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Newsletter Volume 10. Issue 3. May/June 2017

The Society of Light and Lighting

Part of the Chartered Institution of Building Services Engineers

BODY CLOCK WATCHING Why lighting design needs to move to the next stage

THE COMFORT ZONE How poor lighting damages a company’s greatest asset



Secretary Brendan Keely MSLL bkeely@cibse.org SLL Coordinator Juliet Rennie Tel: 020 8675 5211 jrennie@cibse.org Editor Jill Entwistle jillentwistle@yahoo.com Communications committee: Gethyn Williams (chairman) Rob Anderson Iain Carlile MSLL Jill Entwistle Chris Fordham MSLL Mark Ingram MSLL Stewart Langdown MSLL Linda Salamoun Bruce Weil 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 NL 3 2017 is 22 May Published by The Society of Light and Lighting 222 Balham High Road London SW12 9BS www.sll.org.uk ISSN 1461-524X © 2017 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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As an editor it is always gratifying to discover a theme and it was clear that one was coalescing at quite an early stage with this edition of the Newsletter. The workplace is the ‘light’ motif and our cover scheme (a shortlisted project for the Lighting Design Awards) graphically encapsulates just how much that has come on since the days when serried ranks of desks required serried banks of fluorescent light fittings. This scheme is refreshingly radical in using Par 38s to uplight the ceiling. Colour rendering and CCT were carefully considered in creating a DMX-controlled system which cycles through different colour temperatures according to time of day. Because on top of all the other factors now involved in lighting the workspace – where we have moved from typewriter

to tablet and from back office to breakout space – we now have to consider the relationship between lighting and our circadian rhythms, with their direct bearing on our sense of wellbeing. With all the labels that are being bandied about from ‘human centric’ to ‘biodynamic’, the impression is that this is an apparently straightforward matter. But as Inessa Demidova asks (The rhythm of light, p7), is it really enough to fiddle around with the CCT and dimming levels and call it job done when we are dealing with something as complex, subtle and unfathomable as the human circadian system? And as usual are we trying to pin down with prescription something that is unquantifiable? Clearly, as with everything else, continuing research will bring some clarity but there is unlikely to be a simple answer when human beings are so individualistic. In the meantime, it is important to explore the possibilities while avoiding the faddish. What it ultimately boils down to though is creating a comfortable working environment, as Iain Macrae discusses (Why the workplace is a comfort zone, p10). Both Demidova and Macrae agree that while there are unknowns, the basic principles of good lighting practice will always apply. If we put people first, we shouldn’t go too far wrong. Jill Entwistle jillentwistle@yahoo.com

Current SLL lighting guides SLL Lighting Guide 1: The Industrial Environment (2012) SLL Lighting Guide 2: Hospitals and Health Care Buildings (2008) 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) LATEST SLL Lighting Guide 0: Introduction to Light and Lighting (2017) Guide to Limiting Obtrusive Light (2012) Guide to the Lighting of Licensed Premises (2011)

Secretary’s column

‘The technical and publications committee have been busy and we now have the new Lighting Guide 0, an introduction to lighting, together with Factfile 12 on thermoplastics’ us should you no longer wish to receive your benefits of membership. We are always interested to hear from you and your input is appreciated. Meanwhile, we welcome Sill Lighting UK as the latest company to join our Sustaining Member programme. Please feel free to contact us should your organisation wish to take part in the programme and receive the benefits of membership. We have a report on Round III of The Challenge 2017 speaker competition in this issue (see News, p4) and have also added details to the news and features section of the website. The finals at the PLD-C in Paris (1-4 November) are not far away, and we wish current president Jeff Shaw well with his team. And finally, good luck to all those members of the society who have projects shortlisted for the Lighting Design Awards 2017. We look forward to meeting many of you on the night on 4 May at the London Hilton, Park Lane. bkeely@cibse.org

Editorial2 Secretary’s column


News4 Pure skill The 15th Ready Steady Light event celebrates basic engineering and design


The rhythm of light 7 We know about the body clock, but the challenge for lighting designers now is to move beyond simply dimming and CCT tuning, says Inessa Demidova Why the workplace is a comfort zone 10 Based on his Masterclass presentation, Iain Macrae looks at ‘comfort management’ in office lighting design Perception and perspective 13 Maida Hot, managing director of GIA Equation, looks back nearly 20 years to winning YLOTY Focus on hue and eye 14 Iain Carlile finds colour is a key theme in the latest online papers Cover project 15 Shortlisted for the 2017 Lighting Design Awards, Tillotson Designs’ scheme for a New York ad agency uses biodynamic lighting

