Light Lines May - June 2021

The Society of Light and Lighting

LIGHT LINES

VOLUME 14 ISSUE 3 MAY/JUNE 2021

PICTURE PERFECT The new guide for museums and galleries

UNSEEN BENEFITS Getting the measure of non-visual light

Editorial

May/June 2021

FROM THE EDITOR SECRETARY Brendan Keely FSLL bkeely@cibse.org SLL COORDINATOR 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 LL4 2021 IS 10 MAY 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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Unit C, Northfield Point, Cunliffe Drive, Kettering, Northants NN16 9QJ Tel: 01536 527297 E: gary@matrixprint.com

The whole point of the SLL's series of lighting guides is that they deal with the specific issues which arise in any one sector or environment. But whether that is scene setting for liturgical events in a religious building, lighting for patient comfort and practical medicine in a hospital, or conservation concerns in a museum, at heart the guide is about lighting for human needs.

It is a consideration that Mark Sutton Vane underlines in his summary of the forthcoming update of LG8 – Lighting for Museums and Art Galleries (Art of illumination, p5), a revision largely driven by rapid developments in lighting equipment.

'While technology has evolved, humans and their eyes and their feelings have not changed,' says Sutton Vane. 'Light has not changed.' As a result, the guide emphasises the subjective and human responses to light and how those responses can be influenced by the lighting designer.

That aspect of lighting has become a

whole lot more complicated now that we know we are dealing with both visual and non-visual responses. While one arm of academia is still wrestling with how to quantify meaningfully the light we can see, other research has moved into more tenebrous areas, the metrics of non-visual light. Also in this issue, the 2020 Jean Heap Bursary recipient, Manuel Spitschan, outlines his research subject, luox, a new platform for quantifying the non-visual effects of light (A measure of the unseen, p8).

Whatever the metric, as Sutton Vane says, the equation must ultimately add up to human wellbeing.

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)

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Secretary’s column/Contents

May/June 2021

Contents

FROM THE SECRETARY

Twitter: @sll100

• For Mark Ridler's article on the

circular economy in January/ February SLL Light Lines: https://issuu.com/matrixprint/ docs/light_lines_janfeb_2021?fr =sOGYwNzI2ODI0ODk • To download or purchase LG20: Lighting for Facilities Management: www.cibse.org/ society-of-light-and-lightingsll/lighting-publications • To download Factfile FF17: Temporal lighting artifacts: www.cibse.org/society-oflight-and-lighting-sll/lightingpublications/free-downloads • Register free of charge for the SLL AGM: Email sll@cibse.org

by Mark Sutton Vane, who outlines the key considerations in this issue (see p5).

Over the past year or so there have been changes to the infrastructure of Lighting Research and Technology (LR&T). Steve Fotios took over from Peter Boyce as editor in chief at the beginning of 2020, and a number of associate editors have been appointed according to their particular field of lighting: Ashish Pandharipande, John Mardaljevic, Myriam Aries, Mike Royer, Peter Thorns, Luke Price and Teresa Goodman, who also chairs the journal’s editorial board. We thank all involved for their work ensuring that LR&T remains one of the most renowned peer-reviewed lighting research publications in the world.

Finally, we hope that you can join us online from 16:30 on Thursday 20 May for the SLL AGM, Awards and Presidential Address. We look forward to providing a quick roundup of 2020, honouring our brilliant award winners, thanking our outgoing president Bob Bohannon and welcoming the incoming president Ruth Kelly Waskett.

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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THE ART OF ILLUMINATION Mark Sutton Vane looks at the key points in the newly updated LG8 on lighting for museums and galleries

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A MEASURE OF THE UNSEEN Jean Heap Bursary recipient Manuel Spitschan outlines luox, a platform for quantifying the non-visual effects of light

10 VIRTUOUS CIRCLE The SLL has developed three tools to promote the circular economy and sustainability. Bob Bohannon summarises what they are and why they are needed

11 DARK MATTERS

Benedict Cadbury explains why the SLL's new lighting guide to illumination in the night-time environment is indispensable

15 SOURCE AND EFFECT

Iain Carlile selects three recent LR&T papers focusing on the impacts of light in contexts real and virtual

16 EVENTS

COVER: Royal Wharf Pier, River Thames, lighting by DHA Designs, winner of the Public Realm and Landscape category of the Lighting Design Awards 2020

© Gavriil Papadiotis (gavriilux.com)

We hope you enjoyed the 2021 series of LightBytes Online in April. The four events (still available on demand to all members) focused on the circular economy, and featured speakers Steve Shackleton (Fagerhult), Helen Loomes (Trilux) and Tim Bowes (Whitecroft). A big thank you to the sponsors and speakers, as well as our guest speakers Emilio Hernandez (lighting designer at Ström and chair of the GreenLight Alliance, a new organisation with a mission to move towards a more circular economy) and Mark Ridler (head of lighting at BDP). Mark outlined how he and his team are implementing CE principles (see box for link to his article on the subject in the January/February issue of SLL Light Lines).

As ever, the SLL technical and publications committee are very busy. In case you are not aware, the SLL’s most recent Lighting Guide, LG20: Lighting for Facilities Management, authored by Sophie Parry, was published earlier in the year (see box for download/purchase details).

