Light Lines March/ April 23

LIGHT LINES

WORK IN PROGRESS

The new LG7 and the changing office

DAYLIGHT AND NET ZERO

A tool for joined-up lighting

SECRETARY

Brendan Keely FSLL bkeely@cibse.org

SLL COORDINATOR

Cara Littlechild clittlechild@cibse.org

EDITOR

Jill Entwistle jillentwistle@yahoo.com

COMMUNICATIONS

COMMITTEE:

Eliot Horsman MSLL (chair)

James Buck

Iain Carlile FSLL

Jill Entwistle

Chris Fordham MSLL

Rebecca Hodge

Stewart Langdown FSLL

Luke Locke-Wheaton

Rory Marples MSLL

Linda Salamoun MSLL

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

COPY DATE FOR LL3 2023

IS 14 MARCH

PUBLISHED BY

The Society of Light and Lighting

222 Balham High Road

London SW12 9BS

www.sll.org.uk

ISSN 2632-2838

© 2023 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

Unit C, Northfield Point, Cunliffe Drive, Kettering, Northants NN16 9QJ

Tel: 01536 527297

E: gary@matrixprint.com Printed in UK

The office environment has probably been one of the most mutable of all the spaces covered by lighting guidance. With the transition from pen and paper to keyboard and screen, and more recently to portable device, the focus has not only gone from horizontal to vertical, but from two-dimensional to three-dimensional.

Technology, together with changing work patterns, have led to more flexibility, less formality and less overtly hierarchical structures, all of which have radically reshaped the design of the workspace. Ranks of desks with regimental linear downlights have given way to break-out zones, intimate work booths and any number of meeting space configurations. Well, at least in the moneyed, corporate milieu.

FROM THE EDITOR JILL

accelerant, in this process, has been Covid-19. Suddenly working from home became not only a viable option but a working trend.

The author of the new SLL lighting guide on office lighting, LG7, has therefore had a deal to think about one way or another. The last version was published seven years ago. 'Such a dramatic change for many could not have been foreseen when the previous edition was published,' says Simon Robinson in his summary of the updates (p9). 'This revision to LG7 has been perhaps the most significant in a long time.'

Then there is the concern with energy use and, with the growing awareness of the non-visual effects of lighting, the increasing emphasis on health and wellbeing.

The latest catalyst, or perhaps more accurately

CURRENT SLL LIGHTING GUIDES

SLL

SLL Lighting Guide 6: The Exterior Environment (2016)

SLL Lighting Guide 7: Office Lighting (2023)

SLL Lighting Guide 8: Lighting for Museums and Galleries (2021)

SLL Lighting Guide 9: Lighting for Communal Residential Buildings (2022)

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 (2022)

SLL Lighting Guide 13: Places of Worship (2018)

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)

SLL Lighting Guide 19: Lighting for Extreme Conditions (2019)

SLL Lighting Guide 20: Lighting and Facilities Management (2020)

SLL Lighting Guide 21: Protecting the Night-time Environment (2021)

SLL Lighting Guide 22: Lighting for Control Rooms (2022)

Guide to Limiting Obtrusive Light (2012)

Code for Lighting (2022)

Commissioning Code L (2018)

SLL Lighting Handbook (2018)

CIBSE TM66: Creating a Circular Economy in the Lighting Industry (2021)

FROM THE SECRETARY

The new Lighting Guide 7: Office Lighting is now available (see p9). There have been considerable developments in the office environment since the previous edition, which was published in 2015.

The new guide considers hybrid working, addressing uncertainty around how office space will be used in the future. With increased hybrid working and the use of portable devices, people are spending less time at their desk and in the office.

This revision of Lighting Guide 7 therefore now includes advice on lighting for a home office. The publication also draws attention to the embodied and operational energy of lighting equipment as well as looking at circularity principles.

The publication was authored by Simon Robinson and we thank him for his work in delivering the new guide. The PDF is free for SLL members (£70 for non-members). The publication can also be purchased as a hard copy (£45 for members, £90 standard price).

Congratulations to Scott Kluger on winning the SLL Young Lighter 2022 competition. The final took place online in mid-December and Scott did a great job in presenting his project, Daylight Harvester: a tool to enhance lighting operational performance (see p6).

Scott received the SLL Young Lighter 2022 trophy and £1250 prize money. The other three finalists were Anna Forrester, Kenny Cliffe and Hiba Mazhar. The 2023 competition is now open for entries and details can be found on the SLL website under Events and Young Lighter.

There is an online event scheduled for 21 March with Elettra Bordonaro (co-founder of Light Follows Behaviour) and Don Slater (LSE sociology, co-director Configuring Light/Staging the Social research group). The event will be focused on external lighting and social equality. This should be very thought-provoking and I would encourage everyone to register.

The Jean Heap Bursary 2023/2024 is now open for applications. There is up to £4000

• To download Lighting Guide 7: Office Lighting: www.cibse.org/knowledgeresearch/knowledge-portal/ lg7-lighting-for-offices-2023

• To register for the External Lighting and Social Equality event: www.sll.org.uk

• Light Follows Behaviour: https://lightfollowsbehaviour. com/

• To apply for the Jean Heap Bursary 2023/2024: www.cibse.org/get-involved/ societies/society-of-light-andlighting-sll/education/the-jeanheap-bursary

of funding available which is paid in four installments, subject to the submission of progress reports. Each year, a panel of expert judges looks for a specific piece of lighting study or research designed for the benefit of SLL members and the industry as a whole.

