Page 1

Volume 8. Issue 3. May/June 2015


Emergency measures: the new LG12

n MRSE: a

winning young lighter’s perspective



Secretary Brendan Keely MSLL SLL Coordinator Juliet Rennie Tel: 020 8675 5211 Editor Jill Entwistle Communications committee: Iain Carlile (chairman) MSLL Rob Anderson Jill Entwistle Chris Fordham MSLL Wiebke Friedewald Mark Ingram MSLL Stewart Langdown MSLL All contributions are the responsibility of the author, and do not necessarily reflect the views of the society. All contributions are personal, except where attributed to an organisation represented by the author. Copy date for NL4 2015 is 15 May Published by The Society of Light and Lighting 222 Balham High Road London SW12 9BS ISSN 1461-524X © 2015 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

Produced by

I remember being at a lighting conference years ago when architect Piers Gough, one of the speakers, suggested that we really ought to rethink office lighting. Why does it have to be the same linear fluorescent (then) fittings? he asked. Why can’t we have chandeliers if it makes for a pleasantly lit environment? The feathers being ruffled in the audience were almost audible and one person noisily and pointedly gathered up his plastic bags of brochures and headed for the door. I suspect that the project featured on the front cover might prompt a similar response in some quarters. Paper globes are clearly an exceptional response to a particular client brief and environment, but there is a basic principle here. So much in the office environment is about prescription and conforming to norms rather than providing a solution that dares to be different while fulfilling the specific requirements, environment and needs of the people that work there. Kit Cuttle has famously called for a rethink in the way that office lighting is approached with his proposal that we move away from the preoccupation with the horizontal plane, focusing instead on whether or not the users of a space are likely to judge it to be sufficiently and pleasantly lit – perceived adequacy of illumination, as he has coined it. PhD student James Duff has picked up Cuttle’s torch and is currently researching the viability of the mean room surface exitance metric. Winner

Printed in UK


Jill Entwistle

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 Outdoor Environment (1992)

SLL Lighting Guide 7: Office Lighting (2005) – (including Addendum) 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 (2004) SLL Lighting Guide 13: Places of Worship Guide to Limiting Obtrusive Light (2012)


of the Best Presentation in the 2014 YLOTY awards, Duff distills his essential argument for the new approach in this issue (A journey towards change, p8). We look forward to reporting on his results when they are published. There has been a shift from the horizontal to the vertical in recent years, but with the much-anticipated new LG7 coming out later this year, it would be good to see a healthy reappraisal of the standards that have governed office lighting for many years. After all, when you look at recent award-winning schemes for PwC and other corporate heavyweights, it’s remarkable how many chandeliers, domestic-style pendants and table lamps have crept in of late.

Guide to the Lighting of Licensed Premises (2011)

Secretary’s column

Spring. Well it is for our UK and northern latitude members but we say a happy autumn to our antipodean friends. If you didn’t manage to get to the 200 Years of Fresnel lecture in March (see p4) there’s good news. The presentation by Peter Phillipson with HRH The Duke of York (UK Patron International Year of Light 2015) in attendance was recorded and we’re busy editing it now. We will release some video nuggets before the final presentation is loaded on to the CIBSE YouTube channel and let you know when this is available. Also in March we attended the Lighting Design Awards en masse and congratulate all of our members on their achievements on the night. This year’s Ready Steady Light (see p5) was one of the best so far and for most of the day dry. The society’s links with Rose Bruford College continue to be strong, and we also attended the Junior Ready Steady Light competition with entrants from colleges as far away as Norfolk (Norfolk City College won the award for the second time). A special thank you to the supporters of the event, including Philips, iGuzzini, Zumtobel, White Light and Lee Filters. We had the pleasure of hosting the SLL’s Masterclass in Edinburgh Castle and Watershed Bristol in March and April respectively and will end the series Light for Life in London at the Royal Society of Arts on 14 May. Bookings can still be made through the website. The series has been very well received with high quality presentations from our Sponsors in Partnership: Helvar, Philips, Thorn and Trilux, as well as our guest speakers John O’Hagan and Luke Price from Public Health England, and Iain Ruxton of Speirs and Major. The theme of health and wellbeing has generated a great deal of debate, especially during the Lighters’ Question Time. The next series will be themed on light and architecture. We recently welcomed Franklite to our Sustaining Member programme. The Sustaining Members are from both design and manufacturing, and receive hard copies of all SLL publications, access to the SLL publications on the CIBSE Knowledge Portal, use of the SLL’s Sustaining Member logo, their logo on our website supporters’ page and at Masterclass presentations, a free delegate place at a Masterclass, as well as advanced drafts of the publications and an opportunity to comment prior to the final draft. This is an immense package and all at a cost of just £750 + VAT a year. Should anyone wish to


Editorial 2 Secretary’s column


News 4

know more information in relation to the programme please do let me know John Aston will host the AGM on 21 May at RIBA, London. This will be John’s last event as SLL president and an opportunity to thank him for all his hard and inspirational work these past 12 months. The same evening will see Liz Peck accept the presidency. We encourage all members to attend for what promises to be a great evening. We are currently looking for members to volunteer to join the Lighting Research and Technology editorial board. Should you wish to know more details please contact me by 15 May. We are also looking for contributors to the new SLL Retail Lighting Guide, again for more details please contact me by 22 May. The CIE’s 28th Sessional meeting will be held in Manchester on 29 June and the SLL is delighted to be supporting the event. We will be in attendance for the full week and the conference promises to be an inspirational opportunity for learning and knowledge transfer. For anyone with outstanding membership subscriptions you will be contacted soon for the final payment opportunity before being lapsed. We thank all members who have paid and encourage all remaining members who have not paid their subscriptions to continue their support of the society and maximise their benefits. Finally, the entry deadline for Young Lighter of the Year 2015 is 8 May. The competition is one of our major annual events, and entries are welcome from all under 30, irrespective of their geographical location, who are involved in any aspects of lighting design, education, research and manufacture. Brendan Keely

