SLL Light Lines January/February 2020

Page 1

The Society of Light and Lighting



PEOPLE AND LIGHT Peter Boyce on the human factor

PRESCRIBING GOOD ILLUMINATION Healthcare guidance updated

Twitter: @sll100


January/February 2020


FROM THE EDITOR SECRETARY Brendan Keely FSLL SLL COORDINATOR Juliet Rennie Tel: 020 8772 3685 EDITOR Jill Entwistle COMMUNICATIONS COMMITTEE: Linda Salamoun MSLL (chair) Iain Carlile FSLL Jill Entwistle Chris Fordham MSLL Rebecca Hodge Eliot Horsman MSLL Stewart Langdown FSLL Bruce Weil Gethyn Williams 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 LL2 2020 IS 13 JANUARY PUBLISHED BY The Society of Light and Lighting 222 Balham High Road London SW12 9BS ISSN 2632-2838 © 2020 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


Printed in UK


Unit C, Northfield Point, Cunliffe Drive, Kettering, Northants NN16 9QJ Tel: 01536 527297 E:

It ought to be self-evident that one prime consideration should be at the centre of any lighting scheme: how will it affect the people in the space? Why then do so many spaces feel as if people are pretty low on the list of priorities? Budgets, short-termism, compromise, ignorance, indifference, zealotry in applying regulations are among the determinants that, singly or in combination, are likely to militate against decent lighting. And that is just the visual side of the business. When you introduce the non-visual aspects of lighting into the mix it becomes a whole other, and rather more byzantine, ball game. In academic circles it is referred to as ‘human factors’ and is defined by Peter Boyce (see The Human Factor, p5) as ‘the interaction of people and lighting’. This deceptively simple definition covers what Boyce describes as ‘three broad routes through which lighting can affect people and influence their appreciation of lighting: through the visual system, through the

circadian timing system, and through mood and motivation’. And inevitably these routes overlap and interact, just to add to the complexity. The term ‘human centric’ lighting may be au courant but for a lighting system to be truly people-centred it must be more than lip service or a marketing label. ‘Why you should be bothered with [human factors] is simple,’ says Boyce. What users are most likely to complain about ‘is lighting that makes what needs to be seen difficult to see, lighting that is uncomfortable or poses a risk to health, and lighting that makes people and the space look bad. Human factors give you answers to avoid these problems.’



SLL Lighting Guide 0: Introduction to Light and Lighting (2017) SLL Lighting Guide 1: The Industrial Environment (2012) 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 (2014) 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) Guide to Limiting Obtrusive Light (2012) Code for Lighting (2012) Commissioning Code L (2018) SLL Lighting Handbook (2018)

January/February 2020

Secretary’s column/Contents


FROM THE SECRETARY Thanks to everyone who visited us at Light Middle East and those who took part at Ready Steady Light Middle East, a brilliant event with the competitors inventively making the most of left-over exhibition stand pallets, luminaires and black drapes. Our sincere appreciation also goes to Light. Func and Messe Frankfurt for their efforts in delivering the event. We would like to thank everyone who visited our stand at LuxLive back in November, we had a great time. The four Young Lighter finalists were really impressive. The high quality of presentations resulted in the judges again having a difficult time in selecting a winner, and congratulations go to Anna Wawrzyniak, who won the Young Lighter 2019 competition presenting her paper, A Light Booster Metro Car for the Commuting Work Force: human centric lighting in underground transportation. Our thanks go to judges Iain Carlile, Ruth Kelly Waskett and Eliot Horsman along with president elect Bob Bohannon, who chaired the competition as well as presenting the prizes. The brand new peer-reviewed LightBytes People Space Time Place event has been presented in Birmingham and Dublin, and the feedback has been excellent. All those working in any aspect of the built environment must be up to date on relevant research, regulations, applications and technology, and that’s why LightBytes is a must-attend event. The event has 4.5 hours of CIBSE-Accredited CPD. We really appreciate our sponsors and speakers who make the series possible: Soraa, Thorlux Lighting (Richard Caple), Xicato (Roger Sexton), Zumtobel (Graeme Shaw), and Eleanora Brembilla from Loughborough University. We will be visiting Manchester on 30 January, Leeds on 13 February, Bristol on 26 March, Glasgow on 23 April, and wrap up in London on 4 June. Bookings can be made via the website or by contacting us ( We are pleased to announce a brand new SLL publication, Lighting Guide 19 (LG19) – Lighting for Extreme Conditions (see p11). This guidance will cover everything from the Arctic to the Sahara and much in between. The publication can be downloaded from the website by

Twitter: @sll100

members free of charge or purchased in hard copy form. A big thank you to David Holmes, lead author. FactFile 7 Design and Assessment of Exterior Lighting Schemes is also now free to download from the website, with thanks to lead author Alan Tulla. We are gearing up for the Lighting Research and Technology Symposium 2020 at UCL on 18 June this year. Confirmed speakers for the Applying Light for Human Health event include: Mariana Figueiro and Marc Rea from the Rensselaer Polytechnic Institute, John Mardaljevic from Loughborough University, John O’Hagan from Public Health England, Arnold Wilkins from University of Surrey and Peter Thorns from Zumtobel. Topics to be presented, and debated during panel discussions, include: how exposure to light affects human health, what both manufacturers and lighting designers need to know about lighting for health, as well as lighting for better sleep, for night-shift work, day work and in schools. Speakers will also examine lighting for people with dementia, and for people who suffer migraines and other conditions. They will look at how lighting necessary for human health can be implemented and, finally, at the future of lighting for health. The 2020 AGM Notification, Awards and Presidential address details will be emailed to all members shortly. The evening event will take place on 21 May in the Connect Room at the Ortus Building, Maudsley Hospital, in south-east London. As well as the AGM and elections it will be a night to formally recognise the work of the society and its volunteers throughout 2019, and also to honour those who have gone above and beyond the call. We look forward to seeing many of you at the event.











