SLL July/August 2019

The Society of Light and Lighting

LIGHT LINES July/August 2019

VOLUME 12 ISSUE 4 JULY/AUGUST 2019

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GOLD STANDARDS New president on the society’s role

RHYTHM AND BLUES The SLL’s position on circadian lighting Twitter: @sll100

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July/August 2019

Editorial

FROM THE EDITOR SECRETARY Brendan Keely FSLL bkeely@cibse.org SLL COORDINATOR Juliet Rennie Tel: 020 772 3685 jrennie@cibse.org EDITOR Jill Entwistle jillentwistle@yahoo.com COMMUNICATIONS COMMITTEE: Gethyn Williams (chairman) Iain Carlile MSLL Jill Entwistle Chris Fordham MSLL Rebecca Hodge Eliot Horsman MSLL Stewart Langdown FSLL Linda Salamoun MSLL 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.

One of the more alarming developments of our age is the increasing incursion of Newspeak in our language. As anyone familiar with Orwell’s 1984 will know, it involves the use of simplistic expression and euphemism, words which couch reality in the cloak of a directly obverse meaning.

A classic example in our sphere is the phrase ‘value engineering’. It is a term, says incoming president Jim Shove, that he ‘abhors’ (see p5). Neither word is appropriate in a context which both debases the meaning of engineering and devalues the product being specified.

Spec breaking, as it is more candidly known, has been going on for years, but has seemingly got worse as budgets are squeezed and bottom lines obsessed over.

Clients may believe the practice is saving them money, says Shove, ‘but many are not aware of the ramifications this has on the project – from the reduction in appearance to the overall energy usage on the project being substantially increased.’

It also renders pointless the idea of having an expert opinion in the first place. One of his aspirations during his presidency is that the SLL can play some role in upholding standards. ‘We write the guides,’ says Shove, ‘but we seem to have little voice in overseeing their implementation.’

One area where the SLL is attempting to exert its knowledge and expertise is in circadian lighting (not a euphemism but certainly used simplistically). A recent position statement (see p12) aims to bring definition to a woolly concept.

JILL ENTWISTLE JILLENTWISTLE @YAHOO.COM

CURRENT SLL LIGHTING GUIDES

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

SLL Lighting Guide 0: Introduction to Light and Lighting (2017) SLL Lighting Guide 1: The Industrial Environment (2012) SLL Lighting Guide 2: Hospitals and Health Care Buildings (2008) SLL Lighting Guide 4: Sports (2006) SLL Lighting Guide 5: Lighting for Education (2011) SLL Lighting Guide 6: The Exterior Environment (2016) SLL Lighting Guide 7: Office Lighting (2015) SLL Lighting Guide 8: Lighting for Museums and Galleries (2015) SLL Lighting Guide 9: Lighting for Communal Residential Buildings (2013) SLL Lighting Guide 10: Daylighting – a guide for designers (2014) SLL Lighting Guide 11: Surface Reflectance and Colour (2001) SLL Lighting Guide 12: Emergency Lighting Design Guide (2015) SLL Lighting Guide 13: Places of Worship (2014) SLL Lighting Guide 14: Control of Electric Lighting (2016) SLL Lighting Guide 15: Transport Buildings (2017) SLL Lighting Guide 16: Lighting for Stairs (2017) SLL Lighting Guide 17: Lighting for Retail Premises (2018) SLL Lighting Guide 18: Lighting for Licensed Premises (2018)

PRODUCED BY

Guide to Limiting Obtrusive Light (2012)

COPY DATE FOR LL 5 2019 IS 22 JULY PUBLISHED BY The Society of Light and Lighting 222 Balham High Road London SW12 9BS www.sll.org.uk ISSN 2632-2838 © 2019 THE SOCIETY OF LIGHT AND LIGHTING

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Unit C, Northfield Point, Cunliffe Drive, Kettering, Northants NN16 9QJ Tel: 01536 527297 E: gary@matrixprint.com

Code for Lighting (2011) Commissioning Code L (2018) SLL Lighting Handbook (2018)

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July/August 2019

Secretary’s column/Contents

Contents

FROM THE SECRETARY

Twitter: @sll100

on circadian light and, of course, the next LightBytes series.

This will be back in autumn and we are currently in discussions to finalise the line-up of the Sponsors in Partnership, speakers and brand-new peer-reviewed topic. We would like to take this opportunity to thank all of the Sponsors in Partnership from the 2018-2019 series: Fagerhult with presenter Les Thomas, Thorlux with Richard Caple, Xicato with Roger Sexton and Zumtobel with Graeme Shaw.

We are also looking forward to the darc room exhibition and presentations, which take place from 19-22 September at The Old Truman Brewery, Shoreditch, in east London. Paul Ruffles will be there presenting the changes to the Lighting Handbook, as well as revealing some details about the upcoming new Code for Lighting (his presentation takes place from 5-6pm on 20 September). We hope to see many of you there.

We also look forward to exhibiting at LuxLive on 13-14 November at ExCeL where the Young Lighter 2019 final will take place (14 November), as well as attending the Lux Awards the same evening. We have received a large number of entries for this year’s Young Lighter, which had a revised format for 2019, and those that will go through to the next stage of the competition will be notified shortly.

BRENDAN KEELY

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EDITORIAL

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SECRETARY’S COLUMN

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NEWS

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VALUE JUDGEMENT

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AHEAD OF THE FIELD

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READING THE WEATHER

Spec breaking and training: two areas of concern for new SLL president Jim Shove

This year’s AGM and awards, which took place at St Martin’s church in Trafalgar Square

Eleanora Brembilla on improving solar data in CIBSE climate files

12 BODY OF KNOWLEDGE

SLL position statement on circadian lighting, defining the term and clarifying the current state of research

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EYE OF THE BEHOLDER

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EVENTS

Iain Carlile looks at three of the latest LR&T papers on perception

COVER: International Presbyterian Church, Ealing, London, lighting by 18 Degrees. Winner of the Heritage Project of the Year, sponsored by the SLL, at the Lighting Design Awards 2019

BKEELY @CIBSE.ORG

‘To see the participants producing art with light is an extraordinary experience and the results outstanding’

Tom Lee

A big thank you to all those who joined us at the AGM, awards and presidential address back in May. On behalf of the SLL and CIBSE we would like to thank Iain Carlile for his contribution during his presidential year, and welcome new president Jim Shove, whom we look forward to working with (see p5).

