SLL may/june 2016

Volume 9. Issue 3. May/June 2016

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The disappearing act: the real invisibility cloak

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Setting the scene – the new guide to lighting controls 1

Editorial

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: Iain Carlile (chairman) MSLL Rob Anderson Jill Entwistle Chris Fordham MSLL Wiebke Friedewald Mark Ingram MSLL Stewart Langdown MSLL Gethyn Williams 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 NL4 2016 is 20 May Published by The Society of Light and Lighting 222 Balham High Road London SW12 9BS www.sll.org.uk ISSN 1461-524X © 2016 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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One of the more interesting aspects of the International Year of Light was the glimpse it afforded into different aspects of light. In our neck of the woods we see it more or less exclusively in terms of the visible spectrum, but actually the IYL focus was more on the cool science that is emerging from areas such as optics and photonics.

We will be featuring some of these subject areas in a series of articles by Juliet Rennie based on presentations given at the closing ceremony in Mexico.

She begins with a particularly fascinating area of research: invisibility. Professor Sir John Pendry, who holds the chair for theoretical solid state physics at Imperial College London, is among the pioneers in this (electromagnetic) field. He views the idea of making things invisible as a measure of what can be achieved in photonics. His ‘cloak’ might not be quite as literal as that of Harry Potter fame, but the idea of making fantasy reality is

compelling and shows yet again what a fascinating element light truly is.

Jill Entwistle jillentwistle@yahoo.com

LETTERS...LETTERS...LETTERS..LETTERS...LETTERS...LETTERS...LETTERS Your March/April Newsletter editorial and article about lighting in the developing world reminded me of a considerable amount of work we did on this in the early days of the Lighting Education Trust. LET was at that time looking to focus on four main areas of activity, one of which was known as LightAid. LightAid aimed to help communities in developing countries access lighting through solar power. The idea was to develop technical specifications for an array of solar panels that could charge some 50 lamps a day at a central location. Each evening local householders would be able to hire one or more lamps for the evening and return them the following morning for recharging.

The capital cost of lamps and charging stations (of approved design) were to be aided by grants from LightAid. The operation of charging stations provided a local business opportunity.

The rationale behind group charging stations was simple. Reports from aid agencies showed that the chiefs in many remote villages made a living by distributing the kerosene used by the villagers and they were, not surprisingly, more concerned about their income than either having better lighting or saving the planet. Hence the ‘local business opportunity’ meant that the chief could charge a small sum for recharging the villagers’ lanterns as a way of weaning him off kerosene. Gerry Brown, who was

instrumentally involved, was advised that, without such a sop, progress would be negligible.

As it happens, we didn’t get as far as having a chance to prove or disprove this perceived wisdom. During 2001/2002, Gerry and I with a couple of other well known ‘mature’ members of the industry met MPs, ministers, civil servants, aid agencies et al, getting much encouragement, even enthusiasm, until we mentioned that it needed funding. That then got us referrals and introductions to other departments who were bound to want to support it, particularly in relation to the Overseas Aid budget. Only they didn’t.

In parallel, we explored the technical side in some depth, getting considerable support and some initial product development from manufacturers of charging systems, solar cells and lanterns, including a prototype from Osram. Eventually, and with some reluctance, we had to give up when it was made abundantly clear that we would never ‘break into’ the aid business without showing that we were already a big charity with substantial independent income from donations. No existing aid agency wanted us muscling in.

Some 15 years later, I hope the SLL/ IoP event reawakened interest, with their proposals being taken forward. It is time for somebody new to carry the torch.

Hugh Ogus, MBE FCIBSE FSLL

Secretary’s column

Editorial

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Secretary’s column

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News

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Prize lighters 5 One team pulls off a double first at this year’s Ready Steady Light competition Setting the scene 8 Sophie Parry outlines the key areas that will be covered in the SLL’s new forthcoming guide on lighting controls, LG14

be made at www.seaha-cdt.ac.uk/seahaconference-2016/ We hope to catch up with many of you at the Lighting Design Awards on 5 May. It’s an honour to be present and represent the society at this annual awards ceremony, but this year is extra special with the Night of Heritage Light being shortlisted in the Heritage category. This is the first time that the society has entered a project in the awards and to be shortlisted is a great achievement. Fingers crossed for the night and good luck to all members who have entered the awards.

This is the first time that the society has entered a project in the awards and to be shortlisted is a great achievement

The disappearing act 10 In the first of a series of articles arising from the IYL closing ceremony, Juliet Rennie looks at Professor Sir John Pendry’s research into the invisibility cloak Shine and rise 12 Incoming SLL president Jeff Shaw on the spur that YLOTY gave to his professional life Shades of opinion 14 Looking at the current batch of LR&T papers online, Iain Carlile focuses on colour preference Living daylight 15 Cover project: the WWF Living Planet Centre, winner of this year’s CIBSE Lighting for Building Performance Award

We are very happy to support the work of our Sustaining Member Future Designs with its 25th anniversary competition, Design a Light. This is open to all, and I really mean all, whether you are in manufacturing, product design and development, lighting design, art, research, architecture, interior design or education, or indeed anything else. All proceeds will go to Sparks, the children’s medical research charity, and the deadline for entries is 14 July. bkeely@cibse.org

Photography: Matthew Andrews

It just gets better and better… We recently hosted the 14th Ready Steady Light competition with Rose Bruford College and for me it was one of the best years to date, with a full complement of teams from all aspects of light and lighting. Well done to all the teams that entered and, of course, the winners (full details on p5).