Sophie has also worked with Professor Arnold J Wilkins from the University of Essex to produce a new free-to-download document, Factfile FF17: Temporal lighting artifacts (see box), which refers to flicker, stroboscopic effects and phantom arrays.

We thank Sophie and Professor Wilkins for their work.

Since the spring of last year, Liz Peck had been working on a new lighting guide focused on protecting flora and fauna. Now that Liz is unfortunately no longer with us it has been decided that the draft of the Guide to Protecting the Night-Time Environment will be published under her name with minimal changes to her work. Benedict Cadbury has agreed to make the minor amendments and the guide will be published in the coming months (see Dark matters, p13).

Benedict has also been working with Nigel Monaghan on the rewrite of LG9: Lighting for Communal Residential Buildings (see Light Lines March/April).

We thank them both for their contribution and we should see the guide published in the next few months.

Also due this year is the updated LG8: Lighting for Museums and Art Galleries

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News

May/June 2021

THE LATEST NEWS AND STORIES

REPORT CALLS FOR ENLIGHTENED STRATEGY FOR LONDON A new report highlights the need to improve the quality of London's lighting and create more cohesive strategies. 'Our capital has the potential to be one of the best-lit cities in the world, yet for a mix of reasons, it hasn’t treated lighting as a priority,' says the report, published by the city's think tank, the Centre for London. 'This is despite growing evidence of the benefits that good lighting can bring to cities – and the costs if it is ignored.'

Seeing Clearly: How Lighting can make London a Better City is designed to stimulate public debate, says CFL, a politically independent charity. It is based on analysis of recent investments into lighting upgrades made by London boroughs, and reviews of academic articles, policy documents and development plans, with findings tested in interviews with policymakers and practitioners.

The report makes wide-ranging recommendations, including that boroughs should develop lighting strategies based on a framework provided by the Mayor of London, that a hub for lighting resources should be created for both the public and building professionals, and that lighting designers should be engaged early on in the design process.

It also suggests that resources should be made available for residents’ or community groups to bid for funding to carry out lighting improvements, with professional support as part of the package. The report also features a toolkit of basic principles for communities and decision makers working with lighting.

The report was triggered by the Illuminated River Foundation, behind the ambitious project to light up to 15 of the bridges along the Thames, which approached Centre for London to conduct the research. Lighting advisors include Mark Major of Speirs + Major, Elettra Bordonaro, principal of Light Follows Behaviour, Mark Burton-Page, general director of LUCI, and Don Slater, director of Configuring Light.

'We hope it will start a conversation about what we can all do to help create a thoughtful nightscape in London that is more environmentally friendly, makes the city feel more inclusive, celebrates our historic capital and works better for Londoners and visitors alike,' said IRF director Sarah Gaventa.

To read the report go to: www.centreforlondon.org/publication/lighting-london/

ON THE LIGHTER SIDE...

Billed as the first light-emitting tattoo, an OLED device developed by scientists from UCL and the Italian Institute of Technology could be used for purposes as diverse as monitoring the human body (bloodglucose levels, for instance) or the freshness of food.

The tattoo, 2.3 micrometers thick, can be applied with the help of water and pressure like a temporary

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tattoo. 'The tattooable OLEDs can be made at scale and very cheaply,' said UCL's Professor Franco Cacialli, senior author of the paper published in Advanced Electronic Materials.

'They can be combined with other forms of tattoo electronics for a wide range of possible uses.'

The Illumination Engineering Society (IES) has published a collection of essays, papers and 'snapshots' on the theme of what developments lighting experts foresee in the next decade. An open invitation to contribute was issued by the IES and the resultant entries judged by a specialist panel Drawing on a wide range of academic and lighting expertise, the Visionary Challenge encompasses all aspects of lighting from technology to cultural impacts, envisioning what the state of the lighting industry will be in 2030, what the biggest challenges might be and how thinking in lighting should move forward.

To download the document free of charge, go to: https://ies.informz.net/ies/pages/ Visionary_Challenge_2020_Sign_Up

LET TAKES ON NEW STUDENTS AFTER PANDEMIC PAUSE The Lighting Education Trust's (LET) Diploma in Lighting Design is scheduled to restart for new students in May following a year's hiatus caused by the pandemic. While no new students were admitted to the course in 2020, full support was maintained for students already enrolled.

'Though the pandemic presented no significant threat to the survival of LET, the trustees temporarily suspended all activities that incur cost other than maintaining the necessary support to those students able to continue their studies,' said Hugh Ogus, chair of the trustees. 'Thanks to the umbrella of CIBSE, LET has no fixed overheads to drain resources, so has survived in good shape.'

It was also decided not to solicit backing from sponsors until the future was clearer, added Ogus. 'We hope that the support of the companies that contribute to the funding of the trust will continue in the future.

The scope of further developments will be determined by the ability of our sponsors to resume their generosity when there is a degree of normality in the marketplace.'

• Current trustees of the LET are Hugh Ogus (chair), Mike Simpson, Bob Venning and John Aston (representing CIBSE).