Congratulations to all award recipients (see p7) and a thank you to all the brilliant volunteer members who help us to deliver guidance, put on events in the regions or steer the society in other ways. Congratulations also to Karen van Creveld who is the recipient of this year’s Jean Heap Bursary. Karen’s research is titled: ‘Measuring real daylight exposure afforded by various architectural environments and the implications for our health and wellbeing’. We will be posting Karen’s three-monthly updates on the website and we have also uploaded the final report from Amir Nezamdoost’s 2018 bursary: ‘Proposing a new manual blind control algorithm for annual daylight analysis’.

We were delighted to host a Light Graffiti event with photographer and light painter Michael Bosanko again, this time at the London Art House in Islington in association with acdc. The events committee organised the evening and all guests had a great time. To see all of the participants producing art with light is an extraordinary experience and the results outstanding. We are hoping to hold a debate on controls in the autumn and more details will follow.

Initial discussions are currently taking place regarding the opportunity to host a Lighting Research and Technology symposium, Applying Light for Human Health, in the spring of 2020. The event will follow a similar format to the LR&T 50th Volume Symposium back in May 2018 with the great and the good presenting their thoughts on the relationship between light and health. The symposium would build on the SLL position statement released earlier in the year (see p12), the CIBSE/SLL part-funded research by the BRE

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July/August 2019

News

THE LATEST NEWS AND STORIES

INCOMING CIBSE PRESIDENT HIGHLIGHTS ROLE OF BUILDING SERVICES IN CLIMATE CHANGE CHALLENGES Climate change and the adoption of digital technology are areas where CIBSE expertise is playing an increasingly important role in delivering safe, healthy and affordable buildings, said incoming CIBSE president Professor Lynne Jack.

‘We see progressively more challenging commitments to carbon reduction levels’ and ‘a significant acceleration of decarbonisation required,’ said Professor Jack in her inaugural address at the Royal Society in May. Delivering on these targets requires collaboration both throughout the UK built environment and across international borders, she said, highlighting the growing relevance of building services engineers to meeting the challenges.

While emphasising the demand for the particular skills embodied by CIBSE members, Professor Jack also focused on the challenge of attracting and retaining highly skilled practitioners to the sector. She noted the rising percentage of female practitioners in both graduate and student membership, and among CIBSE fellows.

‘Supported by the work of our inclusivity panel we have a strong focus on increasing the proportion of female members and registrants. We also seek to embed an enhanced level of awareness and understanding of diversity and inclusion.’

Professor Jack succeeds Stephen Lisk as CIBSE president. She is currently director of research at Heriot-Watt University’s Malaysia campus.

BURSARY AWARDED FOR DAYLIGHT/WELLBEING RESEARCH Karen van Creveld, who has her own lighting design practice, has been awarded the £4000 Jean Heap Bursary for 2019. Her research topic is ‘Measuring real daylight exposure afforded by various architectural environments and the implications for our health and wellbeing’. Her research is being conducted through the Bartlett.

For more details about the Jean Heap Bursary, email sll@cibse.org

ISO RELEASES NEW LIGHTING STANDARDS ISO has recently published two new lighting standards. Released on the International Day of Light, 16 May, they have been produced in collaboration with the CIE. The first, ISO/CIE 20086, Light and lighting – Energy performance of lighting in buildings, provides a method for calculating lighting use to enable an estimate of the total energy performance of a building. The second standard is ISO/CIE TS 22012, Light and lighting – Maintenance factor determination – Way of working.

Ad de Visser, chair of the ISO technical committee in charge of their development, said the documents were a key tool for organisations to improve their energy performance and help new technologies to evolve.

‘By being able to effectively calculate the energy performance of lighting systems in a building, organisations can make more informed decisions on how to improve it,’ he said.

‘Continuous maintenance is equally important to this goal as it prevents faults in lighting, improving both safety and efficiencies.’ www.iso.org/committee/4418564/x/ catalogue/

ON THE LIGHTER SIDE...

The maxim ‘the right light in the right place at the right time’ (coined originally by dpa lighting consultants) has been taken somewhat literally by designer Kazahiro Yamanaka. The Flying Drone Lamp, as the name suggests, combines technology with traditional lighting, creating an LED luminaire with a small drone that follows a person’s movements around the home, illuminating spaces as needed.

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Stands around the home are used as launch pads (though it can land without a base) with the positions and plan of the space programmed to the device, which is equipped with sensors to track a person’s movements. Blue-sky thinker Yamanaka envisages applications in space: ‘Without gravity, the need for propellers is totally removed.’ www.kazuhiroyamanaka.com

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July/August 2019

Michael Eleftheriades

President’s address

VALUE JUDGEMENT Spec-breaking is one area where the Society of Light and Lighting could help raise standards, said new president Jim Shove in his address ne of his key objectives, says new SLL president Jim Shove, is to promote the society as one of the main arbiters for standards within the construction industry, particularly where spec-breaking is concerned. ‘We write the guides but we seem to have little voice in overseeing their implementation,’ he said in his address. ‘For those involved in the design of projects it is very depressing to see what start out as excellent jobs being ‘value-engineered’, a phrase I abhor.’

Clients may believe the practice is saving them money, he continued, ‘but many are not aware of the ramifications this has on the project – from the reduction in appearance to the overall energy usage on the project being substantially increased.’

Shove acknowledged that the huge

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growth in LEDs and controls made the task more difficult, especially as it entailed a massive influx of low-cost, non-regulated products. ‘The only way is to liaise with all those bodies involved in the building industry – the client, architect, consultant and contractors, as well as government – to try and get them to understand the ramifications of value-engineering.’