Thank you to all the supporters who took time out to meet with myself and the president, Liz Peck, at Light and Building 2016 in Frankfurt. As usual it was an epic show and we were run ragged for the entire time, but for us to meet and discuss our partnerships with so many at the same place and same time is of great benefit to the society. We hope that all those who attended had a great show and that we continue to have excellent relationships with our supporters.

We all very much enjoyed the first LuxLive Middle East exhibition last month in Abu Dhabi. To meet the existing members from the region as well as welcome new members to the society was personally very rewarding. Thank you to both our regional representative, Chris Ackers, and communications committee member Gethyn Williams for helping me with the stand duty, their help was much appreciated.

Final details are now available for the society’s 2016 awards night, presidential address and annual general meeting which will take place on Thursday 19 May in the Chamber and Viewing Gallery at City Hall, London. It will be a night to celebrate the society’s volunteers and award winners, as well as hear from our incoming president, Jeff Shaw.

The AGM will be Liz Peck’s final engagement as president and we thank her for what has been an amazing year.

It will be a great night and we invite you all to join us in this celebration.

Continuing our year of collaboration, we are delighted to announce that the society will be supporting the 2nd International Conference on Science and Engineering in Arts, Heritage and Archaeology (SEAHA), which will be held on 20-21 June 2016 at the University of Oxford, School of Geography and the Environment.

The conference will focus on heritage science research, innovation and best practice in the interpretation, conservation and management of cultural heritage. Lighting, of course, plays a huge role not only in conservation but also the viewer’s experience. The society will be represented with speakers at the conference and, of course, the exhibition. Bookings and enquiries can

Contents

Events

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

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NEWS...NEWS...NEWS...NEWS...NEWS...NEWS...NEWS...NEWS...NEWS...NEWS...NEWS...NEWS...NEWS...NEWS...

Services engineers could save civilisation, says Arup principal Building services engineers are the people who can save civilisation from the threat of climate change, Fiona Cousins told the audience at the CIBSE Annual Lecture at the Royal Academy of Arts in March.

‘It is obvious to anyone that climate change is the greatest challenge facing this generation and the next, and we have never had more tools available to help us fight it,’ said Cousins, principal at Arup New York. ‘Anyone can come up with grand designs, but it takes an engineer to ensure that they work.’

Citing examples throughout history of engineers using their skills to solve societal issues, Cousins said that engineers should not be afraid to use their expert knowledge to challenge people both in other professions and

On the lighter side...

Try sitting down in this. Apparently what some of us will be wearing this autumn/winter, Moschino’s two-tiered confection materialised on the catwalk at the Milan Fashion Week earlier this year.

The metal and Swarovski-crystal chandelier, complete with electric candles, forms a sparkling skirt over a simple black dress. It was conjured up by the fashion house’s creative director, Jeremy Scott, as part of his Burnout collection inspired

by Il Falò delle Vanità – Bonfire of the Vanities – which took place in Florence in the 1490s.

Presumably the wearer would need a special candela-bra underneath.

politics over issues such as sustainability and efficiency. It was also important to collaborate and avoid ‘siloes’, she said.

However, she said that this outlook will require engineering to change from within too. There is no room for ‘just good enough’ when tackling the greatest challenge in a generation, said Cousins.

Engineering professionals will have to commit themselves to push for the highest possible standards in themselves and others when creating projects that work and are sustainable.

‘As an engineer, you have all the knowledge necessary to save the world – what we need now is the confidence to be world leaders too,’ she said. ‘A good engineer is technically competent, a great engineer thinks how their role can benefit wider society.’

Nakamura says laser diodes are future of lighting Laser diodes are the future of lighting, according to green and blue LED inventor and Nobel Laureate Shuji Nakamura.

He has co-founded SoraaLaser, a spin-off from his existing GaN-on-GaN LED company Soraa, to exploit the technology, which he says has clear advantages over LEDs, OLEDs and traditional sources.

‘Laser diodes are droop-free, and can be combined with phosphors to safely produce highly directional output with superior delivered lumens per watt compared to other light sources,’ Dr Nakamura told Lux magazine in a recent interview.

Wilde is honoured

by Lightmongers

Barrie Wilde has been awarded a Master Certificate for his lifetime achievement in the profession by the Worshipful Company of Lightmongers.

‘It is exceptional for this rare award to be given to somebody who is not a member of the Company,’ said former Master Lightmonger Hugh Ogus.