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Guidance

© Sutton Vane Associates

May/June 2021

A typical museum artefact with lighting from different angles from typical museum light fittings – 'a huge range of effects can be created by just altering the brightness or the direction of the light'

THE ART OF ILLUMINATION From conservation to the creation of varying effects, Mark Sutton Vane looks at the key considerations that have been covered in the newly updated Lighting Guide 8 – Lighting for Museums and Art Galleries

Twitter: @sll100

he previous version of LG8, which covers the lighting of museums and art galleries, was published in 2015. However, as with that guide, the number of dramatic changes in lighting technology in the past six years meant that another update was needed.

There are many different professionals with varying amounts of expertise and experience involved in the lighting of museums and galleries. The responsibility for the lighting can well end up with someone who is not an experienced lighting designer. This guide aims to help people with all levels of expertise.

Hopefully, though, reading it may make some non-specialists realise that they need to employ a lighting designer.

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Guidance

'It is not the responsibility of the lighting designer to know what an artefact is made of and then to decide what light level it can stand' 6

© Sutton Vane Associates p The Great Gallery, Wallace Collection, London: the laylight provides much of the light in the gallery

development of the Internet of Things, so this and the various other innovative new lighting control and communication systems are also covered.

But while technology has evolved, humans and their eyes and their feelings have not

changed. Light has not changed. Schemes for museums and galleries are among the most human-centred type of projects that a lighting designer can work on. This guide therefore has a lot of coverage of the subjective and human responses to light

© Sutton Vane Associates

LG8 is not just about museums and galleries, but covers a wide area of building types. It is also about historic interiors, for instance, which are displays in themselves. Hopefully this new version will help the lighting designer, or person responsible for the lighting, emphasise the story, the themes or the brand of the project whatever its nature.

As in other sectors, it is the technology of how light is made and controlled that has changed so much. The 2015 version still had, quite rightly, much information on tungsten halogen and metal halide fittings, and not as much about LED fittings. At the time LED technology was in a rapid period of evolution which made finalising the 2015 version very difficult in this respect. However, the guide makes clear that they are likely to be the principle source for the future in museums and galleries, which has indeed been the case.

As tungsten and metal halide sources are not specified any more, all the references to those types of traditional light source have been removed and replaced with more detail about LEDs and all the new technology that now exists to support them. This includes information about drivers and dimming.

LEDs have even changed the economics of access for maintenance. As they last so long, in some galleries it is now cheaper to hire abseilers to carry out the rarely needed maintenance rather than have the infrastructure needed for big, heavy, high-level access platforms.

The other lighting technology revolution that has occurred more recently is the

May/June 2021

p Fashion Gallery, National Museum Scotland: lighting hierarchy in action, with the backlit runway and fibre optics on black sticks ensuring the fashion exhibit is the brightest item against surrounding dimmer (for conservation reasons) cases, walls and floors

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Guidance

p Kings and Scribes exhibition, Winchester Cathedral: three-dimensional exhibits need balanced illumination to reveal them to best advantage

and how the lighting designer can influence those responses.

The publication starts with the foundations of lighting design and explains what light can do and how it can be controlled. This is important given that some of the readers will not be lighting specialists. Also, where museums and galleries are concerned, there are many particular challenges – such as reducing reflections and glare, and getting colours and relative intensities right – that can only be solved if the principles of light are fully understood.

The three great variables, brightness, colour and direction, are analysed and explained. How these three then control glare, affect the softness of shadows and the rendering of colour, reveal or conceal texture, and all the other effects, then becomes understandable. Using these tools, and many other lighting tools, the designer can make the lighting emphasise the hierarchy of the story being told by the artefacts, the supporting material and the spaces.

Photographs accompanying this article (see previous page) show the lighting of a typical museum artefact with lighting from different angles from typical museum light fittings.

These demonstrate the huge range of effects

Twitter: @sll100

© Sutton Vane Associates

© Sutton Vane Associates

May/June 2021

p The Cast Courts, V&A, London: lighting tests in progress to check angles for uplighting a single figure. A 20-degree, 3000K spotlight is being used

that can be created by just altering the brightness or the direction of the light.

Museum lighting is rarely a blanket solution. There are often lots of details to solve and often the best results are only found by experimentation. With this in mind, new sections have been added to the guide about the importance of experiments and the importance of the aiming, adjusting, focusing and setting of light levels once the exhibits have been installed.

One of the major, perennial challenges of museum and gallery lighting is the damage that light can cause to objects. Light can fade colours and even cause some materials to break down. This is one of the great dilemmas of the museum world. A visitor only knows an object looks beautiful because they can see it. The visitor can only see the object if it is lit. But that light might be damaging the object and destroying its beauty. That is the challenge of lighting some artefacts: see, enjoy and so destroy, or don’t see and don’t enjoy or somewhere in the middle with some enjoyment and an acceptable amount of damage. The guide explains the amount of damage caused by different light levels.

The earlier version of the guide listed the

amount and type of damage that light gives to different specific materials. This was so that the lighting designer could work out what level of light a delicate artefact could accept. This is one big change to the updated guide. It is not the responsibility of the lighting designer to know what an artefact is made of and then to decide what light level it can stand. It is the responsibility of the owner of the artefact to say how much light they are prepared to use to satisfy their decision about the acceptable levels of enjoyment versus damage.

Technology has changed, but how light works, the damage that it can do and the amazing effects that it can create have remained constant and so are explained in detail. I suspect that the reactions of human beings to the lighting, involving eyes and hearts, will also remain constant, and all of these factors are the most important parts of the new version of the guide.

