The Society of Light and Lighting
LIGHT LINES Jan/Feb 2019
VOLUME 12 ISSUE 1 JAN/FEB 2019
CALCULATED MOVE Kit Cuttleâ€™s next step
WELL DISPOSED Designing for health Twitter: @sll100
FROM THE EDITOR SECRETARY Brendan Keely FSLL firstname.lastname@example.org SLL COORDINATOR Juliet Rennie Tel: 020 772 3685 email@example.com EDITOR Jill Entwistle firstname.lastname@example.org COMMUNICATIONS COMMITTEE: Gethyn Williams (chairman) Rob Anderson Iain Carlile MSLL Jill Entwistle Chris Fordham MSLL Rebecca Hodge Eliot Horsman MSLL Stewart Langdown MSLL 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.
COPY DATE FOR NL 2 2019 IS 14 JANUARY PUBLISHED BY The Society of Light and Lighting 222 Balham High Road London SW12 9BS www.sll.org.uk ISSN 1461-524X © 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
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New year, new look, new name. It has been some time since what was the Newsletter and is now Light Lines had an aesthetic overhaul so we hope readers will like its fresher, modernised appearance. The content will continue to reflect the gamut of concerns that currently preoccupy the lighting sphere. Themes at the recent LuxLive conference at London’s ExCeL (The human factor, p5) and the significance of the BCO’s new document on wellness (Healthy light style, p13) reflect that much of this preoccupation is with designing and lighting for people. The term human centric has become something of a marketing mantra and is in danger of becoming devoid of real meaning or proper significance through glibness or misuse. Also part of the health and wellbeing conversation, circadian lighting is another phrase bandied around. The human body clock is an intricate, barely understood thing and a biodynamic lighting scheme is not necessarily the
simple answer to a complex question. As Juliet Rennie points out in her LuxLive conference report, ‘there was general agreement that while humancentric lighting is a good start, there is still a lot of work to be done before claims about the positive health impacts of a circadian lighting scheme could be considered credible’. Andrew Bissell reflects similar concerns in his review of the BCO’s Wellness Matters. ‘What is perhaps needed now is a decision, or more research, to get the lighting design community to a decision on ‘what is healthy lighting design?’.
JILL ENTWISTLE JILLENTWISTLE @YAHOO.COM
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 (2011) Commissioning Code L (2018) SLL Lighting Handbook (2018)
FROM THE SECRETARY
a wider field. Presentations can encompass lighting and product design, architecture, landscape, interiors, engineering, research, or any topic in light and lighting. In the first round the participants will be asked to describe their piece in six Powerpoint slides, which could include video, images with annotation, sound or whatever they feel best represents their idea. The second round will then be an extension of the first, including face to camera. It’s all about you putting forward your ideas or case study. The name of the competition will also change to SLL Young Lighter 2019. The competition is now open for applicants, and more details are on the website. The Jean Heap Bursary 2019 is also open for applicants and with up to £4000 to be won by an individual, we encourage all to start thinking. Again details are on the website. Ready Steady Light is not far away, taking place on Tuesday 26 March with Rose Bruford College. We look forward to a fun day of experimenting and playing with light to deliver award-winning schemes. Entry forms can be downloaded from the website. Finally, we are changing the way we issue the AGM Notification to members. The 2019 AGM will be held at St Martinin-the-Fields in London on 23 May and the notification will be emailed to all members that we have email addresses for. If you have opted out from receiving marketing emails from the society you will still receive the email version as it is directly linked to your membership. For those members for whom we do not have email addresses we will post the notification. Even if we have your email address but you would still prefer to receive the notification by post, please let us know by contacting firstname.lastname@example.org. And please don’t forget to renew your subscription...
THE HUMAN FACTOR
A TASTE OF LIGHTBYTES 2
A MEASURED APPROACH
THE GREEN LIST
HEALTHY LIGHT STYLE
Juliet Rennie reports on trends and themes at LuxLive
Roger Sexton looks at controls options for heritage buildings
Evolving his new approach to metrics, Kit Cuttle proposes a procedure for lighting practice
John Aston explains the ELT and how equipment is eligible for ECA tax relief
Andrew Bissell assesses the BCO’s recently published Wellness Matters
15 ROAD TESTING
Iain Carlile examines recent LR&T papers focusing on exterior lighting
COVER: Gasholders London by WilkinsonEyre, lighting by Speirs + Major. Winner of the 2018 FX Lighting Design award
BRENDAN KEELY BKEELY @CIBSE.ORG
Happy New Year to all SLL members across the globe. 2018 was an excellent year for the society and we hope that 2019 will be equally good for everyone. Welcome to the first edition of Light Lines, the society’s redesigned newsletter. The marketing and communications team, led by Gethyn Williams, has been working hard with our design and print house Matrix to deliver a more stimulating read and we think they have done a great job. We’ve made a few tweaks here and there but the content is still as valuable and we hope you feel the same. To business… The new Handbook has been published and is available to download by members, who can also purchase the hard copy at 50 per cent off standard cost. Who wouldn’t like one of these on their desk? A huge thank you to Paul Ruffles who as editor-inchief brought the publication together, ably assisted by around 70 authors, contributors and reviewers, whom we also thank. Paul received the 2018 Lux Person of the Year at the Lux Awards (see News, p4) for his work on the Handbook, an accolade that is greatly deserved. In addition to launching the Handbook, we had a busy autumn with the release of LG17: Lighting for Retail Premises; the rewrite of what is now LG18: Lighting for Licensed Premises, and the updates to LG1: the Industrial Environment and LG13: Lighting for Places of Worship. Thanks to Simon Robinson, Benedict Cadbury and David Holmes respectively for their efforts, which are much appreciated. All publications are of course available for members to download via the CIBSE Knowledge Portal. Also at the Lux Awards, Emma Beadle was named the SLL Young Lighter of the Year 2018 (again, see News, p4). Congratulations to Emma and all the competitors who contributed with their varied and stimulating presentations. Emma also won the Best-Written Paper award, with Katia Kolovea picking up the Best Presentation Award. This year will see the 25th anniversary of the competition, and the entry format has been changed to make it more approachable and to encourage more participants from