Among his many achievements, Wilde is a former SLL president and recipient of the President’s Medal, and a director of BDP Lighting, which he established in 1988. For the past 10 years he has been principal tutor for the Lighting Education Trust (LET) and its distance learning Diploma in Lighting Design.

He was presented with his certificate by the Lord Mayor of London, Jeffrey Evans (pictured, left, with Wilde).

‘In the lighting profession, Barrie Wilde is one of those people that everybody knows,’ according to the citation. ‘His infectious enthusiasm and readiness to help has lit up many lives, including rallying many a struggling student to convert looming failure into a successful outcome.’

At the same event at Fishmongers’ Hall, one of Wilde’s former students, James Miles, was also the subject of an award, the Lightmongers’ Journeyman Certificate.

LIA opens new laboratories The Lighting Industry Association (LIA) has officially opened its new laboratory facility. Located in Telford, the 1160sqm purpose-built facility is the largest of its type in Europe.

It houses the latest state-of-the-art testing equipment, and employs more than 20 staff and technicians. The aim is to employ more than 60 skilled personnel within the next two years.

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The LIA Laboratories are the UK’s largest independent ISO 17025 test facility dedicated to lighting and an ISO 17065 (product certification) National Certification Body.

Events: Masterclass 2013/14 Events

Prize lighters One team pulled off a double first with two awards at this year’s Ready Steady Light

in Rose Bruford College’s Lighting and Design BA course also gave their support. Each year newcomers are welcomed to take part and members of the public are allowed to see the installations from 6pm until 8pm.

The SLL, with sponsor Philips, also organised the Junior Ready Steady Light competition, which took place on Saturday 19 March, three days before the main event, on the same site.

Following the first heat of JRSL, Rose Bruford College invited the six successful teams to participate in a full day of activities that led up to the final competition and prize-giving ceremony.

Teams are invited to enter from state schools, further education colleges and art organisations working with young people.

The Speirs and Major team achieved the double at this year’s Ready Steady Light, winning both the Best Technical Solution and the Peer Prize. The team’s scheme for the Old Stables showed some exemplary focusing with a doorway sharply defined in red light, while backlit foliage was used to cast shadowy blue light on the surrounding wall.

Winner of the Most Creative Effect award, Aecom went for a simple but highly effective concept, underlighting a bench between two trees, then introducing a narrow, blue diagonal beam of light across the scene.

‘In an interesting twist the artistic prize went to a team from an engineering office, Aecom, and the technical prize went to a team from an independent lighting consultancy, Speirs and Major, which may send a message to the profession as a whole,’ said Kevin Theobald, who led the IALD judges.

However, said Theobald, there was a danger that coloured light was getting overused. ‘Standards and innovation get better

every year, but I am not alone in thinking that the use of colour is now so ubiquitous that it may be necessary to introduce some curbs on its use. Having said that, there were some very clever and interesting schemes on show.’

Ready Steady Light, which celebrated its 14th year in 2016, is held in partnership with Rose Bruford College and supported by the IALD. Further support and equipment is provided by Philips, Lee Filters, Whitelight and Anolis. As well as the two winning teams, others taking part included Brunel, Future Designs, GIA Equation, Light Bureau, MID Lighting, Nulty+, Philips, Rose Bruford, Thorlux, Oddballs and UCL Bartlett.

Each team, led by an SLL member, is randomly allocated a site around the college’s Sidcup campus. As usual participants had to design and execute temporary exterior installations with a range of equipment in just 180 minutes. Students enrolled

Speirs and Major, shown with Liz Peck (second from left) picked up both Best Technical Solution and the Peer Prize

The Aecom team, with Kevin Theobald (right) won the Most Creative Effect award

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The teams at RSL had a day filled with warmth, fun and learning, but obviously with a competitive edge.

The diversity of the teams added to the spectacular results – Brendan Keely, SLL secretary

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Events

The scheme by the Speirs and Major team for the Old Stables that picked up two awards

The Oddballs

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Bartlett B, UCL

Events

Rose Bruford

FUTURE Designs

Aecom’s design won the creative award

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Lighting guides

Setting the scene Electric lighting is a big subject and one whose complexity has grown at a considerable rate as new technologies influence luminaire and lighting design.

Lighting control has been around for many years now and my own earliest recollections of lighting control stem from when I first entered the workplace in the 1980s as an eager young building services engineer. Then my typical lighting designs incorporated manual switching, time clocks and photocells for most projects. Intriguingly, one project, a drama studio for a university, required a desktop control console with a software-based means of creating lighting scenes. Sequences were coded on a separate disc that in turn was inserted into a disc drive on the console.

Those early design features are still found in lighting design and theatre lighting design, and controls are now quite rightly considered a separate and specialised branch of lighting, very much integrated with audio and special effects.

Fast forwarding to 2016, the technology, application and adoption of lighting controls have grown over the intervening years. Within the built environment, the growth in this area has been mostly driven by the need to save energy, as well as the new and exciting possibilities brought about by the integration of controls with IT and the internet.