The issue related to the ‘thorny question’ of competency within the industry, said Shove. ‘There are a lot of individuals who seem to think that being able to use a lighting design programme means that they can call themselves designers. The major issue with competency also relates to the ability to carry out designs for emergency lighting.’

Shove also highlighted the current preoccupation with circadian lighting within the industry. We should be focusing on its

‘We write the guides but we seem to have little voice in overseeing their implementation.

It is depressing to see jobs valueengineered’

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President’s address

‘It is not acceptable to make bold statements about supposed circadian luminaires’

benefits, he said, but he warned that end users and clients ‘are being sold on an idea which at the moment is unsubstantiated’.

He referred to the statement on the subject recently issued by the SLL [see p12] and urged people to read it. ‘I think it is unacceptable for manufacturers to make bold statements concerning their supposed circadian luminaires and designs relating to schools, hospitals and care homes without reference to actual evidence,’ he said. ‘As we know there is a great deal of academic research work being done in this field but until such time as actual empirical evidence is produced we should be very careful not to bring our industry into disrepute by making what may be unsubstantiated claims.’

Shove said that he wanted to build on the work of previous presidents, not only strenthening ties with other bodies such as RIBA, the ILP and the ECA, but continuing the emphasis on education, within schools, construction and specifically the lighting industry. ‘I came across a phrase the other day which I think is very apt: “Talent is everywhere, opportunity isn’t.”

‘To me this sums up the issue we have whereby schools are being pushed to achieve targets and goals set by various governments without any thought given to what the children will do when they leave school other than go to university.’ There is a definite need for schools to consider steering non-academic students towards technical education rather than academic achievement, he said.

A former engineering apprentice himself, he was pleased to see the government’s introduction of the new T Level qualification for 16-18 year olds, he said, where 20 per cent of course time will involve practical experience. He also applauded the Degree Apprenticeships scheme, ‘a further extension of the apprenticeship route into industry’.

Again, it was an area where collaborating with other bodies would help, he said. ‘I hope to work with the other institutions and the Engineering Council to improve the acceptance of apprenticeships within mainstream schooling and industry.’

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Jim Shove: Background ‘How many of us left school thinking, ‘I know, I want a career in lighting?’ I know I certainly didn’t and as with most things in life it happened by accident.’ With a family background in the military (his father was a career soldier who reached the rank of lieutenant-colonel), that was his likely career path until a serious accident left him with problems that precluded joining the armed forces.

In 1969, ‘having made a complete hash of my “O” levels at Shaftesbury Grammar school’ his father gave him the option of resitting the exams or leaving school. An interest in engineering and disenchantment with school led him to a four-year apprenticeship with a local firm, Conelight, in Shaftesbury, combining on-the-job training with day and night release at college to do a City and Guilds course. He completed his City and Guilds with credit in 1974.

As a fully-fledged toolmaker he became involved in the design and manufacture of hydraulic press and machine tools for luminaire manufacture which also covered luminaire design. ‘Conelight was taken over by Marlin in 1977 and I understand that the original factory is now owned by Dextra so the lighting tradition carries on.’

By 1976 he wanted to expand his knowledge about lighting and applied to be a regional salesperson at Thorn Lighting in the Dorset area. While not intially successful, in early 1977 Thorn

offered him a job with the sales team based out of the Cardiff branch office.

‘Over time I completed the Thorn lighting training modules and went on to the training centre in the lamp factory in Leicester. Among those people I came across at that time was a certain Lou Bedocs, now sadly no longer with us, and I also recall receiving a lot of help and advice from the likes of Colin Hunt and Tom Fairhurst.’

In 1981 he moved to Holophane Europe as a project engineer and remained there until 2005 when he was made redundant. He joined Luxonic for a year before moving on to Fagerhult in 2006 where he stayed until retirement in February last year.

‘By my reckoning that means I have been indirectly and directly involved with the lighting industry for 50 years.

Over this time I have seen many changes in technology and I have also been witness to the change in our industry from hand calculations and marking up drawings with a stencil to early manufacturer computer design packages, then DIALux and Relux, and now into the realm of BIM Revit and virtual design.’

He became a member of the SLL in 2008 and was ‘volunteered’ to be the regional lighting representative for the South West Region by former president Stephen Lisk. In 2016 he was invited to join the Executive with a view to becoming president in 2019. ‘After the initial shock,’ he said, ‘I readily agreed.’

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AGM: Awards

SLL members at this year’s AGM and awards

AHEAD OF THE FIELD

Michael Eleftheriades

This year’s SLL AGM and awards were held at a venerable London landmark

t Martin-in-the-Fields, the famous 18th-century Neoclassical church in Trafalgar Square, is celebrated for both its music and its charitable work with the homeless. In May it was the impressive setting for this year’s SLL AGM and awards.

The first major accolade of the evening was the presentation of the Lighting Award to Simon Robinson, current chair of the technical and publications committee.

‘The variety of roles Simon has had over the years has given him a working knowledge of all stages of a project from procurement through to managing the building through life,’ said Paul Ruffles in his citation. ‘This, and the wide range of building types he has worked on, make him an extraordinarily useful member of the technical committee and of the society in general.’

Robinson began as an apprentice electrician at Wakefield Metropolitan District Council, qualifying in 1986. Standing in for a holidaying contract engineer led to a career change and he trained in this field before joining lamp

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Twitter: @sll100

supplier Smith Brothers in 1990. Returning to Wakefield Council in 1993, he took up his first design role in the architect’s department, followed by a move into sales at Apollo Lighting. In 1996 he moved to White Young Green as an engineer. He joined WSP in 2000, progressing to technical director, a post he has held for the past nine years.

His ‘passion for promoting engineering and raising technical standards across the industry has led him to volunteer with various engineering institutions,’ said Ruffles.