THE LATEST NEWS AND STORIES
CHILDREN’S VISION OF URBAN PLANNING WINS YLOTY AWARD IN ALL-WOMEN FINAL Emma Beadle (pictured above with SLL president Iain Carlile, left, and LET chair Bob Venning), a lighting engineer at WSP, has won the Young Lighter of the Year Award in an all-women final. She also won the award for Best-Written Paper. She outlined her project which aimed to engage students at a young age with lighting design: Children’s Utopian Visions of the City: CoDesigning Lighting Masterplans through Play and Exploration. Her presentation looked at developing co-designed lighting masterplans with schoolchildren in Edinburgh. Adopting tested co-design methods for working with children, the project was formed around ethnography, observation, interviews and workshops. Katia Kolovea, a junior lighting designer with Urban Electric Company, won Best Presentation for her paper, also on an urban theme, Light as a Medium to Enhance Communication in Urban Spaces. Runners-up were Carla Piatti, who looked at interactive lighting in public spaces, and Sanny Yuwono, who focused on exterior colour lighting. The winners were presented with their awards at the Lux Awards on 15 November.
LUX AWARD GOES TO LEADING SLL MEMBER FOR SECOND YEAR
Paul Ruffles scooped the Lux Person of the Year Award 2018 last November, the second year running that the accolade has gone to a prominent member of the SLL. Last year the honour went to Peter Boyce. A lighting design engineer, Ruffles has contributed an enormous amount to the profession both through his work with engineering institutions, and through national and international bodies, such as the BSO. He was described by the award judges as an ‘unsung hero’ of the lighting sector. A past president of the SLL (then the CIBSE Lighting Division), he is an honorary fellow of the society as well as a recipient of the President’s Medal and the Lighting Award. He has served on nine SLL committees and has been a member of the SLL technical and publications committee since 1986, chairing it twice. He is currently editor-in-chief of the SLL Lighting Handbook, a new edition of which has just been published. He set up his own practice, Lighting Design and Technology, based in Bath, in 1992.
ON THE LIGHTER SIDE... Luminaires designed to help plants flourish can be a bit, well, worthy. Not any more. Artemide has teamed up with avant-garde architect BIG to create the Gople lamp which marries modern technologies with artisanal traditions, and is as pleasant for humans as it is to plants. Its Venetian-blown glass form comes in white crystal, transparent silver and transparent
bronze. Not the usual RGB, but RWB (red, white, blue), the lamp calibrates its emissions according to the PPFD (photosynthetic photon flux density) values in two phases where appropriate supply of light is crucial: the growth phase features blue light with a 425-450nm wavelength, whereas the blooming phase gives out red radiation between 575 and 625nm.
THE HUMAN FACTOR SLL coordinator Juliet Rennie reports on the main trends and themes which emerged from the conference programme at LuxLive 2018 he extensive conference programme, which featured 10 streams and more than 100 speakers, was a draw for a number of people that we spoke to on the SLL stand and the turnout at the lightspace arena alone was very high throughout. This year’s key topics across the exhibition included human-centric lighting and WELL, versions 1 and 2; compliance, accountability and fire-risk assessment; and connectivity and smart cities. Human-centric lighting and non-visual responses to light seemed to surround each of the conference streams. There was general agreement that while human-centric lighting is a good start, there is still a lot of work to be done before claims about the positive health impacts of a circadian lighting scheme could be considered credible. Dr Octavio Perez spoke of the benefits of appropriate circadian LED lighting on health and wellbeing, referencing his work at Mount Sinai Hospital, which looks at how specific spectra affect human beings. He is currently developing human-centric lighting business intelligence for Madrid-based Lledó Lighting. Cosmin Ticleanu, principal lighting consultant for BRE, outlined The Biophilic Office, its two-year research project and demonstration. The project aims to demonstrate how biophilic design methodologies in office refurbishments can improve occupant productivity and wellness. Following the Grenfell Tower disaster in 2017, the need for more accountability and clear guidelines in relation to compliance and fire-risk assessment has been recognised. SLL immediate past president Richard Caple asked visitors to consider emergency lighting beyond the building, emphasising that its role to assist people to a place of safety often extends beyond the exit door. Connectivity also came into play in the Escape Zone as
Graham McKay, global head of electrical products for BSI, discussed developments such as dynamic signage systems, warning that innovation is not without risk. Michael Grubb shared his experiences of working with internationally recognised brands such as Guinness and Lavazza. His talk focused on the power of light and design in building a brand and how light can be used to influence the retail experience. We also heard from Sonia Pepperell from Thorlux. While referencing the brand new SLL Guide LG17: Lighting for Retail Premises, Sonia asked whether retailers have taken their eye off the ball when it comes to lighting quality. Once again, connectivity was a major theme for the Safer Cities stream. Mark Cooper of Cimcon Lighting discussed a recent project, looking at the management and control of campus lighting, using an app to communicate directly with street
lights in the local area. The panel discussion also looked at the role of technology in developing safer, more sustainable urban environments. This stream also focused on the place-making power of light within our cities, underlining the crucial role lighting can play in boosting the night-time economy and in creating social spaces. While not always groundbreaking or new information, the themes addressed at the conference were of crucial importance to the industry as a whole.