Public and highways authority lighting control is also advancing, with wireless-based two-way communication being used to control individual street lighting luminaires to set light output, periods of operation, report faults and record energy use for fiscal billing.

In summary, the ongoing energy reduction legislation, low carbon project expectations and LED technology have taken automatic lighting controls from ‘nice to have’ to an essential part of the overall lighting design.

Lighting controls and lighting The term lighting control has different meanings to the stakeholders involved in evolving and developing a lighting design. An architect may interpret lighting controls as a means of controlling and making appropriate use of natural light entering a space. An electrical engineer may well add lighting control to a luminaire design to achieve energy efficiency compliance, while a lighting designer may add lighting control to address natural light, compliance, visual comfort and visual effect.

The common denominator for all designers is to start the lighting design process with the fundamentals of the right light, in the right place, at the right time. Once the luminaire-based design is complete, then the process of adding controls to the lighting scheme can begin.

This is where lighting design can get particularly interesting, because in order to add effective controls that meet the design brief (if there is one), various steps must be followed to gather the required information and apply it to the lighting scheme.

Notwithstanding the above, there are many different types

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Photography: Sophie Parry

Controls have now become an essential element in any lighting scheme, for both efficiency and visual effect. Sophie Parry looks at what aspects are covered by LG14, the SLL’s new lighting guide on the subject

A typical office lighting scheme using daylight linking from left to right in order to save energy

of lighting control available and inevitably these controls are bound up in jargon and terminology that often causes confusion, and can adversely affect the delivery of the agreed overall lighting intent.

Lighting Guide 14 (LG14) has therefore been structured to address the development and expectation management of the design development performance, together with the jargon and terminology, and also examine the more subtle but important subjects of human factors – lighting for architectural interest, comfort and energy efficiency.

The guide has also been framed to enable updates as emerging lighting control methods and technologies are introduced to the world of lighting design and are specified/ requested by project developers.

LG14 in detail Following an overall introduction in the first chapter, Chapter 2 provides an overview of the terminology used in lighting controls. This covers: •

Acronyms frequently encountered and supplemented with a brief explanation

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Modes of operation such as manual control, presence detection, absence detection, photo cells and scene setting

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Design features such as daylight linking, constant illuminance control

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Dimming and regulation

Lighting guides

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•

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Lighting for architectural enhancement and effect: the artistic side of lighting control Presentation spaces such as classrooms, lecture theatres where teaching wall screen glare can create a poor and inefficient learning experience for students Circadian lighting where a compatible lighting control system is used to shift the colour of white electric light in order to emulate the colour changes of daylight with the aim of providing the emerging benefits of lighting for health and wellbeing

Chapter 6 examines energy reduction through lighting control.

This is probably the main and only reason most people believe that lighting controls are a project requirement. It is true that well-designed automatic lighting controls can significantly contribute to lighting energy reduction, but by deliberately putting this chapter more than halfway through the guide, we are emphasising that the subject of controls is more than just about efficiency.

This chapter centres on the requirements regarding the application of lighting controls as found in the Building Regulations L2A and L2B, with the English versions being used for analysis although it is acknowleged that other regions have local versions. The first principles and examples are common to all EU countries/regions and stem from BS EN 15193: 2007 Energy Performance of Buildings. Energy Requirements for Lighting.

The examples show what information is required from the lighting controls design to apply the derating factors, and how to determine and account for parasitic lighting loads when undertaking Leni (lighting energy numeric indicator) calculations. There is also an analysis of BREEAM in respect of lighting/lighting controls.

Chapter 7 is concerned with integrated systems, and looks at the integration or interfacing of lighting control devices through a dedicated network. Also covered is the subsequent interfacing/information sharing with other systems

Photography: Kevin Stubbs

Chapter 3 looks at the approach to designing and developing a lighting controls specification by understanding the space, any client preferences/expectations and the development of the lighting scheme. This concludes with a list of the key aspects that would need to be considered, discussed and noted in order to manage the project expectation and apply the resultant design brief to the lighting design.

Chapter 4 provides food for thought on the subject of human interaction with lighting controls. This subject is often neglected and this chapter provides useful information on how lighting controls can be actually applied by end users in a space rather than them having to just accept a set operating configuration, which in many cases is totally automated with no scope for localised manual control or adjustment.

It is therefore important to recognise that lighting is subjective and may need a local control on an individual and/ or task-orientated basis as a means of meeting the end user’s needs. If this aspect is ignored, users often raise complaints and/or find ways to ‘defeat’ the lighting control system, which in turn provides no optimal lighting benefit to the space.

Chapter 5 covers lighting for visual effect and comfort, which is a part of lighting design that most people do not instinctively associate with lighting controls, as not all controls applications are designed with the prime purpose of lighting energy conservation. The main areas covered include:

Lighting control is increasingly used for architectural interest

such as building management systems. Another application for consideration is the incorporation of automatic testing/ monitoring of emergency lighting through a lighting control system. The chapter concludes with a few notes on the emerging subjects of PoE (Power over Ethernet) lighting and controls, an important area, and the use of the internet as a communications pathway.