Photography: John Muggenborg

We are really looking forward to the 2017 AGM, Presidential Address and Awards, starting at 6pm on 25 May at The Royal Society in London. We hope that many of you will be able to join us to celebrate with our award winners and, of course, hear the presidential address from incoming president Richard Caple. It promises to be a varied and enjoyable evening, and is always a great opportunity to catch up with fellow members. Many thanks to all of the 13 teams who joined us for Ready Steady Light 2017 at Rose Bruford College, in Sidcup (see p5). This year’s event was very enjoyable with the sun shining and highly enthusiastic competitors. Congratulations to all the winners: Future Designs who took the Peer Prize, WSP Parsons Brinkerhoff who lifted the Technical Prize and Light Bureau who won the Artistic Prize, supported by the IALD. Many thanks to our partner, Rose Bruford College, their students who delivered the event, and this year’s sponsors who provided the indispensable lighting equipment: Philips, Whitelight, Lee Filters and Erco. The technical and publications committee have been busy (they are always busy, of course) and we now have Lighting Guide 0, together with the new Factfile 12 available on the website, both free to download by members and non-members alike. LG0 is an introduction to lighting so if you know of people who could benefit from the guide please do pass on the links. Factfile 12 tells you all you need to know about thermoplastic diffusers in luminaires and fire safety. You will find all of the Factfiles very useful in your dayto-day design work. The next Lighting Guide, LG15 on Transportation, is imminent. Another upcoming publication is Factfile 9 which details the 2016

update to the Building Regulations and all the relevant documents in England, Scotland and Wales. We approach the last Masterclass of the 2016-2017 season at St Martinin-the-Fields on 18 May. The Knowledge Series: Human Responses to Light has been very popular and we thank all those who have attended over the series. We also thank our supporters: Holophane, Thorn, Trilux and Xicato for their input. Many thanks to all who have renewed their annual subscriptions and those who have contacted us regarding upgrading their membership to Associate (AMSLL) and Member (MSLL). We have been happy to assist with your membership upgrade process. As the deadline date for 2017 subscriptions looms we encourage those who have not renewed their membership to do so or contact



For up-to-date information follow us on Twitter @sll100




Society team wins through to Challenge final for second year

The team of SLL president Jeff Shaw (above) featuring Marina Lodl of Brazil/ USA, is one of the six through to the final of The Challenge. This will be held at the Professional Lighting Design Convention (PLD-C) from 1-4 November in Paris. Lodl’s presentation is The Urban Underground – a sequence of adaptation. The other finalists are Team Koert Vermeulen mentoring Gregor Gärtner of Germany; Paul Traynor with Zhoufei Ren of China/USA; Thorsten Bauer and Anuj Gala of India/ Finland; Anne Bureau and Aditi Govil of

India/USA, and Paul Gregory with Ana Teodora of the UK. Topics range from colour blindness (Ren) and media facades (Gala), through to lighting for autism (Teodora). This is the second year of the competition and again with the SLL as a Knowledge Partner. The winners of the 2015 contest, Pernille Krieger and Eik Lykke Nielsen from Denmark, with their presentation on lighting for the elderly, were coached to the finals by SLL secretary Brendan Keely. Round III of The Challenge speaker competition 2017 took place in February at Brunel University (below).

SLL launches lighting guide and new Factfile The SLL has published a new lighting guide, LG0 Lighting Guide 0: Introduction to Light and Lighting, with Paul Ruffles as lead author. LG0 starts by looking at the issues that affect the quality of lighting and task performance. It also examines how light affects behaviour, safety, and perception of objects and space, as well as covering health, cost and pollution issues. A new Factfile has also been introduced. Factfile LF12: Thermoplastic Lighting Diffusers and Fire Safety is authored by incoming president Richard Caple. It reviews the requirements set out in the Building Regulations in

England and relevant documents in Northern Ireland, Scotland and Wales relating to the use of thermoplastic materials, which are commonplace in lighting fixtures. The next Factfile to be published will be an update to Factfile LF9: Lighting and the 2010 Building Regulations, including the 2016 amendments in England and relevant documents in Northern Ireland, Scotland and Wales. The publications are free to download from the Knowledge Portal by members and non-members.

Keynote lined up for major SEAHA/SLL museum symposium

by the Centre for Doctoral Training in Science and Engineering in Arts Heritage and Archaeology (SEAHA) and the SLL. The aim is to bring together academics, researchers and professionals from across the world to discuss current research in the field, which is viewed as currently being at a crossroads. ‘LED technology has created new opportunities and poses new

Florence Lam, Arup’s global practice leader for lighting design, will be a keynote speaker at the first Museum Lighting Symposium this September. The London event is co-organised



On the lighter side... The piece of cod that passeth all understanding. This idea of making lamps out of dried fish actually first surfaced in 2001 but for unfathomable reasons someone decided to dredge the idea up for DesignMarch 2017 in Reykjavík, Iceland, according to Dezeen. Designers Fanney Antondsdóttir and Dögg Guðmundsdóttir adopted the Icelandic tradition of drying whole fish to create their somewhat peculiar forms of illumination, installing lamps inside the dried skins of large 1m-long cod. The fish are caught and skinned by hand before being reshaped to resemble their original form. The skin is then hung up to dry in the open air. Originally established by the Vikings, the technique still persists in rural areas to prepare Harðfiskur, a popular Icelandic snack. ‘We took a poetic approach and made the fish into an installation of lights,’ Antondsdóttir told Dezeen. Known as Uggi Lights, there are apparently a small number that can be purchased. Don’t all rush.

www.cibse.org/knowledge challenges for colour and vision science, conservation and visitor engagement,’ says SLL secretary Brendan Keely. The conference will take place at UCL from 11-12 September. Registration is now open (closing 31 August), with reductions for students and members of the SLL and The Colour Group (GB) https://museumlightingconference.com

Events: Masterclass 2013/14 Event

Pure skill Ready Steady Light celebrated its 15th anniversary by going back to basic engineering and design

