CCT and CRI answer different questions
Colour temperature describes the appearance of white light. CRI or Ra describes how well colours are rendered compared with a reference source. A 4,000 K fitting can have poor colour rendering, and a warm 3,000 K fitting can have good colour rendering. The two values should be recorded separately.
Choose the colour temperature table when the question is warm, neutral or cool appearance. Choose the CRI ratings table when the question is colour quality for food, timber, fabric, artwork, skin tone, display material or finish selection.
| Question | Better note | Page |
|---|---|---|
| Should the room feel warm, neutral or cool? | CCT in kelvin, adjacent zones and dimming state. | Colour temperature table |
| Will colours look natural enough? | CRI/Ra and the surface being judged. | CRI ratings table |
| How should both values be kept together? | CCT, CRI/Ra, task surface and comparison boundary. | Colour quality notes table |
| Does a cooler lamp make the room brighter? | No; check lumens, lux and task plane. | Room lighting calculator |
| Why do two fittings look different? | CCT, CRI/Ra, manufacturer marking and replacement history. | Luminaire markings table |
Match the search question to the note
People often search CCT and CRI together because the visual problem feels like one issue: a room looks dull, food looks flat, a mirror looks unkind, or two fittings look mismatched. The note should split the cause before a lamp or fitting line is changed.
| Search phrasing | Note to open first | Boundary to keep |
|---|---|---|
| Warm white or cool white for a room | CCT, room use, adjacent zone and scene state. | Does not decide colour rendering or lux. |
| Best CRI for kitchen, mirror or retail display | CRI/Ra, viewed surface and colour-sensitive task. | Does not decide white appearance. |
| Why does this fitting look different | CCT setting, CRI/Ra marking and replacement history. | Wattage alone does not explain appearance. |
| Does high CRI make lights brighter | Lux, lumens and task-plane reading kept distinct. | Colour rendering is not output. |
That split is useful for Australian homes, hospitality venues, retail displays and small workplaces because the same luminaire schedule may need CCT, CRI/Ra, output, watts and beam notes on one line while each value still answers a different question.
Keep the surface in the colour note
CCT and CRI/Ra are more useful when they are attached to the surface being judged. A bare "high CRI" note does not say whether the issue was food colour, timber finish, mirror view, fabric matching, display material or printed marks. A bare CCT note does not say whether the adjacent zone, daylight mix or dimming scene changed the appearance.
| Surface or view | CCT field | CRI/Ra field |
|---|---|---|
| Kitchen bench | White-light appearance at the bench scene. | Food, stone, tile or timber colour where relevant. |
| Bathroom mirror | CCT at face plane and adjacent room. | Skin tone and fabric cue, with glare kept distinct. |
| Retail shelf | Shelf or display-face CCT, including daylight mix. | Merchandise colour, packaging and finish being judged. |
| Hospitality table | Dining scene CCT and dimmed state. | Food, timber, fabric, glass or menu colour where relevant. |
| Workshop or inspection bench | Task-light CCT and local group. | Marking, material colour or sample comparison. |
The note should name the actual face or surface. A line such as "CCT and CRI/Ra recorded for west display shelf under evening scene" is stronger than a general note that the room has neutral white, high rendering light.
Colour temperature is appearance
CCT is recorded in kelvin. Lower values look warmer or more amber. Higher values look cooler or bluer. The choice affects visual character, task feel and how finishes appear, but it does not prove brightness or colour accuracy.
| CCT decision | Strong use | Boundary |
|---|---|---|
| Warm white | Lounges, bedrooms, dining and relaxed evening scenes. | May still need higher CRI/Ra for timber, fabric or artwork. |
| Neutral white | Kitchens, bathrooms, laundries, desks and mixed task rooms. | Does not automatically improve colour rendering. |
| Cool white | Garages, workshops, plant rooms, storage and inspection tasks. | Can feel harsh if output, glare and surface contrast are poor. |
| Tunable or selectable CCT | Separate day, task and evening scenes. | Note the actual setting used for each reading or comparison. |
The warm white vs cool white comparison is the better companion when the decision is room appearance, adjacent zones or task feel.
