At a glance
| Term | What it means (source wording, paraphrased) | Typical fittings | Usually decided by (our reading) |
|---|---|---|---|
| Ambient (general lighting) | CIE: substantially uniform lighting of an area, without provision for special local requirements. | Pendants, chandeliers, wall lights, coves, ceiling downlights | Lighting designer, with the interior designer for decorative pieces |
| Task (local lighting) | CIE: lighting for a specific visual task, additional to and controlled separately from the general lighting. | Bedside and desk lamps, under-cabinet strips, vanity lights | Interior designer and lighting designer together |
| Accent | CIE: directional lighting to emphasise a particular object or draw attention to a spot in the field of vision. | Picture lights, adjustable spots | Lighting designer |
| Decorative (a fitting role) | US DOE roundtable: decorative luminaires such as sconces, pendants, table and standing lamps. | Chandeliers, pendants, wall lights, table lamps | Interior designer; the partner workshop for a bespoke piece |
| Architectural (a fitting role) | US DOE roundtable: concealed architectural lighting, indirect lighting integrated with architectural elements. | Coves, shelf and joinery strips, concealed linear lighting | Lighting designer with the architect, joiner and M&E engineer |
| Display lighting (Part L term) | Approved Document L: lighting to highlight displays, or used in spaces for public leisure and entertainment, such as restaurants. | Not a layer: a compliance category | Lighting designer, M&E and building control |
| Specialist process lighting (Part L term) | Approved Document L: lighting for specialist tasks rather than the space itself; includes art objects with integral lighting such as chandeliers. | Not a layer: a compliance category | As above; see our Part L sheet |
Definitions: CIE S 017:2020 e-ILV; US DOE Lighting Designer Roundtable (April 2008); Approved Document L volume 2, 2021 edition. Read on 5 November 2026.
Two ways to describe a light
Lighting is described in two ways that are easily mixed up. Function layers say what the light does: the CIE International Lighting Vocabulary defines general lighting, local lighting and accent lighting, which are the ambient, task and accent layers of everyday use. Fitting roles say what the fitting is: a US Department of Energy roundtable report separates decorative luminaires, such as sconces, pendants, table and standing lamps, from concealed architectural lighting, which is indirect lighting integrated with architectural elements. A chandelier is decorative in role and, usually, ambient in function. A cove is architectural in role and ambient in function. A bedside lamp is decorative and task.
That is why our hotel lighting design article can list three layers and still count large decorative fixtures in the ambient layer: the two words answer different questions. The drawing shows five fittings in one room labelled by both.
Sources word the layers differently. A 2002 Los Alamos design guide, written for offices and laboratories, lists ambient, task, accent and emergency lighting, and describes accent as used for architectural purposes to add emphasis or highlight a display. The DOE roundtable notes that specifiers were moving from one uniform high level towards layers of light tuned to the functions of a space. Because the words move, a brief should define them. The last section of this sheet does, and the glossary gives each term its source.
Every fitting has a role and a job
The grid puts examples in each combination. It is our arrangement, not a published classification; the sources define the words, not the cells. Its use is practical: every cell in a column is a circuit that can be controlled with the rest of its layer, and an empty cell is a question for the brief.
| Fitting role | Ambient | Task | Accent |
|---|---|---|---|
| Decorative luminaire | Chandelier, pendant, wall light | Bedside, table or standing lamp | Picture light with a decorative arm |
| Concealed architectural | Cove or concealed strip | Under-cabinet or wardrobe strip | Recessed adjustable spot on an artwork |
| Built into joinery | Shelf-edge or niche glow | Light at the work surface or inside a wardrobe | Display niche or case lighting |
Who decides what, by RIBA stage
No standard we read says who specifies decorative lighting. The RIBA Plan of Work 2020 names the stages and says that the Responsibility Matrix, produced at Stage 1, records for each building system whether the design team will give prescriptive or descriptive information. At Stage 4 a descriptive system is designed by a specialist, who in the bespoke case may be the partner workshop. Everything else in the table is our reading of usual practice, to be settled in the Responsibility Matrix for the project. See also bespoke work in the RIBA Plan of Work.