The relationship between lighting and people is complex and crucial. Peter Boyce examines its fundamental importance in design The SLL has revised its guidance on the healthcare sector. Nicholas Bukorovic explains why the update was necessary and what has changed









David Holmes outlines the main areas covered by the SLL’s new guide focusing on lighting for arduous and abnormal environments The BRE has published the results of its study investigating the effects of dynamic ‘circadian’ lighting The latest papers from LR&T range from road illumination to the non-visual effects of light, discovers Iain Carlile

COVER: The Elizabeth Line, lighting by GIA Equation, featuring bespoke lightboxes by Designplan over the platform doors



January/February 2020




LIGHT BOOST METRO CAR FOR DAYLIGHT-DEPRIVED COMMUTERS IS WINNING IDEA AT YOUNG LIGHTER 2019 Anna Wawrzyniak of Peter Andres Lichtplanung, Germany, is the winner of Young Lighter 2019, which last year marked its 25th anniversary. Her presentation theme was A Light Booster Metro Car for the Commuting Workforce: human centric lighting in underground transportation. Wawrzyniak was up against three other finalists during LuxLive at London ExCeL in November. Fatemeh Dastgheib of KTH Royal Institute of Technology, Stockholm, looked at outdoor lighting and the perception of safety from a female perspective. Melissa Kennedy of WSP, London, evaluated the impact of textured light on the sensual atmospheres in art, architecture and design. Nils Voerste of Bauhaus-Universität Weimar, Germany, looked at evidence-based lighting design for urban environments. ‘To see four young, intelligent and creative lighters bring their thoughts and work to LuxLive and present them so clearly was truly great to see,’ said Bob Bohannon (pictured right), president elect of the SLL and chair of the competition. ‘All four had potentially winning ideas or research. The future of our industry is in safe hands with such bright, creative talent. ‘Becoming a finalist for Young Lighter is a great accomplishment to include on any CV,’ added Bohannon. ‘Any employer who has a Young Lighter on their team can be proud of their talent. If you don’t have a Young Lighter then it’s time you reached out on LinkedIn.’

ON THE LIGHTER SIDE... Artist Anish Kapoor didn’t exactly make himself Mr Popular when he nabbed the exclusive rights to the use of Vantablack, then the world’s blackest black. But it seems there was still a black hole in the market as MIT engineers have developed a material that is 10 times blacker. It was exhibited at the New York Stock Exchange late last year in the form of an artwork, The Redemption of Vanity. A collaboration between Diemut Strebe, artist-in-residence at the MIT, and Brian Wardle, an MIT aeronautics and astronautics professor, the work is a $2m 16-carat colour diamond covered with a grown forest of carbon nanotubes. It takes the most reflective substance in


the world and turns it into the darkest, resulting in a now you see it, now you don’t exercise. Which must have been an interesting proposition for the insurance.

‘Lighting regulations and practice often still focus on visual and energy efficiency aspects of light, with little or no attention being paid to ipRGC-influenced light (IIL) responses,’ says the CIE (International Commission on Illumination) in its recently released position statement. ‘Conversely,’ it adds, ‘there are many lighting products entering the market that are intended primarily to influence IIL without careful consideration of other lighting quality aspects. An improper balance between these two approaches can result in lighting conditions that compromise human wellbeing, health and functioning and that fail in terms of overall lighting quality.’ The commission has examined the various marketing terms applied to this area, including ‘human-centric’, ‘circadian’ and ‘biodynamic’ lighting. In the upcoming second edition of the CIE International Lighting Vocabulary it has plumped for the term ‘integrative lighting’ as the ‘official term for lighting that is specifically intended to integrate visual and nonvisual effects, producing physiological and psychological effects on humans that are reflected in scientific evidence’. Among other issues, the statement touches on the importance of daylight, and also recognises that specifications in terms of melanopic EDI ‘are a reasonable route’, with certain provisos. The CIE emphasises the need for research and clarification in the field generally, and outlines its activities in this respect. ‘The CIE is actively engaged with the international community in attempting to provide guidance that is based on solid scientific evidence and consensus,’ says the statement. The CIE and ISO/TC 274 are developing the first international consensus-based technical report concerning integrative lighting, noting both its potential beneficial effects and the possible risks to be avoided. For the full 1800-word statement go to:

January/February 2020


Lighting and people

THE HUMAN FACTOR Peter Boyce examines the complex and crucial relationship between lighting and people uman factors, as applied to lighting, cover the interaction of people and lighting. This interaction works in both directions: lighting affects what people can do and what they choose to do, and people control lighting to give them what they want from it. What I am trying to do here is to convince you, as a person involved with lighting, that human factors matter. Why you should be bothered with it is simple. If you ask anyone who buys, designs or maintains lighting installations what they dislike most the answer will be complaints from users. If you ask users what they are most likely to complain about you will find that it is lighting that makes what needs to be seen difficult to see, lighting that is uncomfortable or poses a risk to health, and lighting that makes people and the space look bad. Human factors give you answers to avoid these problems. Figure 1 shows a conceptual framework for