Mark Sutton Vane, FSLL, is director of independent lighting consultancy Sutton Vane Associates and author of Lighting Guide 8 – Lighting for Museums and Art Galleries. LG8 is scheduled to be published in late spring

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Research

May/June 2021

A MEASURE OF THE UNSEEN The 2020 Jean Heap Research Bursary recipient, Manuel Spitschan, outlines his research subject, luox, a novel open-access platform for quantifying the non-visual effects of light

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he quality and quantity of light in our environment profoundly affect how we feel, how and when we sleep, and how we appreciate a given space. Over the past few years biomedical research has found that different pathways connect the eye to the brain and influence different functions.

We have, of course, known about cones and rods for a long time. While the cones allow us to see colour, motion and spatial detail under daytime lighting conditions (photopic vision), the rods give us rudimentary vision under lighting typically dimmer than natural twilight (scotopic vision).

As has now become more widely known, around 20 years ago a new type of neuron was identified: the intrinsically photosensitive retinal ganglion cells, or ipRGCs, which are sensitive to light independent of the cones and rods. They respond to light due to the photopigment melanopsin. Melanopsin is most sensitive to short-wavelength, or blue light, with a peak sensitivity near 480nm.

The ipRGCs are involved in a range of effects important for our health and wellbeing. Most prominently, they signal the intensity of environmental illumination and thereby track the light-dark signal.

Signals from the ipRGCs are sent to the suprachiasmatic nucleus (SCN), an area buried deep in the brain about the size of a grain of rice. The SCN is our circadian pacemaker, telling our brain and body whether it is day or night – biologically speaking. Through this brain pathway, rhythms in our physiology and behaviour

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become synchronised to the light-dark cycle in our environment.

For example, the body starts producing the 'sleep hormone' melatonin a few hours before our usual bedtime.

Exposure to light in the evening and at night can disturb melatonin production and shift our circadian rhythms. Exposing yourself to light at the wrong time can lead to circadian disruption: the misalignment of our biological clock with solar time, which has negative consequences for mental and physical health in the long run.

Biomedical research on these non-visual effects of light is very much ongoing. We now hold several key pieces of the puzzle, including the primary role of melanopsin in driving these effects, and a developing understanding of how much light is necessary to support optimal health and performance.1 Over the past decade or so, there has also been considerable interest in optimising lighting solutions for the built environment. 'Human-centric lighting' is one of the terms that is often used, and the HCL market is large and growing.

UNDERSTANDING THE NONVISUAL EFFECTS OF LIGHT Recent meta-analyses have shown that melanopsin best explains our current evidence base for the non-visual effects of light,2 simplifying the daunting and challenging task of quantifying the impact a given spectrum of light has. However, the spectral sensitivity of melanopsin and the photopic luminosity curve (Vλ), which is used to calculate (il)luminance, are different.

Vλ reflects a weighted combination of the L and M cones in the retina. Consequently, the non-visual effects of light cannot generally be predicted by (il)luminance, requiring metrics reflecting the melanopsin-weighted (or melanopic) signal.

p Fig 1: Workflow for using luox platform

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Research

May/June 2021

'The luox tool makes calculations to relate the spectrum to physiological responses to light easy, accessible and reproducible' In 2018, the International Commission on Illumination (CIE) published the CIE S 026/E:2018 standard. 3 This includes a set of spectral sensitivity curves for the cones, rods and melanopsin. These curves are used to convert a spectrum (giving radiance or irradiance for each wavelength) into a physiologically weighted, alpha-opic quantity for each photoreceptor class.

For melanopsin, the melanopic irradiance, expressed in mW/sqm, is the spectral irradiance weighted by the melanopsin spectral sensitivity. In addition to these

fundamental quantities, the standard also formalises the melanopic equivalent daylight illuminance (melanopic EDI), which quantifies the illuminance a standard D65 daylight spectrum would have with the melanopic irradiance. In other words: how bright (measured in lux) would daylight have to be to have a matched melanopic irradiance?

HOW LUOX WORKS Lighting calculations are often not simple or can require specialised tools. Which is where luox, a novel web platform for facilitating these calculations, comes in.

The user will upload a spectral power distribution (SPD) – radiance or irradiance – and the platform calculates, using browserside computations, a range of key quantities, including (il)luminance, chromaticity and alpha-opic quantities. The spectrum is visualised and can be compared to a range of CIE reference spectra, including CIE Standard Illuminants A and D65, Illuminants C, E, D50, D55 and D75, the F series, and others.

The user can then download these quantities as a comma-separated (CSV) file.

Additionally, the spectrum can be shared using a new spectral compression library called spdurl, developed by Michael Herf, which directly encodes the spectrum in a URL. The uploaded spectrum can then be

recalled at a later point, simply by pointing to the same URL. Using this scheme, no data are stored on a server. Users are also able to request a digital object identifier (DOI) which creates a permanent meta-data record and URL for a stored record. The workflow is shown in Figure 1.

The luox platform is free – both in the open-source sense and delivered at no cost. A CIE task group is in the process of validating calculated quantities.