Chapter 8 examines system commissioning and handover.

It explores the often overlooked requirement to ensure that lighting controls are optimised for energy reduction (where this is a design requirement). It also goes through the project handover process, to ensure that the end-user is aware of, understands the benefit of and is familiar with how to use the installed lighting controls.

The guide concludes with several case studies for common lighting control applications such as places of worship, classrooms, offices and highways lighting.

LG14 has been written by a group of lighting industry professionals from varying backgrounds that include design, consultancy, academia and manufacturing in order for it to take its place and complement the already established and evolving LG series, the source of so much good practice in the lighting industry.

Lighting Guide 14 (LG14): Control of Electric Lighting is scheduled for publication later this year Technical committee: Sophie Parry (chair) David Holmes Paul Littlefair Simon Robinson

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IYL closing ceremony

The disappearing act In the first of a series of articles that expands on the presentations at the IYL closing ceremony, Juliet Rennie looks at Professor Sir John Pendry’s research into the invisibility cloak Having read all of the Harry Potter books and being a big fan of the films, you can imagine my anticipation when, reading the programme for day one of the International Year of Light closing ceremony, I discovered that Professor Sir John Pendry Professor Sir John Pendry would be telling us how to create a real invisibility cloak.

Pendry holds the chair for theoretical solid state physics at Imperial College London, researching electromagnetic metamaterials whose properties owe more to their microstructure than to the constituent materials. Cited for his ‘seminal contributions to surface science, disordered systems and photonics’, Pendry received the Newton Medal, the highest honour from the Institute of Physics, in 2013.

His research, carried out in collaboration with Duke University, North Carolina, looks into cloaking materials that have the potential to make light flow around a concealed object.

In prefacing his presentation, Pendry said that he and his team wanted to introduce the idea of making something invisible as a measure of what can be achieved in the field of photonics.

Pendry began by introducing Snell-Descartes’ law of refraction, setting the scene for the development of a deeper understanding of how light behaves. Initially, the aim was to find a way to control light more precisely. Comparing light to water in a stream, Pendry used the example of placing a pencil into flowing water. The water would naturally flow around it, meeting on the other side of the pencil and a little way downstream, you would not be able to tell that the pencil was there. If you were to replace the water with light in this instance, the light would hit the pencil and scatter. Pendry explained that his team wanted to develop a coating to go around an object, which would allow light to flow around it in an even, curved way.

Combining his knowledge of Snell’s law and the known behavioural patterns of light, Pendry introduced electromagnetic induction, mathematically described in Faraday’s law of induction. Pendry paused here to joke about the irony of Faraday having limited mathematical knowledge, despite having shaped the modern understanding of mathematics – a joke not wasted on this particular audience. In developing a better understanding of electromagnetism in relation to manipulating the behaviour of light, Pendry discussed how Maxwell’s equations, with particular reference to generating and altering magnetic fields, also informed his research.

Additionally, Pendry observed how Einstein wrote the metric to Maxwell’s equations in his general theory of relativity, predicting

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Pendry wants to introduce the idea of making something invisible as a measure of what can be achieved in the field of photonics the deflection of starlight by the sun during a total eclipse.

Having referenced the fathers of modern optics in relation to his research, Pendry explained that the next challenge was to combine Maxwell’s equations, Snell’s law and Einstein’s theory of relativity, creating something that was easier to understand.

Illustrating his passion for the topic, Pendry went on to describe light as a ‘dance, the steps being the wavelength and the beat being its frequency or rate of change’.

For conventional stealth strategy, an object is black, meaning that it no longer reflects light. However, the object would still be visible to an extent, as it would have a shadow. Pendry and his team set out to hide an object behind a mirage, bending light around it. This could be done he explained, by grading the index of refraction in the cloaking material to bend light by exactly the right amount. Pendry explained that normal materials, such as glass, are not adequate for this task and as a result, he and his team needed to use a new class of material or meta-material, whose property could then be tailored to suit their needs.

The difference between a meta-material and a conventional material is that with a conventional material, its properties derive from its constituent atoms, whereas the properties of meta-materials are determined as much by their internal physical structure as by their chemical composition. These separate units can be engineered for a specific purpose.

The challenge, said Pendry, was to design a material for the screening zone, which had exactly the right refractive index to deflect radiation around the protected zone or object in the desired way. In order to do this, a technique had to be developed for reshaping the trajectory of rays so that they avoid the object that would be hidden, but still emerge from the volume of interest so that they appear not to have been deflected. This distortion would in effect create a hole, where an object could be hidden from view.