The Jean Heap Bursary was launched in 2014, in tribute to the commitment to lighting research and education which Jean demonstrated both within the society and throughout her career in the lighting industry.

And finally, we have recently emailed all members regarding the 2023 AGM and SLL nominations for 2023/2024. We hope to confirm the AGM venue and timings in the near future.

CARE AROUND THE CLOCK

An SLL-supported event focuses on circadian lighting principles in the residential care sector

THE MISSING LINK

Scott Kluger, SLL Young Lighter 2022, outlines his Daylight Harvester – a tool to enhance lighting operational performance

WORKING SHIFTS

Radical changes in the use of office space have meant a significant revision of guidance. Simon Robinson summarises the newly published Lighting Guide 7: Office Lighting

PITCH PERFECT

Mike Simpson outlines the updates in the final version of the soon-to-bepublished SLL guide to sports lighting

WHAT THE EYE DOESN'T SEE

Iain Carlile looks at three of the most recently published LR&T papers on circadian-effective lighting and nonimage forming effects of light

PLACES TO WORSHIP

Continuing the series, Colin Ball considers his Top Five sacred spaces from around the world

EVENTS

'The new guide considers hybrid working, addressing uncertainty around how office space will be used in the future'

COVER: Mirror of Wonders, at the 17th-century Rome office of Fabio Mazzeo Architects. Backlit, with dynamic moving parts, it forms a kaleidoscope of reflections and light play

BRENDAN KEELY BKEELY @CIBSE.ORG

BEIS CONSULTS ON MORE STRINGENT LAMP PERFORMANCE

A proposal to update the ecodesign requirements for lighting products from 2023 and 2027 is currently under consultation by the Department for Business, Energy and Industrial Strategy (BEIS). Based on the efficacy levels now achieved by LEDs, it is proposing that lamps offered for sale in Great Britain must have a minimum energy performance (MEP) of 120lm/W by 2023 and 140lm/W by 2027. The proposal also highlights some exemptions. 'The proposed MEPs are ambitious but reflect what is already technologically and reasonably achievable for lighting products,' says the BEIS.

'We expect the proposed regulations to save 19,700 GWh of electricity by 2050 if adopted in late 2023,' the BEIS document continues. 'This will also result in 1.7m tonnes of traded CO2e of carbon savings over the appraisal period (2022/23 to 2050/51).'

CIBSE will be responding to the proposal through the Society of Light and Lighting and contributing to a wider industry response.

If you wish to contribute to the SLL response please see the CIBSE Consultation web page (www.cibse.org/policy-insight/news/consultation-on-new-ecodesign-requirementsfor-lighting-products) for details of the consultation and send comments to sll@cibse.org by Monday 27 March 2023. The consultation document, impact assessment and draft regulations are all available for review

THE SHADE OF WATER

A British startup company, WaterFilled Glass (WFG), has developed a glazing system that uses sunlight to power an energy-saving heating and cooling system.

Its patented windows, which can be used in new builds or retrofitted, have a thin layer of water between the panes. This absorbs heat from sunlight or other radiation, such as the heat leaving a room.

This warmed water is then pumped through sealed pipes at low pressure to colder areas of the building, through an underfloor system or into thermal storage.

By absorbing thermal energy the glass also limits solar heat gain through the windows, reducing the need for air-conditioning.

Using off-the-shelf glass and parts, it also allows greater daylight ingress and better views as there is less need for shading.

WFG was founded in 2020 by Loughborough University architecture lecturer Matyas Gutai and his colleagues Daniel Schinagl and Abolfazl Ganji Kheybari.

It has completed two prototype buildings using the technology, including Water House 2.0 (pictured), a pavilion at Feng Chia University in Taiwan. Its first commercial projects, an industrial building in Hungary and a residential development in the US, are now under construction.

www.waterfilledglass.com

Extending more than 2000sqm and featuring 102,600 LEDs in 2km of light ropes, a recent temporary lighting installation stared down disconcertingly on Madrid's Plaza de Canalejas.

Evoking the form of a giant floating iris, it was created by Brut Deluxe, an architecture and design studio based in Madrid and Munich. The dynamic red and blue mesh – it appeared to dilate as flecks of flickering lights moved along the lines – floated 9m above the ground, and produced the same effect when seen from above (as pictured).

http://brutdeluxe.com/

Our apologies, point 4 of the ROLAN Manifesto was missing in the news item in the Jan/Feb issue: Apply the [International Dark-Sky Association's] Five Principles of Responsible Outdoor Lighting in all lighting projects: all light should have a clear purpose; light should be directed only to where it’s needed; light should be no brighter than necessary; light should be dimmed down or turned off when not required; use warmer colour lights where possible.

CARE AROUND THE CLOCK

An Age of Light Innovations online event supported by the SLL will focus on the application of circadian lighting principles in the residential care sector

Innovators in Residential Health Care: Circadian Lighting Principles and Practice is the second online event organised by Age of Light Innovations and supported by the SLL. The webinar on 7 March will feature a line-up of leading academics, specialists and practitioners, including Prof Russell Foster, professor of circadian neuroscience at Oxford University, who will give the opening remarks.

Age of Light Innovations seeks to progress the application of lighting for health and wellbeing in all spheres by bringing together academics, practitioners and manufacturers for an exchange of views and information.