Twitter: @sll100

considering the influence of lighting on these aims. It shows three broad routes through which lighting can affect people and influence their appreciation of lighting; through the visual system, through the circadian timing system, and through mood and motivation. The effect of lighting on vision is the most obvious impact of light on humans. With light we can see, without light we cannot. Any stimulus to the visual system can be described by five parameters: its visual size, luminance contrast, colour difference, retinal image quality and retinal illuminance. Thus, it is the interaction between the object to be seen, the background against which it is seen and the lighting of both object and background that determine the stimulus the object presents to the visual system and the operating state of that system. But this is not the end of the story. Most apparently visual tasks have three components: visual, cognitive and motor. The visual component refers to the process

of extracting information relevant to the performance of the task using the sense of sight. The cognitive component is the process by which sensory stimuli are interpreted and the appropriate action determined. The motor component is the process by which the stimuli are manipulated to extract information and/or the actions decided upon are carried out. These three components interact to produce a complex pattern between stimulus and response leading ultimately to task performance. Further, every task is unique in its balance between visual, cognitive and motor components, and hence in the effect lighting conditions have on task performance. It is this uniqueness that makes it impossible to generalise from the effect of lighting on the performance of one task to the effect of lighting on the performance of another. Visual performance is the only thing that changing the lighting conditions can affect directly but visual performance is only part of the structure of the task. Another route whereby lighting conditions can affect work is through the non-visual system. The most extensively examined part of the non-visual response to light is the circadian timing system, a mechanism that synchronises many different hormonal rhythms over a 24hour period (CIE, 2004). The master clock of this timing system is located in the suprachiasmatic nuclei (SCN) in the hypothalamus of the brain. It communicates with other parts of the body through the hormone melatonin circulated by the bloodstream. The SCN receives signals from the retina through the intrinsically photosensitive retinal ganglion cells (ipRGC) but there the similarity with the visual system ends. The response of the visual system to light exposure is fast, detailed and located. The response of the circadian timing system is slow, uniform and non-located. The visual system is an image-processing system that constructs a model of the outside world. The circadian timing system is more like a slow-response photocell that simply tells you if it is day or night. The aspects of lighting that influence the state of the SCN are the amount and spectrum of the radiation reaching the retina, as well as the timing and duration of exposure.



January/February 2020

Lighting and people

ď ą F ig 1: conceptual framework setting out the three routes whereby lighting can influence human performance and behaviour




Phase shift Retinal irradiance



Circadian timing system

Mood Human performance

Other effects?

Cognitive performance

Visual message





Motor performance

Luminance contrast

Colour difference


Exposure to light can produce two distinct effects on the circadian timing system. One is to stabilise, advance or delay the phase of the circadian rhythm. Which occurs depends on the timing of the exposure (Dijk et al, 1995) and has consequences for sleep, mood and task performance. To ensure a stabilised circadian rhythm it is necessary to have a regular rhythmic exposure to light and darkness. This means that people working rotating night shifts are likely to have destabilised circadian rhythms. Prolonged exposure to such states are associated with ill health (Knutsson et al, 2004).


Visual discomfort

Visual performance


Visual size


Alerting effect

Task performance

Circadian timing disruption


Retinal image quality

Retinal illuminance


The other effect is an increase in alertness. There is little doubt that by adjusting the spectrum and amount of light at the beginning of the day and at the time of the post-lunch dip, alertness can be improved (Figueiro et al, 2018, 2019) but there is also evidence that alertness can be enhanced in more ways than just playing with the non-visual system. This is evident when it is appreciated that both blue light and red light can increase alertness (Sahin and Figueiro, 2013). The spectral response of the non-visual system operating through the ipRGC and the SCN is shown in Figure 2 (Rea and Figueiro 2018). It has a maximum at

460nm, in other words at the blue end of the visible wavelengths, so if red light has an effect on alertness it must be operating through some other route. And then there is a general point that, regardless of the spectrum of the incident light, it may be that what the visual system shows us is sufficient to increase alertness. This brings us to the third route whereby lighting conditions can affect people, through mood and motivation. The visual system generates a model of the visual world and that may produce an emotional response. It is this emotional response, among many other factors, that may influence an individual’s mood and motivation. The simplest way in which lighting may influence people in this respect is when it generates a sense of visual discomfort. The four lighting conditions likely to cause discomfort are shadows, veiling reflections, glare and flicker, although, in the right situation, all four can make a positive contribution to the visual scene (Boyce, 2014). Large area shadows can be considered as a simple reduction in illuminance, but localised shadows can cause confusion as well as making it difficult to see detail. Shadows can be reduced by using many light sources in a high-reflectance interior but shadows can also be useful in revealing form. Veiling reflections can make it difficult to see detail by reducing luminance contrast. To occur there has to be a specular surface being viewed and a high luminance source at the mirror angle corresponding to the direction of view. They can be reduced by increasing the amount of inter-reflected light. As for their positive use, highlights used to reveal the specular nature of some materials are veiling reflections by another name. Glare occurs when there is an excessive range of luminances in the visual field. It can be controlled by limiting the luminance of luminaires and by designing installations that conform to the UGR recommendations included in the SLL Code. Finally, instability in light output below about 80 Hz with a high modulation amplitude will be visible to many people and will almost always be considered uncomfortable. However, even at higher frequencies and when the instability is not visible it can cause headaches (Boyce and Wilkins, 2018) and may become visible in situations where there are moving objects