Future Designs celebrated its second success at Ready Steady Light in three years by winning the Peer Prize, while WSP Parsons Brinckerhoff won the Technical Prize and former winner Light Bureau the Artistic Prize. Now in its 15th year, the competition took place as usual at Rose Bruford College, Sidcup, in March and focused on a return to basic engineering and design. This year 13 teams competed against each other, including Llumarlite, Light Projects, Marcus Stefan Lighting Design, DPA, Bartlett (A and B teams), Into Lighting, Arup, Studio 29, Philips and Hoare Lea. Each team was allocated a site around the college campus at random and then had to light it in its natural state with designated equipment, with the additional challenges of no budget and within the time constraints of 180 minutes. Jointly organised by the SLL and Rose Bruford, the event was supported by students enrolled in the college’s lighting and design BA course. Further support and equipment were provided by Philips, Lee Filters, Whitelight and Erco. The judging panel for the Technical Prize was chaired by SLL president Jeff Shaw, while SLL president elect Richard Caple chaired the Artistic Award on behalf of the IALD. ‘This competition is a celebration of the lighting profession in its purest form, with a problem to be solved and just the designer’s own skill and creativity to work with,’ said Shaw. ‘This year’s entries were very impressive. We were particularly struck with the sensitivity to the environment displayed, with great control of light and colour.’ Junior Ready Steady Light, also sponsored by Philips, Lee Filters, Whitelight and Erco, took place three days before on the same site. The teams from state secondary schools took part in a day of activities before the final competition and prize-giving.

Artistic Prize: Light Bureau

Technical Prize: WSP Parsons Brinckerhoff

‘Ready Steady Light is a great way to show young lighters what fabulous design can be achieved with very little by a skilled lighter, and hopefully it will inspire them in their careers as they develop’ – Jeff Shaw, SLL president

Peer Prize: Future Designs




Scheme by Bartlett A team

Future Designs team

MS Lighting

Light Bureau team

WSP Parsons Brinckerhoff team



Hoare Lea Lighting’s scheme

Circadian biology

Rhythm of light

We know about the body clock, but the challenge for lighting designers now is to move beyond simply dimming and CCT tuning, says Inessa Demidova

One of the main points of confusion at the moment is the plethora of terms describing this new approach to lighting. Terms such as human-centric lighting, tunable white, biologically active lighting and circadian lighting are used by different organisations with varying meaning. To help clarify this, we have developed the following definition within our team: circadian lighting strategy. This approach supports the human need for light and darkness cycles to positively impact the human circadian system. This strategy should include both natural and artificial lighting and take into account the changes in colour spectrum, intensity and direction over the course of a day. Trying to define the specifics of this approach, we started looking at the metrics. We have found that at the moment there is no agreed spectral sensitivity function for circadian response.


Lack of specialist input from circadian biologists on specifying lighting systems

Lack of agreed metrics and definitions Limited equipment availability (for instance, tunable spectrum lighting, wallwashers and narrow-beam spotlights) Increased controls and commissioning complexity Energy demand implications and compliance with existing energy codes Potentially compromised aesthetics and user experience


Recent discoveries in circadian biology have expanded our understanding of the importance of light in sustaining healthy biological rhythms in our bodies. The challenge now is defining the optimal way of practically applying lighting design to benefit circadian rhythms. How do we integrate this new knowledge to deliver projects that are meaningful for the health and wellbeing of the occupants we are designing for? From a lighting practitioner point of view, we would like to be able to use the science to create an applicable guidance to realworld situations. The question then emerges – what is the state of the science? What are our ‘knowns and unknowns’? Having completed an extensive overview of current academic papers on the subject we have found that ‘the established knowledge in this field is still premature’ (CIE Statement on NonVisual Effects of Light) and that ‘it is not yet possible to predict the non-image-forming impact of a given illuminant based on its intensity and spectral composition’ (Measuring and using light in melanopsin age by Lucas et al.) In addition to a complex and ever-evolving science, we have identified the following challenges that need to be addressed:



Circadian biology


t Furthermore, surface reflectances and spatial distribution of light across a space will be even more important, as it is the amount of light reaching the photoreceptors across the retina that has to be measured rather than the traditional surface illuminance. For this reason, using lighting design metrics such as cylindrical illuminance and mean room surface exitance (MRSE) would be a better way to predict the amount of light reaching the retina and triggering circadian response. However, we believe that adding awareness of the non-visual effects of light and its effects on our circadian rhythms can bring significant improvements to the experience of light and spaces in architecture. We can use this knowledge to: Create healthier environments Harmonise spaces to be aligned with the natural circadian rhythm Support activity-based lighting Alleviate symptoms of ‘social jetlag’ Design with a new ‘time’ dimension Advocate for dynamic lighting, where a ‘lighting plot’ is developed Provide for flexibility and personal control However, we would advise that lighting design should not be equated with light therapy. Light has a powerful influence on human biology and recommendations on light therapy should be explored and developed together with health specialists. Current recommendations are presented here to raise awareness of the non-visual effects of light and imagine how these can be applied in a more meaningful way across the built environment. Taking into consideration the challenges and opportunities we have identified, four fundamental principles have been formed: Holistic lighting design Lighting should never be considered in isolation but as part of



an architectural solution that takes into account the parameters of the spaces concerned, the activities undertaken at various times throughout the day and the profiles of people in it. We are therefore suggesting a holistic approach to the traditional objectives of architectural lighting: Optimise visual performance Complement the architecture and space Consider the environmental impacts on wildlife Minimise energy use Add a new category: health and wellbeing It is suggested that the effects of light on circadian rhythms should be incorporated into the set of design principles that are relevant to this category.