For this event, founder Dr Shelley James cites the growing body of research which suggests that lighting that actively supports the circadian cycle in older people with dementia can have significant benefits for sleep, mood and other issues such as falls, agitation and cognitive decline. However, she points out that the case is not clear cut.

'The field is still young and many open questions remain about the critical parameters and mechanisms at work, especially for this population,' says James. 'Much of the work to date has been carried out on students and healthy working-age adults with very different visual and non-visual responses.

'It is also clear,' she continues, 'that while a regular light-dark routine plays a vital role in circadian entrainment, it cannot be considered in isolation: other dimensions such as noise, temperature, physical activity and routine nighttime checks also have a part to play.'

A number of residential care providers around the world are nevertheless adopting circadian lighting principles as part of an integrated approach to care. Anecdotal evidence suggests there are benefits in terms of improved resident outcomes, staff motivation and retention, and occupancy rates.

This market has inevitably attracted commercial interest, with lighting manufacturers responding to the business opportunity with ‘circadian’ product ranges. 'However, there are few opportunities for a transparent and constructive dialogue between the scientific, manufacturing and care providers about what is known – and what has yet to be confirmed – about what constitutes an effective circadian lighting solution for older people living with dementia in residential care,' says James.

'As a result,' she continues, 'there is a risk of undermining the whole approach –manufacturers pour money and marketing budgets into "human-centred" products, based on partial knowledge, that do not sell. Cash-strapped healthcare providers are often disappointed by complicated systems that do not seem to deliver on the promises. Scientists can become frustrated that their hard-won evidence does not translate into impact in the real world and face an uphill battle to secure independent funding for their vital work.'

As with similar online working meetings, the aim is to bridge this gap, says James. 'To create a constructive and independent forum for experts to exchange knowledge, best practice and future trends as part of a successful and sustainable business strategy.'

Following opening remarks by Prof Russell Foster, Harvard’s Prof Shadab Rahman will share a recent paper which discusses a 43 per cent reduction in falls following the introduction of circadian lighting. Prof Elisabeth FloGroeneboom from the University of Bergen will then review her ongoing work to study the acute effects of lighting on mood. Ending this session, Prof Stuart Peirson will consider the practical issues posed when conducting research in these complex settings.

These academic presentations will be followed by three case studies: Ed Russell and Jo Cheshire of WCS Care in Warwickshire will review continuing work to upgrade the lighting in both new build and retrofit settings across 13 facilities. Kirsten Sorensen Gosvig from Hillerod in Denmark will share her experience working with circadian lighting for more than seven years, including the staff dismay when the system was temporarily unavailable. Michelle Borreson from Gundersen Health in Wisconsin will focus on the business case, explaining how the investment in a lighting upgrade was paid back in energy savings alone within a year.

Register for the event at: https://www.eventbrite. co.uk/e/innovators-in-residential-healthcaretickets-473414384167

For those unable to view the event live, it will be available as a webinar: https://www.cibse.org/getinvolved/societies/society-of-light-and-lighting-sll/ sll-events/on-demand-webinars-past-presentations

Sponsors of the event are Bios, Glamox Luxonic and Theben

Speakers

Opening remarks: Prof Russell Foster, Oxford University

Emerging science

Asst prof Shadab Rahman, Division of Sleep Medicine, Harvard Medical School

Prof Elisabeth Flo-Groenberg, University of Bergen

Prof Stuart Peirson, Oxford University

Case studies

UK: Ed Russell and Jo Cheshire, WCS Care

Denmark: Kirsten Sorensen

Gosvig, Hillerod

USA: Michelle Borreson, Gundersen Health

 Prof Russell Foster will give the opening remarks

THE MISSING LINK

The year 2022 was a significant one for the UK, with the cost-of-living crisis and geopolitical uncertainties in Europe flooding our news feeds. These events didn’t just highlight our dependency on energy, but also our vulnerabilities.

Back in 2019, the UK government recognised these concerns and set out to deliver a net zero strategy to accelerate the demand for lowering the UK's operational energy and carbon footprint by 2030. However, to achieve these ambitious targets, it is expected that regulatory and performance-based metrics relating to energy and carbon will become increasingly more stringent and mandatory.

In recent years we have seen this shift in the lighting community, predominantly towards measuring energy and carbon in relation to luminaire performance. Whether that has been through improving luminaire efficacy, promoting a circular economy approach towards manufacturing (such as CIBSE TM66), or improving the controls/ monitoring of luminaires, these measures have undoubtedly created a product-based approach to net zero lighting design.

However, to achieve net zero, the lighting community must also look beyond just a product-based approach and start to integrate more passive design principles within lighting design.

In contrast to other building service disciplines that rely on passive design strategies to offset energy through the use of dynamic simulation tools, lighting lacks a similar emphasis towards integrating daylight to offset lighting energy performance. This is reflected within current UK standards and guidelines which still emphasise the use of manual-based calculations and factors to

estimate the daylight contribution of spaces. Building standards such as Leni (lighting energy numeric indicator) require designers to manually reference multiple pages of equations to estimate the daylight contribution of a space, which seems at odds with the simulation processes we have come to rely on today. Although daylight is considered a primary source of light for a building, and is undoubtedly a sustainable source too, our current standards and workflows relating to lighting energy performance and carbon still don’t embrace its full potential.

