Light Lines Sep/Oct 19

IN CONTROLS

Getting to grips with the latest technology

KEEP UP THE GOOD WORK

Why CPD matters

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:

Linda Salamoun MSLL (chair)

Iain Carlile FSLL

Jill Entwistle

Chris Fordham MSLL

Rebecca Hodge

Eliot Horsman MSLL

Stewart Langdown FSLL

Bruce Weil

Gethyn Williams

All contributions are the responsibility of the author, and do not necessarily reflect the views of the society. All contributions are personal, except where attributed to an organisation represented by the author.

COPY DATE FOR LL 6 2019

IS 20 SEPTEMBER

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

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

FROM THE EDITOR

A crucial but frequently vexatious area of lighting is controls. No matter whether it was a simple dimming system for domestic LV halogen that made buzzing noises or incompatibility issues with a complex commercial system controlling LED fittings or the infamous street lighting system which had them burning away in the middle of the day, there seems a deal of scope for difficulty and deviation.

A high percentage of systems are assuredly installed without hitch and work beautifully but complex electronic systems do seem somewhat temperamental and twitchy.

One of the fundamental issues with them is that they have often intimidated users. How many installations have remained at default setting, with blinds adjusted manually if at all and lights remaining on when they should be off?

And now that we have options such as Wi-Fi and Li-Fi on the agenda it seems to have got a whole lot more complicated,

for both the specifier and the user.

It is therefore timely that the SLL and Arup are organising a joint event this month. Two features (see Net Results, p5, and The Wireless and Wherefores, p8) offer a brief preview of some of the themes that may emerge. As Iain Ruxton points out in his piece on Bluetooth, the key thing is that everyone, from specifiers to vendors, ensures that they are up to speed with the technology, which needs to be ‘taken seriously and implemented properly’.

A classic case of the need for CPD (see Working Knowledge, p13).

JILL ENTWISTLE

CURRENT SLL LIGHTING GUIDES

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)

Guide to Limiting Obtrusive Light (2012)

Code for Lighting (2012)

Commissioning Code L (2018)

SLL Lighting Handbook (2018)

FROM THE SECRETARY

We are looking forward to our next event with Arup which will be a panel discussion on lighting controls (see p5). It will be held on the evening of 18 September at Arup, London, and free-of-charge delegate bookings can be made through the website where there is more information about the event, including the line-up of speakers.

We will be exhibiting at [d]arc room this year on 19-20 September at the Old Truman Brewery so we hope to see many of you there. The event is part of London Design Fair and runs from 19-22 September with the last two days open to the public. Paul Ruffles is also presenting a piece on the Lighting Handbook the afternoon of Friday 20 September, a good opportunity to catch up on your knowledge.

We are delighted to confirm that the brand new peer-reviewed LightBytes series will begin on 10 October in Birmingham. The theme of the one-day conference is light and wellbeing, with the following speakers and Sponsors in Partnership: Martin Barclay (Soraa), Richard Caple (Thorlux), Roger Sexton (Xicato) and Graeme Shaw (Zumtobel).

Joining the Sponsors in Partnership will be Eleonora Brembilla, research associate at Loughborough University and daylight specialist. We encourage all to attend the events in the regions, each one has 4.5 hours CIBSE-accredited CPD. The series will also visit: Dublin (21 November), Manchester (30 January), Leeds (13 February), Cardiff or Bristol (26 March), Glasgow (23 April) and London (4 June).

On the subject of companies which generously support the SLL, we are delighted to welcome Trilux Lighting to the SLL Sustaining Member programme.

We are currently gearing up for exhibiting at LuxLive and attending the Lux Awards. The four finalists of the Young Lighter 2019 competition will present their papers at LuxLive on the afternoon of 14 November and join the society at the Lux Awards the same evening, where the winner of Young Lighter 2019 will be presented with the title and, of course, the prize money.

A BIT ON NOMINATIONS

We have been asked to describe and

clarify the annual nomination process, which puts forward an individual, nominated by the SLL executive, to undertake roles in council and the executive committees. These individuals then stand for election by the members at the next AGM.

Each year the society’s nominations panel meets, generally in the autumn. The panel is chaired by the SLL president and includes the immediate past president, past president, president elect and vice president regions. The panel gathers to discuss and decide on the executive and council member nominations, which are then put forward for the consideration of the membership and voted on by the membership. The nominations could include individuals for the role of president elect, vice president, treasurer and council member.

The notification of the executive’s nominations to the membership must be sent at least three months prior to the AGM which must take place between 1 April and 30 June, and is generally held in May. On receipt of the nomination notification, the membership has 42 days to offer alternative candidates for the roles stated in the notification. Any nominee from the membership must include the express consent of the person nominated, as well as at least two names of the society’s members nominating the individual for a specific role.

If there is more than one nomination for the same role a ballot will then be held. If a ballot is necessary it is conducted by the secretariat under the rules and procedures for member ballots set out from time to time by the CIBSE board. It may be conducted digitally.

More information regarding the nominations process and criteria for nominees can be found on the SLL website under ‘About SLL’.

EDITORIAL

SECRETARY’S COLUMN

NEWS

NET RESULTS

Marking the joint SLL/Arup event on lighting controls this month, Francesco Anselmo looks at possibilities offered by the Internet...

THE WIRELESS AND THE WHEREFORES

...while Iain Ruxton asks if people really understand the cons as well as pros of Bluetooth

CHANGE FOR THE BETTER?