‘All sources and types of light contributing to retinal irradiance should be acknowledged for their influences on circadian rhythms’ Daylight first Electric lighting alone cannot provide all the benefits offered by exposure to daylight and should be considered in terms of supplementing and extending its functions. Daylight is the form of light naturally best suited for circadian entrainment. Depending on the exterior local climate and environment, and on the interior tasks and activities, the daylight design will optimise orientation and introduce shading to exclude glare and solar gain, balancing it with maximising openness and direct views to enhance the visual experience.

Circadian biology

We can introduce more daylight penetration into the building, especially those areas used in the morning by many people such as entrance halls and coffee points. We can maximise the opportunities to experience daylight both indoors and outdoors in various bursts throughout the day by creating daylight focus zones such as meeting areas and break-out spaces near windows, facades and atria. Electric lighting should support and supplement the changes and variations in the daylight spectrum and intensity throughout the course of the day, as well as its spatial distribution. All-light-sources-considered approach All sources and types of light contributing to retinal irradiance should be acknowledged for their influences on circadian rhythms. A holistic circadian lighting solution should integrate daylighting, architectural lighting and electronic display lighting into a coordinated experience that is responsive to the circadian needs of the human body.


Right light at the right time Given the lack of agreed metrics and individual differences, there cannot be a simple prescription for any particular amount of light that will be suitable for all people. Not only do activities and tasks vary throughout the day, but also people have a wide range of individual characteristics and light sensitivity. For instance, it is particularly unclear how circadian lighting models should cater for individual differences in circadian phases – on a single office floor the wake/sleep cycle can vary significantly depending on an employee’s age, lifestyle and commute pattern. A sensible approach would be to follow principles of good lighting design, minimise any possible risks to health and wellbeing (flicker, glare) and maximise access to daylight. For example, in the morning and daytime, for the majority of applications use light sources that are rich across the spectrum, especially in the blue region. Where possible, maximising daylight access can be a suitable strategy for this approach. In the evening, use light sources that have a spectral distribution lower in the blue end to support relaxation and prepare the body for sleep.These aspects have to be considered in conjunction with spatial distribution of light, intensity and room surfaces. On the subject of technical lighting considerations, our psychological and physiological reactions to light are much more complex than certain specialised cells in our eyes reacting to the saturation of 480nm wavelength light coming from a source. Can we really claim we are emulating natural conditions simply by adjusting CCT and brightness?

Design recommendations should consider the spatial distribution of light, spectral power distribution, temporal patterns of light, the personal conditions of the occupants/requirements for customised lighting controls and current technological offerings for such applications. Further to that, it is proposed that we reconsider the way lighting design guidelines and metrics are set – taking into account illuminance reaching the retina rather than a task surface, as well as qualities of light beyond intensity and correlated colour temperature.

‘On a single office floor the wake/ sleep cycle can vary significantly depending on an employee’s age, lifestyle and commute pattern’ For future development, we would like to point out emerging professional building standards such as the WELL Building Standard, which considers non-visual effects of light and includes a requirement on circadian lighting design. While we believe this is a step in the right direction, we have identified three main issues with it: The circadian lighting design criterion is very specific on a vertical melanopic lux calculation – 4hrs, 250 melanopic lux at 1.2m facing forward if daylight is to be taken into account. This has significant repercussions for the design, implying very high levels of illumination, and might be difficult to reconcile with approaches such as Cat A office fit-out design, where no furniture layout is provided In addition to that, while the use of daylight is promoted, in dense urban developments where daylight availability is lower, this requirement may enforce higher artificial illumination levels and thus compromise energy performance Furthermore, using melanopic lux and an irradiance toolbox could be a case of prematurely using metrics that have not yet been proven and established We definitely support the general values of the WELL Building Standard but hope its requirements will be adjusted and improved in future versions. In conclusion, the circadian dimension poses new challenges to lighting design practice and has to be approached sensibly, with an understanding of the current unknowns as well as technological limitations. However, it also provides exciting new possibilities to improve the built environment, and with further research could lead to creating spaces that are synchronised with human biology in a more meaningful way. Inessa Demidova is a lighting designer with Arup. This feature is based on a presentation she delivered at ‘Uchronia’, a recent Women in Light and Lighting event, which focused on circadian issues and was hosted by Arup London on 21 March 2017. For more information on Women in Light and Lighting contact Helen Loomes at h.loomes@trilux.co.uk @sll100