The luox platform is at https://luox.app/ and the source code is available at https:// github.com/luox-app/luox under the GPL-3.0 License, making all calculations transparent and allowing contributions from interested users. Manuel Spitschan is currently a research fellow at the University of Oxford and a visiting fellow at the Centre for Chronobiology, Basel.

For any questions, comments or suggestions, the author can be contacted at manuel.spitschan@psy.ox.ac.uk

The 2020 Jean Heap Research Bursary was awarded to Manuel Spitschan, PhD, for his project, luox.app: Development, validation and refinement of a free, open-access tool for calculations related to light and lighting. In addition to the SLL bursary, development of luox was funded by the Wellcome Trust (Research Enrichment – Open Research, 204686/Z/16/C) and the van Houten Fund of the University of Oxford (VH-148).

References 1 https://www.preprints.org/ manuscript/202012.0037/v1 2 https://onlinelibrary.wiley. com/doi/full/10.1111/jpi.12655 3 https://cie.co.at/publications/ cie-system-metrology-opticalradiation-iprgc-influencedresponses-light-0

p Fig 2: The process step by step

Twitter: @sll100

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Circular economy

May/June 2021

VIRTUOUS CIRCLE

The SLL has developed three tools aimed at both manufacturers and designers to help promote the circular economy and sustainability in the lighting industry. Bob Bohannon explains what they are and why they are urgently needed

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uild Back Better was the theme of my SLL presidential address back in May 2020, but on its own, without definition and without action, Build Back Better is just a slogan – the first big question must be what does better look like in terms of lighting when we are being tasked with delivering net zero carbon buildings?

From around 2015, much of our industry was driven by a laser focus on luminaire energy efficiency. While officially predicated on a need for carbon reduction, the true

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Circular economy

May/June 2021

driver was the return on investment made possible by replacing legacy luminaires with ultra-efficient LED versions. As with any business case, the lower the capital cost, the quicker the return on investment, and this, coupled with offshoring of manufacturing, created the low-cost LED luminaire. In many schemes the visual quality of the space and the visual comfort provided to occupants were very secondary considerations.

Therefore it does not require much imagination to suggest that industry and governmental calls to deliver net zero carbon buildings will lead to a renewed focus on any building service that is a consumer of energy. By doing so, with consumption correlating to emissions, we minimise the need for carbon offsetting or as yet largely unproven carbon capture and storage.

Will lighting quality again be under further pressure? So as not to be constrained by a blinkered, energy-only approach, we need to understand and communicate all the aspects that make up better (lighting) in a net zero carbon building.

In discussing the theme of the latest SLL LightBytes, I suggested that we should update the Right Light, Right Place, Right Time mantra for a net zero carbon age and that this might usefully become Minimum Energy, Minimum Resource, Maximum Comfort.

We, of course, have an unavoidable duty to minimise our in-use carbon emissions for the sake of the generations to follow us,

hence Minimum Energy. Maximum Comfort covers a wide range of requirements from visual comfort to wellbeing and the creation of fit-for-purpose stimulating spaces.

This article focuses on Minimum Resource – the other half of the emissions in use equation, being the embodied resources used to build the luminaire and whether that resource use through life is in itself sustainable.

The old joke about how many (fill in your stereotype) does it take to change a light bulb doesn’t work any more. The LED and the driver are often integral to the fitting so if one were to fail you have to replace the whole thing – you simply can’t repair it, life extend it, even if you wanted to. LEDs are more energy efficient and they are part of our green jobs revolution that drives economic growth – all that is true, but it is not the whole story. The huge (pre-Covid) growth of LED lighting had already brought its own problems.

As an example, let’s think about the hospitality sector, increasingly the focus of ever more wonderful lighting designs.

While each individual luminaire is likely to be fairly energy efficient, there are now many more of those fittings, and in a fastmoving sector new fit-outs are common.

Now many would not unreasonably think that we recycled all those replaced conventionally lamped fittings, or those fittings ripped out prior to a hospitality or retail refit, but I present you with an

p The hospitality sector is increasingly the focus of attractive lighting but while individual luminaires are probably energy efficient, there are now many more of them and new fit-outs are common

Twitter: @sll100

inconvenient truth: 'In 2019, 42,000 tonnes of lighting equipment were placed on the UK market,' according to Nigel Harvey, chief executive of Recolight. 'Only 2700 were recovered through WEEE schemes.

The amount officially recorded as reused was zero' So what happened to all these luminaires, not forgetting that the WEEE

'The only person who thinks we can have infinite growth in a finite world is either a madman or an economist' – David Attenborough

directive came into force in 2003 so any equipment 18 years old or younger all proudly bore the crossed-out wheelie bin mark? The harsh reality was that much was sent to landfill. What did go to a grandly named Approved Authorised Waste Treatment Centre saw any value in your old luminaire literally shredded to recover the metals, which themselves would need energy inputs to melt them down for reuse. Green? No. We have to make better use of the resources embodied in our lighting equipment. An unthinking linear economy of Take (resources from the environment), Make (products in factories), Waste (dispose of products into the natural environment) is no longer acceptable. Part of the problem here is that we measure economic growth in terms of sales revenue, but we don’t measure our environmental impact.