As meta-materials have to be fabricated with specific optical properties, which are not otherwise found in nature, this meant that the size of the cloaking region was limited to the micron level. In his work with the University of Birmingham and the

IYL closing ceremony

Rays of light are captured by a cloak and deviated around a hidden object. Observers on the far side of the cloak only see what is behind the cloak, therefore the cloak and hidden object are both invisible

Technical University of Denmark, Pendry assisted in the development of the widely publicised calcite cloak*. Calcite is a transparent material with birefringent or doublerefraction properties, meaning that when light enters the calcite it splits into two rays of different polarisation, travelling at different speeds and in different directions. As calcite is a naturally occurring crystal, the team was able to cloak much larger objects. The only limitation on the size of the cloaking region was the size of the calcite pieces.

The team created the Dr Shuang Zhang with whom calcite cloak by gluing two Prof Pendry worked on the widely publicised calcite cloak triangular pieces of calcite together and placing them on a mirror. This created a triangular region of free space on the reflective surface. Pendry compared the calcite cloak to a lens that works in the opposite way to a regular lens, making objects appear much smaller than they really are. If an object is made to appear small enough, it would in effect be invisible.

Returning to the cloaking potential of meta-materials, Pendry explained that this is not limited to the distortion or manipulation of light. In fact, depending on the precision with which these meta-materials are manufactured, their cloaking properties could be used for all other field lines, including lines of force. As a result, they could be used to negate the effects of electromagnetic radiation. Pendry went on to explain the impact

The professor described light as a ‘dance, the steps being the wavelength and the beat being its frequency or rate of change’ that this could have on medical procedures such as x-rays and, in particular, the interventional MRI scanner. Currently metallic instruments and other sensitive measuring equipment cannot be used with an MRI scanner, as it has such a powerful magnetic field. However, if these instruments could be contained within this cloaking device, they would not interfere with the scanner’s magnetic field.

Pendry said that the biggest impact of such a cloaking device is that it would also be able to operate across a range of frequencies, meaning that it could be tuned to shield objects at radio frequencies used by radar. He explained that cloaking fields using meta-materials excludes fields from inside the cloak and leaves the external fields undisturbed.

Far from the velvety cloak that enabled Harry and friends to roam the halls of Hogwarts after lights out, the invisibility cloak that Professor Pendry describes is more like a black hole, with no communication between the cloaked object and the outside world. *The research was published in the journal Nature Communications in a paper titled Macroscopic Invisibility Cloak of Visible Light. Co-authoring the paper were Shuang Zhang, lead investigator, Xianzhong Chen and Kyle Jiang from the University of Birmingham; Yu Luo and Sir John Pendry from Imperial College, London, and Jingjing Zhang from Technical University of Denmark

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YLOTY: where are they now?

YLOTY

Shine and rise: from presenter to president As Jeff Shaw, associate director of Arup, assumes the role of SLL president this month, he looks back on the spur that YLOTY gave to his professional life I applied for Young Lighter of the Year to try to make my mark in the profession. Having graduated in architectural engineering at the University of Leeds, I joined Arup in 1996 as a lighting designer – five years before Arup had a formal lighting design team. This meant that for the first few years at Arup, until we set up the lighting practice, I also had to ‘pretend’ to be a graduate electrical engineer with regard to job title and training.

It was this arrangement that meant that I always looked for ways to set myself apart as a ‘lighter’ – away from sizing cables and scheduling distribution boards. One such opportunity presented itself in the form of the society’s Young Lighter of the Year competition.

Taking part in YLOTY brought me confidence, which helped me as my career moved forward.

It also inspired me to become more active in the society In early 2001, at the age of 27, fast realising that I would not be ‘young’ for too much longer, I looked for a suitable topic to enter YLOTY; having not done a lighting-specific degree or MSc, I had no research project to fall back on. However, I had worked on the restoration of a small art space in Houston, Texas – the Rothko Chapel. It was a venue that the artist himself had a hand in designing, but that had never quite worked as a space in which to view the artworks he created for it, or in terms of optimal lighting for the conservation of those works.

The project required detailed analysis of the existing lighting, the development of a scheme to optimise the viewing and art conservation conditions, and further analysis to refine this

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and prove it as an approach. This involved some pioneering lighting analysis and visualisation work – including a number of interactive tools that I developed specifically for the project. My Young Lighter submission told the full story of the project – a real mix of art and science, with a focus on daylight (where all good lighting design should start).

The abstract I submitted was shortlisted, and I prepared a detailed written report. Based on this, I became one of four finalists. Then it came time to present. As is usual for me (the same is true for this article), I had left finalising the presentation to the last minute – looking at it today, I see that I last saved the PowerPoint file just a few hours before I presented it. I was fortunate in that presenting to large crowds did not intimidate me too much and that it was not my very first time (I had previously given a talk on daylighting at a CIBSE Technical Conference in October 2000).

At the time, there was no overall winner for YLOTY – all finalists received an award, but there were presentations for best written paper, awarded by the ILE (now ILP), and the best presentation on the night, awarded by the Worshipful Company of Lightmongers, of which I was the recipient. I am very thankful to Hugh Ogus, then Master of the Worshipful Company, who following this invited me to a Lightmongers’ dinner in the City, a white tie event attended by the Lord Mayor. I took my girlfriend with me as my guest, and she is now my wife (though I am not sure that I could honestly say that we got married as a direct result of YLOTY).