Double first Younger talents shine at this year’s Ready Steady Light


Emergency measures Chris Watts outlines the key changes to the newly revised Lighting Guide 12


A journey towards change James Duff summarises his YLOTY paper on MRSE


A visionary thinker 11 As part of an IYL series, John Aston examines a key historical figure in lighting, the scholar and Muslim polymath Ibn Al Haytham Charting a future course Bob Venning, chairman of the LET, looks forward to new developments


The road ahead 14 Street lighting and automotive headlamps are strong themes in the latest LR&T. Iain Carlile provides a summary Cover project 15 Highly commended at this year’s Lighting Design Awards, the scheme for the Nova Building by Michael Grubb Studio


16 3


Royal lecture brings Fresnel to light

SLL sponsors IET event

The SLL will be co-sponsoring the Institution of Engineering and Technology’s seminar, Low Voltage Direct Current: Powering energy demands in our digital world. Inspired by the Code of Practice on Low and Extra Low Voltage Direct Current Power Distribution in Buildings, the event will take place on 18 June.

Research bursary announced this month

Celebrating the 200th anniversary of Augustine Fresnel’s Wave Theory in the International Year of Light, a lecture on the French scientist’s work was delivered by Peter Phillipson, MSLL, at the Royal Institution in March. The Duke of York was guest of honour at the event, the Fresnel Bicentenary Lecture, attending in his capacity of UK IYL patron. Organised by Phillipson on behalf of the SLL, the lecture was supported by the IALD and Philips. Phillipson wanted to reappraise the life and work of Fresnel, whose achievements in progressing lighting knowledge went considerably beyond the eponymous lens. ‘Fresnel produced other prolific and profound lighting research that still affects our understanding of what light is and how we see the world,’ explained Phillipson. ‘That includes the Internet, differing aspects of mobile phones, state-of-theart medicine, and the way light behaves with architecture and fine art.’ His lecture was interspersed with live

experiments and demonstrations with the aid of RI personnel. The event was very well attended with an audience of around 250. After the lecture, the winner of Philips’ Strand Lighting competition – which invited participants to upcycle a vintage Strand fitting – was announced, with shortlisted entries displayed. Paul Nulty Lighting Design took the prize with Anamorphosis (below), a deconstructed chandelier and art piece featuring the classic Strand Pattern 23 II theatrical profile as the focal point.

On the lighter side...

Honorary fellow Turner dies Janet Turner, former design director of Concord Lighting and an honorary fellow of the SLL, has died after suffering ill health for some years. A former interior designer, Turner was a colourful and much-respected figure in the lighting industry, well connected with leading architects and the famous host of many lighting events at the company’s former Holborn showroom in the 1990s. One of her more celebrated projects was the scheme for Peckham Library


The successful applicant for the Jean Heap Research Bursary will be announced at the AGM on 21 May. The deadline has now closed having been extended an extra month to 30 April 2015. The society launched the bursary in November as a tribute to the commitment to lighting research and education which Jean Heap demonstrated both within the SLL and throughout her career in the lighting industry. The selection panel is looking for a specific piece of lighting study or research designed for the benefit of both the industry and SLL members. Applicants had to submit a written paper, along with a short video to outline their research proposal. The winning applicant will present a six-month progress video at LuxLive 2015 in November and the full results of the research will be presented at the Society’s AGM in May 2016

in south-east London designed by Will Alsop, whom she knew well and who she collaborated with on a number of occasions. The author of several books on lighting – including Lighting: an introduction to Light, Lighting and Light Use – she continued to design and lecture internationally after stepping down from her role at Concord. A full obituary will appear in the next issue of the Newsletter.

Who knew urine could be a liquid asset? Boffins at Bristol’s University of the West of England have installed a prototype toilet on campus that uses it to generate electricity. Microbial fuel cell stacks convert it into sufficient power to light up the cubicle. There is a serious side to pee power, as it has been dubbed, which is providing safer sanitary facilities in refugee camps.

Events: Masterclass 2013/14 Events

Double first for students Younger talents shine at this year’s Ready Steady Light competition

Bartlett B’s double-award scheme for the Stables site

Photography: Michael Reilly

In a competition that was always designed to offer a practical (and enjoyable) lighting experience for students and younger lighting designers, it was gratifying to see a student team carrying off two prizes this year: Bartlett Team B won both the Creative (sponsored by the IALD) and the Peer Awards for its highly effective blue light scheme for the Stables site. The all-female Thorlux team got the technical vote, however, for its strikingly simple design for the Old Courtyard site. ChapmanBDSP and Bartlett Team A were commended. Two student teams from Brunel University also took part for the first time, a reflection of the continuing expansion and development of lighting courses. ‘The quality remains very high and all the teams delivered imaginative schemes,’ said SLL secretary Brendan Keely. ‘The grounds of Rose Bruford College were buzzing with activity, and there was a great vibe and camaraderie.’