Paul Littlefair and Cosmin Ticleanu describe an experiment conducted by the BRE to investigate the effects of dynamic ‘circadian’ lighting

WORKING KNOWLEDGE

Juliet Rennie looks into the what, why and how of CPD

PERCEIVED TRUTHS

Iain Carlile selects three of the most recently published papers from LR&T focusing on visual perception and colour

EVENTS

COVER: Linda Salamoun’s creation for Light Graffiti Night, an SLL summer event with artist and photographer Michael Bosanko

EIGHT CONTENDERS COMPETE FOR THE SLL YOUNG LIGHTER AWARD AS EVENT MARKS 25TH ANNIVERSARY

A total of eight contenders have been shortlisted for the SLL Young Lighter of the Year competition, which marks its 25th year in 2019.

The topics for presentations are as ever highly diverse, ranging from daylightinspired lighting to using human-centric lighting in an underground metro car. The following entrants will be competing for the final four places:

• Beatrice Bertolini (GIA Equation, London): Urban lighting meets people –social engaging lighting settings for sustainable cities

• Fatemeh Dastgheib (KTH Royal Institute of Technology, Stockholm): Outdoor lighting and perception of safety from a female perspective

• Melissa Kennedy (WSP, London): Texture within the light – evaluating the impact of textured light upon the sensual atmospheres within art, architecture and design

• Joan-Tähven Vene (DeltaE Engineering, Estonia): Lighting passport for the city of towers and the ways to achieve it

• Anna Tomschik (Black Ljusdesign, Stockholm): Daylight-inspired lighting – design concepts aligned with nature

• Nils Voerste (Bauhaus-Universität Weimar, Germany): Evidence-based lighting design for urban environments – natural and artificial lighting impacts on people’s experiences of public space

• Anna Wawryzniak (Peter Andres Lichtplanung, Germany): A light booster metro car for the commuting workforce – human-centric lighting in underground transportation

• Jie Xu (UCL): Will and how ETFE and glazing materials influence the light distribution of a roof garden?

For Stage Two of the competition, the shortlisted entrants will elaborate on their initial ideas. This will include a three to five-minute piece to camera and a developed presentation or written paper. The judges will accommodate alternative formats, should they be more fitting for the idea or project in question.

For more details go to: www.cibse.org/society-of-light-and-lighting-sll/sll-young-lighter-2019

ON THE LIGHTER SIDE...

Apparently the grass is not only greener but also potentially shinier. Lightsource BP, the oil giant’s solar subsidiary, is on a quest for Britain’s shiniest grass to optimise its new double-sided solar panels which can harness light reflected off the ground.

At a test site near Belfast the bifacial panels showed a 15 per cent increase in electricity output but this can be even higher if the surface beneath is more reflective.

BP is working with a Norfolk seed firm to find the most lustrous lawn material. ‘What we don’t know at this stage is whether the best grass will prove to be a wide-blade cattle grazing grass or a finer golf course variety,’ Chris Buckland, technical director of Lightsource BP told The Guardian. ‘We’re not there yet.”

www.theguardian.com/business/2019/jul/08/ bp-solar-subsidiary-sees-the-light-in-searchfor-uk-shiniest-grass-lightsource-energy

LIGHTBYTES 2019-20 LAUNCHES

The new peerreviewed LightBytes series will begin on 10 October in Birmingham. This year’s theme is light and wellbeing. The Sponsors in Partnership will be Soraa, Thorlux, Xicato and Zumtobel, each of whom will be fielding specialist speakers.

Joining the line-up will be Eleonora Brembilla, daylight specialist and research associate at Loughborough University.

Each one-day conference will have 4.5 hours CIBSEaccredited CPD.

The series will visit Dublin in November, Manchester in January, Leeds in February, Cardiff or Bristol in March, Glasgow in April and finally London in June.

For more details go to www.sll.org.uk

WORKPLACE STANDARD OPEN FOR COMMENT

A draft of BS 12464-1 Light and Lighting –Lighting for Work Places – Part 1: Indoor Workplaces is available for comment. The deadline for feedback is 10 September.

Please go to: http://go.cibse. org/e/698403/projects-2018-03165/h9 8q/46710519?h=u4uOkQne5l7jpnVAw QgNfgMHkb6cwk17TN6CMvoobk

The Internet has now connected almost 60 per cent of the world population1 and the Internet of Things is increasingly expanding, absorbing any object one can think of, sometimes with dubious outcomes2

With a bit of creativity and ingenuity, the same technologies used by the Internet, including the TCP/IP protocol suite and protocols such as HTTP and MQTT, can be used straight away in addition to DMX, Dali and Bluetooth equipment to replace complex and costly proprietary networked lighting control systems.

This alternative way of thinking about controls is possible thanks to the availability of low-cost IP network equipment, easily programmable microcontrollers, such as those available as part of the Arduino family, and inexpensive system-on-a-chip platforms, such as the ubiquitous Raspberry Pi.

The full programmability of these systems is a breath of fresh air for designers who are keen to transform the modalities of interaction with buildings and lighting installations, in the quest to achieve better controls, adaptability of user interfaces and meaningful user experience.