He is a fellow of the IET, the IMechE, CIBSE and the SLL. He has been a member of the SLL’s TPC since September 2010 and chair since Jan 2015. He was author of the updated LG7 on office lighting in 2015 and the brand new LG17 on retail lighting in 2018. He also wrote various chapters of the Lighting Handbook and has contributed widely to other guides and documents.

‘Simon is a truly all-round engineer and a very worthy recipient of the Lighting Award,’ concluded Ruffles.

An honorary fellowship was given to

‘His passion for promoting engineering and raising technical standards has led him to volunteer with various engineering institutions’ Barrie Wilde, former president, who has earned widespread respect for his work in education. He began as a junior electrical engineer with John Lewis.

In 1963 he joined RS&P as an engineering draughtsman in electrical control systems.

The following year he moved to City of London Real Property Company (now Land Securities), as an electrical engineer, responsible for all the lighting for the whole new building stock. He then joined Arup Associates as a group electrical engineer

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AGM: Awards

‘He sums up his mantra for his lifelong passion for delivering lighting education and mentoring as IED: 8 Inspire, Engage, Direct’

consultant since retiring as head of lighting design at ChapmanBDSP in 2017.

‘Graham’s contribution to lighting design is recognised internationally and has inspired a succession of designers,’ said Kevin Theobald, reading a citation by Large’s former colleague Theo Paradise-Hirst. ‘Employing a skilful blend of technical knowledge, attention to detail, coupled with visual imagination, he has shaped his impressive career in both the performing arts, and the built environment.’

He left an early career at the Ministry of Defence to join the lighting department at Glyndebourne. He moved to Theatre Projects Services, as lighting design assistant, eventually becoming a designer in his own right. This involved him in a global career, including two years working as lighting consultant to Shirley MacLaine.

Moving into architectural lighting, he spent nine years at Maurice Brill Lighting Design.

He joined Lighting Design Partnership as a senior designer, becoming a director. When LDP closed, he joined Graham Phoenix to form Phoenix Large Lightmatters. In 2008 he created a lighting design department at Waterman International before joining what was then Chapman Bathurst in 2012.

Since retiring he has worked on a new project with the LET, and has been appointed to sit on the Court of The Worshipful Company of Lightmongers.

His work, said Theobald, ‘demonstrates the art of great lighting design. Practicality and sensitivity, with aesthetic ideas, form both the lighting approach to a building, or the visual script for a live performance.’

Sponsors in Partnership Fagerhult, Thorlux, Xicato and Zumtobel received their certificates, as did the latest LET diploma recipients, Vlad Oltean, Anna Szot and SLL coordinator Juliet Rennie.

The Leon Gaster Award was given to Mariana Figueiro, R Nagare and LLA Price for their paper ‘Non-visual effects of light: How to use light to promote circadian entrainment and elicit alertness’ (LR&T Vol 50, Ed 1).

The Walsh-Weston Award went to Mariska Stokkermans, I Vogels, Y de Kort and I Heynderickx for ‘Relation between the perceived atmosphere of a lit environment and perceptual attributes of light’ (LR&T Vol 50, Ed 8).

This year’s regional award went to Sonia Pepperell of Thorlux who is the representative for CIBSE West Midlands region.

p Simon Robinson with outgoing president Iain Carlile

p Barrie Wild

p Graham Large

p SLL coordinator Juliet Rennie with Bob Venning

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Michael Eleftheriades

in 1968, moving on to Steensen Varming in 1971. Two years later, he was senior group electrical engineer and then head of electrical engineering for the Milton Keynes Development Corporation.

In 1988 he set up the specialist lighting department at BDP, which supported all the company’s offices across the UK and Europe.

In 1994 the unit converted to BDP Lighting with him as director. He and his team won at least 12 national lighting awards for their work.

1988 also saw his involvement with delivering Stem to schools as a science and engineering ambassador, something he continued to do for the next 30 years. In 2005 he became an LET tutor. ‘He and June, his wife, would open his house to student groups to continue their education and mentoring after the LET Workshops were dropped, practising what he preached that you have to generously spend time with students for them to truly succeed,’ said Bob Bohannon in his citation.

He worked as a consultant and in 2016 started his involvement with the LIA, writing the new LIA Certificate Course and becoming both a tutor and registered lecturer at South Wales University. He also structured and wrote the LIA’s new Advanced Interior Lighting Design Course.

‘He sums up his mantra for his lifelong passion for delivering lighting education and mentoring as IED: Inspire, Engage, Direct,’ said Bohannon. ‘He inspired his students and team members. He engaged with pupils, colleagues and clients alike. But to truly help those students, in the nuanced practice of lighting design, you need to direct them on the route to take.’

The President’s Medal, first awarded to Joe Lynes in 2009, recognises a significant and lifetime contribution to lighting. This year’s recipient was Graham Large. His career as a lighting designer extends over more than 40 years, and he continues to practise as a

July/August 2019

Daylight House, Yokahama, Japan, by Takeshi Hosaka.

Photography: Koji Fujii

Daylight research

READING THE WEATHER Eleanora Brembilla, research associate at Loughborough University, outlines current studies into improving solar data in CIBSE climate files e are all fascinated by the weather. It is an extremely common topic (and not just in the UK), yet the science behind weather forecasting is based on complex models, obscure to most of us. It may surprise readers to learn that standard climate files play a very similar role in the building performance simulation community; everyone uses them, but only a few actually question the models hidden within their familiar, functional format.

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Dr Eleonora Brembilla is a research associate in Advanced Building Daylight Modelling at the School of Architecture, Building and Civil Engineering at Loughborough University. Her paper, Improving solar data in CIBSE climate files – survey of measuring networks and test on daylight simulation, was presented at the CIBSE Technical Symposium 2019 at Sheffield University in April

Twitter: @sll100

The New European Standard for Daylight of Buildings (EN 17037) In a major departure from the majority of previous national standards which were founded on relative levels of illumination (in other words, a daylight factor percentage value), the recommended target values in the new standard are founded on the annual provision of absolute levels

When we evaluate daylight levels in a building using simulation tools, we rely on illuminance data provided by climate files to reproduce the outdoor luminous conditions that are typical for the chosen location. Knowing the direct normal and the diffuse horizontal components of the outdoor illuminance allows us to recreate a plausible sky luminance distribution – what the prevailing sky (sun and clouds) might look like at a given particular moment – thanks to the use of empirical sky models

of illumination, for example 300 lux.