‘Work has to be done before claims about the positive health impacts of circadian lighting are credible’
Key messages from the show: • Definitive claims about human-centric lighting should be viewed with a degree of scepticism until we understand more about non-visual responses to light • While it would be futile to stand in the way of increasing connectivity, we must not lose sight of why a space is lit in the first place • In the face of technological development, there is a clear need to refocus on the quality of our lit environment
A TASTE OF LIGHTBYTES In the second of a two-part feature on this year’s series, Roger Sexton outlines the Retrofit and Upgrade segment, specifically looking at controls options in heritage buildings n the latest LightBytes series, the topic of upgrading lighting, and specifically controls, is addressed within the framework of heritage buildings. So what is the role of, and the importance of, controls in historic buildings?
• For energy savings: with automatic daylight harvesting using light sensors and presence/absence control via motion detection being the most common solutions • For art preservation: minimising light exposure on art to prevent photodegradation • For enhanced visitor experience and to aid or enhance a journey through a lit space: to use a theatrical metaphor, it’s not just about highlighting characters in a play; lighting is a character itself • For ease of use and management: to have a single and easy user interface to control different building systems, different source technologies and so on • Related to ease of use, for scenes and presets connected with flexible building usage: for instance, liturgical, community events or televised events The next area to examine is what issues we can expect to encounter as we fulfil these highly varied needs. The following summarises the key challenges: • Dead-end legacy systems: they often do not scale, do not have the (new) functionality you need, do not address new lighting systems, or worse, have been discontinued by the manufacturer • Physical constraints of a listed building: additional cabling may be impossible because it would require drilling, conduit, or routing channels that are not allowed. Further, many wireless solutions cannot deal with complex
u Example of existing instillation with no controls
layouts, or with thick stone walls and heavy beams that cause attenuation • Refurbishment may involve retrofitting new technology into existing bespoke fixtures, for instance, chandeliers Previously, space and heatsinking, and possibly intensity distribution, were ‘all’ that had to be considered. But now radio signal strength too must be accounted for • Phased installations and commissioning necessitate future proofing as some heritage jobs can take years and changes may be required or desired over time • Levels of access for both users and administrators. Everyday users should not be able to accidently change programming and different administrators may need different levels or areas of access – for example, different security keys to enable changing content on beacon apps compared with changing scenes, accent lighting levels, or access to different exhibit areas. The following shows probably the best and most common traditional upgrade to controls using a Dali wired system:
• Change individual luminaire LED drivers to Dali drivers • Add control wiring. This could be the main issue if it’s impossible in a listed building • Add Dali power supplies and controllers or upgrade the central controller. The ‘brain’ symbol by the Dali controller indicates the more traditional, centralised approach where everything comes back to a central controller. This can mean less subtle control options are possible and there’s potential for latency effects • Add proprietary touch panels and apps. Indeed if we look at data retrieval generally it will either be limited or it can be extended but then tied to a given manufacturer • Connect lighting control to a building management system that also controls HVAC, entertainment, security; this would be connected via a gateway. Some systems make this difficult or impossible • There could be problems if more than 64 light points are needed. This is, of course, solvable, for example by bridging to another controller, but at the price of a new circuit
u Example of traditional wired solution
for battery powered/energy-harvesting devices, in particular sensors. BLE’s low power and low bandwidth communication means it is scalable to thousands of nodes, groups, and scenes
Above is an alternative wireless solution which often makes more sense in this application and, in many cases, may be the only option: • Change driver for existing LED source to a smart driver with a power supply, or replace the module (or luminaire) for one with integrated smart modules • No control wiring • Switches and sensors can have ELV supply or be battery powered. (Switches can even be energy harvesting) • Notice that a generic tablet and apps can be used in this scenario. The market will see a Darwinian process with the better solutions rising to the top and surviving Apps can be for commissioning or control or conservation management, and for user interaction using beacon technology inherent with BLE • More data retrieval is possible and the resulting information can be used in decision making for both optimum atmospheres and energy saving • As with the previous example, if there is a building management system involved, the interface will be via a gateway Finally, here is an example similar to the previous one in terms of the new control sections, though it uses a 48V DC grid for
Example of wireless solution
installation savings. They are now bridged to some existing areas where other control systems are already in place, usually wired. Think of the bridge as a translator between two languages, for example, BLE and Dali. So the input signal is BLE and the output is AC plus a Dali or 1-10V control signal to the dimming driver for LEDs, CFLs or other lamp technology. Still there is one user interface controlling both the existing and the new lighting. Next, let’s look at mesh networks which are critical to refurbing historical buildings with complex layouts, particularly churches which, when full of people, will introduce further radio signal attenuation. A flood mesh is a many-to-many network in which all nodes broadcast to all other nodes, and ‘connections’ are based on a ‘publish and subscribe’ model. A Bluetooth mesh network is illustrated and discussed below in terms of scalability and robustness. SCALE • A flood mesh network enables messages to quickly reach all corners of a network, with low latency regardless of where the messages originate. Large areas can be covered but also within these areas... • ...unlike Wi-Fi, BLE has very small data packets. Remember it was designed
Example of wireless control of new lighting bridged to existing wired control of existing lighting
ROBUSTNESS • The small size of the Bluetooth messages and the speed at which they travel – 1Mbit/s (doubled with Bluetooth 5) – reduces the risk of collision. The messages can also be repeated a number of times, providing protection in the event that some get lost along the way. One more way Bluetooth increases network robustness and reduces packet collisions is through the mechanism of adaptive frequency hopping • Bluetooth Mesh transmits messages throughout the network, multi-cast, multi-path. So if one node is disabled, the message will still get through, it’s selfhealing. Similarly if layouts are complex or involve very thick walls such as in an old castle, a route will be found • The lack of a central controller means that there is no single point of failure for the control system • Note the illustration shows how the previously mentioned topic of levels of access can be handled. For example, assume curators can adapt accent lighting which is secure network A but only facilities management administrators can access the emergency lighting on secure network B. Each secure network has its own security key. This is simplicity itself to set up – it’s all software.