The Thorlux team’s design won the Technical Award

Winning teams: SLL Technical Award: Thorlux Lighting (Old Courtyard) Creative Award: Bartlett Team B (Stables) Peer Award: Bartlett Team B (Stables)

John Aston presents the Technical Award to the Thorlux team

SLL Technical Award Judges: Peter Raynham FSLL John Aston MSLL Stephen Lisk FSLL Iain Carlile MSLL Juliet Rennie

Teams: Bartlett A Bartlett B Brunel A Brunel B BuroHappold

Michael Earley, Rose Bruford principal, with Bartlett Team B

IALD Creative Award Judges: Kevin Theobald IALD Professor Michael Earley, principal, Rose Bruford College

ChapmanBDSP DPA Lighting Future Designs GIA Equation iGuzzini

Philips Rose Bruford College Thorlux WSP

Sponsors: Lee Filters, iGuzzini, Philips, White Light, Zumtobel Group


Lighting guides

Emergency measures

Chris Watts outlines the key changes to the newly revised Lighting Guide 12 on emergency lighting

and, where necessary upgraded, not just kept working to the original design. Similarly, where there is a change of use or structure, existing buildings need to be reevaluated to ensure that they are still safe. Another design consideration is that industry warnings have been issued that, where the safety margins of supply capability against likely load requirements have been eroded, this increases the risks of mains supply failure. Emergency lighting fulfils a safety role in reducing the hazards for people suddenly being plunged into darkness, and also has a commercial benefit as stock can be protected from opportunist theft and premises can continue to trade. The implication of these changes is that as engineers we

LG12: Emergency Lighting has been revised not only to include changes in national and European standards, but mostly to meet the revision to the legislative fire safety requirements and the need to cope with any future supply failures. Legislative requirements The major change in legislation for fire protection has been the removal of prescriptive fire certificates and their replacement by a procedure of risk assessments. The old system gave specific requirements for specific applications. While this did not accommodate differing site conditions it gave an easily understood set of rules that had to be complied with and the end result was inspected by fire authorities. Risk assessment now requires the duty holder, who is normally the employer, to be responsible for the safety of the occupants of the premises concerned. Government guides explain how this should be done. The duty holder has to produce a risk assessment showing the people at risk and identifying suitable safety measures. Where emergency lighting is concerned, the guides recommend that if the premises are used outside daylight hours or have any other risk they should have emergency lighting. The risk assessments cover all elements of fire and safety protection so in many cases there needs to be liaison between different systems – for example, fire alarms need emergency lighting to enable control panels and call points to be located and used in a supply failure. Revised issues of European and national standards reflect this need and the guide explains how they should be applied. Government guides recommend that users check the competency of the engineers and subcontractors they employ to help with their risk assessments and the provision of fire protection such as emergency lighting. They are warned that in the event of an inspection by the fire authority they will have to justify the arrangements they have made to provide safety for building occupants. The impact of this procedure for emergency lighting engineers is that we need to be able to understand the user’s particular risks and to produce a system that is appropriate for that application and is compatible with other safety systems. Fortunately, as part of the guidance, the requirements in BS 5266-1 are defined. However, judgement is needed when agreeing with the duty holder the areas that need to be covered and also how to protect specific site hazards. A major difference between the risk assessments and the fire certificates is that the assessment typically needs to be revised every 12 months to ensure it is still valid to protect the premises. One of the implications is that emergency lighting that was perhaps designed 10 years ago must be reassessed,


Self-contained LED system

need to establish and understand our user’s application and operating procedures to be able to propose a system tailor made for the application and which their staff can operate satisfactorily. For example, the testing procedures have to be compatible with the site staffs’ capabilities and workloads, because the duty holder has to be able to provide test records in an inspection. If this causes a difficulty an automatic testing system should be considered Design procedure The most important starting point is to gather the information. The guide now includes details of the input the designer needs from the user. The old days of simply providing set of plans with the injunction to ‘give me a design’ miss a lot of opportunities to maximise the design for the particular site and to understand the user’s preferences for the way the system will work. In many cases the duty holder will not be an engineer and will only have a basic knowledge of the options available. It is therefore important that the designer is able to interpret this information, and then explain and promote his or her design in terms the user can understand. System design When the performance and operational requirements are agreed a number of system options need to be determined. Often a major decision is whether to use a self-contained or central battery supply system. In the past the user often just wanted a fire certificate at the lowest cost, but now they have a responsibility to keep the system operational throughout its life and the lower running costs of a central systems can be more economically viable in the long term.

Lighting guides

also being field tested to explore the safety advantages of the intelligent addressing of exit signs and routes. These can receive input from fire detection systems and help users to direct occupants from specific areas Maintenance of the design It is important that the original specification values are maintained. If an equivalent product is specified it is important that any alternatives are truly equivalent in terms of offering the same output performance and being third-party tested. Otherwise the designer’s calculations are invalid. Testing systems The standards identify that the emergency lighting system must have appropriate testing facilities for the site. However, these are often neglected, relying on users isolating the supplies to conduct the monthly function test. In many cases this is impractical and in some cases dangerous if attempted. The guide highlights suitable methods and explains when the different forms of automatic testing may be beneficial. Documentation The appropriate forms of documentation that should be completed by the designer, installer and verifier are explained together with model templates of these documents, which should be provided by users in the event of an inspection. Compliance with the legislation in accordance with this guide enables us to provide assurance to our users that they have met their obligations for emergency lighting.