Thus, there is a degree of ‘climate connectivity’ in the standard since the prevailing levels of daylight availability (for any specific locale) are determined from annual weather files. This gives a further impetus to ensure that design evaluation and compliance verification are founded on reliable weather data.

See Light Lines May/June p9 for review of EN 17037

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Daylight research

‘Everyone uses them, but only a few actually question the models hidden within their familiar, functional format’ such as the Perez All-Weather one.

This is one of the key principles behind climate-based daylight modelling (CBDM), a technique now mandatory for school designs within the Priority School Building Programme and increasingly used to evaluate daylighting in general (for instance, an option in LEED).

Figure 1: the number and completeness of solar irradiance data measured in Met Office weather stations have been greatly improving over the past 20 years. The graph shows the portion of missing data at several Met Office stations, for each year in the period 1998-2017

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SIGNIFICANT UNCERTAINTIES The problem, however, is that illuminance is very rarely measured by weather stations’ equipment, let alone its separate direct and diffuse components. Instead, a luminous efficacy model is applied to convert irradiance (total radiant energy) into illuminance (the visible part). Most simulation tools ‘read’ irradiance values rather than illuminance from a climate file, and they then apply the conversion within the software. Irradiance is therefore incredibly important for daylighting applications, but also for other vital building performance analyses such as overheating potential or building systems’ sizing. But,

Additional Information • E Brembilla, J Mardaljevic, A Mylona, Improving Solar Data in CIBSE Climate Files – Survey of Measuring Networks and Test on Daylight Simulation, in: CIBSE Tech Symp, Sheffield, UK, 2019. https://dspace. lboro.ac.uk/2134/37440 • E Brembilla, J Mardaljevic, Climate-Based Daylight Modelling

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and this has surprised many building simulation users, the irradiance data contained in existing climate files is in most cases not measured either. It is, instead, derived from cloud cover, which – together with sunshine duration – used to be one of the few indicators of sky conditions that was routinely recorded in a large number of weather stations.

There is little doubt that the stacking of several empirical models to go from a cloud cover value (expressed in oktas,

for compliance verification: Benchmarking multiple stateof-the-art methods, Building and Environment, 158 (2019) 151–164. https://doi.org/10.1016/j. buildenv.2019.04.051 • J Mardaljevic and J Christoffersen.

‘Climate connectivity’ in the daylight factor basis of building standards.

Building and Environment, 113:200–209, 2 2017. https://dspace.lboro.ac.uk/ dspace-jspui/handle/2134/22300

integer numbers from 0 to 8 indicating clear to overcast conditions) to a sky luminance distribution introduces significant uncertainties in the final results of any building simulation. However, the developers of the first generations of climate files were left with no other choice, due to the lack of irradiance or illuminance measurements in sufficient quantity and quality. To create a Test Reference Year (TRY – also called Typical Meteorological Year, TMY), representative of the climate – not weather – in a specific location, at least 10 years of continuous data recording is necessary, ideally collected at hourly time steps. The months that better represent the typical conditions are then extracted from this multi-year series and collated together to form a TRY. SIGNS OF IMPROVEMENT In the past 20 years the availability of irradiance measurements collected by the Met Office over the UK territory has greatly improved (Fig 1). There are now around 50 stations that have been collecting good quality, hourly global

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Daylight research

p Figure 2: location of solar radiation/illumination measurement stations belonging to the BSRN, to PHE and to the Met Office

irradiance data for more than 10 years.

Two weather stations (one in Camborne, Cornwall, and one in Lerwick, Shetland) also collect direct normal and diffuse horizontal measurements at one-minute time steps, as they are part of the Baseline Surface Radiation Network (BSRN), a worldwide network established to provide highly accurate data for model validation.

In addition to these agencies, Public Health England (PHE) has been measuring global illuminance in nine British locations, but most of them have not recorded data for a sufficient number of years yet (Fig 2).

We can hope that data accuracy and availability will only increase with time.

Twitter: @sll100

A NEW APPROACH The method we are proposing in this project is to improve radiometric and photometric data contained in the CIBSE climate files by basing them on Met Office irradiance data. As only global values are recorded, a separation model is required to determine direct normal

and diffuse horizontal components. After testing several of them, we settled on the Skartveit and Olseth model, which correlates reasonably well with measured data from both BSRN stations and does not depend on a lot of other variables (often poorly resolved) in order to work.

Tests on the Perez luminous efficacy model also confirmed its suitability to derive illuminance values from irradiance. Climate files obtained with this new approach showed biases against measured values of only 11 per cent, compared to the -30 per cent of existing files (particularly in the direct normal irradiance component).

The last step was to find out whether this improvement in input climate data led to an equivalent improvement in CBDM results. We created three different weather files for Camborne, representing the year 2016: first, using measured irradiance from BSRN data, as a reference; second, using derived irradiance data with the model currently used in CIBSE climate files; and, third, using the newly proposed approach based on Met Office global irradiance data and the Skartveit-Olseth separation model.

We chose a side-lit, south-facing classroom space as a case study for the simulation, and we analysed the resulting indoor average illuminance on the working plane. Compared to the reference data (obtained by using the climate file constructed with BSRN measures), the current and the proposed solar radiation models respectively showed a bias error of -8 per cent and of 6 per cent when considering total illuminance. However, when considering only direct sunlight illuminance (used by some CBDM metrics and analyses), the biases found for the current and proposed models were -35 per cent and 10 per cent respectively, showing a marked improvement.