| RIBA stage (2020) | What is decided for lighting (our reading) | Usually led by (our reading) | Typical output |
|---|---|---|---|
| 1 Preparation and Briefing | How much lighting design the project needs and who is appointed; layers wanted in each space; the entry for decorative lighting in the Responsibility Matrix. | Client, interior designer, project lead | Lighting brief (the template below) |
| 2 Concept Design | Mood and layer strategy per space; where decorative pieces sit; first ideas for scenes. | Interior designer with the lighting designer | Concept images, a layer sketch |
| 3 Spatial Coordination | Positions, coves and voids; ceiling heights; driver and hatch positions; early word with the structural engineer for heavy pieces. | Lighting designer, architect, M&E and structural engineers | Coordinated reflected ceiling plan |
| 4 Technical Design | Luminaire specification; dimming method; controls; shop drawings for bespoke pieces; compliance position. | Lighting designer, M&E engineer, partner workshop for bespoke pieces | Luminaire and controls schedules, shop drawings |
| 5 Manufacturing and Construction | Samples and mock-up approved; manufacture; delivery; first and second fix. | Partner workshop, contractor, electrician | Approved samples, installed fittings |
| 6 Handover | Commissioning of scenes and focus; operation and maintenance information; spares. | Installer, lighting designer | As-built records, O&M information |
Glossary
Each definition is paraphrased from the source in the right-hand column. The CIE terms are from the free online e-ILV of CIE S 017:2020, the International Lighting Vocabulary, second edition, which carries the number of each term.
Layers and roles
| Term | Meaning | Source |
|---|---|---|
| General lighting | Substantially uniform lighting of an area without provision for special local requirements. The ambient layer. | CIE ILV 17-29-007 |
| Local lighting | Lighting for a specific visual task, additional to and controlled separately from the general lighting. The task layer. | CIE ILV 17-29-008 |
| Accent lighting | Directional lighting to emphasise a particular object or draw attention to a spot in the field of vision. | CIE ILV 17-29-023 |
| Direct lighting and indirect lighting | Direct: 90 to 100% of the luminaire's light reaches the working plane directly. Indirect: 0 to 10%. | CIE ILV 17-29-014, 17-29-018 |
| Decorative luminaire | A luminaire such as a sconce, pendant, table or standing lamp. The report notes decorative fittings often use a diffuse lens or shade to hide the lamp and give an even glow. | US DOE Lighting Designer Roundtable, Apr 2008, section 5.2.1 |
| Concealed architectural lighting | Indirect lighting integrated with architectural elements, such as a cove, giving smooth, glare-free light. | US DOE roundtable, section 5.2.2 |
| Display lighting | Lighting to highlight displays of exhibits or merchandise, or lighting used in spaces for public leisure and entertainment, such as dance halls, auditoria, conference halls, restaurants and cinemas. | Approved Document L vol 2, 2021 ed., Appendix A, p. 85 |
| Specialist process lighting | Lighting to illuminate specialist tasks within a space rather than the space itself. Includes illuminated signs, and art objects with integral lighting, such as sculptures, decorative fountains and chandeliers. | Approved Document L vol 2, 2021 ed., Appendix A, p. 89 |
Quantities and qualities of light
| Term | Meaning | Source |
|---|---|---|
| Luminous flux (lumen, lm) | The amount of light a source emits, weighted for the human eye. | CIE ILV 17-21-039 |
| Illuminance (lux, lx) | Luminous flux arriving on a surface, per unit area. | CIE ILV 17-21-060 |
| Luminous intensity (candela, cd) | Luminous flux per unit solid angle in a given direction. | CIE ILV 17-21-045 |
| Luminance | Luminous intensity per projected area in a given direction: what is seen as the brightness of a surface. | CIE ILV 17-21-050 |
| Beam angle | The full angle between the two directions where intensity falls to half of the centre-beam intensity. A full angle, not a half angle. | CIE ILV 17-27-077 |
| Correlated colour temperature (CCT) | The temperature of the Planckian radiator whose colour is nearest that of the source, in kelvin. | CIE ILV 17-23-068 |
| Colour rendering index (CRI) | How closely the colours of objects lit by the source match those under a reference light. | CIE ILV 17-22-109 |
| Discomfort glare | Glare that causes discomfort without necessarily impairing sight of objects. | CIE ILV 17-22-102 |