The possibility of using web technologies also means that the user interface to lighting installations can be modified according to the ever-changing requirements of the particular users, making it always up-to-date. This opportunity to reprogramme hardware openly with project-specific software is key to avoiding systems obsolescence. It also has the potential to transform the way we approach the design and specification of control systems, creating new professional roles at the intersection between interaction

References

NET RESULTS

Marking the joint SLL/Arup event on lighting controls this month, Francesco Anselmo discusses how the web offers alternative possibilities

design and software development. The following are three case study examples showing how this approach has been successfully applied to real projects.

BENJAMIN WEST OFFICE, LONDON

For this project, the brief was to deliver a tunable white lighting solution, including an intuitive web-based user interface that allows the office staff to directly adjust the lighting without the need for recommissioning. The lighting and interaction design for the new office of the Benjamin West design team has focused on assisting their move from a daylit environment to a subterranean space with almost no access to daylight.

The solution has created a variety of lighting zones within the open space and the two personal working/meeting spaces, where LED lighting has been designed to recreate the effect of skylights.

Despite the high density of luminaires, the lighting control project cost has been

1 Source: https://internetworldstats.com/stats.htm

2 Refer to the https://twitter.com/internetofshit feed for some amusing and disturbing reflections on the status of the Internet of Things

q Interior view of the Benjamin West office. Tunable white lighting can be adjusted individually for the majority of luminaires

Francesco Anselmo, MSLL, is associate director, IoT, interaction and lighting at Arup. The joint SLL/ Arup event on lighting controls will take place on 18 September at Arup’s London office in Fitzroy Street, W1

q Examples of the lighting control user interfaces based on the OpenHAB framework and developed for Benjamin West

q The use of tunable white lighting recreates the effect of skylights

minimal, with the controls delivered using DMX, cost-effective DMX hardware and open-source software including Open Lighting Architecture (https://www.openlighting.org/) and OpenHAB (https://www.openhab.org/) installed in an Apple Mac Mini, which acts as the main lighting controller and user interface server.

The user interface has been customised to the needs of the users, including the names of the people operating it, and has used a layered approach to browsing the controls, from high-level scene settings down to individual controls of luminaires.

MYCUP, BANK OF AMERICA

MERRILL LYNCH

This was an ephemeral lighting installation designed by the Interactive Architecture Lab at UCL and Arup, and commissioned for Earth Day by Bank of America Merrill Lynch and arts partner Create London. Comprising 8000 plastic cups, the installation aimed to educate and inspire employees to recycle at work as part of the bank’s commitment to environmental sustainability.

The lighting core at the centre of the geodesic structure illuminated the surrounding space through the filtering layer of the translucent outer envelope created by the plastic cups. The positioning of the LEDs revealed the inner structure and the surrounding space through the glowing skin of the sphere, using a multiplicity of dynamic lighting behaviours.

The source code of the myCup installation is publicly available at the following address:

https://github.com/aruplightlab/ mycup

 Night-time view of the myCup lighting installation

q The illuminating core of the myCup geodesic dome comprised 32 DMX-controlled LEDs and their auxiliary electrical equipment

The lighting core included 32 DMXcontrolled LED modules, arranged so that each one was illuminating the face of a truncated icosahedron. Arup developed a 3D interactive web-based interface for visitors that allowed anyone to play with the lit sculpture through an ad-hoc Wi-Fi connection.

Visitors could just select the Wi-Fi SSID named as the artwork and a pop-up browser window would let them access the web user interface, without the need to install a specific mobile application.

In this way, the richness of visual sensations offered by the interplay of light, darkness and reflections, both inside the sphere and in the surrounding environment, was created by the visitors. They were given a direct role in shaping the sculpture’s lit behaviour, allowing them to activate the lighting with gestures and collaboratively generate ever-changing lighting patterns.

q

different planes

COLONIES, JOHN BRADFIELD CENTRE, CENTRAL WORKING, CAMBRIDGE

Colonies is a large, interactive chandelier designed by Arup and Install Archive to stimulate and engage the guests of the John Bradfield Centre, the Central Working co-working space in Cambridge.

It consists of a network of lines of light that are activated by a web-based user interface that can be reached by anyone connecting to the building public Wi-Fi network.

The user interface replicates the visual arrangement of illuminated segments in a regular grid, allowing users to choose colours from a palette and freely paint the colour on each segment collaboratively. The status of the lighting is in fact shown in real time over multiple web browsers.

The lighting installation also exposes a simple API (application programming interface) that the tech startups hosted in the office can use to link to the many datasets generated as part of their work.

The installation is monitored remotely by Arup using a ‘heartbeat’ mechanism that automatically sends alarms when a connectivity problem is reported.

The source code of the Colonies installation is publicly available at the following address:

https://github.com/aruplightlab/ dots_and_boxes

 Colonies has a simple API (application programming interface) that tech startups in the office can use to link to the many datasets generated as part of their work

 The user interface replicates the visual arrangement of illuminated segments

Colonies: lighting segments are arranged in

THE WIRELESS AND THE WHEREFORES

Iain Ruxton, one of the participants in the SLL/Arup event, asks if people really understand the cons as well as the pros of Bluetooth

The advent of Bluetooth wireless lighting control integrated into the lights themselves offers appealing opportunities for many lighting designers and specifiers. However, the pros and cons of the technology are not understood in any depth by most of the people specifying, buying, and even selling it.

While Bluetooth control may solve some problems, it may also create others if it is not implemented carefully and knowledgeably.