The proposed approach outlined here has the potential to significantly improve the accuracy of solar irradiance data in CIBSE climate files, as well as that of building performance simulation results. The findings will need to be tested both for additional locations and for longer time periods to ensure their scalability, but these preliminary results are a very promising start.

‘The problem is that illuminance is rarely measured by weather stations’ equipment, let alone its separate direct and diffuse components’

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SLL statement: circadian lighting

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Prague-based energy company Innogy installed one of Europe’s largest biodynamic lighting installations in 2017 with the aim of improving the wellbeing of the occupants

BODY OF KNOWLEDGE While increasingly discussed, ‘circadian lighting’ is a complex concept, subject to misuse and misunderstanding.

The SLL has issued a statement defining the term and clarifying the current state of research his statement defines the society’s understanding of the term circadian lighting. It highlights areas of established research on the topic, providing an overview of what is commonly accepted, as a result of sufficiently robust research and evidence.

The document also seeks to identify areas where further research is required. The intention is not to reach a decisive conclusion but to raise awareness of the areas where more information may be required.

While the statement uses the phrase

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circadian lighting, there are a number of terms which are used interchangeably. For example, human centric lighting, which is arguably problematic in that lighting design and the use of artificial light generally centres on human beings. It refers to the creation of a lighting system which adapts to the changing needs of an individual throughout the day to allow them to receive the varied spectrum and quantity of light in relation to their natural circadian rhythm. This statement focuses on artificial lighting that is described or marketed as circadian or human

centric lighting. However, it is recognised that, for stimulation of the circadian system and support of human health, there is no substitute for daylight.

In his editorial piece for Vol 48, Issue 2 of Lighting Research and Technology, Professor Peter Boyce wrote that human centric lighting, ‘…considers both the visual and non-visual effects of light and that widens the range of possible visual effects from visual performance and comfort to sleep quality, alertness, mood and behaviour with consequences for human health...’

In this sense, human centric or circadian lighting implies a transition from traditional approaches to lighting design and application, referring to the creation of a lighting system, dynamic in both intensity and spectrum, which can be controlled to stimulate the human circadian system.

In gaining a better understanding of the effect that light has on an individual’s health and wellbeing, elements including timing and duration of exposure to light, quantity and spectrum of light, and the spatial distribution also need to be considered.

Dr Mariana Figueiro highlights developments in our understanding of non-visual responses to light since the discovery of the intrinsically photosensitive retinal ganglion cells (ipRGCs) in 2001 in her research paper, Non-visual effect of

July/August 2019

SLL statement: circadian lighting

light: How to use light to promote circadian entrainment and elicit alertness, published in Vol 50, Issue 1 of LR&T. It is understood that the light-dark cycle informs our biological clock, with the level of light signalling the appropriate responses within the human sleep-wake cycle. The body will release or suppress hormones, depending on the need to be alert or to rest in relation to the time of day and incidence of light on the retina.

As a result, circadian lighting has the potential to support biological rhythms where they may otherwise be disrupted.

In recognising that a high-intensity, shorter wavelength of light acts to suppress the release of melatonin, helping us to wake up in the morning, and a less intense, warmer white light assists in the release of melatonin, helping us relax in the evening, these elements can be incorporated within a dynamic lighting scheme in an attempt to support circadian rhythms. The potential benefits of this are increased alertness during the day, with improved sleep at night, resulting in a positive effect on wellbeing.

Obviously, this leaves out myriad other factors which also have an impact on an individual’s wellbeing.

Alongside CIBSE and the BRE, the society is involved in an ongoing study on the effects of circadian lighting on health and wellbeing.

We look forward to seeing the results from this study which are due to be published in 2019. The research has compared two lighting conditions so far, one with existing fluorescent lighting and another with tuneable LED lighting.

Researchers are monitoring both the objective measures, including the light levels within the test space and the light exposure of the participants, along with the subjective measures such as questionnaires at the end of each lighting condition, and regular computer-based tests to monitor participants’ reaction times.

Further studies have suggested that by introducing circadian lighting to a work environment, there is the potential to mitigate some of the negative side effects of circadian misalignment or desynchronisation. This is generally accepted as a positive application of circadian lighting, with the intention of reducing disruption to occupant sleep-wake cycles by

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The 19th-century General Savings Bank Upper Austria, Linz, where 10 pendants simulate daylight, cycling from warm white (2700K) to cool white (6500K). Lighting by Das Licht

actively manipulating the suppression and release of melatonin. However, as highlighted

by Deborah Burnett, principal and partner at Benya Burnett Consulting, in her article for LED Magazine, First do no Harm, ‘… with the link between light and health, there are no time-honoured rules, an established body of rules or proven best practices that can be used to redefine this paradigm of lighting design with health benefits’. In this sense, Burnett compares the installation of circadian lighting to projects, based on unsupported claims, to ‘a poor man’s version of practising medicine without a license’.

Introducing an element of individual control also plays a part in the application of circadian lighting. A number of studies has shown a positive occupant response when given control over certain elements of their surrounding environment, including lighting, temperature and the amount of natural light

entering the space. This in turn has led to a feeling of increased wellbeing while in the space. However, it is important that there is a balance between areas with individual control according to preference and any centrally controlled colour and timing schedules that may be in place for a space or building.

It is essential for the lighting industry to recognise the current limitations in our knowledge of the implications of introducing circadian lighting. Under no circumstances should commercial sales be prioritised when there is a lack of factual or proven evidence for the claims being made. Referring back to Professor Peter Boyce’s editorial, he states, ‘The further the outcome is from the direct effects of lighting on human physiology, the more likely it is that factors other than lighting will intervene.’

There have been various attempts to quantify circadian light and its impacts, with a view to creating a metric for practical application. For example, the WELL Building Standard. This standard introduced the concept of melanopic lux, which focuses on luminous efficiency function, peaking at 480nm and based on the action spectrum of melanopsin – as opposed to the more

‘There are no... proven best practices that can be used to redefine this paradigm of lighting design with health benefits’ – Deborah Burnett

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SLL statement: circadian lighting

‘The SLL recognises the need for additional, properly designed and monitored field studies’ traditional photopic luminous efficiency function, peaking at around 555nm, based on the foveal cone photoreceptors.