Before you start thinking that I’m a bit of a Luddite, stuck in a pre-LED world where everything looked better through (2700K tungsten) tinted spectacles, then I should point out that our industry is not alone. We would all applaud the rapid uptake of PV

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Circular economy

solar generation, but it has been estimated that we could be facing 80m tonnes of endof-life PV modules by 2050, that could form more than 10 per cent of global e-waste.

The high energy efficiency of LED luminaires does not solve the problem of lighting sustainability without ensuring that the technology itself is sustainable.

Adopting the circular economy is the accepted process of maximising resource usage, keeping (in our case) lighting assets at their highest value, in other words as an effective luminaire for as long as possible.

I will not dwell too long on the topic of what the circular economy is, others before me have already done so. However, the other day I found myself penning an article entitled ‘How many Presidents does it take to change a Light Bulb? Why? Well as David Attenborough will be the first to remind us, the environment will not wait.

We need practical action right now. This will most likely take the form of legislation, supplier innovation, specifier or clientled demand, dissemination of practical knowledge and the adoption of assessment methods. So what could this president of the SLL do?

A team of us got together and we started listening, consulting, learning, engaging, and what is soon to come out of that process is a suite of three tools.

The objective is to give information to all, enable supply push by creating a nuts and bolts tool for manufacturers, and to stimulate demand pull by giving specifiers and clients the questions they need to ask.

The first tool in the suite is the forthcoming CIBSE SLL Technical Memorandum on The Adoption of the Circular Economy in the Lighting Industry.

It describes the background to the circular economy in general, including the drivers behind its adoption, but most importantly it provides guidance on how the circular

May/June 2021

economy affects each sector of the industry, what opportunities it may bring them and what to do next.

We are also near the completion of the SLL’s Circular Economy Assessment Method for Manufacturing (CEAM-Make) which allows manufacturers (or specifiers, if they so wish) to assess the performance of their luminaire and its supporting ecosystem in terms of its circular economy performance. The products are rated a score out of four. The objective is to move as many products and manufacturers from zero to hero (four) as quickly as possible by giving them the detailed issues to consider.

The assessment method is comprehensive, covering product design, manufacturing, materials and supporting ecosystem.

The CEAM-Make may be a little too indepth for a busy specifier to use every time they need to choose between luminaires, or in the transition period where manufacturers have not yet fully completed their CEAM-Make assessments. Therefore, the third part of the suite of tools is the SLL's CEAM-Design, being a specifier support tool. You could almost think of it as a triage tool, being essentially the most important questions to ask a manufacturer.

All the tools in the suite have been created in full consultation with people knowledgeable in the field, from manufacturers to product designers, lighting designers and end users. The tools will be updated, but the hope is that they will deliver the practical know-how, understanding and level playing field for claims that make an already green industry in terms of its product’s in-use energy performance, truly sustainable.

While I hope that our suite of tools (and we have already thought of at least another two to add to them) delivers real and measurable change, I must sound one note of advice for future

p Lighting is not uniquely complex: the product as a service concept already covers jet engines to copiers, while the toner cartridge itself is a poster child for remanufacture

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SLL presidents: don’t write brand new Technical Memorandums or software tools in combination with your busy year as president. If you do it is highly unlikely that either your bank manager or your family will still be talking to you at the end of it. It is perhaps best summed up by Peter Fordham of Sainsburys: 'Bob, you were either brave or you didn’t think it through.'

Having said that, in my presidential address I also said that I couldn’t do it alone. Much of the SLL’s and CIBSE’s work is only made possible by its volunteers. Many, many people have played their part in this work, too many to list them all but special thanks must go to Kristina Allison, Andrew Bissell, Sophie Parry, Anastasia Mylona, Simon Fisher, Roger Sexton, Mark Ridler, Tim Bowes and Tom Ruddell.

Bob Bohannon, MSc, FSLL, MIET, is a lighting designer, sustainability expert and educator, and, until May, president of the SLL. He is also currently leading the team writing the SLL's Circular Economy Fact File and Assessment method

The three tools, newly developed by the SLL to promote the circular economy in lighting, are scheduled to be available by early summer: • CIBSE SLL Technical Memorandum on The Adoption of the Circular Economy in the Lighting Industry • Circular Economy Assessment Method for Manufacturing (CEAM-Make) • CEAM-Design: specifier support tool

sll.org.uk

Guidance

May/June 2021

© Courtesy of Tim Peake

DARK MATTERS

p Nocturnal view of the UK seen from space

For the first time the SLL is expanding its advice on illumination and the night-time environment into a full lighting guide.

Benedict Cadbury summarises why such guidance is now indispensable

Twitter: @sll100

light schemes, so this guide could almost iz Peck was writing this excellent have formed a checklist for the project: guide, LG21: Guide to Protecting skyglow, obtrusive light, bat flyways, fish, the Night-time Environment, in visitor views, extending the economic day the months before her untimely of Ironbridge, curfews, luminance-based death in January 2021, bringing it very near design, spectral reflectance and light source to completion. It was a subject that she was spectral radiation, daytime appearance, glare passionate about, in her work protecting mitigation through positioning, aiming and bats from the negative effects of light, in her louvres, and finally an overall lighting impact architectural lighting design, and also in her assessment – all were included. wide-ranging work for the SLL. It is easy to identify examples of dreadful Bob Bohannon had the privilege to exterior lighting where the benefit to the work alongside Liz on the award-winning owner of the illumination is more than scheme for the Iron Bridge at Telford, and cancelled out by the negative side-effects on reading this guide it was good to see just of light spill on neighbouring properties how much of the knowledge and advice set and those who live and work in them. The out within it were incorporated into the rot started with 500W halogen floodlights lighting design of the bridge. Liz had long had with PIR control and then expertise in mitigating the negative effects Durdle Door in Dorset, lit by Michael Grubb Studio for over-sensitive NoHL continued with wide-angle LED floodlights of lighting on bats and Bob had extensive at 5000K. It culminates in glaringly bright experience in delivering zero direct upward