To those considering entering YLOTY I would like to stress that one enters any lighting-related topic – it does not have to be research, it just has to be interesting and to tell a story.

I was successful presenting a project that I’d carried out as part of my day job. The better you know your topic, the better the result will be; and do as I say rather than as I do – make sure you prepare well in advance for the presentation especially.

Ensure you are comfortable with what you are going to say, and are not reading from a script on the day. The more you practice, the better it will be.

YLOTY: where are theyYLOTY now?

Rothko Chapel in Houston, Texas, completed in 2000, and subject of the award-winning YLOTY presentation

Apart from the immediate financial reward of the prize money, taking part in YLOTY brought me confidence, which certainly helped me as my career moved forward. It also inspired me to become more active in the society. Within a short period of time I had gained sufficient experience for both MCIBSE and MSLL. My passion for spreading the word about lighting and educating the lighters of the future led me to join the SLL education and membership committee in 2004, under the chairmanship of Jean Heap. I learnt a lot from Jean during this period, and I took over as chairman of the committee after her unfortunate death in late 2007.

What experience and insight I gained over the years, starting with YLOTY and then later gleaned from Jean Heap and the education and membership committee, is what led to my part in the setting up of the now successful Jean Heap Bursary fund in her memory – another avenue for the society to support younger lighters in research and encouraging them to share the results of this to the wider community.

My long tenure as chair of the committee is now coming to an end, with my election as the next president of the society – my inauguration will be just over 15 years after my Young Lighter presentation. I’m assuming that this makes me very much an old lighter now.

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LR&T essentials

Shades of opinion Looking at the latest online papers from Lighting Research and Technology, Iain Carlile singles out studies on colour preference Lin et al postulate that colour preference varies with the lighting application. They undertook a psychophysical experiment using three different LED sources in three different applications: restaurant, retail display and a supermarket. From the comparisons made by observers, they found that colour preference for the three different LED sources was not the same in each application, and that none of the existing single value measures was able to predict the preferred source for each application. They note, however, that for the application of standards and guidance a single measure is still necessary.

They therefore suggest the use of a colour distortion icon to describe hue and saturation changes.

Szabó et al look at preferred colour rendering for shops.

They investigate the optimal LED spectral power distribution (SPD) for the lighting of different colour textiles, fruits and vegetables, meat and bakery products. The spectra of the LED light sources were tailored towards different colour quality metrics, such as the colour rendering index (CRI) and the colour quality scale (CQS), and small and large-scale experiments conducted to identify which metric best correlates to the observer’s preference. Based on their results they recommend optimal SPDs for retail environments.

Smet and Hanselaer investigate the application of memory and preferred colours to colour rendition metrics (which assume that colour rendition and quality improve when the colour of familiar objects is rendered more closely to what is expected or preferred). Four different visual appreciation and naturalness perception metrics were compared with psychophysical data. The authors concluded from their studies that naturalness requires higher object saturation levels than those provided by the CIE reference illuminants in fidelitytype metrics, but not as high as for visual appreciation.

Considering both art preservation and presentation in the lighting of paintings, Pridmore investigates the balance between cool-warm (bluish-yellow) lighting. He presents radiometric

Preferred colour rendering for shops: paired comparison results for textiles (Szabó et al)

The recommendations are made primarily for the balance between cool-warm appearance, colour diversity, clarity and contrast. While the author’s recommendations do not agree with all previous studies, they are closely supported by a number of other recent ‘preferred illuminant’ studies, adding to the debate as to the best way to light artworks.

Iain Carlile, MSLL, is an associate of DPA Lighting Lighting Research and Technology: OnlineFirst

While the traditional paintings is a CCT of 4000K or

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

less, the author’s conclusions

n Colour preference varies with lighting application Y Lin,

recommend 4500K-5500K

M Wei, KAG Smet, A Tsukitani, P Bodrogi and TQ Khanh

recommendation for lighting

and colorimetric methods of predicting cool-warm balanced illuminants. While the traditional recommendation for lighting paintings is a CCT of 4000K or less, the author’s conclusions recommend 4500K-5500K at 95-100 CRI. The reasoning behind this is that other illuminants (daylight or Planckian) have more power in their short or long wavelengths resulting in bluish or yellowish illuminants affecting the clarity of how the painting is viewed.

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n A study of preferred colour rendering of light sources: shop lighting F Szabó, R Kéri, J Schanda, P Csuti, A Wilm and E Baur

n Memory and preferred colours and the colour rendition of white light sources KAG Smet and P Hanselar

n Preferred illumination for paintings: Cool-warm balanced colour temperature predicted from radiometry and colorimetry RW Pridmore

Cover project

Living daylight Atelier Ten’s scheme for the WWF won this year’s CIBSE Lighting for Building Performance Award The WWF’s £20m Living Planet Centre in Woking uses natural daylight wherever possible to reduce dependence on artificial lighting and minimise energy usage. Maximising the use of natural light and an installed lighting load of 5.5W/sqm were significant contributors to the 90.66 per cent BREEAM pass mark which gave the WWF building an Outstanding rating.