Roger Sexton is vice president specifier service at Xicato
LightBytes venues and dates Bluecoat, Liverpool: 24 January The Hospitium, York: 28 February The Engine Shed, Bristol: 28 March The Royal Society of Edinburgh: 25 April The Royal Society, London: 9 May For full details go to: www.cibse.org/ society-of-light-and- lighting-sll/slllightbytes-series
A MEASURED APPROACH Evolving his suggested new approach to lighting metrics, Kit Cuttle proposes a procedure for lighting practice procedure for lighting practice is proposed that is based on a redefinition of the prime purpose of indoor lighting, stated as 'to satisfy (or better to exceed) peoples’ expectations for how lighting may influence the appearance of their surroundings'. 1 In its present form, the procedure employs a spreadsheet to guide practitioners who have taken the step of devising a list of lighting design objectives (LiDOs) that relate to how the quantity and distribution of illumination may influence the appearance of an indoor location, to the development of a direct flux distribution (DFD) specification that can confidently be expected to achieve the practitioner’s chosen combination of lighting design objectives. The outline of the procedure is shown in Figure 1.
THE LIDOS PROCEDURE The model of indoor lighting on which the procedure is based comprises an enclosed space in which: • Flux from luminaires is applied directly on to selected target surfaces to create a direct flux distribution • The portions of this direct flux that are reflected back into the space comprise the first reflected flux • Multiple inter-reflections of the first reflected flux within the volume of the space generate the indirect flux field This illumination distribution may be characterised by two metrics: • Mean room surface exitance (MRSE) is
the spatial average of exitance values (lm/ sqm) of the surrounding surfaces in an enclosed space. As exitance is the density of luminous flux exiting (or emerging) from a surface, MRSE equals the average density of the indirect flux field within the volume of the space and serves as the metric for ambient illumination (see Figure 1). • Target/ambient illuminance ratio (TAIR) is the ratio of the illuminance (direct + ambient) of selected target surfaces or objects to the ambient illuminance, so that for a specific surface TAIR = (E_ s(d) + MRSE) ⁄ MRSE is the direct illuminance of surfaces. This metric may be used for planning the direct flux distribution (DFD) within a space by selecting target surfaces and specifying TAIR values. These two metrics relate to specific aspects of how lighting may influence the appearance of peoples’ surroundings. MRSE is suggested as the index of peoples’ overall assessments of how brightly lit (or dimly lit) a space appears, and typical dim-bright assessments based on recent but limited research studies 2,3 are tentatively proposed in Table 1. TAIR values are related to assessments of visual emphasis, for which target surfaces may be room surfaces, or may be selected objects ranging from work tasks to merchandise, artworks or safety hazards. Typical assessments of how lighting may influence visual emphasis are again tentatively proposed in Table 2. Despite the reservations, it is proposed that these two metrics taken together may be applied with reasonable confidence to specify how the ambient illumination and the distribution of direct flux are likely to affect the appearance of a room and its contents.