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Guidance

'Humans are naturally a diurnal species, but we have the tools to turn night into day anywhere on a crowded planet shared with other humans, flora and fauna'

moving LED displays, and garish Christmas illuminations at first floor level flashing on and off all night.

This is an area where guidance is indispensable. The SLL Guide to Limiting Obtrusive Light, written by Peter Boyce, was first published in 2012. Nine years on it is time to expand this into a full lighting guide, with additional material relating to LED light sources, and consideration of how light can affect human and animal circadian systems. Legislation lumbers up slowly in the rear: the Clean Neighbourhoods and Environment Act (2005) includes light on the list of statutory nuisances, which means that property owners (and the lighting designers who may work for them) are legally obliged to consider the effect of any exterior lighting on neighbours.

Electric light is capable of being harmful not only to humans, but animal and plant species. For humans, glare and flicker are obvious problems. First, flicker does not have to be visible to have an effect; secondly, many LED lights which operate satisfactorily on full power produce increasing flicker as the driver dims the light source, hence if lights are planned to be dimmed in use, for example with daylight-linking, the flicker factor/flicker index needs to be ascertained at 50 per cent and 25 per cent as well as 100 per cent output. Although sky glow might not

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May/June 2021

at first be thought of as bad for health, if it means that city centre dwellers sleep less well because of the lack of complete darkness outside, this clearly has an implication for their wellbeing.

PROTECTED SPECIES More than half the world’s species are nocturnal, thus exterior illumination in or near their habitats can cause problems, particularly if it is in operation throughout the hours of darkness. Bats are at the top of the list, but nocturnal birds such as owls suffer; many small mammals, such as mice and shrews, rely on darkness to avoid predators. A significant number of animals and birds are protected in the UK; the Appendix lists 101 vertebrates in this category, including the dormouse, hedgehog, otter, red squirrel, shrew, barn owl and many songbirds, not forgetting crested newts and natterjack toads. Disturbance of any of these species is illegal, therefore lighting designers need to consider carefully the effect of an exterior lighting scheme not just on neighbouring properties but also on native wildlife. This is especially pertinent on the edge of a built-up area or a greenfield site in the countryside.

BLUE LIGHT Blue light is of particular interest when considering circadian entrainment and the negative effects of electric light on wildlife.

In the past street lights were generally monochromatic sodium; now LED street lights, generally 4000K–5000K, contain a good deal of blue light. A 4000K LED source typically has a blue-light content of around 33 per cent, whereas a warmer 2700K light source has only 16 per cent.

As a general rule, blue-rich white light disturbs nocturnal creatures more than warmer, narrow-waveband sources, so it is essential to consider the spectral distribution of a light source in assessing its impact on the natural environment.

SHOULD IT BE LIT? The first question has to be whether or not the lighting is necessary or justifiable.

Much of it is indeed necessary, for example for safety of movement, security, or work such as loading vehicles. The next category is desirable, for instance to extend the economic 'day' of a town centre, lengthen the time that leisure facilities can be used,

or illuminate landmarks. At this point the lighting designer and client need to make a realistic assessment of the negative effects to weigh against the benefits.

LESS IS MORE There is a tendency to think that more or brighter lighting is better. If a private client or hotel asks for a garden to be lit, it is far more effective to light a few well-chosen focal points rather than flood the whole space with uniform illuminance. Of course, safety considerations mean that steps and the edges of any water features need accent lighting, but this can be local and discreet.

LIMIT THE HOURS There is no reason to exclude external lighting altogether because of harmful side-effects on wildlife or human neighbours. Clients frequently want features lit on winter evenings, which might mean 4-9pm. Having conducted a lighting impact assessment it might well be decided that, with a curfew at 9pm, the entire scheme would be acceptable, whereas if it was to run to midnight, then a restriction on the number of luminaires and/or their lumen output would have to be imposed.

The guide offers practical advice and useful suggestions, whether for sports pitches, heritage buildings or car parks, drawn from the author’s extensive experience. Good practice examples are given and there is a checklist of considerations before a lighting scheme is submitted for planning permission.

Humans are naturally a diurnal species, but we have the tools to turn night into day anywhere on a crowded planet shared with other humans, flora and fauna. The power to use these lighting tools should be used wisely, with care and consideration.

Not every building needs lighting, not every surface needs to be lit, and we should be cognisant of the impact of any light that escapes our projects.

Lighting Guide 21: Guide to Protecting the Night-time Environment, substantially written

by Liz Peck and finalised by Benedict Cadbury, is scheduled for publication this summer.