It is important that the designer explains this and provides examples of suitable systems. The format of the luminaires is also an important consideration; the user may want the luminaires to be aesthetically compatible with the design of the mains luminaires or they may need to meet operational requirements such as weatherproofing or a robust construction. The way the luminaire operates should also be determined. While most areas can just be illuminated in the emergency condition (non-maintained) others, such as those in areas of dimmed lighting – cinemas, for example – must be illuminated at all material times (maintained). In the past non-maintained was normally used as it reduced the need for excessive lamp replacement servicing but with the introduction of LED sources lamp life is considerably extended. The maintained luminaire can offer many advantages as it removes the need for separate mains and emergency luminaires in some locations while offering low power consumption. It also does not need to be activated by the final circuit monitor. The guide identifies future system developments, including new technologies such as the compound system which uses a central control unit to provide the charging supply to the luminaires as a safety low voltage supply (SELV). The control unit provides addressable operational instructions to the luminaire and can switch operation from maintained to non-maintained functions and also initiate test operations. The luminaires then signal back confirmation of their correct operation. The luminaires contain their own charge regulator and emergency battery so are able to function as standalone devices if communication with the central controller is lost. A number of dynamic signalling emergency systems are

SLL LG12 Committee Chris Watts (Chair) Lou Bedocs John Fitzpatrick Paul Littlefair Bernard Pratley Peter Raynham

Paul Ruffles Peter Thorns Colin Todd Ian Watts Graham White

The impact of this procedure for emergency lighting engineers is that we need to be able to understand the user’s particular

Images courtesy of Eaton Cooper and P4

Centrally powered system

The revised LG12: Emergency Lighting is scheduled to be published in early summer

risks and to produce a system that is appropriate for that application and is compatible with other safety systems. 7


A journey towards change James Duff, winner of the Best Presentation Award, Young Lighter of the Year 2014, summarises his paper on Kit Cuttle’s proposed mean room surface exitance metric

As lighting designers, we exercise our creativity against a backdrop of codes1,2, standards3 and recommended practice documents,4 each advocating a range of lighting parameters. Although specifying bodies have added various lighting quality criteria to their pronouncements,5,6 it is obvious, to me at least, that the central factor remains horizontal illuminance, typically measured at a workplane. How many times have you heard a space referred to as a 300 lux room or a 500

lux room? This will invariably mean horizontal illuminance. The lay person thinks that it is the be all and end all of lighting, but this is because we give them good reason to. They don’t know any better, but as competent lighting designers we do; yet we continue to quote it in reports and set it out as the main target in spaces where its application makes little sense. In addition, we intuitively know that the values we copy and paste from guidance documents will be in excess of what most people within the space will actually require. To me, it is utterly perplexing that we choose to ignore the matter and not place more energy into finding an improved alternative. In a paper presented at PLDC 2011 in Madrid, I first read of the relative visual performance (RVP) model,7 but more intriguingly, I read that Christopher Cuttle had applied this procedure to investigating exactly how much additional illuminance we are specifying, compared with what people actually need.8 Cuttle demonstrated that a normal-sighted 30-year-old, reading 12pt black text on white background paper, at a distance of 350mm, requires just 20 lux to read with optimal speed and accuracy (Fig 1). In addition, the same observer requires just 100 lux to read 6pt text, a not very common task these days. Even at 100 lux, this value is far less than the 300-500 lux we typically provide in such scenarios. This undoubtedly heightened my sense of confusion. Following this, I began to think about the myriad of spaces where such strenuous visual tasks are not prevalent – airport concourses, galleries, shopping centres, restaurants, bars, foyers and so on. How much light do we need here? Luckily, some good research already existed. In a study of emergency egress from buildings,9 Peter Boyce conditioned subjects to 500 lux in an open-plan office before plunging them into low, or very low, illuminance levels, with the instruction that they were to find their way out. As well as timing them, he had installed infrared cameras so he could monitor their progress. ‘At a mean

Fig 1: As applied by Cuttle, the illuminance necessary for high levels of relative visual performance (RVP) under varying illuminance levels, text size and background contrast



We intuitively know that the values we copy and paste from guidance documents will be in excess of what most people within the space will actually require. To me, it is utterly perplexing to choose to ignore the matter illuminance of one lux on the escape route people are able to move smoothly and steadily through the space at a speed very little different from that achieved under normal room lighting,’ concluded Boyce. Further investigation led me to an edition of The Illuminating Engineer, published more than 100 years ago by the Illuminating Engineering Society of Great Britain.10 It contains a report titled Illumination Requirements for Various Purposes, and within is a table listing 34 activities, along with corresponding illuminance values based on several field surveys. Reading is listed at 30 lux; schoolrooms are also 30 lux; commercial offices are 40 lux and libraries range from 15 to 50 lux. Admittedly none of the indoor activities go as low as the one lux finding from Boyce’s research but, broadly, it can be seen that the lighting recommendations of 100 years ago showed substantial agreement with the data derived from the RVP model. From our own thoughts and experience, it should be apparent that workplane illuminance is still the most widely used metric in the indoor lighting specification process and from the above paragraphs, it can be seen that we are specifying levels of it that are considerably in excess of what is actually required. There are, in fact, colossal differences between the illuminance levels required for the visual performance criteria that standards are claimed to ensure and the levels that the standards specify.

that MRSE be applied as an indicator for PAI, such that PAI would be specified within standards and predicted by various levels of MRSE, which would change according to the different activities in a space. By now, most avid readers of lighting publications will have encountered Cuttle’s ideas in some form or another. Disappointingly though, most still brush them off as overly complicated or too radical a change from the current status quo. If we dig a little deeper, this is really not the case. In fact, lighting standards as they currently read, inadvertently specify levels of MRSE. How so?, you might ask. Well, consider the definition of MRSE as put by Cuttle. It uses the product of direct illuminance and surface reflectance, then divides by the ability of the room to absorb this flux. Alternatively, this can be worked out if we know the area of each room surface, in addition to the total illuminance on each surface and the surface reflectance, with suggested values for both of these criteria already given in European lighting standards. The sketch in Fig 2 shows a theoretical office that is 1m long, 1m wide and 1m high. If we apply recommended values of surface illuminance and surface reflectance, as given in the current European standards, we can actually derive what value of MRSE is typically being provided in current buildings. It is really not as complex as people seem to believe. Adopting MRSE would not induce the radical changes that many have envisaged, but rather afford designers the freedom to manipulate and configure the values given in Fig 2 to most efficiently produce a perceived level of brightness. Why we might go there While the PAI criterion is concerned with providing adequate quantities of ambient light, Cuttle has combined this with an approach he calls Target Ambient Illumination Ratio to produce illumination hierarchies based around a defined quantity of ambient light. An in-depth explanation of this design procedure is explained elsewhere,11 but the approach has been described as all-encompassing and it truly is.14 After carefully considering, trialling and finally adopting it myself, I can confirm the