THE FIRST STAGE: AMBIENT ILLUMINATION As indicated in Figure 1, throughout application of the procedure practitioners may opt to give priority to either illumination efficiency or illumination hierarchy. For the first stage of the procedure the practitioner needs to specify the ambient illumination with an MRSE value, and if the lighting design objectives involve taking account of the human activity in the space, and how that space may fit into a sequence of lit spaces as people pass through the building, then priority is given to the ‘hierarchy’ track. An illumination hierarchy is an ordered distribution of illumination encompassing all visible surfaces within the space, and an MRSE value is chosen to specify the overall perceived brightness of illumination (PBI) to be achieved. Alternatively, if the objective is to provide a level of ambient illumination that will be assessed as adequate, that is to say, sufficient for whatever goes on in the location but nothing more than that, then the ‘efficiency’ track is the appropriate option. In this case the aim would be to select an MRSE value specified in a standard or recommended practice document as sufficient to provide the perceived adequacy of illumination (PAI) level appropriate for the category of activity associated with the location. Some research effort will be required to develop a comprehensive scale of PAI values related to activity categories. It will involve obtaining assessments for a broad range of locations to gain typical measures of how the concept of ‘adequacy’ relates to different types of indoor human activities. Regardless of which option is taken, the
‘The sequence of the procedure is to first light the space, and then give attention to the details, which is a reversal of practitioners with options for taking more proactive roles, such as creating conventional practice’ ordered distributions of illumination to
outcome of the first stage of the procedure is that an MRSE level is specified for every space. As has been explained, the MRSE level specifies the average density of the indirect flux field. It is the dimensions and surface reflectance values of the room that determine the first reflected flux (FRF) which will be required to generate this level of diffused indirect flux within the volume of the space. As FRF specifies the rate at which luminous flux is being added to the indirect flux field, so room absorption (Aα ) specifies the rate at which it is being absorbed. The interrelationship of these concepts is indicated in the following approximate expression: 1
Where Es, ρs and A s are respectively the illuminance, reflectance and area of surface s. It may be noted that (1- ρs) equals absorptance αs, and that Aα is the measure of the capacity of the room to absorb flux. (Those who find this expression mathematically challenging may be relieved Table 1: tentatively proposed perceived brightness of illumination to mean room surface exitance relationship
PERCEIVED BRIGHTNESS OF ILLUMINATION (PBI) BRIGHT SLIGHTLY BRIGHT NEITHER DIM NOR BRIGHT SLIGHTLY DIM DIM
to note that the procedure spreadsheet performs all the necessary calculations.) THE SECOND STAGE: TARGET ILLUMINATION Once the required total FRF for a space is specified, the practitioner moves on to the second stage which involves deciding how to introduce direct flux into the space, and this becomes the vital characteristic of the lighting application. For example, a regular grid of luminaires would have the effect of producing a uniform illumination distribution, and this outcome has often been regarded as a desirable quality for general lighting applications. A practitioner whose lighting design objectives include illumination uniformity should find that application of the procedure would steer towards a successful lighting solution. However, the procedure also provides
achieve lighting design objectives specific to individual circumstances and locations. For locations where no surfaces or objects are selected as demanding visual emphasis, illumination efficiency would be given priority, and this requires target surfaces to be selected for high reflectance to achieve the required FRF with least absorption losses. Alternatively, for situations where the practitioner chooses to select target surfaces and objects for visual emphasis, this involves developing an illumination hierarchy comprising an ordered distribution of TAIR values to achieve an envisaged visual effect. Figure 2 (overleaf) introduces the Illumination Hierarchy Spreadsheet, which may be used for the most simple or complicated lighting design objectives. When the aim is to achieve a practitioner’s envisaged distribution and balance of illumination within a space, priority is given to the illumination hierarchy track. The procedure guides the practitioner towards a solution for which the DFD provides for an overall level of perceived brightness of illumination chosen specifically
Figure 1: the Lighting Design Objectives (LiDOs) Procedure which guides a practitioner from having specified LiDOs relating to how the quantity and distribution of illumination may influence the appearance of a lit space, to developing the specification of direct flux distribution (DFD) that would achieve the envisaged balance of LiDOs
MRSE (LM/M2) 150 120 90 60 30
Table 2.: tentatively proposed visual emphasis to target/ambient illuminance ratio relationship
EMPHATIC STRONG DISTINCT NOTICEABLE ABSENT
40 10 3 1.5 1.0
for the location together with a specified distribution of visual emphasis. When the aim is to comply with a prescribed minimum MRSE value, the procedure guides the practitioner towards a solution that will provide for perceived adequacy of illumination with optimal flux utilisation. However, whichever priority is opted for, the DFD is planned as a distribution of TAIR values, and the output of the procedure is a listing of direct flux to be delivered on to each of the selected target surfaces, as is shown in the seventh column of Figure 2 (below). The procedure described here is based on a simple model of how lighting influences the appearance of peoples’ surroundings. It treats the illumination distribution as two components: a direct flux distribution, specified by a schedule of direct flux on target surfaces, and an indirect flux field, which is assumed to be sufficiently diffuse to be specified by a single MRSE value. The ‘hierarchy’ track is based on the proposition that assessments of perceived brightness of illumination relate to the indirect flux field, and assessments of visual emphasis relate to the direct flux distribution, specified by a listing of TAIR values. On the other hand, the ‘efficiency’
track provides for an overall appearance of illumination adequacy without visual emphasis. Of course, there is more to lighting, but these are concepts that relate measurable and predictable illumination metrics to human visual response. Practitioners are free to download the spreadsheet (see website details, right) and apply the procedure, and hopefully, the day will come when lighting standards specify illumination adequacy in terms of MRSE or some similar metric.
practitioner this prospect: provide these levels of flux on to the selected target surfaces to achieve your chosen balance of lighting design objectives. From thereon, achieving the envisaged balance of ambient and target illumination is a matter of everyday illumination engineering. •
The Illumination Hierarchy Spreadsheet may be downloaded from https://1drv.ms/x/ s!AteYXbEsDomRvR7K0F-mBqURyiA1 For more information about the LiDOs Procedure go to: www.dropbox.com/s/ vixlhidbpxybv80/More%20about%20the%20 LDO-DFD%20Procedure.docx?dl=0
FROM LIDOS TO DFD This model of peoples’ responses to the visual effects of lighting may be applied to a wide range of applications. A practitioner may plan illumination hierarchies for varied objectives – to give visual emphasis to architectural features or displaying merchandise, highlighting information panels, selectively illuminating work surfaces or drawing attention to safety hazards. The sequence of the procedure is to first light the space, and then give attention to the details, which is a reversal of conventional practice. The output of the procedure specifies the direct flux distribution as a listing of target surface flux values that offers the
References 1. Cuttle, Christopher. Lighting Design: A perception-based approach. Abingdon: Routledge 2015, 132pp. 2. Duff J, Kelly K and Cuttle C. Spatial brightness, horizontal illuminance and mean room surface exitance in a lighting booth. LR&T 2017; 49(1): 5-15. 3. Duff J, Kelly, K and Cuttle C. Perceived adequacy of illumination, spatial brightness, horizontal illuminance and mean room surface exitance in a small office. LR&T 2017; 49(2): 133-146.