Today, there is a growing emphasis on adopting dynamic simulation tools to help close the performance gap between energy prediction and energy in-use, and there is an opportunity to help improve the integration of daylight when it comes to measuring the

lighting energy performance of buildings. My proposal for the SLL Young Lighter competition was therefore to develop a tool that could help bridge this gap, to investigate how daylight simulations could be used to help inform lighting design processes and provide a more holistic approach towards achieving net zero (Fig 1). The development of this tool began with identifying a software programme that is widely used in the architecture and engineering communities. The visual programming tool Grasshopper, with environmental plugins Ladybug/Honeybee, were adopted as together they allow the flexibility to design algorithms alongside simulation engines such as Radiance to provide reliable results. More importantly, visual programming tools such as Grasshopper best reflect how designers operate today, as they

Based on his winning presentation, Scott Kluger, SLL Young Lighter 2022, outlines his Daylight Harvester – a software tool designed to enhance lighting operational performance

p Fig 1: Daylight Harvester proposal overview

p Fig 2:Daylight Harvester at concept phase

have helped to shape designers not only as tool users, but also tool makers.

Let’s firstly begin at the conceptual design stage and show how the Daylight Harvester algorithm could be adopted. Before a lighting scheme has been developed, the algorithm can be used to provide initial energy parameters for a lighting scheme with daylight dimming controls. Let’s take a hypothetical office building in an urban context as an example and test a typical floorplate shown in Fig 2.

To begin with, as with any lighting project, illuminance thresholds determined by space type are categorised as, for example, office areas, breakout spaces and so on. In step two, the maximum energy requirements of each space type are then derived from Approved Document L, which is considered an important compliance document relating to lighting energy performance in the UK.

Next, a climate-based daylight analysis is carried out using the useful daylight illuminance (UDI) metric to measure the percentage of time during the year daylight achieves an acceptable range of illumination. In this case, the minimum illuminance value is derived from the illuminance values shown in step one and the maximum is assumed at 3000 lux for when blinds are likely to be drawn.

In step four, daylight performance is then averaged across each space to a single value to estimate the percentage of time daylight achieves the acceptable illuminance range throughout the course of the year. In step five, this information is then post-processed to estimate the kWh/sqm/yr of each space with daylight control.

However, within the design and specification process, it’s recognised that power is a much more useful unit compared to energy, so the algorithm can convert cumulative energy into average power across a year. The values shown in step six show the average power consumption

required to achieve Approved Document L, but to help optimise the lighting design process, the tool can also estimate the maximum power allowance of a space with daylight control, shown in step seven.

The idea is that the installed power of a space can be theoretically increased as long as daylight controls are operating to remain compliant with Approved Document L. In this example, average power consumption across this office floor has increased by almost 1200W, but its overall energy consumption remains the same across a year. The intention is to provide designers with increased flexibility when designing for visual comfort and the overall lit impression of architectural spaces, whether that be through layers of light, providing decorative fittings with lower efficacies or additional lighting to suit architectural details.

At the concept phase (RIBA stage 1-2), it is

also important to measure energy performance spatially, the reason being that changes to spatial layouts, facades and materials can have a huge effect on lighting energy performance with daylight controls. In this example, the baseline condition from Fig 3 can be compared against proposed changes to the design, such as the rearrangement of interior spaces in option one or reduced glazed openings in option two, or changes to a lighter material palette in option three. In this way the algorithm can help to quantify these architectural changes and push for a more energy-efficient lighting design at a much earlier stage.

Buildings are inherently complex and access to daylight will vary depending on a variety of design factors such as external obstructions or room orientation. Rather than just increasing power for spaces that are already well daylit, these savings could be used to offset spaces which have limited access to daylight and require more artificial lighting and energy to improve visual comfort (Fig 4).

It’s hoped that by using this algorithm during the concept phase, daylight can play a more active role in maximising visual comfort and energy performance simultaneously. The aim is also to create a more holistic approach towards measuring the lighting energy performance of a building,

p Fig 4: Daylight offsetting

p Fig 3: Lighting energy performance through spatial analysis

'The lighting community must look beyond just a product-based approach and start to integrate more passive design principles within lighting design' E

instead of the traditional room-by-room analysis of spaces which are isolated from one another.

Following on from the conceptual design phase, the algorithm can be adapted to also suit the technical phases of a project, to help inform lighting controls and provide a benchmark of performance for daylight dimming systems. In contrast to the previous stage, which focused on the spatial characteristics of lighting energy performance, here the focus is on the predicted performance of the daylight dimming system itself, simulating individual sensors to mimic how a daylight dimming system would operate.

Each daylight sensor records hourly daylight illuminance values across a year, which are then processed against the required illuminance threshold of the space to create an hourly artificial illuminance schedule (Fig 5). The data can then be used to produce a temporal map, illustrating when artificial lighting is required, its output and duration.

This can help to inform lighting control strategies which can respond to seasonal variations, to reduce task illuminance or vary the illuminance threshold depending on daylight availability. This information can then be postprocessed into an hourly power schedule with daylight dimming. One benefit to identifying seasonal power loads is that it can provide a useful tool for designers to compare predicted performance with in-use performance.

As we move towards a more performancedriven future, it will become more relevant that the systems we design for operate as intended. By giving designers a tool to benchmark daylight sensor performance, it's hoped that this information can help to improve the design and commissioning of daylight dimming systems and improve the performance gap.