January/February 2020

(stroboscopic effect, Bullough et al, 2012) or where the background is dark and eye movements are large (phantom array effect, Lee et al, 2018). Flicker in whatever form is best avoided but when attached to a small area it can be used to attract attention. However, perception is much more sophisticated than just producing a feeling of visual discomfort. With or without visual discomfort, every lighting installation sends a ‘message’ about the people who designed it, who bought it, who work under it, who maintain it, and about the place it is located. Observers interpret the message according to the context in which it occurs and their own culture and expectations. The importance of this message is sometimes enough to override conditions that might be expected to cause discomfort, as shown by the fact that lighting conditions that would be considered extremely uncomfortable in an office are positively desired in a nightclub. According to what the message is, the observer’s mood and motivation can be changed. Every lighting designer appreciates its importance but it is mainly in the context of retailing and entertainment that the message a lighting installation sends is given the importance its potential to influence behaviour deserves (Custers et al, 2010). Fortunately, systematic design procedures giving priority to the appearance of the space rather than task performance are being developed (Cuttle, 2018). While each of these routes has been discussed separately, it is important to appreciate that they can also interact. An example would be a situation where the lighting provides poor task visibility, so that visual performance is poor and the worker’s mood is sour. There are multiple interactions of this type that can occur. To further complicate the picture, it is necessary to appreciate that while visual performance for a given task is determined by lighting conditions alone, a worker’s mood and motivation can be influenced by a wide range of physical and social factors, lighting conditions being just one among many (CIBSE, 1999). Nonetheless, it should now be apparent why anyone interested in lighting needs to understand the human factors involved. These human factors are the basis of many lighting recommendations and much lighting guidance and, hence, are the justification for much lighting practice.

Twitter: @sll100

Lighting and people

 Fig 2: model of the spectral sensitivity of the circadian timing system measured by the suppression of the melatonin concentration plotted against wavelength (Rea and Figueiro, 2018)

Spectral sensitivity 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 400







Wavelength (nm)

References Boyce PR. Human Factors in Lighting, 3rd edition. Boca Raton, FL: CRC Press, 2014. Boyce PR, Wilkins A. Visual discomfort indoors. LR&T 2018; 50: 98-114. Bullough JD, Sweater-Hickcox K, Klein TR, Lok A, Narendran N. Detection and acceptability of stroboscopic effect from flicker. LR&T, 2012; 44: 477-483. CIBSE. Environmental Factors Affecting Office Worker Performance: A Review of Evidence, CIBSE Technical Memorandum TM24, London: CIBSE, 1999. Commission Internationale de l’Eclairage. CIE Publication 158, Ocular Lighting Effects on Human Physiology, Mood and Behaviour, Vienna: CIE, 2004 and Erratum, 2009. Cuttle C. A fresh approach to interior lighting design: The design objective – direct flux procedure. LR&T, 2018; 50: 1142-1163. Custers PJM, de Kort YAW, IJsselsteijn WA, de Kruiff ME. Lighting in retail environments: Atmosphere perception in the real world, LR&T 2010; 42, 331-343. Dijk D-J, Boulos Z, Eastman CI, Lewy AJ, Campbell SS, Terman M. (1995) Light treatment for sleep disorders:

Consensus report II Basic properties of circadian physiology and sleep regulation. Journal of Biological Rhythms, 1995; 10: 113-125. Figueiro MG, Nagare L, Price LLA. Non-visual effects of light: How to use light to promote circadian entrainment and elicit alertness. LR&T, 2018, 50: 38-62. Figueiro MG, Kalsher M, Steverson BC, Heerwagen J, Kampschroer K, Rea MS. Circadian-effective light and its impact on alertness in office workers. LR&T 2019; 51: 171-183. Knutsson A, Hammar N, Karlsson B. (2004) Shift worker mortality scrutinized, Chronobiology International 2004; 21:1049-1053. Lee C-S, Lee J-H, Pak H, Park SW, Song D-W. Phantom array and stroboscopic effects of time-modulated moving light source during saccadic eye movements. LR&T 2018; 50: 772-786. Rea MS, Figueiro MG. Light as a circadian stimulus for architectural lighting. LR&T 2018; 50: 497-510. Sahin L, Figueiro MG. Alerting effects of short wavelength (blue) and long wavelength (red) lights in the afternoon. Physiology and Behavior, 2013; 116-117: 1-7.


January/February 2020


Courtesy of Glamox Lighting

ď ą Klinikum Hospital, Hanover

CLINICAL REAPPRAISAL The SLL has revised its guidance on the healthcare sector. Nicholas Bukorovic explains why the update was necessary and what has changed he first notable thing about the new edition of Lighting Guide 2 (LG2) is that it has been given the new title of Lighting for Healthcare Premises (the 2008 version it replaces was called Hospitals and Health Care Buildings). While it still majors on hospitals it also recognises the growing need for a new model of clinics and medical centres to help with the care of the elderly and the growing numbers of the population suffering from age-related dementia. The publication also includes and identifies the urgent future requirement for the social and medical care of mental and drug-related



patients, and therefore aims to be as holistic as possible in trying to provide a rather more inclusive insight into the requirements of all these new facilities. The new edition of LG2 has been specifically produced to ensure that our guidance is up to date with modern lighting practice, and to illustrate varying ways of lighting the modern hospital environment. It should also be noted that while the 2019 edition includes a number of changes and several new sections, an initial review of the 2008 publication, even after 11 years, found it to still be an informative and authoritative guide to healthcare lighting. The Department

of Health’s opinion was that LG2: 2008 adequately served its industry and was still regarded as an important document. The continued partnership between the NHS and the SLL is very important because the NHS must believe in the publication and the benefits it brings to their estates. LG2 is referenced and endorsed in the Health Technical Memorandum (HTM) series and the Health Building Notes (HBN). NHS England and NHS Improvement commends this document for its advice and guidance on healthcare-related lighting requirements. LG2 2019 has been totally revised, with many new sections giving advice on lighting