There are, it appears, currently four major motivations for specifying Bluetooth lighting control:

• Early-adoption… gadget appeal

• The provision of control where the addition of data wiring is challenging

• Potential savings in installation cost

• Internet of Things connectivity

The first of these reasons is clearly flawed reasoning – in fact it isn’t reasoning at all. Given that lights still require wiring for power anyway, there has to be a compelling reason to deploy wireless controls. Specifying this technology for its gadget appeal or gimmick factor is unlikely to end well. Buy the latest internetenabled ironing board that converts to a lawnmower for your own home if you must, but don’t risk a client’s money on it.

The other three motivations (and there are other cases) may provide some convincing reasons…

First, retrofit projects upgrading pointfor-point to LED might be much easier with wireless controls – there’s no need to add wiring in order to deliver control, and in the case of historic buildings, no need to carry out difficult or even impossible interventions in historic fabric. Even in a project where

Iain Ruxton, MSLL, is an associate at Speirs + Major

it is physically possible to add control cabling, disruption to building users may be reduced enormously by just changing over luminaires. In other circumstances, the ability to fix tiny, battery-powered, non-networked sensors to artworks or other objects might carry the day.

Second, in some circumstances it might be that not having to run data cabling, not having to install traditional lighting control modules, not having to install a physical lighting control network, and so on can mean substantial savings in installation cost.

Third, the nebulous temptation of the Internet of Things could offer some additional functionality, whether this be information beacons, sensing, phone apps, or a completely unnecessary interaction between your lights and your toaster. Some of these things require wireless. Others can be achieved with wired systems anyway. Yet others, especially those promoted to the consumer market, are utterly pointless.

Whatever the reasoning, specifiers need to understand the reality of wireless controls. While the technology is often sold on the scarily naive basis of ‘stick a load of kit in and it’ll work like magic’, the reality is that radio of any sort is hard. It’s complicated, highly susceptible to environmental circumstances and notoriously hard to troubleshoot, largely due to the fact that you can’t see it and it doesn’t necessarily go from A directly to B.

In the networking industry, professionals designing wireless networks in complicated spaces use specialist equipment to carry out a thorough radiofrequency survey of a space as a starting point, but the naive, slow-to-change, insular lighting industry seems to proceed on the basis of ‘it’ll be all right’.

Radio doesn’t like going through, or echoing off, thick hard walls, metal surfaces and structural slabs. It’s not crazy about large crowds of people as the human body is a fantastic radio frequency attenuator. Low-powered radio such as Bluetooth Low Energy has a limited range – more limited than most vendors will admit. Mesh networks, where nodes are not only a receiver but a repeater that passes on the message, are touted as the answer, but have to be intelligently designed or supersmart in self-managing or they will flood with messages bouncing around, and fail.

The bandwidth of these protocols is low –if the system isn’t properly thought out, then you’ll be lucky if everything synchronises smoothly. And there’s a load of other systems around that might be sharing the same space in the RF spectrum – it’s getting crowded in the ether. If you need a mesh network to function, which nodes will be repeaters and which won’t? Will you need standalone repeaters that aren’t even lights? Will you need to gateway your wireless network on to a wired network to connect it to another room or floor?

Another practical issue with wireless controls is the lack of standardisation. Although there is a ratified Bluetooth Mesh for Lighting Control Standard from the Bluetooth Special Interest Group, it has very little traction as yet.

Currently, a number of vendors have their own protocols running over BLE. Some are better than others, but none of them are directly interoperable. Some have gateways which allow interfacing with other control systems, others are entirely self-contained. Some scale well. Others just can’t cope with more than a few devices. Many don’t support emergency lighting test requirements. Quite a few seem to be based on the assumption that an iPhone is an appropriate user interface for an entire building… which it isn’t. And beyond the world of Bluetooth, there are other wireless protocols out there which have traction in some areas of the industry and have similar issues in terms of proprietary software stacks and lack of interoperability.

The reality is that most projects will not be 100 per cent wireless – we will live in a hybrid world of controls, where wired systems using Dali, DMX, or whatever will have to co-exist and be integrated with wireless systems. The aim has to be to create unified control environments where the user isn’t aware of what is wired and what is wireless –it all just has to work together seamlessly.

All these challenges are solvable, and wireless controls can deliver great solutions and great advantages, but only if the technology is taken seriously and implemented properly. If we are not careful as an industry, we will blow the opportunity as inadequately designed projects fail, and wireless lighting controls technology gets a bad name.

‘If we’re not careful, we will blow the opportunity as inadequately designed projects fail, and wireless controls technology gets a bad name’

It’s time for all of us

– specifiers, vendors, developers and clients – to educate ourselves… quickly.

q A new control system at London’s Science Museum marries DMX with Bluetooth Low Energy for the first time.

An intuitive lighting control app was developed by Sutton Vane Associates

CHANGE FOR THE BETTER?

Can alertness and sleep patterns be improved by varying the colour and intensity of illumination through the day? Paul Littlefair and Cosmin Ticleanu describe an experiment conducted by the BRE to investigate the effects of dynamic ‘circadian’ lighting

Our circadian rhythms control patterns of alertness and sleep, and the release of various hormones1. Daytime exposure to light, especially blue light, helps synchronise the circadian clock, enabling us to feel alert during the day and sleepy at night.

People who work outdoors or in welldaylit spaces are exposed to high levels of light, which is effective in synchronising their circadian rhythms. However, many people work in poorly daylit spaces with

relatively low levels of electric light. In these circumstances it may be harder for the body to maintain its circadian rhythms.