This brings us to the last aspect of this algorithm and how it can be adopted for the

in-use phase of a project. To illustrate how this can be used, the algorithm was applied to a proposed office refurbishment in London. Within the growing context of the circular economy and reducing embodied carbon, rather than simply replacing all the existing fluorescent lamps with LEDs to improve energy performance, the algorithm was used in this case to improve the existing daylight control of the luminaires.

Following a similar strategy to the previous technical section, individual daylight sensors were used to measure hourly illuminance values of daylight. The impact of glare was also measured as it was an important contributor towards increasing light levels when the blinds were closed (Fig 6). This information was then post-processed to provide the hourly power schedule required to maintain 500 lux on the task plane.

Once the results had been finalised, a comparison between the existing and predicted performance of the daylight dimming system identified around 64 per cent in energy savings within daylit zones, which amounted to 17 per cent in energy savings for the overall office.

This information helped to quantify our design decision to maintain the existing luminaires within daylit zones and focus the replacement of luminaires within non-daylit zones instead. Here the use of daylight simulation tools helped to not only provide operational energy savings, but also helped to reduce the embodied carbon with the refurbishment.

As lighting professionals, we need to approach lighting buildings holistically and think beyond just a product-based approach towards achieving net zero. By developing an algorithm that can improve the accessibility of daylight within lighting energy performance calculations, the Daylight Harvester approach can help spark a better integration of daylight and artificial lighting together – and help improve the lighting design process towards a net zero future.

Scott Kluger, MCIBSE, MArch, BAS, is senior daylight designer at Hoare Lea

p Fig 5: Hourly illuminance and power schedule for daylight dimming system

p Fig 6: Illuminance and blinds performance of daylight sensor

'The intention is to provide designers with increased flexibility when designing for visual comfort and the overall lit impression of architectural spaces'

WORKING SHIFTS

Radical changes in the use of office space have meant a significant revision of guidance. Author Simon Robinson summarises the newly published Lighting Guide 7: Office Lighting

This revision to LG7 has been perhaps the most significant in a long time. Not because of the amount of information that has changed or been introduced, but due to the way in which many of us now use our office space. Such a dramatic change for many could not have been foreseen when the previous edition was published.

One of the key strengths of LG7 in providing guidance to

owners and designers of office spaces is the understanding that the vast majority consist of small rooms having no more than two or three desks. These are often rooms within buildings that have other primary functions.

The guide is laid out in the same way as the previous edition. Chapter 2 gives an overview of the whole document with detailed chapters on the following areas: types of office, speculative development, daylighting in offices, electric lighting in offices, embodied and operational energy and carbon, detailed room design information, and a useful chapter on worked

examples which cover different office types.

Because of the way many of us now use our office space, the issues associated with lighting for home working have dedicated sections and a worked example. Both embodied and operational energy are significant topics affecting office lighting, along with a circular design and use approach. LG7 now covers these areas in more detail.

Perhaps the most significant technical change to the guidance is the introduction of context modifiers following the revision to BS EN 12464-1- Light and lighting. Lighting of work places — Indoor work places, in 2021. It is fair to say that this introduction raised a few eyebrows when energy use is considered against the recommendation to increase lighting levels in some situations. LG7 takes a pragmatic approach to explain the intended use of context modifiers and how they are applied to task, surrounding and background areas.

'Such a dramatic change for many could not have been foreseen when the previous edition was published'

 'The guidance for home offices is intended to bring lighting considerations to the fore – they might not be seen by users of these spaces as having such an important influence'

HOME WORKING

The future for the traditional office is looking increasingly uncertain. Change had already begun in the years before the Covid-19 pandemic, with people moving to laptops instead of desktop computers and, latterly, to tablets allowing increasing levels of flexibility in where they chose to carry out their work tasks. Many people are choosing to redefine their working environment to include their homes for some or all of the time.

LG7 therefore provides guidance for those creating a dedicated home office or converting rooms such as bedrooms for the purpose. A worked example is also now included in Chapter 13 which discusses the decor and desk placement as important elements in creating or adapting a room into an office. The issues associated with occupational health are obviously just as important when working at home and good lighting has an important role to play.

As with traditional workplaces, the colour and texture of the decor and furniture will have a significant impact on the way lighting is reflected within the space. Converted bedrooms might start out with walls and floor coverings which were suited to a relaxing space but which may not be ideal for an office environment where the occupant could

spend many hours having to concentrate on specific tasks.

An office environment is better suited to pale shades which will help to reflect the available light. In the worked example, LG7 points out that removing dark or heavily patterned wallpaper and replacing it with either a plain

pale-coloured wallpaper or painted surface is one of the best ways of improving the lighting. Changing floor coverings for a lighter shade or using a pale-coloured rug will also help, as will changing curtains or blinds. An adjustable blind would also give more control over natural light and could be considered.

p Illumination levels: 'LG7 takes a pragmatic approach to explain the intended use of context modifiers and how they are applied to task, surrounding and background areas'

p LG7 covers all types of offices, with worked examples, as well as key issues such as embodied and operational energy and carbon

'The future for the traditional office is looking increasingly uncertain'

As the significant increase in energy costs and the need to consider the environmental impact of how we use energy are important factors, the optimisation of available daylight is an important consideration and decor changes can help, as can the correct placing of the user's desk. The guidance for home offices is intended to bring these considerations to the fore, as they might not immediately be seen by users of these spaces as having such an important influence on not only their energy use, but how the space makes them feel, especially if they spend many hours each day there.