January/February 2020


application, but ultimately it should be remembered that the key objective of this publication is to define the quantity and quality of light and, more importantly, to encourage specifiers to replicate as close as possible the conditions under which we have evolved. While detailing good application and design principles, the publication promotes the importance of giving priority to daylight and then complementing it by electric lighting. This is because we know daylight to have unique and complex qualities which, to some extent are still not fully understood and, where the non-visual effects of light on health and wellbeing are concerned, cannot yet be replaced by electric lighting. Looking at the document in more detail, Part A: General Recommendations has been updated to account for current legislation and the modern way we light our health centres. In addition, the reference values given in Table 1 (General Lighting Schedule; Internal Lighting) have been updated and expanded to include all the new mental health sections, and generally harmonised with BS EN 12464-1. The text also reemphasises the importance of colour within a hospital environment, together with the increasing use of artworks and places of calm or worship within healthcare buildings, all of which need the harmonious balance of colour and light to be successful. The introduction of the design energy efficient rating (DEER) within the 2008 edition was intended to encourage better design practice and was more aggressive in its requirements, at the time, than Part L. However, it was never wholly embraced simply because it was more guidance than legislative so this has now been removed from the 2019 edition. Part B, Specific Recommendations, has been totally revised with greater emphasis on the creation of stimulating and exciting visual environments within the entrance and atria areas to match the current architectural trend for these spaces. More advice and guidance has been given for corridors and stair areas, along with greater emphasis on the need for uniformity. However, the publication also recognises that in practice certain areas and designs specifically benefit from a more relaxed level of uniformity which can be seen as comforting and homely, resembling the style of

Twitter: @sll100

Courtesy of Arup

ď ą Kinghorn Cancer Centre. Garvan Institute of Medical Research campus

lighting that may be found in hotel corridors. The section on ward lighting is probably considered the most important of the publication so great detail has gone into rewriting this, with greater emphasis on the provision of daylight within these areas. It also encourages the use of climate-based

daylight modelling to accurately determine its effectiveness and usefulness at delivering diffuse light into the space. In the previous 2008 publication the illumination levels given over the bed area were in line with BS EN 12464-1. This stipulated that the task-related requirement on the beds should be 300 lux with 60 per cent uniformity, which catered for simple nursing procedures, while examinations required 1000 lux at 70 per cent uniformity for medical treatment. In practice it was found that the uniformity was generally abused by the provision of something like 1000 lux at the pillow end and 50 lux (or lower) at the foot of the bed.

‘LG2 recognises that certain areas and designs specifically benefit from a more relaxed level of uniformity which can be seen as comforting and homely’



January/February 2020

Courtesy of Whitecroft Lighting


 Queen Elizabeth University Hospital, Glasgow

A lot of hospital trusts do not like this practice and find it uncomfortable for the nursing staff to work with. Therefore a lot of them have implemented their own standards by demanding that 300 lux be provided at the foot of the bed, not an unreasonable request given the accuracy and availability of luminaires and light sources in today’s market. So, the 2019 publication now recommends that 300 lux average be provided over the whole bed with a minimum of 150 lux at the foot of the bed together with a uniformity level of at least 50 per cent over the whole bed area. Unfortunately, night lighting is still seen as a bolt-on accessory to the main lighting and all too often poor and unacceptable night lighting designs are carried out. As a consequence they are usually switched off or the engineered solutions discarded, and staff implement their own makeshift solutions. Night lighting is still a very misunderstood


element of hospital lighting, so the section has been expanded to encourage the lighting designer to think of innovative solutions which help provide the balance between the provision of a good sleeping environment and meeting the needs of the nursing staff. In all previous LG2 publications the use of uplighting within a night-lighting solution was excluded because of the risk of introducing shadows or reflected images that can cause phantasmagoria in a number of patients. However, that number is actually very small and indirect lighting can bring a huge number of benefits, so LG2: 2019 removes this obstacle and encourages the use of indirect lighting, while providing caution to the designer to heed the warning that if an indirect method is employed they should ensure that no (or the absolute minimum) of shadows be produced by their scheme. With the increased coverage of mental health centres and institutions within the

publication reference is often made to antiligature fittings. However, no standard has ever been published that defines the term anti-ligature and while we all seem to have a good idea as to its meaning there is generally no consideration given to the luminaire’s appearance. As a consequence, designers and installers tend to go for IP 65 industrial grade luminaires that do nothing for the visual aesthetics of an area. The requirement for anti-ligature therefore needed to be adequately defined to try to avoid luminaire selection by default. In the absence of a universally acceptable definition, LG2: 2019 now provides a simple interpretation along with some guidance on evaluating suitable luminaires that may not be classified or intended for that purpose. Imaging suites and operating theatres are also now commonly installed in smaller cottage hospitals and even within some retail/commercial centres, so this section has been expanded and brought into line with BS EN 60601-2-41: 2009. The publication also includes a whole new section on highsecurity hospitals and mental health units together with a totally revised and expanded section on external lighting. With the ever-increasing portfolio of the NHS estates the need for energy efficiency is probably more important now than ever before but, not at the expense of a quality lit installation so LG2 contains a revised chapter on controls, light sources, luminaire construction and efficacies. Lighting Guide 2 (LG2) – Lighting for Healthcare Premises can now be downloaded in PDF form free of charge to members. It is also available in hard copy form for £26 (members) or £52 (standard price)

LG2 task group Chair and author: Nicholas Bukorovic, MBA Consulting Engineers Andrew Bissell, director of light4 Cundall Jemima Unwin, lecturer in light and lighting, UCL Nigel Monaghan, FSLL Tim Bowes, lighting technology development manager, Whitecroft Lighting

January/February 2020


 Tereos distillery, Lillebonne, France

TAKEN TO EXTREMES David Holmes outlines the main areas and issues covered by the SLL’s brand new guide focusing on lighting for arduous and abnormal environments