Dynamic ‘circadian’ lighting 2,3 is now being marketed using dimmable, colour-changing LEDs which provide brighter, bluer light in the middle of the day, and dimmer light with less blue content later on in the day when it is time to relax. BRE carried out an experiment, funded by the BRE Trust and CIBSE Research Fund, to investigate the effects of dynamic lighting, and its timing,

on human subjective assessments, activity and reported sleep.

THE EXPERIMENT

The experiment3,4 took place in an open-plan office space in Norwich, UK. There was very little daylight: the windows were small and heavily obstructed by overhangs and nearby buildings. A total of 36 people worked in the space, and 23 of them (19 women and four men) opted into the experiment.

Initially (February 2018) the space had constant fluorescent lighting (Condition 1, see Fig 1). Most of the lighting was 4000K (white) but some luminaires had 3000K (warm white) replacement lamps. Some of the tubes had been removed when the occupants complained that the lighting was too bright, so the lighting was non-uniform. The mean horizontal illuminance was 377 lux, in line with the 300 lux recommendation for computer users in offices, but desk illuminances ranged from 129 lux to 1017 lux.

After two weeks of monitoring the existing lighting, at the start of March 2018 it was replaced with LED lighting. For the first week the new lighting was maintained at constant light output and colour to allow participants to adapt to the appearance of the new lighting. Then the LED lighting was programmed to change dynamically (Condition 2, see Fig 2) and there was

q Fig 1: office space with the original fluorescent lighting

a further two weeks’ monitoring.

Figure 3 shows how the LED lighting changed with the time of day. In the early morning the lighting became brighter and bluer until at 10.30am it was at its coolest setting (6500K colour temperature). From 12.30 onwards the colour started to change again to become a standard white from 2pm. At 4pm it started to become dimmer and redder, with a 2700K colour temperature (similar to domestic lighting) by 6.30pm. The y axis in Fig 3 is scaled in a quantity called EML (equivalent melanopic lux). This measures the light entering people’s eyes, weighted by the spectral response of the special cells in the retina (ipRGCs) that are understood to influence circadian rhythms. These cells are particularly sensitive to blue light. For comparison, the previous fluorescent lighting had a mean EML of 101, though this varied widely over the space. The WELL Building Standard v2 recommends5 at least 150 EML in a non-daylit space, and for maximum credits 240 EML.

Most of the change in EML over the day was due to the change in colour temperature of the LED lighting. Visual illuminances did not vary as much, with mean horizontal illuminances ranging from just over 350 lux at the beginning and end of

the day, up to 488 lux in late morning. The aim was to give people an appropriate level of light to work by at all times.

Additional variable lighting conditions were administered in the second phase of the project during November-December 2018. Twenty participants took part. For the first two weeks of monitoring (Condition 3), the LED lighting was programmed to change dynamically (see Fig 4) in a different way,

t Fig 2: space lit by the new LED lighting at different settings: 2700K and 50 per cent lumen output (top left); 3500K and 30 per cent lumen output (top right); 4000K and 40 per cent lumen output (bottom left); and 6500K and 80 per cent lumen output (bottom right)

with higher EML values. Mean horizontal illuminances varied from around 600 lux at the beginning of the day to around 1120 lux in late morning and then back down to around 670 lux at the end of the day.

Once the monitoring for Condition 3 was finished, the LED lighting was set (Condition 4) to a constant light output and colour (4000K) to replicate typical office lighting (mean horizontal illuminance 480 lux, mean EML 149), and monitored for two more weeks.

RESULTS

The participants provided subjective assessments of the space after each condition, and responses in the morning and afternoon on two days a week to assess their subjective alertness, reaction time and concentration.

With the new dynamic LED system (Condition 2), the average scores for subjective alertness, both in the afternoon and averaged across the day, were significantly better than with the old constant fluorescent lighting (Condition 1). However, no statistically significant differences were found in the average scores for subjective alertness between dynamic (Condition 3) and constant (Condition 4) LED lighting. Also, there were no statistically significant correlations between increases in circadian-weighted lighting (more EML) and variations in subjective alertness between the two conditions tested in each phase of the project.

Many people work in poorly daylit spaces with low levels of electric light, and it may be harder to maintain circadian rhythms

Figure 5 shows the results. Most people felt more alert under the dynamic LED lighting in Condition 2 compared to the constant fluorescent lighting in Condition 1, but this also happened for the small number of people who received less light in Condition 2. The increase in alertness did not depend significantly on how much extra light people had with the LEDs. All participants received more light in Condition 3 compared to Condition 4, and the increase in light level was much more uniform across participants compared to the first conditions.

However, the higher light levels in Condition 3 did not lead to higher scores, on average, for subjective alertness; only half of the participants felt more alert under the dynamic LED lighting (Condition 3).

Participants also undertook computer tests to assess their reaction time and concentration. There were no statistically significant differences in either between the two conditions tested in each phase of the project. Around half of the participants agreed to wear an Actiwatch device to

monitor their activity and sleep patterns; there were negligible differences in sleep under the first two conditions.

Participants were asked whether they would prefer dynamic or constant lighting. On average, just over half of them preferred dynamic lighting for their office, typically brighter in the morning and following the variation of natural light outdoors throughout the day. Just under one third preferred the constant lighting.