The All-Party Parliamentary Group of MPs for Dark Skies was formed in 2019. Its first policy paper, urging the government to adopt 10 policies to help resolve light pollution, was launched on 9 December 2020. It can be viewed and downloaded at https://appgdarkskies.co.uk/policy-plan sll.org.uk

LR&T essentials

May/June 2021

SOURCE AND EFFECT Three of the most recent Lighting Research and Technology papers focus on the impacts of light in varying contexts both real and virtual, finds Iain Carlile ee and Lee note that with an increase in coloured lighting in the built environment, there still exists little empirical research on how people perceive it. They have therefore investigated the effect of coloured lighting on people's pleasure and arousal, and how this may differ with ethnicity.

Using the Mehrabian and Russell’s emotional state model, which measures pleasure, arousal and dominance (PAD), an experiment was conducted to investigate the effect of six lighting colours: red, green, blue, yellow, orange and purple. A controlled laboratory experiment was conducted using a colour-changing LED luminaire and involving 82 participants. Their ages ranged from 19 to 45 years, with an equal mix of male and female, 48 Caucasian and 34 Asian. They were exposed to different coloured lighting states at different illuminance levels to simulate potential different applications. Each participant completed a PAD questionnaire about their emotional states under the coloured lighting.

The results showed significant differences in pleasure and arousal for the six different colours. Ethnicity had significant effects on the impact of lighting colour on pleasure, but not on arousal. Blue was considered the most pleasant colour, being significantly higher than red and purple, with red being the least pleasant. Asians found red and purple significantly less pleasant than all other colours of light and tended to feel less pleasant under red, orange and purple lighting conditions than Caucasians.

Ru et al’s paper examines the acute effects of office illumination on cognitive performance during daytime hours, specifically whether the type of task and level of task difficulty moderate the effect of daytime illuminance on cognitive functioning. An experiment was

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conducted in a simulated office environment, where 30 participants (mean age 20.46 years +/-1.81, 10 male and 20 female) were exposed to high and low illuminances at the eye (high illuminance of around 1036 lux and low illuminance of around 108 lux) using T8 fluorescent light sources with 6500K CCT (Ra 81). The experiment was conducted during working hours throughout which time the participants were tested on varying difficulties of tasks designed to probe sustained attention, response inhibition, conflict monitoring and working memory.

Subjective impressions of mood and sleepiness were also recorded.

The authors found that exposure to high versus low illuminance significantly improved the speed on the response inhibition task, and accuracy and speed in the working memory task. These effects were moderated by task difficulty, showing more pronounced effects for the easy tasks.

Subjective sleepiness and negative mood were unaffected by illuminance. No significant

effects were observed for the sustained attention and conflict monitoring tasks. The authors conclude that the effect of illuminance on cognitive performance appears to be moderated by the type and difficulty of the task, and cognitive tasks are not necessarily reflected in subjective affective experiences.

A study by Rockcastle et al compares perceptions between a modern immersive head-mounted virtual-reality (VR) display and the real space. An experiment was conducted in which 53 participants took part. The participants viewed either a real space, illuminated with a dimmable LED lighting system, or a virtual representation of the space captured using a high-dynamic-range (HDR) camera. In all 30 participants (11 male, 18 female, one other) viewed the real space while 23 participants (eight male, 15 female) viewed the immersive HDR photographs displayed in the VR head-set.

Age was evenly distributed between the groups (around 80 per cent aged 18-33 and 20 per cent aged 34-58). Different lighting conditions were presented to the participants, who rated visual comfort, pleasantness, evenness, contrast and glare.

The results were similar when they evaluated well-lit scenes, but significant differences were observed under dim and highly contrasted lighting scenes. This suggests that virtual reality can be a reasonable surrogate for subjective analysis of realworld lit environments when evaluating well-lit scenes. However, it may not provide an adequate medium for dimly lit or highly contrasted scenes.

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) Effects of coloured lighting on pleasure and arousal in relation to cultural differences H Lee and E Lee Diurnal effects of illuminance on performance: Exploring the moderating role of cognitive domain and task difficulty T Ru, KCHJ Smolders, Q Chen, G Zhou and YAW de Kort Comparing perceptions of a dimmable LED lighting system between a real space and a virtual reality display S Rockcastle, M Danell, E Calabrese, G Sollom-Brotherton, A Mahic, K Van Den Wymelenberg and R Davis

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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 SLL AGM, AWARDS AND PRESIDENTIAL ADDRESS Date: 20 May Time: 4.30pm To register, please email sll@cibse.org

AVAILABLE WEBINARS INCLUDE GOOD INDOOR LIGHTING MAKES PEOPLE HEALTHY AND HAPPY The Good Light Group has a mission fulfilment of our 2025 mission: that 1,000,000 people worldwide know about the beneficial effects of Good Light on the body and brain and that 100,000 people worldwide live, work and learn in buildings with Good Light.

Speaker: Jan Denneman, chair of board for Good Light Group, a global non-profit organisation Denneman talks about the mission of the Good Light Group to ensure, by 1925, that 1m people worldwide know about the beneficial effects of good lighting on the body and brain, and that 100,000 people worldwide live, work and learn in buildings with good lighting Panel discussion: with SLL president elect Dr Ruth Kelly Waskett and Professor Peter Raynham 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 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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