Twitter: @sll100

good place to start would be the luminaire manufacturer, in order to determine that a particular range of luminaires is capable of performing the tasks required of it. In order to provide good lighting conditions for any workplace it is necessary to consider carefully several points. Some of these points have gained more importance in recent legislation: • • • • • • • • • • • • •

The illuminance of the task The plane of the task Illuminance uniformity Modelling Obstruction Lighting of the general surround Surface reflectances Glare Colour properties Stroboscopic effects Photobiological safety Maintenance Energy consumption

Most of the situations for which we design lighting are within normal bounds of temperature and humidity. However, there are many environments where the luminaires are subject to one or more extremes. The guide aims to help designers and specifiers in choosing and applying the correct lighting systems for use in unusual situations where the environment will adversely affect the operation or performance of the system. The supplier or specifier needs to understand the impacts or restrictions each environment will pose on the luminaires and any supporting supplies and controls, so that they can mitigate these effects and provide a robust,

Courtesy of Sammode Lighting

here are so many different types of both buildings and industries in this modern age that it is sometimes difficult to envisage what may be classed as a ‘normal’ working environment. However, there are many installations where extra care must be taken when it comes to the choice of luminaire, due to either abnormal or extreme conditions within the working area. This new lighting guide is therefore divided into sections describing most of the arduous environments that the lighting designer or specifier is likely to come across. Each section considers some applications or types of area peculiar to that extreme type of environment. The list is not exhaustive, and reference should be made, in many cases, to a luminaire manufacturer rather than the application itself. An extreme condition has been taken to mean a building or a particular room within a building or, indeed, an external area, where people carry out any activity in conditions that could be harmful to either the safety of the individuals or the luminaires providing the artificial lighting, as well as where processes produce such conditions. There are, of course, many working areas where more than one extreme condition is present, and it is advised that all relevant sections are studied together so that a lighting solution can be found that will function correctly. If there is a particular use that cannot be found in this guide, then advice must be sought from a qualified body such as the Health and Safety Executive or the Fire Service, which have specialist officers dealing with most eventualities. However, a

safe, maintainable and long-lasting solution. It must be borne in mind also that the lowest cost luminaire may not be the cheapest solution over a long period of time. Making a higher initial outlay on luminaires that are designed to operate in certain environments, using the best materials, will usually be the less expensive option over time, when cheaper and less robust products may have had to be replaced or repaired several times. The guide features sections that look at each form of extreme condition in turn and describe the problems likely to be encountered and possible ways to compensate or protect against these conditions.


There are many environments that can be described as being ‘cold’. Theoretically, as luminaires for internal use are tested at an ambient temperature of 25°C, then any constant temperature below this would be regarded as cold. However, for the purposes of this guide, temperatures below 5°C are of more concern.



January/February 2020


 Maintenance hangar, Manchester Airport


Courtesy of

In the same manner as cold environments, any temperature above 25°C can be described as being ‘hot’. However, in most instances the hot or humid situation will be out of the control of individuals. Such internal areas will include production areas in factories where temperatures in excess of 40°C may be experienced. Steam laundries and sauna rooms are also areas where high temperatures are expected, this time combined with high levels of humidity.


As dust is present in all but specialist clean areas it is difficult to define what comprises a dusty environment. Under normal conditions where small amounts of non-combustible dust are expected a choice of an enclosed luminaire with an ingress protection rating of IP5X may be all that is needed. However, there are some environments that are normally very dusty and which, if dust is allowed to enter the luminaire, could be extremely dangerous.


Chemicals can have an adverse effect on all luminaires, the extent of which varies with the materials and chemicals involved. The types of areas that are pertinent here are large in quantity and must be looked at individually. An obvious application is any manufacturing process involving the use of chemicals either directly as their creation or indirectly as part of another process.

 A typical prison cell using cornice lighting


There are many instances where the lighting designer can enhance the ambience of a certain area or activity by placing specialist luminaires in water. It must be mentioned that any luminaire submersed under water is in a very alien environment.


Many industrial processes involve arduous atmospheres and it may be necessary to wash down the area on a regular basis. If the washing down process uses water jets then luminaires with a suitable ingress protection rating will be required. Clean rooms can consist of small cubicles or vestibules, or be very large facilities. They are found extensively in semiconductor manufacturing, biotechnology and other fields that are very sensitive to contamination. There are also clean rooms that are manufactured in modular form such that they can be installed and linked together.


Courtesy of Thorlux Lighting

Care must be taken when the lighting designer is proposing luminaires for use in a marine environment, due to the hostile conditions which can be prevalent. Such uses can be floodlighting of dockyards, container and cargo terminals, jetties and quaysides. In addition, any lighting involved with offshore oil rigs, mobile platforms and wind farm structures will also need special consideration due to movement and vibration.


There are basically two types of vibration. The first type is known as primary vibration


and is due to a luminaire being mounted on to a structure which is itself vibrating. The other type of vibration is known as secondary vibration, and this is due to an internal oscillation from the electrical circuit within the luminaire. Impact involves a collision between an object and a luminaire. The effect of that impact may be nothing at all, or catastrophic. Vandalism against luminaires is less easy to describe. It can range between a small amount of graffiti on a diffuser to complete disintegration of the entire unit.