DISCUSSION

The overall conclusion is that although people felt subjectively more alert under the new lighting system, there appeared to be no correlation with how much light they received or the way in which the system was operated. This contrasts with results from some other studies2,3 , although these mainly used high illuminances or very blue light.

from 142 to 413. This has important implications for using lighting to influence circadian rhythms. In multi-occupant spaces with conventional ceiling lighting, it is very difficult to achieve a standard ‘dose’ of light for everyone. If people are facing the walls, or, as in this case, near a walkway, they will have less light reaching their eyes than people with their backs to the wall facing into a brightly lit space.

• A balanced visual environment is important. For Conditions 1 and 2 the occupants had white desks and had complained about too much light being reflected from them. To avoid unwanted glare effects in Conditions 3 and 4, they were replaced during the summer with similar desks in a light oak finish, which allowed higher illuminances to be used.

p Figure 3: variation in average EML for the LED lighting with time of day Condition 2, March 2018

p Figure 4: variation in average EML for the LED lighting with time of day Condition 3, November 2018

There could be various explanations for this. The experiment had a relatively small sample size. People vary in their reactions to light and to their normal exposure to light; 18 of the 23 initial participants took at least one break to go out of the building during the day, so they would have been exposed to daylight then.

Nevertheless there were some valuable findings from the study. Further details are given in a BRE Information Paper3 , but these can be summarised as:

• Light levels vary across a space. Even though the new LED lighting appeared more uniform and all the lamps were working, there were still big differences in the amount of light reaching different people’s eyes. Under the 6500K (late morning) setting, EML values ranged

• Effective lighting control is critical. Dynamic lighting requires effective controls that work reliably, and exactly as programmed. One of the potential installations considered (in another location) had advanced colour-changing LEDs, but the controls did not work properly and the building managers changed the system to work at a static light level. The dynamic lighting system used for BRE’s study had reliable controls, and was programmed to vary slowly between settings. Overall, the participants preferred the dynamic lighting, and elected to keep it at the end of the study.

Paul Littlefair and Cosmin Ticleanu are principal lighting consultants at Building Research Establishment (BRE). This article first appeared in the June 2019 issue of CIBSE Journal

p Figure 5: absolute difference in subjective alertness scores plotted against the relative difference in EML: top – Condition 2 (the first dynamic LED lighting condition) vs Condition 1 (the original fluorescent lighting); bottom –Condition 3 (the second dynamic LED lighting condition) vs Condition 4 (constant LED lighting). A positive difference in subjective alertness means that people felt more alert under the dynamic lighting

References

1. Ticleanu C, King S, Littlefair P et al. Lighting and health. BRE Trust Report FB74, Bracknell, IHS Markit, 2015.

2. Ticleanu C. Report describing initial literature review on circadian lighting. BRE Client Report B137170-1001. Garston, BRE, 2017. Available from www.cibse. org/knowledge/knowledge-items/ tail?id=a0q0O00000CF7o9QAD

3. Littlefair P and Ticleanu C. Lighting for circadian rhythms. BRE Information

Paper. Bracknell, IHS Markit, to be published 2019.

4. Ticleanu C and Littlefair P. Circadian lighting effects on performance and wellbeing – A field study comparison of fixed and variable lighting conditions. To be submitted to Lighting Research and Technology.

5. IWBI. The WELL Building Standard v2 pilot. New York: International WELL Building Institute, 2018

www.bregroup.com

WORKING KNOWLEDGE

Not everyone is aware of the wider benefits of continuing professional development, nor of the many forms it takes. Juliet Rennie looks into the what, why and how of CPD

As a society, we like to shout about the fact that most of our events are an opportunity to add to your continuing professional development (CPD). In a recent discussion it became clear that while CPD is an established part of a lot of people’s working lives, this isn’t true for everyone. We thought that it would be useful to outline what it is, why it is important, and how it can be recorded and used to your professional advantage.

WHAT IS CPD?

As explained on the CIBSE website, CPD refers to

the ‘systematic maintenance, improvement and broadening of knowledge and skills’. By continuing to learn beyond your initial training, you can stay on top of the demands and priorities of your profession. This is particularly valuable in a time of rapid technological development and an increased need for crossindustry collaboration. Often CPD events will

‘While CPD is an established part of a lot of people’s working lives, this isn’t true for everyone’

also provide a platform for debate and the sharing of ideas between professionals from a range of disciplines.

Additionally, when you start in a new position you may gain additional managerial or leadership responsibilities. This requires another set of skills, outside your chosen specialism, which CPD can help to provide.

Members of the SLL are encouraged to maintain their CPD and it is a requirement for SLL and CIBSE members and those who hold Engineering Council registration. Should you wish to apply for one of the higher grades of membership, or if you wish to become a chartered engineer, you will be asked to demonstrate the ways in which you meet the Engineering Council’s competency criteria, and part of this is a commitment to maintain your development.

WHAT COUNTS AS CPD?

Throughout the year, the SLL and CIBSE regional committees will deliver a number of technical seminars on a range of topics: from the lead author of a new publication outlining key points of the latest guidance, to training in how to use modelling or design software. Generally, these events are all free to attend and are also open to all.

The SLL also runs its annual LightBytes series. We have recently been in the process of finalising the 2019-2020 series, which will be focusing on light and wellbeing.

‘CPD is not limited to structured or formal activities, and can include on-the-job learning, private study, professional institution work, or writing articles’

Each event consists of a full day of peer-reviewed, bite-sized, CIBSEaccredited CPD presentations, delivered by industry experts. The series runs from October 2019 to June 2020 in locations around the UK and Ireland.