ILLUMINATION HIERARCHY SPREADSHEET 180104 PROJECT NAME:
HOTEL RECEPTION AREA
LM/M^2 SURFACE REFLECTANCE
SURFACE ABSORPTION M^2
WALL 2, EXCL MURAL
SURFACE AREA M^2
CEILING WALL 1
DIRECT SURFACE ILLUMINANCE LX
TARGET SURFACE FRF LM
WALL 3, SOLID
WALL 3, GLAZED
Figure 2: A worked example of the Illumination Hierarchy Spreadsheet.
ROOM SURFACE ABSORPTION
TOTAL DIRECT FLUX
REQUIRED TOTAL FIRST REFLECTED FLUX
TARGET SURFACES FIRST REFLECTED FLUX
THE GREEN LIST The government’s Energy Technology List supports efficient lighting technology. Former SLL president John Aston summarises the scheme and considers how qualifying equipment is eligible for ECA tax relief
n the UK lighting accounts for some 20 per cent of the generated electricity despite recent advances in lighting technology and controls. Switching to more efficient lighting units now represents a significant opportunity to reduce energy consumption by 65-85 per cent. While most new construction projects use efficient white lighting there remains a large estate of existing, non-domestic buildings whose lighting could be improved – both in quality and energy efficiency.
q The disruptive change caused by LEDs has led to constant review of ETL criteria
‘In lighting it is not acceptable to focus solely on energy efficiency’
The Energy Technology List (ETL) scheme has supported the adoption of energyefficient lighting technology since 2001. Since this date there have been regular reviews of the criteria that need to be met to qualify for the ETL; the last review was completed in 2017 and the new thresholds came into force in February 2018. The ETL scheme for energy-saving technologies covers a wide range of
products used in the built environment. It is designed to encourage the adoption of the best products available in each of the accepted categories, including lighting. Qualifying equipment is currently eligible for enhanced capital allowance (ECA) tax relief*. Every product covered by the scheme has to meet a number of defined eligibility criteria, which are used as a basis for qualification. Since being added to the Energy Technology Criteria List in 2001, the
lighting industry has experienced near continuous and dramatic change as LED technology has developed. As a result the criteria have been reviewed and strengthened around every two years in order to maintain the focus of ETL support on high-performance energy-saving products.
CRITERIA UPDATES Updates to the performance criteria that set the eligibility of lighting equipment have always involved both product research and stakeholder consultation, to ensure that the ETL scheme continues to support higher performance products. The criteria not only define the efficacy of eligible products but also their minimum quality threshold; in lighting it is not acceptable to focus solely on energy efficiency. Virtually all lighting schemes that become the subject of an ECA claim are installed in workplaces, where comfort, wellbeing and productivity must always be taken into account alongside energy efficiency. The energy performance of any lighting system is determined by four primary factors: • The efficacy of the lighting product, or luminaire • The careful application of the chosen lighting equipment through design • The use of appropriate controls to ensure lighting is only on when it is required • System commissioning carried out when the building is occupied and users can provide the correct information for setting system parameters This is the reason why many of the consulted stakeholders stress the importance of using an experienced, qualified lighting designer to create the optimum solution for efficiency, comfort and safety. Involving a designer will ensure that there is a properly developed design based on the client’s specific needs and defined by a specification. The resultant design documentation then becomes the essential benchmark against which the finally commissioned system may be verified and signed off. Exactly the process encouraged in Part L of the Building Regulations. MOST RECENT CHANGES The revised ETL criteria for lighting were last published in March 2018 – a single
‘Since being added to the list in 2001, the lighting industry has experienced near continuous and dramatic change as LED technology has developed’ sub-category ‘Efficient White Lighting Units’ defines the required performance of white lighting. A new sub-category was created to accommodate the use of white LED modules in backlit signs. The revised documents were also simplified and the clarity improved. The efficacy thresholds for the main lighting sub-category were raised by some 25 per cent compared to the previous figures – a clear reflection of
the rapid efficacy improvements brought about by the introduction of solid state sources. The ETL scheme rightly continues to support the use of highly efficient lighting solutions in the built environment, encouraging the use of the best-performing lighting products that have been applied and commissioned correctly. Please refer to the updated Lighting Guidance Note, issued in June 2018, for further information (see box below).
*Tax relief through the Enhanced Capital Allowance and First Year Tax Credits Scheme for energy saving technologies is available until the end of March 2020.