SLL Masterclass 2016-17

Why the workplace is a comfort zone

Based on his presentation for the latest Masterclass series, Iain Macrae looks at the priorities for achieving a well-balanced office lighting scheme In some offices, employees are clearly suffering. The common symptoms they display are headaches, eyestrain, low mood, poor concentration, unhappiness at work, even a feeling that they are misunderstood. Many of these symptoms may be affected by light; more specifically it is suggested that these symptoms are directly affected by the following: Looking at digital screens Reading without pausing to rest the eyes Activities involving extended focus Being exposed to bright light or glare Straining to see in very dim light So poor lighting could lead directly to lower performance by a company’s most valuable asset: its people. Traditionally we have used part of the construction ratio to justify why people are so important. The first part of this ratio is construction cost. To save here you might design using cheaper products, of lower quality or shorter lifespan. Or you could perhaps use products that are easy to purchase and

that make the installation and commissioning processes easier. The second part of the ratio is about maintenance. For every £/€ spent on construction, the ratio suggests that we spend five on maintaining the building. Simple and easy replacement of building components is one way to save, but ensuring that the luminaire operates effectively for a long time is even better. Or it could be through long service intervals, for instance using onepiece designs that remove the need for cleaning or accessing the inside of the luminaire. The final part of the ratio is about people, our employees. The cost of staff over the lifetime of a building is significant, originally suggested at 200 times the construction cost. Staff cost varies as part of the business operating costs, but examples in the EU show staff costs are around 90 per cent of operating costs for a typical office (1:5:200). Fundamentally, though, this ratio has proved to be wrong. Recent research rejects this and suggests a ratio of 1:0.4:12 is more realistic . But what is clear is that getting the best out of your staff is paramount if a company wants to get value for money in business. Even Richard Branson recognises this: ‘If the person

Good communication is about sending and receiving messages: with the increase in connected devices used in offices, we have to think about new measures current in the market relating to colour and contrast



SLL Masterclass 2016-17

The Task: the light on to a surface where an activity is being undertaken or performed The Space: the light that reveals the surroundings in which the task is being performed The Face: the human element, the light that reveals expression and body language, because communication is vital to people and that is about revealing the right visual stimuli and conveying accurate facial signals Good communication is about sending and receiving messages, 80 per cent of which are visual, so good lighting for the human rather than our equipment should be the priority. Good vertical illuminance is important throughout an office space, including break-out spaces and conference rooms where communication is the primary activity. It’s also important to see the facial expressions of colleagues against a balanced background (including both colour and light), as this will determine how well our message is received. So light for communication should incorporate all these elements. Light has to reveal our face, with just the right amount of shadow, so that we can read expression across a room, across a video feed and perhaps across many faces. The light needs to reveal and balance the background surfaces, so that contrast is not too high. At the same time we are likely to be reading or taking notes and our lighting has to allow us to see our notebook or use our touch screen. With the increase in connected devices used in offices, we have to think about a few new measures current in the market relating to colour and contrast. First, colour, defined as the measure and impression of the colour composition of light viewed by people and by technology. We can argue about existing and proposed metrics – Ra, Rf, Rg and CCT – we’ve had these discussions. But let’s introduce TLCI, the Television Lighting Consistency Index, the measure of the ability of light to provide good camera images without the need to balance or adjust the camera. It’s a property of the light source and the optical effect on the spectral output. We can

generate it simply for all light sources using free software. But why should we include it? Communication in offices, and indeed at home or the ‘coffee shop’ office, needs good light colour quality. Given that the camera takes, processes and transmits the image that we see across our smart device, it’s important to know that we are creating the best quality image in the first place. At least we should make it easy for the camera to reproduce what is being seen. Our second problem is flicker. The variation of contrast through time. Remember that time and movement impact our ability to detect flicker. Our eyes don’t focus on one spot. The eye builds up a picture by constant movement – research suggests this ocular microtremor (OMT) can be as high as 120 movements a second. There is no clear conclusion as to why, but OMT may be used to calibrate or compare or provide finer resolution for the brain. Flicker that is slower than this

‘Poor lighting could lead to lower performance by a company’s most valuable asset: its people’ may confuse our vision. Poor lighting with flicker is detectable especially as you move your eye quickly across a room. The question we face is how to define flicker limits so that people do not suffer ill effects. Research doesn’t agree, even with recent recommendations. There is evidence that the eye can detect transitional effects of flicker up to 800Hz, but single receptors in our eye do not act alone, so we still need to investigate a precise recommendation. It’s also not clear if frequencies above 200Hz actually make it to the brain. The current standards from Public Health England recommend >15 per cent flicker factor (FF); IEEE1789:2105 suggests 100Hz at <3 per cent FF for no observable effect, but then also a 162Hz minimum. What if we can detect and process flicker up to and above 800Hz? When we consider technology, say a typical modern camera, <6 per cent FF is normally acceptable for slow motion, so in the case of flicker the human-centric approach is still more demanding. Screen manufacturers know there is a problem, or perhaps have recognised an opportunity. Projection standards for years sat at 60Hz, recently 100 or 120Hz. Now monitors are produced with refresh rates as high as 240Hz, and the public are reportedly impressed with the image quality and comfort levels. If display screens produce improved comfort we should consider lighting, camera and display in our future office comfort. It’s worth noting that as we near 100 per cent PC saturation, our technology is becoming more user friendly but more of a challenge for lighting. In flicker it might be the interference between lighting frequency and screen refresh rates. What is clear is that tablet and smartphone use continues to grow. 81 per cent of office staff reportedly use them in daily work. For the first time in 2015 there were more users with mobile devices globally than those with access to a desktop PC. More and more of these are used in team environments, sharing content in ways we couldn’t at the turn of the century. The transition has been fast and most staff now use @sll100