It is important to point out that in addition to explosive environments, other arduous situations could be present, such as water, steam, high or low temperatures. Therefore, thorough investigation must be carried out prior to the design process. These sections are followed by sections on emergency lighting and remote lighting techniques. Technical information is then provided on lamp performance beyond standard temperatures and conditions in the form of a chart showing relative luminous flux due to starting conditions in various ambient temperatures. It is hoped that LG19 will be beneficial to many who are involved, directly or indirectly, with lighting design or maintenance of areas where extreme conditions are present. David Holmes is the author of Lighting Guide 19 (LG19) – Lighting for Extreme Conditions. It can now be downloaded in PDF form free of charge to members. It is also available in hard copy form for £23 (members) or £46 (standard price)

January/February 2020


BODY OF EVIDENCE The BRE has published the results of its study investigating the effects of dynamic ‘circadian’ lighting in a Norwich office he BRE Trust has published its report on the study it conducted recently into socalled circadian lighting (see Light Lines September/October). Lighting for Circadian Rhythms by Dr Paul Littlefair and Dr Cosmin Ticleanu outlines the experiment, funded by the BRE Trust and CIBSE Research Fund, and gives the conclusions drawn from the study, carried out in an openplan office space in Norwich, UK. The aim was to investigate the effects of dynamic lighting, and its timing, on human subjective assessments, activity and reported sleep. The study began by monitoring the existing installation, constant fluorescent lighting, for two weeks. At the start of March 2018 it was replaced with LED lighting. For the first week


this was maintained at constant light output and colour to allow participants to adapt to its appearance. Then the LED lighting was programmed to change dynamically, with the coolest morning setting at 6500K and the warmest (2700K) by 6.30pm. There then followed a further two weeks’ monitoring. Additional variable lighting conditions were introduced in the second phase of the project during November-December 2018. For the first two weeks the LED lighting was programmed to change dynamically in a different way, with higher EML (equivalent melanopic lux) values. Mean horizontal illuminances varied from around 600 lux at the beginning of the day to around 1120 lux in late morning and then back down to around 670 lux at the end of the day.

able 1: examples of vertical visual lux levels equivalent to 240 EML, T 200 EML and 150 EML for typical light sources of different correlated colour temperature (derived from the WELL Building Standard)

Light Source

Correlated Colour Temp

Visual Lux for 240 EML

Visual Lux for 200EML

Visual Lux for 150EML



533 lux

444 lux

333 lux



414 lux

345 lux

258 lux



316 lux

263 lux

198 lux



235 lux

196 lux

147 lux



218 lux

182 lux*

136 lux

*This represents melanopic equivalent daylight illuminance (MEDI)

Twitter: @sll100

Following this phase, the LED lighting was set to a constant light output and colour (4000K) to replicate typical office lighting (mean horizontal illuminance 480 lux, mean EML 149), and then was monitored for two more weeks.

RESEARCH FINDINGS Greater alertness The average scores for subjective alertness were significantly better with the new dynamic LED system than with the old constant fluorescent lighting. However, the comparisons of average subjective alertness scores with the LED systems set up to provide variable lighting and constant lighting revealed no statistically significant differences. Extra light not a factor Most participants felt more alert under the dynamic LED lighting compared to the constant fluorescent lighting, but this also happened for the small number of people who received less light (Condition 2; see overleaf for definitions of conditions). The increase in alertness did not depend significantly on how much extra light people had with the LEDs. All participants received more light with the dynamic LED lighting at a lower level (Condition 2) compared to the constant LED conditions (Condition 4), and the increase in light level was much more uniform across participants compared to the first conditions. However, the higher light levels in Condition 3 did not lead to higher scores, on average, for subjective alertness – only half of the participants felt more alert under the dynamic LED lighting (Condition 3).



January/February 2020


Condition 1: Old constant fluorescent lighting the office’s existing lighting (19 February to 2 March 2018)

Lighting for circadian rhythms

‘There is still considerable uncertainty about how much light is required for circadian entrainment’ Other factors not affected There were no statistically significant differences in test scores for reaction time, concentration and in sleep metrics between the two conditions tested in each phase of the project. Preference for dynamic lighting In each phase, participants were asked whether they would prefer dynamic or constant lighting. On average, just over half of them preferred dynamic lighting for their office, typically brighter in the morning and following the variation of natural light outdoors throughout the day. Just under one third preferred the constant lighting. More questions to answer Overall, there is still considerable uncertainty about how much light is required for circadian entrainment – in other words for a person’s circadian rhythm to align with the rhythms of light. People vary in their normal daily routines and in how much daylight they are exposed to. In addition, even in a space with ‘uniform’ electric lighting some people may receive significantly more light into their eyes than others, depending on which way they face. More research is therefore still needed to understand better the potential impacts of lighting on circadian entrainment and wellbeing in real-life situations – and how


Condition 2: New dynamic LED system with variable LED lighting at a lower level (12-23 March 2018)

Dr Paul Littlefair and Dr Cosmin Ticleanu Fire and Building Technology Group, Building Research Establishment Ltd.

Condition 3: New dynamic LED system with variable LED lighting at a higher level (12-23 November 2018) Condition 4: New dynamic LED system set up to provide constant lighting (3-14 December 2018)

best to quantify these in order to produce clear recommendations and guidelines for lighting than can support healthy circadian rhythms and wellbeing.

occupiers, and lighting designers, manufacturers and installers. It is free to download from: www.

In addition to summarising the results of the project, the BRE Trust report provides guidance on circadian lighting to building owners and

For the SLL position statement on circadian lighting, go to:

Table 2: examples of vertical illuminance of 250 lux at 8000K adjusted for other typical light sources of different correlated colour temperature (derived from DIN SPEC 5031-10023).

