UGR19: What It Is, Why It’s Mandatory in Offices, and How to Comply Without Hassle
David Torres
2026-05-25 10:04:19
UGR<19: what it is, why it is mandatory in offices and how to comply without complications
The comprehensive technical guide to specifying, installing and certifying office lighting in accordance with BS EN 12464-1, the Health and Safety at Work etc. Act 1974 and the Workplace (Health, Safety and Welfare) Regulations 1992.
1. What UGR is and how it is calculated
UGR stands for Unified Glare Rating. It is a numerical value defined in the standard CIE 117:1995 that measures the glare sensation produced by a lighting installation on an observer in a specific space.
Unlike other parameters such as lumens or lux, UGR is not a fixed characteristic of the luminaire: it is the result of how the luminaire interacts with a specific space. The same LED panel can give a UGR of 17 in a large room and a UGR of 21 in a small room.
The four factors that determine the UGR of an installation
The brightness of the light source in the direction of the observer. Luminaires with microprismatic diffusers or opal optics have lower luminance at oblique angles.
UGR worsens when luminaires are in the worker's frontal field of view, particularly between 0° and 65° from the vertical.
A larger room with light-coloured walls gives a better UGR for the same luminaire. The UGR<19 on the data sheet is calculated for reference dimensions.
Several well-distributed luminaires usually give a better UGR than few high-power luminaires concentrated at specific points.
UGR can be verified in two ways: from the UGR tables manufacturers include in their photometric data sheets (for standard room dimensions) or with lighting simulation software such as DIALux or Relux, which calculates the actual UGR for the project's specific dimensions. For projects where compliance must be documented (ISO certifications, public tenders, health and safety audits), software calculation and delivery of the report to the client is recommended.
2. The UGR scale: what each value means
UGR is a dimensionless index with no unit of measurement. The lower the value, the less glare and the higher the visual comfort. Here is the visual scale with its main applications:
CAD, museums
Offices (EN 12464-1)
Corridors, warehouses
Unsuitable
| UGR | Glare level | Typical application | Compliance |
|---|---|---|---|
| < 10 | No perceptible glare | Precision laboratories, operating theatres | ✅ Compliant |
| 10–13 | Imperceptible glare | Museums, galleries, jewellers | ✅ Compliant |
| < 16 | Very low glare | Technical drawing, graphic design | ✅ Compliant |
| < 19 | Low — OFFICE LIMIT | Offices, meeting rooms, classrooms | ⭐ MANDATORY |
| < 22 | Moderate | Shops, reception, retail | ⚠️ Transit |
| < 25 | Noticeable | Corridors, light warehouses | ⚠️ Transit |
| < 28 | High | Industrial areas without detail work | ❌ Unsuitable |
| > 28 | Very high — disturbing | Unacceptable in working areas | ❌ Unsuitable |
The UGR<19 value was established by the European standard BS EN 12464-1 as the acceptable glare limit for tasks with high visual demands, particularly at workstations with display screens. Above 19, most workers perceive the glare as uncomfortable consciously or unconsciously, leading to cumulative eye strain — a particular concern in the United Kingdom, where short winter daylight hours mean offices rely heavily on artificial lighting for much of the working year.
3. The legal framework: what the law actually requires
Meeting UGR<19 in offices is not a recommendation: it is a statutory obligation arising from the combination of three legal frameworks:
Health and Safety at Work etc. Act 1974 and the Workplace Regulations 1992
The Health and Safety at Work etc. Act 1974 places a general duty on employers to ensure, so far as is reasonably practicable, the health, safety and welfare of their employees. The Workplace (Health, Safety and Welfare) Regulations 1992, regulation 8, specifically requires that every workplace shall have suitable and sufficient lighting. The Health and Safety (Display Screen Equipment) Regulations 1992 add further obligations for DSE workstations. Enforcement is carried out by the Health and Safety Executive (HSE) and local authorities. The HSE references BS EN 12464-1 and the SLL Code for Lighting as the technical benchmark.
BS EN 12464-1:2021 — Light and lighting of indoor work places
This is the technical standard that sets the reference values. For working zones in offices, it stipulates three parameters that must be met simultaneously:
Minimum illuminance on the working plane (0.75 m above the floor).
Maximum UGR in areas with display screens, reading and detail work.
Colour rendering index to ensure faithful colour perception.