Where we might go If the current situation cannot be supported by logic, reason or research, then we may ponder how, or indeed what, we can change to possibly improve it. Cuttle has put forward a similar argument to the earlier paragraphs and he concludes that what is needed is a fundamental reevaluation of the purpose of lighting standards. He suggests that their purpose changes from providing a quantity of illuminance that relates to a visual task, to predicting whether or not the users of a space are likely to judge it to appear adequately illuminated or, to use the term that he has coined, the perceived adequacy of illumination (PAI).8,11 Cuttle has also introduced mean room surface exitance (MRSE) as a metric to serve as an indicator of the typical assessment of the brightness within an indoor space.12,13 To understand the concept of exitance, keep in mind that while illuminance is concerned with the density of luminous flux incident on a surface, exitance concerns the flux exiting, or emerging from, a surface. MRSE is, within the volume of a room, the average density of lumens emerging from all of the surrounding room surfaces. Cuttle has proposed

Fig 2: A theoretical office space, showing parameters recommended within current lighting standards that facilitate calculation of mean room surface exitance



approach encourages you to try picture the lit environment and: • Direct attention away from the working plane • Place emphasis on appearance, with particular focus on surfaces and their properties • Pay due attention to levels of brightness • Design illumination hierarchies based on items and areas of importance Further to this, the same approach can be used for art galleries, warehouses and offices alike. If we must recommend a single metric, procedure or design approach, then surely this presents some promise? Even if this sounds like it is an obvious yes, there are still some barriers that must to be overcome. How we might get there Before Cuttle’s approach can ever be adopted, a number of issues must be addressed. As I see it, these are: • Development of software capable of computing MRSE • A method, or instrument, capable of measuring MRSE in a practical manner • Actual proof that MRSE, when compared with horizontal illuminance, is a better predictor of subjective perceptions and impressions of brightness in a lit environment At the Dublin Institute of Technology, my PhD research is attempting to address all of the above issues. It is nearing its latter stages and I have found myself more frequently thinking, what if? What if we have software that calculates MRSE, what if we have a simple method to measure MRSE and, most important, what if we know that people respond better to levels of MRSE than they do to horizontal illuminance? What then?

Recommendations in The Illuminating Engineer 100 years ago show agreement with data derived from the RVP model


Adopting MRSE would not induce the radical changes that many have envisaged, but rather afford designers the freedom to manipulate and configure existing values to most efficiently produce a perceived level of brightness

References 1 Illuminating Engineering Society of North America, the IESNA Lighting Handbook, 10th Edition, New York: IESNA. 2 Society of Light and Lighting. 2012. The SLL Code for Lighting. CIBSE. Page Bros. Norwich. 3 Committee of European Standards. 2011. EN 12464-1: 2011. Light and Lighting – Lighting of workplaces. Part 1: Indoor Workplaces. London: CEN. 4 Society of Light and Lighting, The SLL Lighting Handbook, 2009, London; CIBSE. 5 Duff, JT (2012) ‘The 2012 SLL Code for Lighting: the Impact on Design and Commissioning’, Journal of Sustainable Engineering Design: Vol. 1: Iss. 2, Article 4. 6 Duff JT and Kelly K. In-field measurement of cylindrical illuminance and the impact of room surface reflectance on the visual environment. Proceedings of the SLL and CIBSE Ireland International Lighting Conference, Dublin, 12 April 2013, (accessed 16 May 2013). 7 Rea, MS, and Ouellette, MJ, 1991. Relative visual performance: A basis for application. Lighting Research and Technology,23(3): 135-144. 8 Cuttle C. Perceived adequacy of illumination: A new basis for lighting practice: Proceedings of the 3rd Professional Lighting Design Convention, Professional Lighting Designers Association, Madrid, 2011. 9 Boyce PR, 1985. Movement under emergency lighting: The effect of illuminance. Lighting Research and Technology,17: 51-71 10 Loe, DL and McIntosh, R. 2009. Reflections on the Last One Hundred Years of Lighting in Great Britain. The Society of Light and Lighting. CIBSE. Page Bros. Norwich. 11 Cuttle, C. ‘A new direction for general lighting practice’. Lighting Research and Technology, February 2013; vol. 45, 1: pp. 22-39. 12 Cuttle, C. Lighting by Design, 2nd edition, Oxford, Architectural Press, 2008. 13 Cuttle, C. ‘Towards the third stage of the lighting profession’, Lighting Research and Technology, March 2010; vol. 42, 1: pp. 73-93. 14 Boyce, PR, ‘Lighting Quality for All?’, Proceedings of the SLL International Lighting Conference, Dublin, April 2013.