who works at your company is 100 per cent proud of the brand and you give them the right tools to do a good job, and they are treated well, they’re going to be happy.’ Lighting at work is one of those vital tools that contribute to people doing a great job. So we have a number of problems in offices. It could be outof-date lighting or even modern and high-glare lighting, and we know poor lighting contributes to poor comfort for employees and affects their performance. To correct for these mistakes, first we have to think about lighting in office spaces as being about more than just the luminaires or simply lighting the desk. I would recommend a lighting framework, perhaps 12 ways of thinking about light, the people and the space that would encompass performance, efficiency and comfort. As other Masterclass presentations have examined aspects such as efficiency, I am focusing on the third element, comfort. So what’s the first key to good illumination? Fundamentally it’s about lighting the important surfaces in a space within the view of your staff: the walls, displays, the desk, books, keyboard, screen, the face, and the space surrounding the task area, for the benefit of our colleagues and perhaps the camera. This can be simplified into three main components:

SLL Masterclass 2016-17


modern software on modern high-brightness screens. Even recommendations such as Lighting Guide 7 have caught up. However, staff incidents of back problems are still increasing and ergonomics will be a driver away from simple laptops and poorly positioned screens to lighter more mobile devices, a clear benefit to our health. This trend requires clever lighting, great modelling, light to the task, space and face, reduced glare and also controls that allow you to adapt the lighting to the situation. If we light from above and direct light down we get harsh shadows under the eyes, around the mouth, nose and chin. Often this form of lighting gives rise to a dark background and makes it difficult to read faces. Modern optics designed to lift the face and the space should give less shadowing and a lighter background by avoiding a harsh cut off and deliberately playing light to the walls. Looking at the three images of the same man in different lighting conditions (see below), you can agree that in the image on the left he looks aggressive, even angry. By the time we get to the right-hand image we have lifted his face to one that we can read easily. Now the apparent anger has been revealed as concentration, he is listening intently. We have done this by considering those three fundamental aspects of light. In this case the task is clearly seeing his face, but the space behind him can’t be ignored either. If we light only for the desk surface our light and view will be focused on the desk. Our colleagues will be poorly revealed and the walls often dark. Overly intense light sources, luminaires, skylights or windows will give rise to glare. We’ve known for half a century that glare can be a problem either directly or through reflection. Modern trends to glossy screens can pose a problem, especially as we tend to use them at odd angles. But the very fact that we can move tablets easily and that most business laptop screens are matt finish means

the intensity of the luminaire is less of a problem than before, especially when the luminaire is designed with this in mind. Control of the brightness of the light source and across the luminaire (recessed or surface) is vital to controlling glare both for the eye and the computer screen. While recessed luminaires cannot add light directly to the ceiling, the flow of light they generate and the reflected light within the space makes a difference. Using a combination of recessed, surface or suspended luminaires designed to light the task, the space and the face, we can meet the most demanding of customer needs. Modern luminaires need to hide the light source or at least mitigate its brightness to comfortable levels. We can do that with careful LED positioning, controls and optics. We did it with other light sources, LED should be no different. The balance of brightness across a luminaire and on to the ceiling is every bit as important now as it was and we shouldn’t forget the lessons learned in the past. Comfort management is a combination of efficient optical design combined with good design practice, counterpoising the light for task, space and face – providing just the right balance for the people we value most at work, our staff. This feature is based on a Masterclass presentation given by Iain Macrae on behalf of Thorn Lighting, a Sponsor in Partnership of the Society of Light and Lighting. Iain has subsequently moved to work as application director at Wila Nordeon UK Exposing the myth of the 1:5:200 ratio relating initial cost, maintenance and staffing costs of office buildings. Will Hughes, Debbie Ancell, Stephen Gruneberg and Luke Hirst, School of Construction Management and Engineering, University of Reading 1

Lighting conditions directly affect how we interpret facial expression, in this case ranging from apparent anger (left) through to what is actually intense concentration in the third image, where there is a more balanced lighting composition



YLOTY Where are they now?

Perception and perspective Maida Hot, managing director of GIA Equation, looks back nearly 20 years to a turning point in her career In 1999 the lighting community was quite small – a distinctive combination of over-50s (I need to be careful here) equipped with more theoretical lighting background, coupled with a rising number of younger lighting designers, passionately striving to further pave the way for a fully recognised profession which could be viewed as a necessity on a project team. There were two key factors in making my decision to apply for YLOTY: already having some base material from my recently completed MSc in Light and Lighting at the Bartlett (1996-1998) and nearing the end of my 30s. No thought of a potential career benefit crossed my mind then. My entry into a lighting career was first inspired by a lighting lecture at the Bartlett back in 1994, a year after my graduation from a five-year long MA in electronics engineering, nothing at all to do with the built environment. I had originally wanted to study architecture, but chickened out from doing it with the excuse that I was not good enough at hand sketching, and science was a much easier option for me. My secret hope was that I could combine both, and that lecture opened my eyes – voila – I can actually do it, they do not exclude each other. At that time I was training to be a ‘well-rounded’ services engineer in a creative engineering company called Fulcrum Consulting. They supported me to go for the MSc in light and lighting and pushed me all the way to heading their Illumination Department at the end of my studies. They also encouraged me all the way to becoming a chartered engineer in the same year, showing their full commitment to professional development. My YLOTY paper was based on my studies of the perception of brightness in the complex visual environment. I chose the beautiful, historically rich St Martin-in-the-Fields church in Trafalgar Square as a case study. It was before its renovation and the interior lighting was based on a rather standard church approach with bright chandeliers providing almost all the illumination. Neither was there an abundance of daylight. I was extremely lucky that Dr Kevin Mansfield knew the then Reverend Nicholas Holtam (now Bishop of Salisbury) and I could have exclusive access to the church to carry out the studies – various user group questionnaires to collect subjective responses combined with quantitative measurements using a luminance scanner together with a point luminance meter. The perception of brightness, darkness and glare were explored in the study. The guidance from the Bartlett teaching staff, Peter Raynham and Dr Stephen Cannon-Brookes, was invaluable.