However, CPD is not limited to structured or formal activities such as technical seminars, courses or e-learning. Other CPD activities include on-the-job learning, private reading and study, in-house programmes, professional institution committee work, writing papers and articles, supporting or mentoring others and volunteering for a professional body. As a member of the SLL, for instance, you will also have access to the internationally recognised Lighting Research and Technology journal, and by reading the research papers included you will remain informed about the cutting edge of lighting research while adding to your CPD. There are a number of ways that CPD can be fitted into your routine if attending evening events is not always practical.

WHY IS IT IMPORTANT TO RECORD YOUR CPD?

Logging your CPD is useful for a number of reasons, and some professional bodies also require a record of skills and knowledge acquired for you to hold certain grades of membership. This enables you to identify and set goals which might address gaps in your current knowledge, or areas that you would like to find out more about. By having an up-to-date account of your CPD, your progress becomes measurable and

it’s easier to remain motivated to achieve your aims within a given time period.

It’s important to note that logging and recording your CPD are two separate activities, where the first just involves a factual record of what you did. For example, ‘attended SLL Technical Seminar on LG14: Control of Electric Lighting’. A record, on the other hand, focuses on the outputs of the CPD activity for the ‘maintenance and enhancement of competence, appropriate to the individual and their job’.

Being able to refer back to your CPD will enable you to compare what you have learnt with your original goal, informing your future aims and plans.

Thankfully, CIBSE has a huge amount of helpful CPD-related resources (see below). Additionally, you can log and record your activities in the CPD area of your MyCIBSE account, available to members and nonmembers by registering on the website.

ACTION THAT YOU CAN TAKE

As mentioned above, the SLL and CIBSE run CPD events and peer-reviewed presentations throughout the year. In addition, the SLL relies on the work and dedication of its membership. By contributing to your regional committee, for

• To get in touch with your regional representative, or if you are interested in speaking at an SLL event: sll@cibse.org

• Information on SLL/CIBSE CPD events and presentations: www.sll.org.uk

• Details of how to contribute to and join the special interest groups and networks: www.cibse.org/networks

example, or speaking at an SLL event, you give others the opportunity to add to their CPD, as well as your own.

CIBSE also has a number of special interest groups, including the Daylight Group, which holds events and provides an opportunity to share knowledge and network on a range of specialist topics.

In terms of providing support to those at the earlier stages of their careers, the Young Engineers Network (YEN) runs events which provide a forum for young engineers within CIBSE. YEN also has regional centres that run a number of events. Additionally, the Women in Building Services Engineering (WiBSE) network aims to inspire the next generation and create the support network that will enable more women to join, stay and progress within this industry and, specifically, CIBSE as an institution.

If you’re looking to undertake a more formal or structured CPD course, the Engineering Council has a course database. Additionally, there is the Directory of CPD providers available via CIBSE.

There is also guidance on delivering a CIBSEapproved training and development scheme, and information for trainees available through the Training and Development Forum.

• Directory of CPD providers: www.cibse.org/membership/ continuing-professionaldevelopment-cpd/

• Guidance on delivering a CIBSEapproved training and development scheme, and information for trainees from the Training and Development Forum: www.cibse.org/membership/ training-and-development/

PERCEIVED TRUTHS

Iain Carlile selects three of the most recently published papers from Lighting Research and Technology

focusing on visual perception and colour

Chinazzo et al’s paper investigates how the visual perception of daylight in an interior space can vary with the ambient temperature. A test was conducted in an officelike environment, with 84 participants (aged 1830, 42 male/42 female, with normal or correctto-normal vision) taking part. The ambient temperature was varied in the space using radiant heating, while the daylight illuminance was varied through the use of neutral foil filters applied across the north and south-facing glazing.

Experiments were conducted with ambient temperatures of 19 degrees C, 23 degrees C and 27 degrees C, and horizontal illuminances of around 140 lux, 610 lux and 1440 lux. Visual perception evaluations were recorded twice during each experiment using a subjective questionnaire.

From the results it was found that there were cross modal effects of ambient indoor temperature and visual perception, with the apparent warmth of daylight increasing with temperature. An increase in temperature resulted in higher illuminances being perceived as more pleasant. In addition, the perceived brightness under high daylight illuminance was lower than has been reported in past studies under electric lighting conditions, suggesting that high illuminances may be more tolerated in a naturally lit environment.

q Percentage of participants ranking each colour among the top three most influential (‘Experimental validation of colour rendition specification criteria...’, MP Royer et al)

Validationofcolourrenditionspecificationcriteria varied to match none, one, two or all three of these criteria. Participants rated the objects’ colour appearance for saturated-dull, normalshifted, like-dislike and acceptable-unacceptable. From the results of the experiment the authors note that colour preference criteria could be adjusted slightly to improve performance.

therearedifferencesinratedsaturationbased onchromaticitygroup(Figure7),with Duv beingthestatisticallysignificantdifferentiator.Morethanforotherratedattributes,itis speculatedthattheobserversmayhaveconsideredsaturationofthelight,ratherthanthe appearanceofonlytheobjects.

3.2.Influentialobjectsandhues

Also looking at perception, Wei et al conducted an experiment investigating how light sources with different spectral features affect perceived colour fidelity, and if the effect can be reflected by two existing colour fidelity measures, namely the CIE R a and IES R f . Three pairs of white light LED sources with similar IES R f but different CIE R a values were evaluated by 14 observers (12 male, two female, aged 20-28, with normal colour vision) using eight physical colour samples. From the results of the experiment the authors found that the IES R f performed better than the CIE R a in evaluating white LED colour fidelity.