HOW TO CLAIM AN ENHANCED CAPITAL ALLOWANCE
FOR LISTED TECHNOLOGY CATEGORIES CHECK THE ETL WEBSITE TO MAKE SURE A PRODUCT IS LISTED
MAKE A QUALIFYING CAPITAL PURCHASE
FOR “UNLISTED” TECHNOLOGY CATEGORIES CHECK WITH YOUR INSTALLER, SUPPLIER, OR MANUFACTURER
KEEP SUPPORTING DOCUMENTATION
Credit visual: DBEIS
CLAIM ALLOWANCE THROUGH CORPORATION TAX OR INCOME TAX RETURN
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/ file/694123/ENERGY_TECHNOLOGY_CRITERIA_LIST_February_2018.pdf www.gov.uk/government/publications/lighting-guidance-note-for-the-energy-technology-list-etl Criteria for lighting controls: www.gov.uk/government/publications/lighting-controls-criteria- for-etl-inclusion Criteria for Efficient White Lighting Units (EWLUs): www.gov.uk/government/publications/efficient-white-lighting-units-criteria-for-etl- inclusion
Health and wellbeing
HEALTHY LIGHT STYLE Andrew Bissell assesses the BCO’s recently published document, Wellness Matters, from a lighting point of view An example of high-level evaluation of potential valueadd from a suite of health and wellbeing measures for a refurbishment project where the existing building suffered from poor lighting, very limited access to daylight, inadequate ventilation and thermal comfort t
© Elementa Consulting, from BCO’s Wellness Matters
hen we design, health and wellbeing are now at the forefront of our minds more than ever. You are also more likely to realise your lighting design if you demonstrate how it supports the principles of health and wellbeing, for example, access to views, daylight, vertical and horizontal lighting levels, glare control, light quality and so on. This change from focusing on reducing energy consumption to supporting people’s health and wellbeing – not that we should suddenly ignore our energy consumption – is largely due to several factors: the now-widespread education on the circadian system; adoption of WELL® Certification; the introduction of Fitwel®, and improved awareness of the impact
internal environments can have on us. There has always been competition for talented staff and in the past perks such as signing-on bonuses, bike loans and so on have tended to help candidates choose an employer. Nowadays, while the perks may still exist, it is likely to be the quality, and specifically how seriously a company takes health and wellbeing, which will entice the candidate to choose your company. Most offices in the UK are designed to the British Council for Offices (BCO) standard. Over the years this has been developed and expanded, and there is currently a 150-pluspage BCO Guide to Lighting which sits alongside other BCO guides. At this time, it does not discuss health and wellbeing directly; that subject has been addressed
in the recently published BCO Wellness Matters document. The BCO recognised the importance the workplace had in maintaining and improving people’s health and wellbeing. Equally there was the recognition of how the workplace can improve or indeed disrupt productivity. Moreover, there was a recognition that the different motivations at each stage of developing the workplace, for example, acquisition, design, construction, refurbishment and so on, can be a barrier to delivering the best solution. The result is a document that establishes why wellness matters. It has a review of the existing health, wellbeing and other workplace standards such as WELL®, Fitwel®, BREEAM, Ska and LEED; presents 10 wellbeing themes
Health and wellbeing
and 55 outcomes; prepares a roadmap for various types of project and presents a series of case studies. From a lighting perspective there are three themes to review, which appear under the publication’s headings See, Outside and Sense. Within those three general themes there are then four outcomes, See (no 10), Outside (no 21) and Sense (nos 47 and 51). See (10) is the basic function of safe vision; Outside (21) is crime prevention; Sense (47) is lighting environment quality, comfort, control and cognitive function, while Sense (51) covers visual environment, view content, quality, control and cognitive function. As a measure the theme of Nourish has 12 outcomes. All four outcomes are discussed in each roadmap component : Strategy (new construction), Strategy (refurbishment and fit-out), Design + Construction (new construction + major refurbishment), Design + Construction (refurbishment or fit-out) Occupation Is all this a bit long winded? It seems so at first glance, but it also works in that you find specifically the information you need about all 55 outcomes depending on the
type of project and exactly where you are in the design/handover process. Does anything stand out as a positive or a negative? The front end of the document picks up on a very relevant point and one which has been discussed in the lighting community since WELL® hit the UK market. Namely that there needs to be a cautious approach to adopting headlinegrabbing statements or relying on only a few pieces of research. Another positive is where the outcomes discuss the quality of light, the spectral properties of glazing, views of nature, equitable access to views, luminance and illuminance, material colours, functional requirements of individuals and groups, and monitoring the installation post-occupancy. Of course, all of this is discussed in the various lighting guides but what is great is that all members of the design team, including the client, architects, interior designer and contractor, are now reading and learning about the importance of these finer elements of lighting design. The phrase circadian lighting is mentioned regularly throughout the document without specifically saying if this must be achieved with daylight or if an LED-only solution is acceptable. Equally there is no mention of whether the WELL® approach is correct or incorrect. In many ways it is impossible for
the BCO to make such a statement as the lighting community cannot make that call yet themselves. However, those individuals who may only read this document and not the learned guides and associated press, could be excused for thinking that an LED circadian lighting system is all you need. There are repeated comments about views, the quality of views and that highquality views should be equitably accessible by all of the staff. Added to that, there is a reminder to check that a planned development will not take away the daylight you currently enjoy which is helping to keep you healthy. Unfortunately there is also the inevitable comment that in reality you cannot always have a view and as such ‘views should be provided where possible’. How will a developer respond to such a comment? Final thoughts? This is a great document in that it succinctly explains to everyone in the design team, including the end users, that there is more to lighting design than lux levels. What is perhaps needed now is a decision, or more research, to get the lighting design community to a decision on ‘what is healthy lighting design?’. Andrew Bissell, FSLL, is lighting director of Cundall Light4. Wellness Matters is published by the British Council for Offices and is free to BCO members, £108 to non-members. More details at www.bco.org. uk/HealthWellbeing/WellnessMatters.aspx
From the Roadmap section: an example of how lighting fits into the overall context of new construction site selection
ROAD TESTING Iain Carlile looks at four of the latest LR&T papers which all focus on exterior lighting The first paper, by Davidovic et al, looks at the colour temperature of street lighting, investigating the subjective impressions of pedestrians. A pilot project compares warm white (3000K CCT) and neutral white (4000K CCT) LED lighting conditions. Both lighting conditions had comparable photometric parameters including horizontal and semi-cylindrical illuminance, and threshold increment values. A sample population of 139 university students were asked to subjectively assess the two different lighting conditions by responding to a questionnaire. Grading was provided on appearance of human faces, colour of light, colour rendering and overall impression of the two conditions. It was concluded that the warm white condition was consistently preferred from a pedestrian perspective, although the authors note that the research was carried out with only a limited representation of people and range of locations. Bará et al’s paper investigates the relative contribution of different lighting applications to the brightness of the urban night sky, also considering their patterns of use. The lighting applications considered included streetlights, and residential and vehicular lighting. Taking the time signatures of use for each of the different applications, the authors were able to calculate their individual contribution. The authors present their method for determining the time signatures of the different lighting elements through the use of wide-field time-lapse photography. The preliminary results revealed that in addition to the dominant contribution from street lighting, lighting leaking out from residential windows may also account for a significant contribution to the zenithal night sky brightness. The contribution from vehicular lighting was shown to be significantly smaller.
