The Essential Ingredient

THE ESSENTIAL INGREDIENT

Control systems have shifted from optional extra to an integral element of most lighting schemes. Sophie Parry outlines the changes and additions in the newly updated SLL guidance

Lighting Guide 14: Control of Electric Light was first published in 2016 and has proved popular with designers and specifiers ever since.

The aim of the original LG14 was to demystify, as far as possible, the subject of lighting controls, and allow informed and objective decisionmaking for the application of controls to lighting projects. A decade ago, it was quite common for lighting controls to be seen as an optional extra to schemes, and they would often be ‘value engineered’ out of a project.

In the eight years since LG14 was first conceived, the lighting industry has evolved to the extent that automatic lighting controls are now an essential and integral part of the vast majority of lighting designs. The overarching reason is the versatility of LED light sources and their easier controllability. This means that lighting control systems have seen a notable rise in use in the following applications:

● Energy reduction: the cost of energy has risen significantly, and controls can easily deliver an annual financial saving on energy costs of at least 20-30 per cent, in addition to the savings made with LED lighting. This lowering of operational energy also supports the reduction of operational carbon as we move towards a net zero carbon future.

● Wellness: there is also the growing appreciation of the importance of wellness. Both daylight and electric light play their part in this area, and need to work in harmony to deliver good quality illumination that considers both photopic and melanopic light. This would be very challenging to realise without a compatible lighting control system.

● Exterior lighting: there has been a significant rise in the use of external lighting that goes beyond just providing functional night-time illumination. Many external lighting schemes now use coloured light, for instance, and will alter the lighting scenes to suit particular events and occasions, or further accentuate the architectural features of a building facade. The flip side to this area of growth is that night-time light pollution has increased. In addition to good luminaire and lighting design, lighting controls can help reduce light pollution in most project applications, as well as saving operational energy and reducing operational carbon.

WHAT’S NEW IN LG14

Looking at the second edition chapter by chapter, the following is a brief summary of what has been introduced or updated.

Chapter 1

This is an overview of advances in lighting control technology and applications since the first edition was launched in 2016.

Chapter 2

There have been significant updates to the terminology and acronyms used in lighting controls. I have noticed that specifications often ask for certain aspects of lighting control performance on projects where the specification author is not entirely clear what the terminology means and can deliver. There is therefore information on the less than obvious terminology and its application.

Chapter 3

This focuses on how to approach a design and manage the client’s expectations.

The best approach is to first design the lighting and specify the luminaires to be used, then determine with the client how the lighting should be controlled to suit their requirements. These will include meeting legislative or performancerelated energy conservation stipulations, in addition to the client's specific needs. Once the performance criteria are established, the correct lighting controls can be selected and added to the lighting design. It’s also a good idea at this stage to revisit the luminaire schedule to ensure that the luminaires contain, or can be supplied with, compatible control gear to ensure correct operation with the lighting control system.

Chapter 4

What about the people who actually use the spaces that are lit and controlled? This chapter looks at human factors in typical spaces and where different modes of lighting control are known to be the most effective. Here you will note when you should be specifying absence or presence detection, or if a risk assessment shows that automatic lighting controls which suddenly switch the lights off unexpectedly could be a health and safety risk.

Chapter 5

Lighting controls are not always used for the primary task of saving energy. Controls can also be used for creating visual interest and visual comfort, as this chapter discusses. The correct luminaire control gear and a compatible lighting control system will also be required for the correct operation of integrative lighting schemes.

Chapter 6

Energy reduction is nevertheless the most common application for lighting controls but apart from the financial benefits of saving energy, how do we know how much lighting energy should be saved in order to meet legislative requirements such as Approved Document L of the Building Regulations? LG14 uses Approved Document L, Vol 2, for England as the basis of discussion as this version was updated in 2021/22, and is therefore the most up-to-date Building Regulation in the four devolved nations when it comes to lighting energy efficiency limits.

The Leni (lighting energy numeric indicator) calculation method can be found in its simplest form in this version of Approved Document L and is reproduced with additional commentary in the second edition of LG14.

Leni is derived from BS EN 19193-1 Energy Performance of Buildings – Energy Requirements for Lighting. It is currently the most accurate method of predicting lighting energy usage. It also allows for the benefits of lighting controls to be factored into the calculation. The output of the calculation is expressed in kWh/sqm per annum.

This means that the projected cost of lighting energy and the carbon footprint can then easily be calculated. If factoring in or factoring out the energy-saving benefits of lighting controls, the lighting design starts to get interesting. This exercise can make two points:

● The annual energy savings as a return on making the investment in automatic lighting controls, as opposed to not using automatic lighting controls.

● That the inclusion of automatic lighting controls might make the difference between compliance or non-compliance with Approved Document L of the Building Regulations for England.

That said, lighting designers often shy away from using Leni because it can seem daunting and time-consuming. However, as the built environment moves towards a net zero carbon future, designers will have to embrace new design methodologies of preserving the required lighting quality and using less energy.

Chapter 7

The data sharing of room occupancy status provided by networked lighting control systems was already possible when LG14 was first published in 2016. The most common example at the time was to share room occupancy data in real-time with the BMS system in order to optimise the performance of HVAC systems.

There has also been a noticeable increase in the use of controls to automatically test, and generate fault and test reports, for emergency lighting installations.

There has been much talk about intelligent buildings, and some early adopter projects, as well as the use of digital, IoT and wireless-based lighting controls. This area of development also allows the sharing of collected data, by virtue of the fact that the lighting control network is already covering all areas in a typical building. The use of this network with auxiliary sensors to collect additional useful data such as space usage, lighting energy and maintenance, temperature, humidity and air quality makes it possible to create a more pleasant environment for the end-user. It also enables more informed decision-making relating to building comfort, wellness, FMand energy costs.

That said, this new technology also brings new engineering and design challenges, including cybersecurity considerations, which are also explored in this chapter.

Integrative lighting showing the shift in colour temperature throughout the day

Chapter 8

This chapter on commissioning and handovers should be the most obvious subject, but sadly in practice it is not the case.

Often the more simple lighting controls installations are not fully commissioned and tested, which means they are not likely to deliver the design intent or the return on investment expected by the end user.

Part of commissioning should also include a handover process, usually to the facilities manager, that also explains what can be done at a site level to effect maintenance or system changes, and also often in layman's terms to the end-users of the space. Typical examples might include how to use a scene-setting switch in the conference room, or why some luminaires appear dimmer close to the windows, and that there is no need to call the FM and report a lighting fault.

Chapter 8 also points towards CIBSECommissioning Code L (Lighting) which was revised in 2018. This provides the means of developing a commissioning method statement for a lighting installation project where the luminaires, controls, emergency lighting and auxiliary data interfaces with other services all form the basis of a common lighting design.

LG14 concludes with case studies for places of worship, education and offices.

Sophie Parry, FSLL, is a chartered engineer andhead of the Trilux UK Akademie. She is chair ofthe SLL’s technical and publications committee

Lighting Guide 14 (LG14): Control of Electric Light is scheduled for publication in September

Author: Sophie Parry CEng MIETFSLL (Trilux Lighting)

Case study contributors: David Holmes Hon FSLL; Simon Robinson CEng FIETFIMechE FSLL (WSP Consulting)