Royer et al present the results of an experimental study examining colour rendition specification criteria based on IES TM-30-18. Twenty five participants (10 male and 14 female, aged 20-70, with normal colour vision) took part in the study, evaluating 90 lighting scenes in a test room filled with objects. The lighting scenes included nine chromaticity groups, each with 10 systematically varied colour rendition conditions designed to meet or not meet the IES TM-30-18 colour preference specification criteria: Fidelity Index (R f ) Gamut Index (R g ) and Red Local Chroma Shift (R cs,h1).

The different colour rendition conditions

Aswithothersthathavereportedon equivalentquestions,4,5,15,38–40 redwasthe huemostfrequentlyindicated(72%)asbeing inthetopthreemostinfluentialcolours (Figure8).Comparedtopriorresponses fromthislineofexperiments,thepercentages forredwerelower,withyellowgainingthe most–likelyduetothechangeinsizeand prevalenceofdifferentobjects.Likewise,the selectionofinfluentialobjectswasmore diverse,withthestrawberries(8),green pepper(6),purplecoat(6),andflower photo(6)receivingthemostidentifications amongthethreemostinfluentialobjects.All othershadfewerthanfour,includingthe Cokebox(3).Thischangeinresultsjuxtaposesthesimilarityinmodelsofsubjective qualities,perhapsillustratinglessofaneffect ofspecificobjects.Thisideaisbolsteredby thesimilarityoffindingsfromtwoother studiesthatusedsubstantiallydifferentviewingarrangements.10,11

Lighting Research and Technology: OnlineFirst

In advance of being published in the print version of Lighting Research and Technology (LR&T), all papers accepted for publishing are available online. SLL members can gain access to these papers via the SLL website (www.sll.org.uk)

Influence of indoor temperature and daylight illuminance on visual perception

The results also showed that models based on R f , R g and R cs,h1 were superior in predicting colour preference when compared to those using other measures of colour rendition.

Iain Carlile, FSLL, is immediate past president of the SLL and a senior associate at dpa lighting consultants

Thisversionofthefinalquestionnaire includedanewquestionregardingtheaspects ofinfluentialobjectsthatwereimportant.The resultsareprovidedinFigure9.Basedon previousresponsesoninfluentialobject groups,itwasexpectedthatobjectfamiliarity wouldbeakeyfactor;however,itwasranked fourth,behindthecolouroftheobjects,the amounttheyvaried,andtheircontrastwith adjacentcolours.Personalpreferencesand roompositionreceivedfewselections(participantswereinstructedtochooseoneor more).Overall,theseresultscontinueto supporttheinclusionofred-specificLocal ChromaShiftinspecificationcriteriaand indicatereasonablybroadapplicabilityofthe recommendations.

G Chinazzo, J Wienold and M Andersen

Perceived colour fidelity under LEDs with similar R f but different R a M Wei, M Royer and H-P Huang

4.Discussion

4.1.Theroleofchromaticity

Experimental validation of colour rendition specification criteria based on ANSI/IES TM-30-18

MP Royer, M Wei, A Wilkerson and S Safranek

Theresultsofthisexperiment,where chromaticitywasonlyasignificantfactor forratedsaturation,contrastwiththepreviousexperiment,whichindicatedstatistical significanceforatleastonevariablerelatedto chromaticity(CCT, Duv orCCT*Duv)forall fourstudiedoutcomemeasures.However,this contrastrequirescontext:thetrendsdidnot change,justthelevelofstatisticalsignificance.

Figure8

Percentageofparticipantsrankingeachcolouramongthetopthreemostinfluential

Events

2019

1 SEPTEMBER (UNTIL DECEMBER)

Illuminated River (continuing programme of Unescoendorsed events to celebrate first four London bridges to be lit)

Venues: River Thames, assorted starting points https://illuminatedriver.london/whatson

18 SEPTEMBER

Lighting controls (joint SLL/Arup event)

Venue: Arup, Bloomsbury, London W1 www.sll.org.uk

2 OCTOBER

Lighting and the WELL Building Standard

SLL and CIBSE South West

Location: Bristol sll@cibse.org

3 OCTOBER

Lighting and the WELL Building Standard

SLL and CIBSE South West

Location: Exeter sll@cibse.org

4 OCTOBER

CIBSE training: Emergency Lighting to Comply with Fire Safety

Venue: CIBSE, Balham, SW12 training@cibse.org

10 OCTOBER

SLL LightBytes: Light and Wellbeing

Location: Birmingham www.sll.org.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

23-26 OCTOBER

Professional Lighting Design Convention (PLD-C)

Venue: Rotterdam Ahoy! 2019.pld-c.com

18

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

14 NOVEMBER

Lux Awards

Venue: London Hilton, Park Lane https://luxawards.co.uk

21 NOVEMBER

SLL LightBytes: Light and Wellbeing

Location: Dublin www.sll.org.uk

25 NOVEMBER

DIALux Lighting Software:

Foundation Level (Lighting Industry Academy)

Tutor: Liz Peck

Venue: Marriott Hotel, Slough www.thelia.org.uk

LightBytes

The LightBytes Series is kindly sponsored by Soraa, 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

SEPTEMBER: ARUP/SLL EVENT ON LIGHTING CONTROLS AT 8 FITZROY STREET