Within their article Quantifying Circadian Light and its Impact, Dr Mariana Figueiro and Dr Mark Rea state the following in reference to WELL and melanopic lux: ‘Photometric units have not yet been established for the circadian luminous efficiency function; consequently, quantifying light in terms of melanopic lux has yet to be defined.’

They go on to explain that as the impact of melanopic lux on the suprachiasmatic nuclei is unknown, it is impossible to use the action spectrum for the suppression of melanopsin to describe how affective artificial light or daylight are for stimulating the human circadian system. Within this article, Dr Figueiro and Dr Rea conclude that, ‘…a metric based on melanopsin alone will be fundamentally inaccurate and incomplete as a representation of the spectral and absolute sensitivities of the human circadian systems’.

In their work at the LRC at Rensselaer Polytechnic Institute, Dr Figueiro and Dr Rae have been developing alternative metrics and tools to assist designers and specifiers in the practical application of circadian light in the built environment. They have proposed a metric called the circadian stimulus (CS).

As outlined in the LD+A article, Designing with Circadian Stimulus, by determining the spectral irradiance distribution of light incidence at the cornea, you can then calculate circadian light (CLA), ‘…which is irradiance at the cornea weighted to reflect the spectral sensitivity of the human circadian system as measured by acute melatonin suppression after a one-hour exposure, and CS, which is the effectiveness of the spectrally weighted irradiance at the cornea from threshold (CS = 0.1) to saturation (CS = 0.7).’

While efforts to produce a metric for circadian lighting are a step in the right

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direction, with regard to providing a quality lit environment that does not have a detrimental effect on health and wellbeing, it is premature in relation to our understanding of the elements that affect the human circadian system.

It is these other intervening factors that we need to understand before we can provide a useful evaluation of the benefits of circadian lighting. At present, we understand that individual lighting requirements will differ on basis of age, chronotype and duration of exposure among other factors. A light history or context is required to provide a circadian lighting solution that will cater to individual requirements. The factors that contribute to good circadian health are cumulative and will vary from person to person.

There needs to be further clarification regarding the other parts of our brain which are influenced by light. The majority of studies so far have been carried out in laboratory conditions, or have simply been reports by manufacturers containing enthusiastic and

References 1. Professor Peter Boyce, Editorial: Exploring Human Centric Lighting, LR&T, Vol 48, Issue 2 (2016) 2. Dr M Figueiro, R Nagare and LLA Price, Non-visual effects of light: How to use light to promote circadian entrainment and elicit alertness, LR&T, Vol 50, Issue 1 (2018) 3. Dr Russell Foster, The Scientists View – Spectral: Human Centric Lighting at the Leadenhall Building (2016) www.cibse.org/knowledge/knowledgeitems/ detail?id=a0q0O00000CF7o9QAD 4. Cosmin Ticleanu, Report Describing Initial Literature Review on Circadian Lighting, BRE Client Report (2017), project jointly funded by CIBSE and the BRE Trust www.cibse.org/knowledge/knowledgeitems/ detail?id=a0q0O00000CF7o9QAD 5. Deborah Burnett, First do no Harm, LEDs Magazine (2015) www.ledsmagazine.com/articles/print/ volume-12/issue-10/features/designer-scorner/first-do-no-harm.html 6. WELL Building Standard – 54: Circadian Lighting Design, Q4 Version 2018 https://standard.wellcertified.com/light/ circadian-lighting-design 7. Dr M Figueiro and Dr M Rea, Quantifying Circadian Light and its Impact, www. archlighting.com (2017) www.archlighting.com/technology/ quantifying-circadian-light-and-its-impact_o 8. Dr M Figueiro, Kassandra Gonzales and David Pedler, Designing with Circadian Stimulus, LD+A magazine (2016) www.

anecdotal responses from occupiers of a space where new lighting has been installed.

Often people will have a positive response if a new, high-quality lighting system is introduced, especially when replacing something that may have become outdated. Therefore, there is a need for more field studies, with enough participants to produce representative data sets, while also taking certain human factors, such as responses to change, into account.

The SLL recognises the need for additional, properly designed and monitored field studies of this kind, along with further laboratory research, in order to recommend or advise on the use of circadian lighting. Additionally, while research is ongoing, certain questions should be asked with regard to the validity of products or services claiming to offer the suggested benefits of circadian lighting. The SLL looks forward to the publication of the BRE and CIBSE research findings, and will continue to monitor the work of lighting researchers around the world, both in LR&T and more generally.

lrc.rpi.edu/resources/newsroom/LDA_ CircadianStimulus_Oct2016.pdf

Further reading • KL van Someran, C Philip Beaman and L Shao, User’s Experience of Lighting Controls – a case study, LR&T, Vol 50, Issue 7 (2018) http://journals.sagepub.com/doi/ full/10.1177/1477153517709063 • FS Yilmaz, People Friendly Lighting Controls – User Performance and Feedback on different interfaces, LR&T, Vol 48, Issue 4 (2016) http://journals.sagepub. com/doi/full/10.1177/1477153515583180 • T Moore, DJ Carter, AI Slater, User attitudes towards occupant controlled office lighting, LR&T, Vol 34, Issue 3 (2002) http://journals.sagepub.com/doi/ pdf/10.1191/1365782802lt048oa • T Moore, DJ Carter, AI Slater, A study of opinion in offices with and without user controlled lighting, LR&T, Vol 36, Issue 2 (2004)http://journals.sagepub.com/doi/ pdf/10.1191/1365782804li109oa • F Tan, D Cacaido, A Pandharipande, M Zuniga, Sensor Driver Human-in-the-loop lighting control, LR&T, Vol 50, Issue 5 (2018)https://journals.sagepub.com/doi/ abs/10.1177/1477153517693887 • Professor Karolina Zielinska-Dabkowska, Human Centric Lighting – The new X Factor? Arc Magazine (2018) www.arcmagazine.com/human-centric-lightingthe-new-x-factor/ For a full further reading list go to www.sll.org.uk

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LR&T essentials

EYE OF THE BEHOLDER Iain Carlile looks at three of the latest Lighting Research and Technology papers which examine different aspects of perception q

o and Steemers have carried out a study assessing the illumination of concert lighting in a complex architectural space. Experiments were undertaken in King’s College Chapel, Cambridge, under four different electric lighting scenes. Using structured questionnaires, 78 participants (both performers and audience members) assessed the lighting scenes from different viewing locations within the chapel.