International Year of Light

A visionary thinker Following his initial report on the IYL opening ceremony, John Aston examines one of the figures who featured prominently in the proceedings, the scholar and Muslim polymath Ibn Al Haytham

Alhazen used the camera obscura to show that light travelled in straight lines, and to prove that we saw because light

© 1001 Inventions

entered our eyes

Creative illustration depicting Ibn al-Haytham experimenting in Cairo to prove that we see because light from objects travels in a straight line into our eyes (Source: 1001 Inventions – The Enduring Legacy of Muslim Civilization)

In my introduction to the Fresnel lecture in March I paraphrased the saying that ‘if we fail to study history, then we are doomed to repeat our mistakes’, and suggested that this could also easily be applied to the study of science. Looking back to the Golden Age of Enlightenment in the Middle East, and Ibn Al Haytham in particular, is a good illustration of this point. This age spanned nearly five centuries – from the 8th to the 13th – while most of what we call Europe today was in the depths of the Dark Ages. Scholars of many faiths and nationalities worked and studied in the Arabian seats of learning, and bequeathed much original thought and research to later generations. Ibn Al Haytham (who was also known as Alhazen, which I will use from now on) was born in Basra in c965 AD and carried out much of his work in Cairo, where he died in c1040 AD. This year we are also celebrating the 1000th year since his Book of Optics was published around 1015 AD. This book was later translated into Latin (in the late 12th or early 13th century) and became a reference source for many later scientists studying

light, astronomy and geometry. Roger Bacon, Leonardo da Vinci, Galileo, Descartes, Huygens and Kepler are all known to have read Alhazen’s book. It can therefore be argued reasonably that this book contributed to the Renaissance and development of science in Europe. The Book of Optics actually ran to seven volumes and dealt with Alhazen’s theories on light, colour, vision, reflection and refraction; the final volume recounts the many experiments he carried out to prove his theories. At the time of writing this book there were two principal theories of vision: one was that the eye emitted rays that showed the viewer the colour and form of objects, while another suggested the objects sent ‘agents’ to the eye to define the visual perception. Euclid and Ptolemy favoured the former and Aristotle the latter; Alhazen supported Aristotle and sought to prove this theory. The desire to prove his theory of vision did lead him to study both reflection and refraction in greater depth than he might have. The most important point for us was the fact that he


© 1001 Inventions


International Year of Light YLOTY

A creative representation bust of Ibn al-Haytham made by artist Ali Amro for 1001 Inventions to celebrate the IYL

wrote down his theories and attempted to prove them, a demonstration of his scientific approach: ‘The duty of the man who investigates the writing of scientists, if learning the truth is his goal, is to make himself an enemy of all that he reads, and...attack it from every side. He should also suspect himself as he performs his critical examination of it, so that he may avoid falling into either prejudice or leniency.’ He also referred to ‘systemic and methodological reliance on experimentation and controlled testing’ in his scientific studies. These statements effectively show that Alhazen’s approach to science was very close to the approach we take today – or should. If we cannot show clearly and unequivocally that a particular theory can be proved by experiment and testing then that theory remains just that, a theory. Research must always be pursued with complete objectivity and a rigorous methodology, which Alhazen recognised 1000 years ago. When he observed something that he wished to look into more deeply he studied it and attempted to reproduce it. One of these observations led him to describe and experiment with the camera obscura, or pinhole camera. Although not an original discovery, because both the Chinese and the Greeks were aware of this phenomenon, Alhazen used it to show that light travelled in straight lines, and to prove that we saw because light entered our eyes. Alhazen also experimented with lenses and mirrors of all types showing that viewing objects through thick materials such as glass or water appeared to enlarge them. Developing this work he looked into how reflections from a spherical mirror might be calculated; he succeeded in this task by using geometry but he never did work out how to do it with algebra. This became known as ‘Alhazen’s Problem’ and it was not solved until 1997. Today, we probably only know about this work because he wrote down his findings. Even then it might not have become widely known if his Book of Optics had not been translated into Latin, as part of a wider ambition to make Arabic knowledge more accessible. This initiative took place in Toledo, where


scholars of many faiths and nations worked together to gather and disseminate the knowledge gained through the Golden Age of Enlightenment. The Latin version of his work meant it could be read by later European scholars, who would take his pioneering work forward and build on his knowledge with further research, experiments and study. A sort of ‘optics primer’ for the Renaissance generation. I feel that the most impressive element of Alhazen’s work was not so much his work on light – important though it was – but his recognition that science was a subject that demanded rigorous proof and that theories, experiments and tests needed to be written down for the benefit of later generations. By passing on the knowledge gained it could be critically examined in the light of additional and subsequent discoveries; it could act as a catalyst to further advances and avoided the need to do it all again. He was a man with a really modern approach to reason, logic and the gaining of knowledge for the wider benefit of humanity. It could be summed up in his own ‘theology’: ‘I constantly sought knowledge and truth, and it became my belief that for gaining access to the effulgence and closeness to God there is no better way than that of searching for truth and knowledge.’ It is an objective that has also been set by the campaign ‘1001 Inventions and the World of Ibn Al Haytham’, launched at the IYL opening ceremony. This campaign is designed to encourage young people to pursue Stem (science, technology, engineering and maths) careers through a wide range of educational experiences. It also promotes intercultural understanding, as well as entrepreneurial and scientific thinking. It is an ambition that our own society fully supports.

Ibn al-Haytham’s sketch of the human optical system. The oldest known drawing of the nervous system from Kitab alManazir of Ibn al-Haytham (from a manuscript held in the Süleymaniye Library, Istanbul), in which the eyes and optic nerves are illustrated. It shows a large nose at the bottom, eyes on both sides and a hollow optic nerve that flows out of each one towards the back of the brain. (Source: Reflections on the Optics of Time © Muslim Heritage)