| Flicker | Perceived unsteadiness of a light whose brightness or colour fluctuates with time. | CIE ILV 17-22-092 |
| Luminous efficacy | Luminous flux emitted divided by the power consumed (lumens per watt). | CIE ILV 17-21-089 |
| Light output ratio (LOR) | A luminaire's total light output divided by the output of its lamps outside the luminaire: the luminaire's efficiency. | CIE ILV 17-29-052 |
| Maintenance factor | Illuminance from an installation after a stated time divided by its illuminance when new. | CIE ILV 17-29-146 |
Equipment and electrical
| Term | Meaning | Source |
|---|---|---|
| Luminaire | An apparatus that distributes, filters or transforms the light from at least one source and includes the parts to fix and protect the sources and, where needed, circuit auxiliaries and the means to connect them to the supply. | CIE ILV 17-30-001 |
| Light source | A surface or object emitting light. | CIE ILV 17-27-001 |
| Control gear (driver) | A unit between the power supply and a light source that supplies it with its rated voltage or current; it can include dimming, power factor correction and interference suppression. An LED driver is LED control gear. | CIE ILV 17-28-048 |
| Dimmer | A device for varying the luminous flux from light sources. | CIE ILV 17-28-063 |
| Extra-low voltage (ELV) | A voltage not exceeding 50 V a.c. or 120 V ripple-free d.c., whether between conductors or to earth. | Approved Document P, 2013, Appendix A |
| Scene | A stored lighting setting that sets several circuits to chosen levels at once, such as arrival or night, recalled by one control. | Our wording; no source read |
Not defined here: unified glare rating (UGR), which is not among the terms we found in the vocabulary list, and SELV, whose definition is in BS 7671, which we did not read. A term from a Part L document is for compliance, not for naming a layer.
A one-page lighting brief
A brief is a one-page list of questions the project must answer. Put it in front of the client, the lighting designer, the M&E engineer and the workshop at the start of the design, and keep it up to date. The fields below are our arrangement; the paste-in versions that follow carry the definitions into a contract.
| Field | What to write | Why it matters |
|---|---|---|
| A. Project and space | Project, space, use, ceiling height, finishes, daylight, who occupies it and when. | Everything below depends on it. |
| B. Layers and scenes | For each space: what supplies ambient, task and accent light, and the scenes wanted (for example arrival, evening, night). | A layer you do not name does not get a circuit. |
| C. Light quality | Colour temperature range and whether it is tuneable, colour rendering target, lowest dimming level, flicker. Take figures from data sheets (see colour temperature). | Colour temperature is not colour rendering. |
| D. Decorative luminaires | Type, number, approximate size and hanging height, glass and metal, who designs it, and whether design information is prescriptive or descriptive. | Sets the responsibility for the shop drawing. |
| E. Controls and dimming | Dimming method, who supplies and commissions the controls, occupancy or key-card control (see dimming protocols). | Fix it before the fittings are ordered. |
| F. Electrical and structure | Supply, driver position and access (see LED drivers), fixing and declared weight, emergency lighting. | Heavy and electrical items cross three trades. |
| G. Compliance and documents | Part L position (see Part L and chandeliers), conformity papers, data sheets, operation and maintenance information. | Ask for the papers at the start, not at handover. |
| H. Programme and approvals | Design freeze, sample and mock-up approvals, who signs each (see shop drawings and mock-ups). | Late changes to finish or dimming cause rework. |
Specification wording
Paste into your schedule or specification and replace anything in [square brackets] with your own figures. Wording is a starting point: your specification governs.
In this brief 'ambient', 'task' and 'accent' lighting mean general lighting, local lighting and accent lighting as defined in CIE S 017:2020, International Lighting Vocabulary (terms 17-29-007, 17-29-008 and 17-29-023). 'Decorative luminaire' means a luminaire such as a sconce, pendant, table or standing lamp, and 'concealed architectural lighting' means indirect lighting integrated with architectural elements. Where a term is not defined here, [lighting designer] is to define it in writing before the schedule is issued.