Penalties and electrical regulations (BS 7671 / IET Wiring Regulations)
Breaches of lighting requirements under the Health and Safety at Work etc. Act 1974 can result in unlimited fines in the Crown Court and fines of up to £20,000 per offence in the Magistrates' Court, with directors facing personal disqualification and up to 2 years' imprisonment under the Sentencing Council's Health and Safety Offences guideline. The HSE may also issue improvement notices or prohibition notices. The electrical installation must also comply with BS 7671 (the IET Wiring Regulations), and the work should be carried out and certified by a competent person registered with a Part P scheme such as NICEIC or NAPIT.
4. Requirements by zone in an office installation
The standard distinguishes between different zones within the same office building. The table below sets out the complete requirements for each space:
| Zone / space | Lux min. | UGR max. | Ra min. | Colour temp. | Compliance EN 12464-1 |
|---|---|---|---|---|---|
| Open-plan office | 500 | < 19 | 80 | 4,000 K | ⚠️ Mandatory |
| Individual office | 500 | < 19 | 80 | 3,000–4,000 K | ⚠️ Mandatory |
| Meeting room | 500 | < 19 | 80 | 3,000–4,000 K | ⚠️ Mandatory |
| Training room | 500 | < 19 | 80 | 4,000 K | ⚠️ Mandatory |
| Reception / front desk | 300 | < 22 | 80 | 3,000 K | 📋 Recommended |
| Archive and documentation | 300 | < 25 | 80 | 4,000 K | 📋 Recommended |
| Server room / data centre | 500 | < 19 | 80 | 4,000 K | ⚠️ Mandatory |
| Break room / canteen | 200 | < 22 | 80 | 3,000 K | 📋 Recommended |
| Corridors and circulation areas | 100 | < 28 | 40 | 4,000 K | ℹ️ Basic |
| Toilets and changing rooms | 200 | < 25 | 80 | 4,000 K | ℹ️ Basic |
| Staircases | 150 | < 25 | 40 | 4,000 K | ℹ️ Basic |
Specifying UGR<19 for the panels in the work area but installing standard downlights (UGR 22–25) in the meeting rooms. Meeting rooms are working zones with display screens (projectors, large displays, laptops) and must meet UGR<19 exactly like the open-plan area.
5. Which luminaire types meet UGR<19
Not all luminaires labelled "UGR<19" meet this value under all installation conditions. The table below gathers the most common types with their actual characteristics:
| Luminaire type | Typical UGR | Format | Meets <19 | When to use |
|---|---|---|---|---|
| Recessed 600×600 LED panel (UGR<19) | < 19 | 600×600 mm | Yes | Offices, meeting rooms, training rooms. The most common product for compliance. |
| 600×600 microprismatic LED panel | < 16 | 600×600 mm | Yes | Graphic design, CAD, operating theatres. Maximum glare control. |
| Standard downlight (smooth reflector) | 22–25 | Ø 150–200 mm | No | Corridors. Does not meet UGR<19 for workstations. |
| Downlight with anti-glare lens | < 19 | Ø 150–200 mm | Yes | Suitable for offices if certified by the manufacturer. |
| Suspended LED linear luminaire (direct/indirect) | < 16–19 | 600–1,200 mm | Yes | Excellent for open-plan. The indirect component eliminates glare. |
| Surface-mounted with opal diffuser | 19–22 | Variable | Varies | Check data sheet. Opal diffuser does not guarantee UGR<19 automatically. |
| Track-mounted spotlight | 24–28 | Variable | No | Unsuitable for DSE workstations. Only accent lighting. |
| Industrial high-bay luminaire | 25–28 | Variable | No | Exclusively for industrial or logistics use. |
The catalogue UGR value is calculated for a reference room with specific dimensions (typically 8×8 m, height 3 m, reflectances 70/50/20). In small rooms (<4×4 m), the actual UGR can be 2–3 points higher than the catalogue value. For projects where compliance must be certified, always request the complete photometric data sheet with UGR tables and verify with simulation software.
Osram LED panel 600×600 UGR<17 — the benchmark for regulatory compliance
The 600×600 LED panel with Osram technology and UGR<17 certification is the most requested solution in office projects with regulatory requirements. Direct recessed fitting into 600×600 modules of suspended ceiling, complete photometric data sheet with UGR tables for all room dimensions and BS EN 12464-1 certificate supplied with every unit.