Education YLOTY

Charting a future course

Bob Venning, chairman of the LET, looks forward to new developments

This may be the International Year of Light, but how many of you know that 2015 is also the 20th anniversary of the founding of the Lighting Education Trust? Two decades ago the continuance of the MSc in Light and Lighting, run at the Bartlett School of Postgraduate Studies UCL, was under threat as Philips, who had generously sponsored the course for many years, decided that it could no longer continue to support it. Up stepped Hugh Ogus who, with colleagues in the industry and The Worshipful Company of Lightmongers, set about raising money to ensure the course’s future. With the help of a group of manufacturers and independent lighting consultants we have been able to maintain consistent funding and to date the LET has been able to donate more than £500,000 towards the MSc lighting course. But the scope of the LET is much wider than just maintaining the MSc course. It also has a remit to support any lighting educational initiative that the trust considers worthwhile. First, we have taken back in-house the LET’s Diploma in Lighting on the retirement of the course director at London South Bank University. The course has been updated and expanded from five modules to 13, with four assessed assignments and an assessed lighting design project followed by an examination, which will still be moderated and marked by LSBU. The new course is called the LET Diploma in Lighting Design and will start in September 2015. The breadth and

depth of knowledge being imparted will make this course both unique and valuable to employees and employers alike. In between the Diploma and the MSc we have been assisting Brunel University in creating a new Lighting Design Pathway attached to its product design degree. We have also been helping to find companies who would take interns for a year to gain industrial/design experience, with the hope that they will enter the industry. The first batch of students to have gone through the process has now entered the lighting industry with companies such as Aether Lighting, Philips, GE and Hoare Lea. We would welcome hearing from any company who would like offer internships and we will pass on their details to Brunel. There is currently a proposal on the table for the LET to take on the provision of the prizes for the Young Lighter of the Year competition. As both the SLL and ILP are trustees of LET it seemed a neat way of combining the responsibility for judging into one body. Another example of how the trust is helping to support educational initiatives. All this takes money, of course, and we are very grateful to all our sponsors to date who have supported us. However, we are constantly looking for more and new sponsors so that we can develop our educational support. The Diploma course will generate some funds but not enough. If you would like to support us with £2000 or £3000 a year for, say, three years, or any amount that you can afford for that period of time, then we would like to hear from you. We can assure you that all of the money will go towards supporting lighting education. There are benefits for sponsors. If you are a small company, for instance, and would like to train your staff to a higher level, then the distance-learning course LET Diploma in Lighting Design might prove to be a viable option. We offer a 10 per cent discount for one member of staff enrolling for every £1000 sponsored. Help us secure the future of lighting education for the next 20 years by supporting us. I think you will find that it is the best investment you can make for your company and for your staff. For more details of the LET and its sponsors go to: www. or contact


LR&T essentials

The road ahead Street lighting and automotive headlamps are key themes in the latest issue of LR&T says Iain Carlile

Median proportions of all fixations and critical fixations per category during after-dark sessions (Fotios et al, Part 2)

Boyce’s editorial considers the barriers to adoption of sophisticated lighting controls. He identifies the following difficulties: return on investment, long-term operation and human input into the system. He also suggests ‘…equipment interchangeability and support contracts…’ would be useful in making sophisticated lighting controls more widely accepted. In his opinion piece, Fotios considers the number of points used in the response scales of questionnaires and how this can result in a forced choice to be made, potentially manipulating the results. The methodology recommended in CIE Technical Report 212: 2014 is to randomise and counterbalance, and to use null condition trials, he says. That methodology might be incomplete and a little flawed but it’s a good starting point for a discussion, ‘because methodology matters’, argues Fotios. Three papers consider the lighting of residential roads. In the first part of a two-part paper, Fotios et al investigate pedestrians’ critical visual tasks, using eye-tracking equipment to record their visual fixations during both daytime and nighttime. They found that pedestrians fixated on the path at near distance while focusing on other pedestrians at a far distance. At night the path was more likely to be the primary focus. In the second part, Fotios et al use different approaches to interpret the eye-tracking results and the apparent importance of fixation on other pedestrians. Three approaches were considered: proportion of time, proportion at critical moments, and probability of an approaching person being fixated one or more times. They found the proportion of all fixations and the probability of fixating people were affected by the number of people encountered. Only the critical fixations showed no trend. Again looking at road lighting, Lin and Fotios consider facial recognition by pedestrians at night. Analysing the results from their own experiments and previous studies, the authors found the effect of lamp spectral power distribution (SPD) is more significant when the task is difficult (small or brief observation). Meanwhile Whang et al propose an innovative vehicle headlight design. Light rays from four Lumiled K2 LEDs pass