The results were not entirely surprising, but for me it was a turning point in realising how the various lighting guides can be misinterpreted, and how much more lighting research was needed to further explore human perception of light and translate it into good practice. Winning YLOTY in 1999, along with my dear Bartlett friend David Robertson, was great fun and gave me further confidence in pursuing my professional career in lighting. Perhaps that had something to do with NDY approaching me in 2000 to head up NDYLIGHT in London. After 10 years of working there with a great team and realising lighting schemes for some amazing projects across the globe, honing both design and consultancy skills, it was then time to move to a firm solely dedicated to full lighting consultancy. Heading up GIA Equation gives me the chance to increase the time I’m involved in actual lighting design, my true passion. It is a daily joy to be working with our talented and extremely dedicated team. One of the crowns for our efforts was an IALD Award in 1995 for the external illumination of the Knightsbridge Estate in heart of London (pictured below) and we are going from strength to strength. It is still rather disappointing that a relatively small amount of lighting research is carried out considering the significance of light in people’s everyday lives. Although the importance of lighting is now well recognised, credible independent research and its translation into quality lighting practice is a long way from matching its significant role. The lighting community needs to keep providing both artistic and scientific fuel to the profession to translate lighting designers from Tier 2 to Tier 1 consultant on the projects. As a base support of this, more good quality YLOTY submissions are vital. I very much hope many young lighting designers out there will gladly take on the challenge.



LR&T essentials

Focus on hue and eye Iain Carlile finds that colour is a key theme in the latest online papers In the fourth part of their paper considering colour preference, naturalness and vividness assessments, Khanh et al investigate the effect of different correlated colour temperatures (CCT) and colour saturation levels on the test subjects’ personal assessments of still-life arrangements. Four different CCT values were used (3100K, 4100K, 5000K and 5600K). From the results of the experiment, the authors identify that CCT preference significantly depends on subjective judgement. Xu et al’s paper presents the development of a colour discrimination index (CDI), considering important applications where discrimination is important, such as surgical procedures, industrial inspection and museum lighting. Two psychophysical experiments were conducted, one using images on a computer display and the other in a real-life application, using images and biological materials respectively. The results of the experiments were used to develop a CDI to predict the discrimination capability of a light source. The CDI model incorporated three parts: overall colour difference, CCT and a reflectance dataset based on Munsell samples. The authors also found that three wavelength regions (425nm, 505nm-525nm and 660nm) were effective in enhancing the colour discrimination. Wang et al looked at optimising the spectrum of LEDs to improve the texture visibility of biological tissue. The method of optimisation was based on comparing pairs of colour patches using images of biological tissue and maximising the perceptual colour difference between them. A psychophysical experiment was conducted to evaluate the proposed method. The authors found that illumination spectra that were optimised according to human perceptual colour differences significantly improved tissue texture visibility when compared to illuminants such as CIE D65 and an LED light source with a CCT of 5500K. Also considering the spectra of LED light sources, Hytönen et al examine the effects on growth and nutritional composition of lettuces grown in greenhouses under artificial lighting at northern latitudes. The effects of LED lighting with different spectral compositions were investigated, comparing growth, development and nutritional quality of lettuce. It was found that,

in the absence of daylight, 2700K warm white (WW) sources and warm white supplemented with blue spectra (WWB) provided equal growth and product compared to conventional high-pressure sodium lighting. Results also showed that the far-red component in the light spectrum is more critical than green light, and that a red and blue spectrum increased the concentration of vitamins in lettuce. However, biomass accumulation was insufficient when daylight was excluded. The results of the investigation may have the potential to improve the nutritional quality of greenhouse crops. Iain Carlile, MSLL, is an associate of DPA Lighting 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) Colour preference, naturalness, vividness and colour quality metrics, Part 4: Experiments with still-life arrangements at different correlated colour temperatures TQ Khanh, P Bodrogi, QT Vinh, X Guo and TT Anh The development of a colour discrimination index L Xu, MR Luo and M Pointer Optimising the illumination spectrum for tissue texture visibility H Wang, RH Cuijpers, IMLC Vogels, M Ronnier Luo, I Heynderickx and Z Zheng Effects of LED light spectra on lettuce growth and nutritional composition T Hytönen, P Pinho, M Rantanen, S Kariluoto, A Lampi, M Edelmann, K Joensuu, K Kauste, K Mouhu, V Piironen, L Halonen and P Elomaa

The effects of LED light spectra on lettuce growth and nutritional composition (Hytönen et al)



Cover project

Par lamp for the course Shortlisted for the 2017 Lighting Design Awards, Tillotson Designs’ scheme for a New York ad agency combines retro with cutting edge