6. The financial and legal consequences of non-compliance
Specifying or installing luminaires that do not meet UGR<19 in working zones is not only a technical problem. It has concrete legal and financial consequences for the client, the facilities manager and the installer:
| Risk | Applicable legal framework | Financial consequence |
|---|---|---|
| HSE inspection | The Health and Safety at Work etc. Act 1974 and the Workplace Regulations 1992 require suitable lighting. An inspection can lead to improvement or prohibition notices. | Unlimited fines in Crown Court, up to £20,000 in Magistrates' Court |
| Work-related injury from eye strain | If it is proven that inadequate lighting contributed to the injury, the employer may face a personal injury claim. | Civil personal injury claim + uplift in employers' liability premiums |
| Occupational ill health | Chronic eye strain may be recognised as occupational ill health, with potential claims against the employer. | Sick leave costs + compensation + RIDDOR reporting obligations |
| Failed health and safety audit | Corporate contracts and certifications (ISO 45001) require documented compliance. | Loss of contract / mandatory remediation |
| Installer's liability | If the installer specified luminaires without UGR<19, the client can invoke professional negligence. | Professional indemnity claim + duty to remedy |
If the end client refuses the UGR<19 solution on cost grounds and asks to install cheaper luminaires without this requirement, the installer must obtain written confirmation that the client is aware of the regulatory breach and accepts it under their own responsibility. Without this documentation, in the event of a future claim, liability falls back on the installer as a professional with a duty of care and a duty to advise. Factorled supplies the data sheet for every product with the certified UGR value so that it is documented in your project file.
7. How to specify an office project correctly
These are the steps that installers and consultants working with Factorled follow on office projects with UGR<19 compliance:
Floor plan with exact dimensions of each zone, clear height, wall/ceiling/floor reflectances and workstation positions.
Classify each zone according to the table in section 4 to establish the maximum UGR, minimum lux and required Ra.
Verify that the data sheet states the UGR value calculated for room dimensions close to the actual project.
Calculate with DIALux or Relux entering the actual room dimensions. Archive the report in the project file.
Install panels or linear luminaires so that the longitudinal axis is parallel to the worker's main line of sight.
Measure actual lux on the working plane (0.75 m) after installation. Record measurements in a commissioning report.
Data sheets with certified UGR, simulation report and commissioning record. This is the installer's legal protection.
8. Installer's verification checklist
Before considering an office lighting installation as complete, check all of the following points:
Installers working with Factorled can request this checklist in PDF format alongside the product data sheets. It serves as installation documentation and as evidence of professional diligence in the event of inspection or claim.
9. The impact of UGR on productivity
When a client questions the additional cost of UGR<19 luminaires compared with cheaper options, these are the figures that close the conversation:
CIBSE studies show that inadequate lighting can reduce productivity by up to 15% in office work.
Cornell University research: up to 25% more errors in reading and data-handling tasks.
Chronic eye strain is one of the leading causes of sick leave in office work — particularly relevant during the dark British winter months.
20 employees × £45,000 × 5% lost productivity = £45,000/year in hidden costs versus £15–25 per luminaire.
The cost difference between a standard LED panel and a UGR<19 LED panel of equivalent quality is £10–22 per unit. In a 300 m² office with 30 panels, that difference is £300–660. An HSE fine in the Magistrates' Court starts at thousands of pounds and can reach £20,000 per offence; in the Crown Court fines are unlimited. The cost of a personal injury claim runs into five or six figures. Put this way, the client who understands the numbers always chooses the right product.
Conclusion
UGR<19 is neither a technical nicety nor a sales argument: it is a legal requirement that protects employees' health, protects the installer from liability and protects the employer from penalties.
Meeting it is neither complicated nor especially expensive if it is specified correctly from the outset of the project. The most common solution — 600×600 LED panel UGR<19 — is a standard, economical product widely available in the Factorled catalogue.
The only mistake without an easy fix is discovering it after installation, when an already delivered project must be dismantled, replaced and re-documented.
Factorled products with UGR<19 certification
- 600×600 LED panel UGR<19 — 36 W and 40 W: the most requested product for offices. Direct recessed fitting into 600×600 modules of suspended ceiling.
- 600×600 microprismatic LED panel UGR<16: for graphic design areas, CAD and technical rooms with the highest visual demands.
- 300×1200 LED panel UGR<19: for modular ceilings in rectangular format. High lighting uniformity.
- Recessed LED linear luminaire UGR<19: for spaces with continuous plasterboard ceilings.
- Suspended LED linear luminaire direct/indirect: direct and indirect components for maximum visual comfort in open-plan.
- UGR<19 LED downlight with microstructured lens: for projects where a suspended ceiling is not an option.
View our UGR<19 catalogue for offices
Factorled offers a complete range of UGR<19 LED panels, recessed and suspended linear luminaires, and downlights with glare certification compliant with BS EN 12464-1. All our UGR<19 products are supplied with a complete photometric data sheet, materials list for the project file and technical support for project verification.