CONTEXT MODIFIERS

The use of context modifiers has been given more prominence than previously with the aim of improving the lighting of workplaces based on the specific tasks being undertaken or persons using them.

While it is a common belief that the

introduction of context modifiers is something new, good lighting design has always considered the specific needs or constraints of a space.

As an example, where a general illumination level of 500 lux may be the guidance level for the task area on a desk surface, the specific desk in question may be used to carry out very detailed work and therefore the context has changed from what could be considered a general working space.

In this case the illumination level of the task area would increase by one level on the scale of illuminance to 750 lux. Surrounding and background areas would also be increased accordingly. Unless any surrounding desks were in close proximity and used for a similar purpose, the context change may only apply to the single desk and not the whole space.

LG7 covers the use of context modifiers in different situations and office types. It is important to consider the tasks, surrounding

and background areas, and the different illumination levels that may be required rather than treating the whole space as a single task area. In this way, appropriate illumination levels can be achieved without resulting in the excessive increases in energy use that some observers have suggested can be attributed to the greater emphasis now placed on context modification.

EMBODIED ENERGY, EMBODIED CARBON AND CIRCULARITY

LG7 has previously included guidance on energy use and this edition continues to put energy consideration at the forefront of designers' minds. In 2021, CIBSE launched the hugely successful TM66: Creating a circular economy in the lighting industry. This asks designers to look at the reuse of serviceable equipment as too many luminaires are thrown away long before the end of their useful life and when they could be reused or repurposed. LG7 continues the theme of circularity and introduces considerations for embodied energy and carbon.

Embodied energy has been difficult to determine for products that use multiple components from different locations. There are, however, common sense considerations that can be made. For example, a luminaire manufactured in the Asia-Pacific region may have less embodied energy than one manufactured in Europe. However, the embodied carbon involved in transporting it to Europe could result in the overall impact on the environment being higher.

Clearly reusing the existing luminaires (perhaps with some onsite modification or refurbishment) will reduce the embodied carbon of the lighting scheme as fewer, or even no new luminaires are being manufactured and shipped to complete the installation.

Maximising the use of daylight is an important way of reducing operational energy as luminaires that are not switched on are obviously using either no energy or a minimum amount to operate control functions.

Author of LG7, Simon Robinson, FSLL, is technical director of WSP and former chair of the SLL technical and publications committee

Lighting Guide 7 (LG7): Office Lighting can now be downloaded at: www.cibse.org/knowledgeresearch/knowledge-portal/lg7-lighting-foroffices-2023

PITCH PERFECT

which will have an influence on the speed of the action and hence the visual task. Usually, the higher the level of play the more stringent the lighting requirements. We also have to take into account the different users:

LG4 has been the longstanding SLL guide to sports lighting and reflects the current trends both in terms of the sports themselves and lighting techniques. Since the last guide was published in 2006 we have seen the growth in participation at an amateur level, new sports becoming popular and greater coverage from broadcasters.

We have also seen a technological revolution both in lighting, with the switch to LEDs, and broadcasting, in terms of what is delivered to our screen. In 2018 EN12193, the European standard for sports lighting was published and our task group included authors from that work group. All of these have driven the updates to the latest edition of LG4. The guide is concerned with the lighting of sports spaces, and other playing and recreational areas.

It takes into account a number of different factors. One is level of play

• The players have to be able to see in order to perform to their optimum level. Small balls moving fast will require more light than large balls moving slowly.

• The spectators may be watching at close distance or at the back of a stadium so the lighting must enable them to see the action.

• These days television plays an

important part in making sport available to the widest possible audience. But as an audience we are no longer satisfied with the wide picture showing all the action. We demand close-ups showing the strain on the competitors' faces, multiple camera angles (including aerial ones) and instant slow-motion replays. Picture quality has gone from HD to 4K and to 8K. The broadcasters are continually looking for greater impact and are equipped with the latest broadcasting technology to achieve this. The lighting must therefore ensure that the highest quality pictures can be obtained.

'We have seen a technological revolution both in lighting, with LEDs, and broadcasting, in terms of what is delivered to our screen'

Following his preview of LG4 in September 2021, Mike Simpson outlines the updates in the final version of the soon-to-be-published guide to sports lighting

p Typical sports hall with limited switching between luminaires

p La rge horse-racing track with floodlighting system designed for televised coverage but with control of obtrusive light

Many people may just use the guide to look at the specific lighting requirements for a particular sport, but within the guide there is plenty of advice on all aspects of an installation and it represents a summary of the many years of experience of the authors. This is drawn from practical experience, including the pitfalls.

Specific recommendations for individual sports are given whether played indoors or outdoors. This is where you will find advice for 51 individual sports from archery to wrestling. In some cases the governing body may have established the lighting requirements which should also be considered, but for many LG4 will be the primary reference source. In all cases we have been careful to align with other standards to avoid confusion.

Within these individual sections are some new sports that weren’t previously mentioned. But after much debate greyhound racing has been taken out, although if you are planning to build a track the old guide can always be referred to.

Larger indoor and outdoor venues, whether single-use or multi-use, have their own section. For these the siting of the

lighting is critical to achieving the correct performance and minimising glare. This is something that needs to be considered at the earliest possible stage of the design as lighting positions rely on the physical structure of the venue. If this is overlooked it can be impossible to achieve the right lighting result if the mounting positions do not exist. Often such decisions are taken before the lighting designer is onboard.