through a total internal reflection lens. The rays are then split into two beams by a prism and guided to each headlamp using a light pipe. Qiu et al also consider the design of low-beam headlamps, using a parabolic reflector, compound lenses, combined prisms and a high-brightness LED. Moving to human factors, Sloane et al investigated the effect of home-based light treatment on people with dementia and their family carers. They found that using a blue-white light treatment improved both sleep and role-strain of carers, but no improvement in dementia subjects was noticed. Borisuit et al consider the lighting of workplaces, and their contribution to work satisfaction, productivity and wellbeing. Overall, subjects preferred daylight for visual acceptance and glare. In the course of an afternoon, it was also found that changes of photometric variables modulated changes in visual light perception, alertness and mood. It has previously been found that 12-channel LEDs with a high colour quality scale (CQS), colour preference scale (Qp) and a high CQS gamut area scale (Qg) give a preferred SPD. Baniya et al note that, due to their complexity, 12-channel LEDs are not considered commercially exploitable. They therefore investigated generating simplified LED SPDs with the same quality values. Results suggest that preferred complex LED SPDs can be optimised for efficiency and cost without sacrifice in light colour quality. Alshaibani presents a method of determining the CIE sky type whereby the ratio of the luminances of two sky elements and the ratio of the luminance of one sky element to the horizontal illuminance can be used. Also considering natural light, Whang et al present a novel circle-focus Fresnel sunlight concentrator, which reduces the physical weight while increasing the tolerance to different angles of sunlight incidence. Iain Carlile, MSLL, is an associate of DPA Lighting Design Lighting Research and Technology Vol 47, No 2, April 2015 Editorial: Advancing lighting controls Peter Boyce Opinion: Methodology matters Steve Fotios Using eye-tracking to identify pedestrians’ critical visual tasks, Part 1. Dual task approach S Fotios, J Uttley, C Cheal, N Hara Using eye-tracking to identify pedestrians’ critical visual tasks. Part 2. Fixation on pedestrians S Fotios, J Uttley and B Yang Effect of home-based light treatment on persons with dementia and their caregivers PD Sloane, M Figueiro, S Garg, LW Cohen, D Reed, CS Williams, J Preisser and S Zimmerman User-acceptance studies for simplified light-emitting diode spectra RR Baniya, R Dangol, P Bhusal, A Wilm, E Baur, M Puolakka and L Halonen Effects of realistic office daylighting and electric lighting conditions on visual comfort, alertness and mood A Borisuit, F Linhart, J-L Scartezzini and M Münch An innovative vehicle headlamp design based on a highefficiency LED light pipe system AJW Whang, KC Jhan, SM Chao, GW Chen, CH Chou, CM Lin, CM Chang, KY Chen, YL Lai Investigating methods for measuring face recognition under lamps of different spectral power distribution Y Lin and S Fotios An innovative Fresnel-type concentrator based on a macroparabola AJW Whang, CH Chou, SM Chao, YC Chen, CM Lin, KC Jhan, CM Chang, KY Chen and YL Lai The use of sky luminance and illuminance to classify the CIE Standard General Skies K Alshaibani Design of an LED-based headlamp low-beam system using combined prisms P Qiu, A Ge, J Wang, J Cai, L Zhu and Z Du

Cover project

Globular cluster

Highly commended at this year’s Lighting Design Awards, the scheme for the Nova Building in Bournemouth flies in the face of lighting orthodoxy

It is a brave lighting designer who uses that much-maligned student standby, the paper globe, as the staple fitting in an office lighting scheme. But new ways of working are demanding different ways of designing and lighting the workspace, and Michael Grubb’s scheme responds creatively and practically to the client’s brief. Amigo Loans wanted to avoid the sterility of conventional commercial lighting for the Nova Building in Bournemouth, and instead provide a scheme more in sympathy with the surroundings, promoting the company’s brand and ethos, as well as engaging with staff. The lighting remit included hot-desking workstations, meeting rooms, boardrooms, the café-restaurant area, social breakout spaces and an in-house massage room, with LED and fluorescent sources specified throughout. ‘The lighting scheme was designed to be honest and freeflowing, to remove any sense of hierarchy between the various spaces,’ says Grubb. ‘A continuous cluster of decorative globes that meandered through rooms created a connection between each space. Additional lighting was added around the walls to provide balance, and to emphasise the tone and texture of the raw stone finish.’ Pendants, especially the copper fittings suspended over the serving counter, add a more intimate note to the café-restaurant areas. Additional lighting was added to the performance space and the graphic information boards.

‘The lighting scheme was designed to be honest and free-flowing to remove any sense of hierarchy between the various spaces’ – Michael Grubb

Project: Nova Building, Bournemouth Lighting design: Michael Grubb Studio Award: Highly Commended (Workplace) For a profile of the LDA 2015 Workplace category winner, ChapmanBDSP’s One Embankment Place, see Newsletter March/April 2014 (p11)



2015 5-7 May Lightfair Trade show and IALD conference Venue: Javits Center, New York 7 May SLL and CIBSE Merseyside and North Wales LG8: Lighting for museums and art galleries Venue: Blundells Hill Golf Club, Merseyside 14 May SLL Masterclass: Light for Life Location: Royal Society of Arts John Adam St, London WC2 14 May EA113 CPD Lighting and Energy Efficiency Venue: Place Hotel, Manchester 18 May Exterior Lighting Diploma Module 3 (Organised by the ILP) Venue: Draycote Hotel, Nr Rugby 19 May How to be Brilliant with: Rebecca Weir, Light IQ (ILP event) Venue: ACDC Lighting Studio, London N1 Time: 6.30pm 21 May SLL AGM, Presidential Address and Awards Venue: RIBA, 66 Portland Place, London W1 21 May Lightscene (ILP event) Venue: Northampton Saints Rugby Club 29-31 May 3rd International Conference of Artificial Light at Night (ALAN 2015) Location: Sherbrooke, Quebec, Canada

21 May: SLL AGM and Awards, RIBA, Portland Place, London W1

10 June Light, Time and Health: Biology to Architecture (ILP event) Speaker: Russell Foster, Professor of Circadian Neuroscience and head of the Department of Opthalmology, University of Oxford Venue: Royal Institution

Lighting Masterclasses: Masterclasses are kindly sponsored by Helvar, Philips, Thorn and Trilux. For venues and booking details :

27 June-4 July 28th Session of the International Commission on Illumination (CIE) Venue: University Place, University of Manchester 30 June How to be Brilliant with: James Siddle, Ideaworks (ILP event) Venue: ACDC Lighting Studio, London N1 Time: 6.30pm 23-24 September Professional Lighting Summit (Organised by the ILP) Venue: Queen Hotel, Chester 28-31 October PLDC 2015 (with SLL as Official Knowledge Partner) Venue: Ergife Palace Hotel, Rome october-2015/professional-lightingdesign-convention-2015

LET Diploma (in association with London South Bank University): advanced qualification by distance learning. Details from or email Mid Career College: the college runs various courses across the whole spectrum of lighting and at sites across the UK. Full details at LIF courses: details from John Hugill, 0208 529 6909, or email

SLL may/june 2015  
SLL may/june 2015