Space [ ]; use [ ]; ceiling height [ ] mm. Ambient light from [ ]; task light from [ ]; accent light on [ ]. Scenes wanted: [arrival / evening / night]. Colour temperature [2700] K [fixed / tuneable]; lowest dimming level [ ] per cent; colour rendering index not less than [90], as the data sheets show. Dimming method: [ ], to be fixed before fittings are ordered.
[Interior designer] sets design intent and finish. [Lighting designer] sets the layer strategy, levels and controls. [Partner workshop] provides shop drawings, declared weight and driver details for bespoke pieces. [M&E engineer] provides the supply and controls. [Structural engineer] approves the fixing. Design information for decorative lighting is [prescriptive / descriptive], as recorded in the Responsibility Matrix.
Terms used on this page
- General lighting
- Substantially uniform lighting of an area without provision for special local requirements: the ambient layer (CIE ILV 17-29-007).
- Local lighting
- Lighting for a specific visual task, additional to and controlled separately from the general lighting: the task layer (CIE ILV 17-29-008).
- Accent lighting
- Directional lighting to emphasise a particular object or draw attention to a spot in the field of vision (CIE ILV 17-29-023).
- Decorative luminaire
- A luminaire such as a sconce, pendant, table or standing lamp, as the US DOE lighting designer roundtable report uses the term.
Standards and sources
- CIE S 017:2020 ILV: International Lighting Vocabulary, 2nd edition (e-ILV): term numbers as cited; free online.
- US DOE, Lighting Designer Roundtable on Solid-State Lighting (Apr 2008): sections 5.2.1, 5.2.2.
- Los Alamos Sustainable Design Guide, chapter 5 (NREL, 2002): ambient, task, accent in offices and laboratories.
- Approved Document L volume 2, 2021 edition incl. 2023 amendments (England), Appendix A: display lighting p. 85; specialist process lighting p. 89.
- RIBA Plan of Work 2020 Overview: stage names; Responsibility Matrix.
Questions we are asked
What is the difference between ambient, task and accent lighting?
In the CIE vocabulary, ambient corresponds to general lighting: substantially uniform lighting of an area without provision for special local requirements. Task corresponds to local lighting: lighting for a specific visual task, additional to and controlled separately from the general lighting. Accent is directional lighting to emphasise an object or draw attention to a spot.
Is a chandelier ambient or decorative?
Both, because the words answer different questions. Decorative is the fitting's role: it is seen as an object. Ambient is its usual job: it contributes to the overall level. For Part L, Approved Document L names chandeliers in its definition of specialist process lighting; what that means for the efficacy figures is set out in Part L and chandeliers.
What is the difference between decorative and architectural lighting?
A US Department of Energy roundtable report treats decorative luminaires, such as sconces, pendants, table and standing lamps, separately from concealed architectural lighting, which is indirect lighting integrated with architectural elements such as a cove. In short, you look at a decorative fitting and you look at what an architectural one lights.
Who specifies decorative lighting?
No standard we read says. The RIBA Plan of Work 2020 has a Responsibility Matrix, produced at Stage 1, that records who designs each building system and to what level. In practice the interior designer sets intent, the lighting designer the layers and levels, the M&E engineer the supply and controls, and the partner workshop the shop drawings for a bespoke piece. Write it into the matrix for your project.
What should a lighting brief contain?
The space and its use, the layers and scenes wanted, the light quality, the decorative pieces and who designs them, the controls and dimming method, the electrical and structural points, the compliance papers and the approvals. The template above gives eight fields and paste-in wording.
Is there a standard for light levels by layer?
Not one that covers every space. BS EN 12464-1 is the usual workplace source and is paywalled, and our lighting levels by space sheet shows what each source covers. Levels are for the lighting designer to set and to check at commissioning.
Download the factsheet
A two-page A4 PDF with the layers at a glance, the labelled room section and paste-in wording for the definitions, the brief and the responsibilities, to keep with your project file.