‘The lighting solution is both forward thinking, yet quotidian in spirit’ – Tillotson

Photography: John Muggenborg

The lighting scheme for the New York HQ of US ad agency R/GA echoes the minimal white interior in aiming ‘to paint the backdrop for creativity to thrive’, says Tillotson. The customised light fittings, primarily clusters of LED Par 38s, are simple and unorthodox in an environment typically dominated by linear LED and fluorescent fittings. Each coffer in the waffle-slab ceiling is uplit with a retrofit Par 38 LED lamp. 10,000 lamps were bundled into groups of four, an arrangement repeated throughout multiple floors. ‘The Par 38 lamp employed is humble in form, but powerful in impact,’ says Tillotson. ‘This complex lamp married with a clean, simple socket strikes a fine balance. The lighting solution is both forward thinking, yet quotidian in spirit.’ A carefully orchestrated composition of LEDs allows good colour rendering and colour change. For maximum flexibility, a DMX control system communicates wirelessly to each zone of lamps through an area network. The system mimics natural ryhthms throughout the day, shifting from a colour temperature of 2700K in the mornings, through to 4000K at noon and gradually back to a warmer temperature in the evening. There is also a facility to override the system to incorporate colour and alternative programmes for special events. Lighting can also be used as an indicator of occupancy and/or space. The open office space is interrupted by conference ‘huddles’, meeting pods that are each lit from above using direct linear LED fixtures which backlight the polycarbonate perimeter panels and provide ambient light to each room, matching the overall colour temperature throughout the day. ‘The proprietary technology uses a variety of LED diodes to tune and perfect colour combinations,’ says Tillotson. ‘Shades across CIE colour space are produced with astounding colour rendering capability. Colours are both vivid and complex because they are derived from a rich combination of sources. Multiple shadows are eliminated because the light has been blended to perfection. The result is beautiful light with a single clean shadow.’ Lighting design: Tillotson Design Associates Architect: Foster + Partners Arup Cosentini Associates




2017 4 May Lighting Design Awards Venue: London Hilton Park Lane http://awards.lighting.co.uk 9-11 May Lightfair International Trade Show and Conference Venue: Pennsylvania Convention Center www.lightfair.com 10 May Fundamental Lighting Course (Organised by the ILP) Venue: Regent House,Rugby jo@theilp.org.uk 12 May Lighting for Health and Wellbeing (SLL and HCNW lighting paper including a look at the WELL Building Standard and LG7) Speaker: Sophie Parry MSLL Venue: The Quaker Centre, Milton Keynes www.sll.org.uk 15-19 May Exterior Lighting Diploma Module 3 (Organised by the ILP) Venue: Draycote Hotel, Rugby dip@theilp.org.uk 16 May Lighting for Good Exploring ethics in lighting, democracy in design and Stem among other activities (Organised by the ILP) Venue: Marshalls Design Space London EC1 jess@theilp.org.uk 18 May Masterclass: Lighting Knowledge Series Human Responses to Light Venue: St Martin-in-the-Fields, Trafalgar Square, London WC2 www.sll.org.uk 23 May Electric Know-How for Architectural Lighting Designers (Organised by the ILP) Venue: BDP, Clerkenwell, London EC1 jess@theilp.org.uk 25 May SLL AGM, Presidential Address and Awards Venue: The Royal Society, London SW1 www.sll.org.uk 25 May How to be Brilliant (Organised by the ILP) Venue: Marshalls Design Space London EC1 jess@theilp.org.uk

25 May: SLL AGM, Presidential Address and Awards, The Royal Society, London SW1

9-12 June Guangzhou International Lighting Exhibition Venue: China Import and Export Fair Complex, Guangzhou www.light.messefrankfurt.com.cn

Lighting Masterclasses: Masterclass: The Lighting Knowledge Series is kindly sponsored by Holophane, Thorn, Trilux and Xicato. For venues and booking details: www.sll.org.uk

14-15 June Professional Lighting Summit (Organised by the ILP) Venue: Crowne Plaza, Glasgow jess@theilp.org.uk 20-22 June Immersive Art: lighting culturally significant works of ar (Workshop/seminar by Via Verlag) Venue: Art History Museum, Vienna www.via-verlag.com/ 20 July How to be Brilliant (Organised by the ILP) Venue: Marshalls Design Space London EC1 jess@theilp.org.uk 11-12 September Museum Lighting Symposium (Organised by SEAHA and the SLL) Venue: UCL, London WC1 https://museumlightingconference.com 1-4 November Professional Lighting Design Convention Venue: Palais des Congrès de Paris http://pld-c.com 15-16 November LuxLive 2017 Venue: London ExCeL http://luxlive.co.uk 16 November Lux Awards 2017 Venue: InterContinental London â&#x20AC;&#x201C; The O2 http://luxawards.co.uk

LET Diploma: advanced qualification by distance learning. Details from www.lightingeducationtrust.org or email LET@cibse.org CIBSE Training: various courses across the whole spectrum of lighting and at sites across the UK. Full details at www.cibse. org/training-events/cibse-cpd-training LIA courses: details from Sarah Lavell, 01952 290905, or email training@thelia.org.uk For up-to-date information follow us on Twitter @sll100

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SLL May/June 17  

SLL May/June 17