CIBSE Lighting Guide 7 (LG7) is the UK industry standard for office lighting design. Published by the Society of Light and Lighting (SLL), the guide outlines how to create visual environments that support productivity, comfort, and wellbeing in workplaces.
The 2023 revision brought significant changes. Hybrid working patterns, portable devices, and the shift away from fixed desks meant the previous 2015 edition no longer reflected how people actually use office space. The current guide addresses these realities head-on.
For architects, lighting designers, and electrical engineers working on commercial fit-outs, understanding LG7 is not optional. Clients expect schemes that meet compliance, and non-compliant installations can create problems with building regulations, BREEAM assessments, and occupant satisfaction.
The 2023 revision introduced several key updates that affect how you approach office lighting design.
For the first time, LG7 includes dedicated advice for home office environments. The guide recognises that hybrid working is here to stay. It covers décor considerations, desk placement, and how wall reflectance affects the lit environment in domestic settings.
BS EN 12464-1:2021 introduced context modifiers, and LG7 has given them increased prominence. These modifiers allow you to adjust baseline illuminance recommendations based on specific factors:
This approach moves away from one-size-fits-all lux values towards schemes tailored to actual occupants and their work.
LG7 now addresses embodied energy alongside operational energy. The guide encourages reusing serviceable luminaires rather than replacing entire installations. This aligns with CIBSE TM66, which focuses on creating a circular economy in the lighting industry.
LG7 works alongside BS EN 12464-1:2021 to establish illuminance recommendations for different office tasks and areas.
The guide recommends two primary maintained illuminance levels for general office work:
These figures represent starting points. You apply context modifiers to determine the final target for each specific situation.
People working at screens need regular visual breaks to prevent eye strain. The long view within an office should be illuminated to support this. BS EN 12464-1:2021 recommends:
These are baseline figures for a well-balanced scheme, not targets to hit exactly. Direct/indirect luminaires or wall-washing techniques help achieve these levels while creating visual interest.
Previous editions of LG7 focused on maintaining uniform illuminance across a notional working plane. The 2023 revision takes a different approach, emphasising the task area itself.
This change acknowledges that modern workers engage with tasks at various heights and orientations. Tablets, smartphones, and touchscreen monitors mean the horizontal desk surface is no longer the only relevant plane.
Glare remains one of the most common complaints in office environments. LEDs present particular challenges because they concentrate light output into small areas, making them more apparent in the field of view than older lamp technologies.
UGR (Unified Glare Rating) quantifies the likelihood of discomfort glare from a lighting installation. For general office space, LG7 requires a UGR of 19 or below. Higher values may be acceptable in circulation areas, reception spaces, and breakout zones where feature lighting is appropriate.
Several factors affect whether your installation will meet UGR requirements:
299 Lighting specifies luminaires with appropriate optics for office applications and provides UGR analysis as part of the lighting design service, ensuring schemes meet compliance before installation.
Video conferencing has become standard in modern offices. The shift to hybrid working means people regularly communicate with colleagues and clients via screen. This creates specific lighting requirements that traditional horizontal illuminance alone cannot address.
BS EN 12464-1:2021 introduced mean cylindrical illuminance as a design criterion. This measures how much light falls on vertical surfaces, particularly at face height. The standard specifies calculation heights of:
Adequate cylindrical illuminance ensures faces are properly lit during video calls, avoiding the harsh shadows or underlit appearances that undermine professional communication.
Modelling ratio describes the balance between diffuse and direct lighting. Completely diffuse illumination appears flat and bland. Purely direct lighting creates strong contrasts and harsh shadows.
For office environments, an acceptable modelling ratio falls between 0.3 and 0.6 (30% to 60% of horizontal illuminance value). Direct/indirect luminaires help achieve this balance by distributing light both downward onto work surfaces and upward onto ceilings.
Selecting the right luminaires is fundamental to achieving compliance. Different office layouts and ceiling configurations call for different approaches.
Linear luminaires offer flexibility for open-plan offices. Available as individual units or continuous runs, they create clean lines of light while delivering even illumination across large floorplates.
Direct/indirect linear profiles work particularly well for LG7 compliance. The upward component lights the ceiling, contributing to wall and ceiling illuminance targets while reducing contrast. The downward component provides task illumination.
299 Lighting supplies linear systems with LG7-compliant optics, available in bespoke lengths and any RAL colour finish. Our office lighting range includes microprismatic diffusers that achieve UGR19 or below.