The award recognises ‘innovative lighting design that delivers outstanding lighting quality for occupants and most effectively demonstrates energy efficiency’ – CIBSE The main office space is over two levels – a lower level beneath a mezzanine podium level – each space requiring a different lighting treatment. The curved timber diagrid roof with embedded skylights is designed to bring in as much daylight as possible – there is an average daylight factor higher than two per cent in all naturally daylit spaces – but brought its own challenges for aspects of the artificial lighting at podium level. Pendants clashed architecturally with the clean lines of the ceiling, which restricted the lighting to a limited number of positions within the diagrid itself.

After modelling the space and collaborating closely with the architect, Atelier Ten came up with a recessed downlight solution. Bespoke inclination adapters for the fittings to match the varying angles of the ceiling ensure seamless integration.

At the time of design LEDs could not provide the necessary punch so CFLs were used, but fittings allow for an upgrade to LEDs. LED uplights are mounted at the springing point of the ceiling to provide a soft wash to the diagrid at night.

The lower office space had to be flexible to allow for varying work patterns and use. The solution here was a grid of linear suspended fittings that underline the building’s architectural grid. The 28W T5 fittings were produced to a custom length, and give an average illuminance of 300 lux. Each pair of Daliaddressable fittings is controlled by a photocell/occupancy sensor for daylight and presence control.

There is a high degree of individual control, within BREEAM requirements, with both desk-based task lighting and an app that allows users full control from their PC or laptop.

Project: WWF Living Planet Centre, Woking Lighting design: Atelier Ten Architect: Hopkins Associates Contractor: Wilmott Dixon Electrical contractor: Des Electrical

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EVENTS...EVENTS...EVENTS...EVENTS...EVENTS...EVENTS...EVENTS...EVENTS...EVENTS...EVENTS...EVENTS

2016 5 May Lighting Design Awards Venue: London Hilton, Park Lane http://awards.lighting.co.uk

19 May SLL AGM and Awards Venue: Chamber and Viewing Gallery, City Hall, London SE1 www.sll.org.uk 24 May Technical Meeting – LG7: Office Lighting (SLL Scotland) Presenter: Simon Robinson, technical director, WSP/Parsons Brinkerhoff Venue: 3 Rothesay Terrace, Edinburgh Time: 6.30pm-8.30pm www.sll.org.uk 24-26 May Smart Lighting 2016 Venue: Milan Marriott Hotel, Milan www.smartlighting.org 26 May SLL Masterclass Inside Out: Lighting and Architecture Location: The Royal Society, London www.sll.org.uk 9-12 June Guangzhou International Lighting Exhibition Venue: China Import and Export Fair Complex www.lightstrade.com/exhibition/ 15-16 June Professional Lighting Summit (Organised by the ILP) Venue: The Waterfront Hotel, Brighton jess@theilp.org.uk 20-21 June SEAHA: 2nd International Conference on Science and Engineering in Arts, Heritage and Archaeology (Supported by the SLL) Venue: School of Geography and the Environment, University of Oxford www.seaha-cdt.ac.uk/seahaconference-2016/ 19 July How to be Brilliant (Organised by the ILP) Speaker: Peter Veale, director of Firefly Lighting Design Venue: Marshalls Design Space, EC1 www.theilp.org.uk/brilliant

19 May: SLL AGM and Awards, City Hall, London

28 September How to be Brilliant (Organised by the ILP) Speaker: Lee Barker-Field, head of lighting design, Aecom Venue: Marshalls Design Space, EC1 www.theilp.org.uk/brilliant

Lighting Masterclasses: Masterclasses are kindly sponsored

by Philips, Thorn, Trilux and Xicato.

For venues and booking details : www.sll.cibse.org

27 October How to be Brilliant (Organised by the ILP) Speaker: Filip Vermeiren, founder and director of Inverse Lighting Venue: Marshalls Design Space, EC1 www.theilp.org.uk/brilliant 9 November Fundamental Lighting Course (Organised by the ILP) Venue: Regent House, Rugby jo@theilp.org.uk 13-15 November IALD Enlighten Europe Venue: Prague Marriott Hotel, Prague www.iald.org 23-24 November LuxLive and lightspace dot London Venue: ExCel, London http://luxlive.co.uk 14 July Deadline for the Future Designs Design a Light competition, supported by the SLL, in aid of children’s medical charity Sparks. The winning design for a children’s light will be announced at the Sparks Winter Ball on 30 November. www.sparks.org.uk/event/competitiondesign-a-light-for-sparks/

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

Photography: www.cgpgrey.com

11 May How to be Brilliant (Organised by the ILP) Speaker: Paul James, mondo*arc Venue: Marshalls Design Space, EC1 www.theilp.org.uk/brilliant