In particular, broadcasters need to ensure the lighting will deliver good quality pictures from all camera angles while ensuring the lighting doesn’t cause flare in the camera lens. An addendum to the previous edition of LG4 was issued to take account of updated requirements from broadcasters, in particular the flicker caused by discharge lamps. With the introduction of LED sources, cameras can operate at high shutter speeds for slow motion without any specific measures being taken. Similarly for 4k and 8K broadcasting it has not been necessary to increase levels. However, uniformity and colour consistency have become more critical.

In the past the guide has followed typical practice which meant that the whole range of traditional light sources

would be used. Typically fluorescent for indoor or high intensity discharge (HID) for larger indoor and outdoor venues. With HID we had to consider the effect of power failures and the time to restrike. Many smaller recreational schemes would use high pressure sodium with an acceptance of its poor colour qualities. It was also not possible to dim HID which meant providing different light levels had to be done by switching, not always the easiest way to maintain uniformity.

The new LG4 has been written for the future and the assumption that all new or refurbished projects will be using LEDs. Dimming is possible and there is no longer a time to wait for the lights to come on after a power failure. Practically the poorest colour rendering is above Ra70 so the minimum recommended colour rendering in the guide has been uplifted to Ra>70 for outdoor applications and >Ra80 for indoors. Players in particular will appreciate the better quality of light in the future.

One big plus for the LED is that it now outstrips all previous light sources in terms of efficacy which means less energy use than before. This is just one of the environmental considerations addressed in the guide. The other is the growing demand for the control of stray light from sports installations. For larger stadiums, the light tends to be contained within the stands, but for community and recreational activities there is little to stop the light shining on to adjacent buildings or into the sky, and it is these situations where the lighting is likely to be used daily into the evening.

Specific criteria to manage this are included and refer to well-established guidelines. Also, with LED sources, light control can be better so we can satisfy environmental concerns at the design stage.

The new LG4 is essential reading for anyone involved in lighting for sport and leisure facilities, and will ensure that lighting is designed to the highest standards.

Mike Simpson, FSLL, is global applications lead at Signify and a former president of both the SLL and CIBSE

SLL Lighting Guide 4 (LG4): Sports Lighting is scheduled for publication in the second quarter of this year

'Players in particular will appreciate the better quality of light in the future'

p Di agram showing the reflections of a luminaire, walls and ceiling at the water surface of an indoor swimming pool in calm water

WHAT THE EYE DOESN'T SEE

Iain Carlile looks at three of the most recently published Lighting Research and Technology papers, which feature circadian-effective lighting and non-image forming effects of light

Rea et al examine circadian-effective lighting and suggest that a new way is needed to assess luminaires in this respect. Consistent exposure to bright days and dim nights is necessary for circadian entrainment, and therefore good sleep and good health. Given that as humans we spend a large portion of our life indoors, much of our circadian entrainment will come from electric lighting systems.

Recognising that within the lighting industry there has been a long tradition of providing lighting products and applications for human vision, the authors suggest that because lighting also affects the non-visual circadian system, the lighting industry should begin to provide products and applications for human health too.

To do so, new tools are required to allow lighting practitioners the ability to compare and assess the efficiency of luminaires for providing circadian-effective light to a building’s occupants. To support this, a novel measure is proposed for

quantifying luminaire efficiency based on electric power (watts) needed to reach the circadian stimulus (CS) criterion of CS = 0.3 at the eyes of a standard observer. The proposed measure is termed standard-observer-watts (SOWatt).

The measure can be carried out in both a virtual and real environment, and can be used in conjunction with other luminous functions. The authors present examples of how SOWatt can be applied to ceiling mounted, accent and tabletop luminaires. They note that the proposed measure provides a convenient and useful scale for supporting energy-efficient circadianeffective lighting.

Gkaintatzi-Masouti et al investigate the non-image-forming (NIF) effects of light. They maintain that lighting design simulation tools need to combine various luminous and temporal factors in order to predict how architectural design and lighting design can affect eye-level light exposure.

Undertaking a detailed literature review, the authors present the current state of research looking at the implementation of lighting for NIF effects in building design computer simulation models. They point out that while interest in simulation of light for NIF effects is growing, there is still no common method to perform the simulations.

Gaps are identified in current simulation workflows, which need further investigation before they can be applied to design guidelines. These include the exact relationship between light quantity, spectral composition, directionality timing, duration, light history and human response, and also how best to model a real person’s complex behaviour in a space.

Also looking at NIF, Li et al's study assesses the effects of dynamic light on alertness, cognitive performance, mood and mental fatigue. An experiment was conducted in which

participants undertook complex cognitive tasks and a psychomotor-vigilance-test (PVT) under two conditions – dynamic light (4000K-12,000K, melanopic equivalent-daylight-illuminance [EDI] between 224-420 lux) and static light (4000K with a melanopic EDI of 224 lux) conditions. Both had horizontal task illuminance equalling 500 lux on the desk.

Different responses to light under the varying conditions were assessed, including psychological, behavioural, biochemical and electrophysiological. The authors identified that exposure to the dynamic light condition had significant benefits on subjective sleepiness, positive mood and task performance, which may be moderated by the difficulty of task. The intervention effect of dynamic light on fatigue was identified during an electrophysiological activity, but was not observed in the biophysical measurements.