For spaces with lower ceilings, recessed downlighting provides efficient task illumination without the visual bulk of suspended fittings. The key is selecting products with appropriate beam angles and glare control.
Multiple optic options allow you to tune light distribution for specific layouts. Adjustable downlights provide flexibility for spaces that may be reconfigured over time.
Where ceiling heights allow, suspended luminaires create visual interest while delivering compliant illumination. Rings, slim linear profiles, and decorative pendants can define zones within open-plan layouts.
Height adjustment capabilities mean you can position luminaires at the optimal distance from work surfaces, maintaining illuminance levels even in double-height spaces.
LG7 emphasises energy efficiency alongside visual performance. Smart control systems play a central role in meeting both objectives.
Offices with good daylight provision can reduce electric lighting energy significantly. Photocell sensors monitor ambient light levels and dim luminaires automatically, maintaining consistent illumination while reducing power consumption.
The 2023 LG7 revision encourages early collaboration with architects to maximise daylight penetration. When natural light can illuminate workspace effectively, designers should make the most of this resource.
PIR and microwave sensors detect movement within spaces, switching or dimming lights based on occupancy. This prevents energy waste in unoccupied areas.
Modern sensors distinguish between presence (someone is there) and absence (no one has been detected for a defined period). This distinction allows more sophisticated control strategies.
Wireless protocols like Casambi eliminate the need for complex control wiring. 299 Lighting integrates Casambi into linear, suspended, and downlight luminaires, enabling scene setting, scheduling, and app-based control without gateway infrastructure.
Bluetooth mesh networks scale easily across large floorplates. Individual luminaires or groups can be controlled independently, supporting different activities in adjacent zones.
DALI (Digital Addressable Lighting Interface) remains the standard wired control protocol for commercial installations. It provides individual luminaire addressing, enabling precise control and monitoring.
For emergency lighting, DALI systems offer centralised testing and reporting capabilities. This simplifies compliance with BS 5266 requirements and reduces maintenance burden.
Emergency lighting is a legal requirement in commercial buildings. LG7 references the relevant British Standards and includes guidance on integrating emergency provision into overall office schemes.
Safe evacuation depends on adequate illumination of escape routes, changes in level, and emergency exits. BS 5266 sets specific requirements for minimum illuminance along escape routes.
Emergency lighting must operate automatically during mains power failure. Self-contained units with integral batteries or central battery systems both meet this requirement.
Standalone emergency fittings can disrupt design intent. Converting main luminaires to include emergency function maintains visual consistency while meeting compliance.
299 Lighting supplies emergency conversion kits for linear, suspended, and downlight products. Our team ensures conversion kits are incorporated correctly in accordance with ISO and British Standards.
Regular testing is mandatory for emergency lighting systems. Self-test luminaires automate the monthly function test and annual duration test, recording results for compliance documentation.
DALI emergency systems provide centralised monitoring and reporting across entire installations. This reduces the manual effort required to demonstrate compliance during inspections.
LG7 recognises that office spaces vary significantly. The guidance addresses different scenarios with appropriate recommendations.
Large open floorplates require uniform illumination across the working area, with flexibility to accommodate changing desk layouts. Grid-based luminaire arrangements work well, though care is needed to maintain visual interest.
Zoned control allows different areas to operate at different levels. Collaborative spaces may benefit from brighter, more dynamic lighting while focused work areas need consistent, glare-free illumination.
Individual offices present different challenges. Smaller volumes mean fewer luminaires, but proportionally greater impact from each unit. Local dimming control gives occupants personal adjustment of their environment.
Glazed partitions between cellular offices and open-plan areas affect light distribution. LG7 includes worked examples showing how to handle these configurations.
Meeting rooms need multiple lighting scenes. Presentation mode requires different illumination than collaborative discussion or video conferencing.
Scene-setting capability lets occupants select appropriate conditions with a single action. Dimmable luminaires with indirect distribution support video conferencing, while accent or feature lighting can be introduced for client-facing spaces.
Relaxation areas and breakout spaces allow more creative lighting approaches. UGR requirements can be relaxed where feature lighting supports the design intent.
These areas often benefit from variety in luminaire types and warmer colour temperatures. The goal is creating an environment distinct from the task-focused workspace.
Many commercial developments target BREEAM or WELL Building Standard certification. Lighting contributes to multiple credit categories.
Efficient lighting with appropriate controls earns credits in the Energy category. Daylight provision, glare control, and colour rendering performance contribute to Health and Wellbeing credits.
LG7-compliant schemes generally align well with BREEAM requirements. The emphasis on occupant comfort and energy efficiency addresses assessment priorities directly.