Light Source

Correlated Colour Temp

Adjusted illuminance



592 lux



425 lux



350 lux



560 lux



324 lux



304 lux



299 lux

Daylight D65


239 lux

*This represents melanopic equivalent daylight illuminance (MEDI)

January/February 2020

LR&T essentials

ROAD TESTING The latest papers from Lighting Research and Technology range from road illumination to the non-visual effects of light, discovers Iain Carlile paper by Fotios reviews the weightings made by the CIE in document CIE115:2010 in order to determine the P-class lighting design recommendations. P-class concerns lighting for minor roads. CIE115:2010 gives a number of parameters (travel speed, traffic volume, traffic composition, parked vehicles, ambient luminance and facial recognition) with weighting factors, with the summed weighting factor identifying a particular lighting class with average and minimum illuminance values. From a literature review Fotios identifies that some of these parameters are relevant due to their association with a pedestrian RTC (road traffic collision). However, the review was unable to substantiate the class selection process, due to a number of factors: little evidence of lighting needed to offset risks such as differing speed of traffic, whether weighting factors and intervals between options are relevant, and if parameter weightings are relevant. Further, Fotios notes that if the primary aim is to light for pedestrians, since the weighting factors tend to focus on the chance of a pedestrian RTC, with other factors not being represented (for example, discerning obstacles and hazards, identifying movement of other pedestrians) then the



weighting system gives false confidence to designers that their design is meeting pedestrians’ needs. Figueiro et al present the results of a case study investigating the application of lighting for non-visual effects on a building’s occupants. The authors note that laboratory studies have shown that (depending on the time of exposure) a sufficient amount of shortwavelength light and exposure duration can entrain or disrupt the synchrony between our biological clock and our local position on Earth. They have also shown that alertness can be enhanced both day and night by light across the entire visible spectrum. Using a novel luminaire designed to promote entrainment and alertness, field tests of light exposure were conducted in office environments. The results revealed that tailored lighting interventions can help entrain occupants and increase alertness during working hours (when properly applied). Siemiginowska and Iskra-Golec’s paper presents the results of a laboratory experiment investigating blue light exposure and EEG (electroencephalographic) activity, to see if a person’s chronotype could moderate the effect of monochromatic blue light. An experiment was conducted in which a group of 30 young male volunteers were exposed to two different lighting

P Siemiginowska and I Iskra-Golec 47,8 47,6

Power [μV]

47,4 47,2

Evening types PWL Evening types MBL


Morning types PWL 46,8

Morning types MBL

46,6 46,4


Afternoon Timing of exposure


 EEG theta spectral power band in two light conditions: polychromatic white light and monochromatic blue light (P Siemiginowska and I Iskra-Golec)

conditions of comparable luminance on room surfaces at eye level when seated. These were: monochromatic blue light (MBL) at 460nm, and polychromatic white light (PWL). After four hours of exposure, EEG measurements were taken in the morning, afternoon and evening. It was found that the blue light effect differs depending on the length of exposure and an individual’s chronotype. MBL had a significant influence on EEG activity in the afternoon hours in morning-orientated types. The authors note that the observed effect was only based on a study of young men, limited to a particular time of the day (afternoon hours) and chronotype (morning type), and as such the results should be treated carefully. Iain Carlile FSLL is the immediate 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 ( A review of design recommendations for P-class road lighting in European and CIE documents – Part 1: Parameters for choosing a lighting class S Fotios Light, entrainment and alertness: A case study in offices MG Figueiro, B Steverson, J Heerwagen, R Yucel, C Roohan, L Sahin, K Kampschroer and MS Rea Blue light effect on EEG activity: The role of exposure timing and chronotype P Siemiginowska and I Iskra-Golec

Figure 4 EEG theta spectral power band in two light conditions (LC): polychromatic white light (PWL) and monochromatic blue light (MBL) in morning-oriented (N ¼ 15) and evening-oriented types (N ¼ 15) after 4 hours of exposure (mean across the participants)

Twitter: @sll100 47,6 47,4


January/February 2020

Events Flow, Turkish Airlines Lounges, Istanbul, Softroom (Surface Design Award lighting finalist)


30 JANUARY SLL LightBytes: light and wellness Venue: Castlefield Rooms, Manchester 7 FEBRUARY CIBSE training: Emergency Lighting to Comply with Fire Safety Requirements Venue: CIBSE, Balham, SW12 11-13 FEBRUARY: SURFACE DESIGN SHOW, FEATURING LIGHT SCHOOL

11 FEBRUARY SLL and CIBSE Scotland Region: Technical Seminar on the Expanded SLL Lighting Handbook Venue: Edinburgh Training and Conference Centre 11-13 FEBRUARY Light School, Surface Design Show Venue: Business Design Centre, London light-school 13 FEBRUARY SLL LightBytes: light and wellness Venue: The Tetley, Leeds 8-13 MARCH Light and Building Venue: Messe Frankfurt 17 MARCH SLL and CIBSE Scotland Spring Lecture: Lighting outside the borders of standards Speaker: Henrik Clausen, director of Fagerhult Lighting Academy Venue: University of Strathclyde, Technology and Innovation Centre, Glasgow 21 MARCH Junior Ready Steady Light Venue: Rose Bruford College, Sidcup


24 MARCH Ready Steady Light Venue: Rose Bruford College, Sidcup

LightBytes The LightBytes Series is kindly sponsored by Soraa, Thorlux Lighting, Xicato and Zumtobel. For venues and booking details:

26 MARCH SLL LightBytes: light and wellness Venue: The Engine Shed, Bristol 16-17 APRIL CIBSE Technical Symposium: Engineering Buildings, Systems and Environments for Effective Operation Venue: University of Strathclyde, Technology and Innovation Centre, Glasgow 22 APRIL CIBSE West Midlands region: Lighting for Retail Premises SLL LG17 CPD seminar by Simon Robinson, WSP Venue: Birmingham Chamber of Commerce 23 APRIL SLL LightBytes: light and wellness Venue: Royal College of Physicians, Glasgow

LET Diploma: advanced qualification by distance learning. Details from or email CIBSE Training: various courses across the whole spectrum of lighting and at sites across the UK. Full details at