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

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)

Standard observer watts: Evaluating the efficiency of circadian-effective luminaires using a standard observer methodology

MS Rea, A Bierman, A Thayer, C Jarboe and M Figueiro

Simulations of non-imageforming effects of light in building design: A literature review

M Gkaintatzi-Masouti, J van Duijnhoven and MPJ Aarts

Diurnal effects of dynamic lighting on alertness, cognition and mood of mentally fatigued individuals in a daylightdeprived environment

Y Li, W Fang, B Guo and H Qiu

p

Typical lighting scenes in study of the effects of dynamic light (Li et al)

PLACES TO WORSHIP

Continuing the series, Colin Ball considers his Top Five sacred spaces from around the world

During the difficult years of lockdown

I discovered a deep reserve in strength in connection with my local church, St Paul’s Bow Common, which happens to have won the national award for the best modern church in the UK. Currently I act as sacristan, a role which involves maintaining the seasonal colours and preparing all items for each mass, including the candles. I’ve learnt so much about darkness, and medieval candle techniques that I don’t think I could have learnt in any other context.

Preparing for the festivals throughout the year has enriched my understanding of the times of bright celebration, as well as the darker, intimate festivals of remembrance, vigil and anticipation. Conducting these in a brutalist, contemporary space really magnifies the differences of each occasion. The best example of this being the stark bleakness of Good Friday which can really be felt in a raw concrete and black brick space. This immediacy of experience is what, for me, puts these five spaces as the most impactful I’ve experienced so far.

Shah Cheragh

('King of the Light'),

Shiraz, Iran

One of the holiest shrines in Iran, the 12thcentury Shah Cheragh mosque is encrusted with thousands of mirrored mosaics. As you walk through the crystalline space you are immediately aware of the greater palaces, glimpsed in the reflections, transmitting through the insubstantial material of light. The effect is of seeing a greater reality that lies within and permeates this one.

Selimiye, Edirne, Turkey

Completed in the 16th century and considered to be imperial architect Mimar Sinan’s masterpiece, this mosque is the culmination of his spatial experiments and features a dome around the size of the Hagia Sophia's, but slightly higher, the first time that this had been achieved in Ottoman architecture. But it’s the concentric rings of lamps hovering just above your head that makes it truly spectacular. An instant expression of the glory of the heavens.

King’s College Chapel, Cambridge

The last truly gothic building in Europe before a transition into Renaissance classical architecture, the reduction of stone to maximise glass and light reaches its climax here below the famous fan vaulted ceiling. What strikes me with this chapel is the elegant minimalism of a simple box elevated to such grandeur.

The Bayon, Angkor, Cambodia

One of the purest expressions of Mahayana Buddhism, this is one of the few ancient temples that you can enter, many previous forms being stupa, or shaped domes, that you only experience externally. This complex pulls you into complete darkness before a single stairway allows you on to the roof with the explosion of Buddha images in all directions.

Chapel of Unity, Coventry Cathedral, UK

An incredible expression of illumination in darkness. Architect Basil Spence has folded the walls so that light bleeds in through cracks between the panels. The coloured windows sit within deep recesses expressing a beauty that can be found in and in-between all things.

Colin Ball is lighting director London at BDP

Events 2023

For details of all upcoming webinars, go to: www.cibse.org/society-oflight-and-lighting-sll/sll-events/upcoming-webinars-and-online-content

For previously recorded CPD webinars (including regional webinars), go to: https://www.cibse.org/get-involved/societies/society-of-light-andlighting-sll/sll-events/on-demand-webinars-past-presentations

ONLINE EVENTS

INNOVATORS IN RESIDENTIAL HEALTH CARE: CIRCADIAN LIGHTING PRINCIPLES AND PRACTICE (online discussion organised by Age of Light Innovations and supported by the SLL)

Date: 7 March

www.eventbrite.co.uk/e/innovators-in-residential-healthcaretickets-473414384167

EXTERNAL LIGHTING AND SOCIAL EQUALITY

Date: 21 March

Speakers: Elettra Bordonaro, co-founder of Light Follows Behaviour, and Don Slater, LSE sociology, co-director Configuring Light/Staging the Social research group www.sll.org.uk

EVENTS

EUROLUCE

Date: 18-23 April

Venue: Fiera Milano, Milan www.salonemilano.it/en/exhibitions/euroluce

LIGHTFAIR

Date: 21-25 May

Venue: Jacob K Javits Convention Center New York www.lightfair.com

ENLIGHTEN EUROPE 23: BRING THE LIGHT (organised by the IALD)

DATE: 30 June-1 July

VENUE: Cafe Moskau, Berlin https://iald.org/Events/IALD-Enlighten/IALD-EnlightenConferences

AVAILABLE WEBINARS INCLUDE RESPONSIBLE OUTDOOR LIGHTING AT NIGHT CONFERENCE 2022

All 44 videos, including introductions, presentations and panel sessions, are now available from the ROLAN website https://go.cibse.org/ROLAN22

AGILE LIGHTING RESEARCH: BRIDGING THE GAP BETWEEN THEORY AND PRACTICE IN HUMANCENTRED LIGHTING

(interdisciplinary debate sponsored by the SLL)

Curator: Shelley James, Age of Light Innovations

Chair: Ruth Kelly-Waskett, Hoare Lea