Buyukkinaci et al examine the viability of changing lighting levels based on traffic density, average speed of passing vehicles, as well as road and ambient conditions. Augmenting studies on fixed-position observers previously undertaken by the authors, investigations into moving observer positions were made. It was found that at constant speeds, at the speed limit of the urban roads, visibility levels in the calculation areas remained within the acceptable limits, and that a change in luminous flux did not significantly affect the visual performance of the drivers up to two lower lighting classes. A case study was carried out varying the lighting class between M3 and M5 when the vehicular speed stays constant but traffic density reduces. The authors estimate that by doing so around 40 per cent energy savings can be achieved when suitable lighting control and traffic monitoring systems are used. Considering a different approach to reduction in energy from road lighting, Muzet et al evaluate the performance of an optimised combination of road surface and lighting. A three-year study was conducted comparing two conventionally designed
p Samples of luminance measurements on the four sections of the Lumiroute project (Muzet et al)
sections with an optimised surface and lighting combination. Measurements were taken for road photometry, luminance and power consumption at regular intervals. It was found that where the surface and lighting had been optimised, better performance and increased efficiency were achieved in comparison with the conventionally designed sections. Iain Carlile, MSLL, is an associate of dpa lighting and current president of the SLL
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) Warm white versus neutral white LED street lighting: Pedestrians’ impressions M Davidovic, L Djokic, A Cabarkapa, M Kostic Estimating the relative contribution of streetlights, vehicles and residential lighting to the urban night sky brightness S Bará, Á Rodríguez-Arós, M Pérez, B Tosar, RC Lima, A Sánchez de Miguel, J Zamorano Road lighting automation scenarios depending on traffic speed and volume B Buyukkinaci, S Onaygil, O Guler, MB Yurtseven Evaluation of the performance of an optimised road surface/lighting combination V Muzet, F Greffier, A Nicolaï, A Taron, P Verny
Shortlisted for Light and Surface Interior award: Morpheus Hotel atrium, Macau. ZHA/Isometrix Lighting Design
24 JANUARY SLL LightBytes Venue: The Bluecoat, Liverpool email@example.com 5-7 FEBRUARY Light School at the Surface Design Show (Supported by the ILP) Venue: Business Design Centre, London www.surfacedesignshow.com/light-school 12 FEBRUARY CIBSE training: Emergency Lighting to Comply with Fire Safety Requirements Lecturer: Ian Watts Venue: CIBSE, Balham, SW12 firstname.lastname@example.org 28 FEBRUARY SLL LightBytes Venue: The Hospitium, York email@example.com 4 MARCH CIBSE training: Lighting – Legislation and Energy Efficiency Lecturer: Liz Peck Venue: CIBSE, Balham, SW12 firstname.lastname@example.org 25 MARCH Junior Ready Steady Light Venue: Rose Bruford College Sidcup, Kent www.sll.org.uk 26 MARCH Ready Steady Light Venue: Rose Bruford College Sidcup, Kent www.sll.org.uk 28 MARCH SLL LightBytes Venue: The Engine Shed, Bristol email@example.com 9-14 APRIL Euroluce Venue: Fiero Milano, Milan www.salonemilano.it
5-7 FEBRUARY: LIGHT SCHOOL, SURFACE DESIGN SHOW, BDC, LONDON
25 APRIL SLL LightBytes Venue: The Royal Society of Edinburgh firstname.lastname@example.org 2 MAY Lighting Design Awards Venue: Troxy, London E1 https://awards.lighting.co.uk
LightBytes The LightBytes Series is kindly sponsored by Fagerhult, Thorlux Lighting, Xicato and Zumtobel. For venues and booking details: www.sll.org.uk
9 MAY SLL Lighting Knowledge Series: LightBytes Venue: The Royal Society, London email@example.com 19-23 MAY Lightfair International Tradeshow and Conference (sponsored by the IALD and IES) Venue: Pennsylvania Convention Center www.lightfair.com 5 JULY CIBSE training: Lighting Design – Principles and Application Lecturer: Liz Peck Venue: CIBSE, Balham, SW12 firstname.lastname@example.org 12 JULY CIBSE training: Emergency Lighting to Comply with Fire Safety Requirements Lecturer: Ian Watts Venue: CIBSE, Balham, SW12 email@example.com
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