Analysis of the results revealed that the ratios and functions describing uniformity, brightness and light patterns are common explanatory variables for predicting perceived visual clarity, visual uniformity, brightness and spatial intimacy. Generally these perceived qualities were found to be best described by uniformity-related attributes, except for visual clarity, which had a greater relation to visual acuity-related measures. The authors note that in order to understand the luminous appearance of a complex architectural space, multiple methods of assessment must be combined.

A paper by Lynes investigates the use of Fourier analysis being applied to the illuminance profile around the curved surface of a small cylinder, considering one, two and three light point sources, and an extended light source. The analysis revealed only one odd harmonic, with an amplitude equal to half the illumination vector.

The lighting at any point in an open space can be described by the harmonics of illuminance around three mutually perpendicular cylinders. Visual discomfort is often associated with the presence of even harmonics. Lynes therefore suggests that field studies of cylindrical illuminance could be undertaken using a rotating photoreceptor driven by a microprocessor in order to undertake harmonic analysis in situ.

Also examining perception, Raynham et al propose a novel method to predict

Two of the electric light settings used in King’s College Chapel (Lo and Steemers)

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perceived adequacy of illumination.

Considering the metric of mean room surface exitance (MRSE), the authors argue that since MRSE describes the average interreflected flux density within a room and is independent of location or the direction of view within the room, then MRSE cannot be applied or has limited value in many realworld situations.

The authors therefore propose the use of mean indirect cubic illumination (MICI) instead, a new metric which describes the inter-reflected flux density at a point in a room and thus is a function of position within the room, but is independent of view direction. The authors note that MICI can Lighting Research and Technology: OnlineFirst All papers accepted for publication in LR&T are available online. SLL members can gain access to these papers via the SLL website (www.sll.org.uk)

Methods for assessing the effects of spatial luminance patterns on perceived qualities of concert lighting

be better applied in a room where it is not possible to view all of a room’s surfaces from all points of the room. It may also be useful to describe a room where the lighting is very non-uniform. In regular rooms it was found that the average MICI value was similar to the MRSE value, therefore the authors assume that perceived adequacy of illumination (PAI) can be predicted from average MICI value. Studies of MICI have so far been in uniformly lit spaces, devoid of daylight, and so further research is required to explore the relationship between MICI and PAI. Iain Carlile, FSLL, is the immediate past president of the SLL and a senior associate at dpa lighting consultants

VWL Lo and KA Steemers

Fourier components of cylindrical illuminance JA Lynes

A new metric to predict perceived adequacy of illumination P Raynham, J Unwin, L Guan

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Events 2019

5 JULY CIBSE training: Lighting Design – Principles and Application Venue: CIBSE, Balham, SW12 training@cibse.org 12 JULY CIBSE training: Emergency Lighting to Comply with Fire Safety Venue: CIBSE, Balham, SW12 training@cibse.org 23 JULY CIBSE training: Lighting – Legislation and Efficiency Venue: CIBSE, Balham, SW12 training@cibse.org 3-5 SEPTEMBER Shanghai International Lighting Fair Venue: Shanghai New International Expo Centre (SNIEC) http://shanghai-international-lighting-fair. hk.messefrankfurt.com/ 4 SEPTEMBER DIALux Lighting Software: Foundation Level (Lighting Industry Academy) Tutor: Liz Peck Venue: LIA, Telford www.thelia.org.uk 19 SEPTEMBER How to be Brilliant: Speakers: Arfon Davies and Nicola Rigoni of Arup on daylight and wellbeing Venue: The Old Truman Brewery, E1 www.theilp.org.uk/brilliant

3-5 SEPTEMBER: SHANGHAI INTERNATIONAL LIGHTING FAIR AT SNIEC (PICTURED)

23-26 OCTOBER Professional Lighting Design Convention (PLD-C) Venue: Rotterdam Ahoy!

2019.pld-c.com 8 NOVEMBER CIBSE training: Lighting – Legislation and Efficiency Venue: CIBSE, Balham, SW12 training@cibse.org 13-14 NOVEMBER LuxLive Venue: ExCeL London http://luxlive.co.uk 14 NOVEMBER SLL Young Lighter 2019 final Venue: LuxLive, ExCeL London www.cibse.org/society-of-light-andlighting-sll/sll-young-lighter-2019

24-26 SEPTEMBER Trends in Lighting Forum and Show Venue: Opera House, Bregenz, Austria www.forum-trends.lighting

14 NOVEMBER Lux Awards Venue: London Hilton, Park Lane https://luxawards.co.uk

15-17 OCTOBER Light Middle East (including Ready Steady Light ME with the SLL and Light Middle East Awards) Venue: Dubai International Convention and Exhibition Centre www.lightme.net

25 NOVEMBER DIALux Lighting Software: Foundation Level (Lighting Industry Academy) Tutor: Liz Peck Venue: Marriott Hotel, Slough www.thelia.org.uk

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LightBytes The LightBytes Series is kindly sponsored

by Fagerhult, Thorlux Lighting, Xicato and Zumtobel. For venues and booking details: www.sll.org.uk

LET Diploma: advanced qualification by distance learning. Details from www.lightingeducationtrust.org or email LET@cibse.org CIBSE Training: various courses across the whole spectrum of lighting and at sites across the UK. Full details at cibse.org/training-events/cibse-training

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