WELL focuses specifically on how buildings affect occupant health. Light is one of the seven concept categories, covering visual acuity, circadian rhythm support, and glare control.
Meeting LG7 illuminance and UGR targets positions schemes to achieve WELL light credits. Circadian lighting strategies, which vary colour temperature and intensity throughout the day, can earn additional points.
299 Lighting advises on BREEAM and WELL lighting requirements from the briefing stage, helping project teams target specific credits with appropriate specifications.
Demonstrating compliance requires appropriate calculations and supporting information.
Lighting design software generates predicted illuminance, uniformity, and UGR values for proposed schemes. These calculations form the basis of compliance documentation.
Calculations should show maintained illuminance (accounting for lamp depreciation and maintenance factors) rather than initial values. This ensures the scheme remains compliant throughout its service life.
Luminaire datasheets, LDT files, and photometric data support design calculations and provide evidence of product performance. This documentation should be retained for building records.
299 Lighting supplies complete technical data for specified products, including photometric files, spacing tables, and emergency lighting information where applicable.
Comprehensive design reports bring together calculations, product specifications, and compliance commentary. These documents demonstrate that the scheme has been designed to meet LG7 requirements.
Our design calculation packs include an easy compliance check system, showing which areas meet lighting recommendations and highlighting any special considerations.
Context modifiers give designers flexibility to adjust baseline recommendations. Using them correctly requires understanding when increases or decreases are appropriate.
Higher lux levels may be warranted when:
Reduced illuminance may be appropriate when:
The key is documenting your reasoning. Calculations and reports should explain which modifiers have been applied and why.
Several issues regularly cause compliance problems in office lighting schemes.
Calculations assume specific surface reflectances for walls, ceilings, and floors. When actual finishes differ significantly from assumed values, illuminance levels may not match predictions.
Dark feature walls, exposed concrete ceilings, or deep-coloured flooring all reduce light reflection. Schemes need higher installed power to compensate, or surface treatments need adjustment.
UGR problems are expensive to fix after installation. Specifying the wrong luminaire optics or failing to account for viewing angles leads to complaints and potential remediation costs.
Check UGR calculations for all typical viewing positions during design development. Adjust luminaire selection or positioning before procurement.
Manual switching only, or absence of daylight linking, wastes energy and may prevent BREEAM credit achievement. Control strategy should be established early and coordinated with electrical design.
Luminaire light output declines over time due to LED depreciation and dirt accumulation. Schemes designed to exactly meet targets at installation will fall below compliance before end of life.
Apply appropriate maintenance factors to ensure maintained illuminance meets requirements throughout the service period.
LG7 recommends 300 lux for predominantly screen-based tasks and 500 lux for predominantly paper-based tasks. Context modifiers allow you to adjust these figures based on occupant needs and task characteristics. 299 Lighting calculates appropriate levels for each zone during the design process.
UGR (Unified Glare Rating) measures the likelihood of discomfort glare from artificial lighting. Office spaces require UGR19 or below to prevent eye strain and headaches. Achieving this rating requires selecting luminaires with appropriate optics and positioning them correctly relative to viewing positions.
299 Lighting delivers complete LG7-compliant office schemes, from initial consultation through to installation support. We provide photometric calculations, UGR analysis, emergency lighting design, and technical documentation. Our in-house Light Engineers have over two decades of commercial project experience.
Yes. The 2023 revision includes dedicated guidance for home office environments. It addresses décor considerations, desk positioning, and how existing room finishes affect the lit environment. This reflects the shift to hybrid working patterns following the pandemic.
LG7 emphasises energy efficiency through intelligent controls. Recommended features include daylight linking, occupancy sensing, and scene setting. 299 Lighting specifies wireless Casambi systems and DALI protocols that deliver these capabilities without complex wiring installations.
LG7-compliant schemes align well with BREEAM requirements in the Energy and Health categories. Credits are available for efficient lighting, appropriate controls, daylight provision, and glare control. 299 Lighting advises on credit targets from the briefing stage to help you maximise assessment scores.
Cylindrical illuminance measures light falling on vertical surfaces at face height. It matters for offices where video conferencing occurs, ensuring faces are properly lit during calls. BS EN 12464-1:2021 specifies calculation heights of 1.2m (seated) and 1.6m (standing).
LG7 encourages reusing serviceable equipment to reduce embodied carbon. Where existing luminaires meet performance requirements, they can be retained. 299 Lighting assesses existing installations during lighting surveys and recommends which products can be kept.