AGM, AWARDS AND PRESIDENTIAL ADDRESS (held on 20 May 2021) Watch at: www.gotostage.com/channel/99978c30d5d3478486d85 f02f912d1bc/recording/c2cb1bc7ca8a44b59122b80205fc7067/watch

SLL LR&T APPLYING LIGHT FOR HUMAN HEALTH SYMPOSIUM LIVE (held in November 2020) Speakers include: Prof Russell Foster, Mariana G Figueiro, Luc Schlangen, Mark Rea and Arne Lowden Register to watch the sessions on demand: https://cibse.force.com/s/lt-event?id=a1E3Y00001jWBS7UAO

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