CRI/Ra is colour rendering
CRI/Ra belongs with surfaces where colour judgement matters. It is especially relevant for kitchens, mirrors, wardrobes, retail displays, hospitality finishes, artwork, timber, fabric and inspection tasks. A poor rendering source can make colours look flat or shifted even when the lux level is adequate.
| Surface or task | Why CRI/Ra matters | Companion note |
|---|---|---|
| Food preparation | Food colour and freshness cues can shift. | CCT, bench plane and shadow check. |
| Bathroom mirror | Skin tones can look wrong under weak rendering. | Face plane, glare and IP/exposure boundary where relevant. |
| Wardrobe or fabric | Similar colours can become harder to separate. | Vertical face, control state and daylight condition. |
| Retail display or artwork | Display and finish appearance is part of the task. | Beam aim, surface finish and measured point. |
| Workshop inspection | Markings and material colours may need clearer rendering. | Task lux, local shadows and glare. |
CRI/Ra is still a simplified mark. It does not replace seeing the actual surface under the actual fitting, but it is a useful schedule field and should not be collapsed into CCT.
Do not use one value to repair the other
Changing from warm white to cool white may make a space feel cleaner, but it will not repair low CRI/Ra. Choosing a high-CRI fitting may improve colour judgement, but it will not change the white appearance unless the CCT also changes. Raising output may improve task visibility, but it can make glare or reflections worse.
| Symptom | Do not assume | Check instead |
|---|---|---|
| Room feels dull | The CCT is too warm. | Lumens, lux, surface reflectance and task plane. |
| Colours look wrong | The room needs cooler white. | CRI/Ra, surface finish and daylight condition. |
| Fittings look mismatched | They have different wattage. | CCT setting, CRI/Ra marking and replacement note. |
| Bench looks harsh | CRI is too high. | Output, beam spread, glossy surface and glare path. |
Note both on the schedule
A useful luminaire line separates output, input power, CCT and CRI/Ra. The luminaire markings table keeps those fields apart so the schedule can be checked if a replacement fitting is proposed.
The colour quality notes table keeps white appearance, CRI/Ra, task context and comparison boundaries in one schedule-friendly note.
| Schedule field | What it means | What it does not mean |
|---|---|---|
| lm | Light output. | Brightness at the task plane without area, UF and MF. |
| W | Input power. | Light output or colour quality. |
| K or CCT | White-light appearance. | Colour rendering quality. |
| CRI or Ra | Colour rendering cue. | Brightness, glare control or CCT. |
| Beam angle | Spread from the fitting. | Whether the layout is comfortable by itself. |
When the surface is important, note the actual surface as well as the number. "CRI/Ra recorded for timber dining table" is more useful than a loose "high CRI" note with no assessed surface.
Split colour from output, load and dimming
Lighting schedules often place colour, output and electrical fields on the same line. That is fine as long as each field keeps its own meaning. A change from 3,000 K to 4,000 K is an appearance change. A change from 800 lm to 1,000 lm is an output change. A change from 10 W to 7 W is an input-load change. A change in driver or scene level can alter what the user sees, but it is still a control or equipment field, not a CRI/Ra field.
| Mixed issue | Keep with CCT/CRI | Send elsewhere |
|---|---|---|
| New lamp looks brighter and cooler. | CCT and surface note. | Lumens, lux and task-plane reading. |
| Display colours improved after retrofit. | CRI/Ra, surface and comparison condition. | Beam aim, measured lux and glare if the view also changed. |
| Dimming makes the scene warmer. | CCT setting or dim-to-warm behaviour if known. | Dimming range, driver behaviour and active scene note. |
| Lower wattage fitting looks different. | CCT and CRI/Ra markings. | Connected load, annual kWh and luminous efficacy. |
| Two adjacent zones do not match. | CCT setting, CRI/Ra and replacement history for both zones. | Control grouping and scene-state notes. |
The luminous efficacy calculator can compare lumens per watt, but it does not describe white appearance or colour rendering. The dimming range calculator can note a dimming percentage, but it does not decide whether a colour scene suits the surface.
When both values change in a retrofit
An LED replacement can change CCT and CRI/Ra at the same time as output, beam and dimming behaviour. A before-and-after note should name each changed field rather than saying the new light is simply better or worse.
| Changed field | What to write | Why it matters |
|---|---|---|
| CCT changed | Old and proposed kelvin values, or selectable setting used. | Explains white appearance and adjacent-zone mismatch. |
| CRI/Ra changed | Old and proposed rendering mark where known. | Explains surface colour judgement. |
| Output changed | Lumens and measured lux note if available. | Separates brightness from colour quality. |
| Control changed | Scene, dimmed level or driver behaviour. | A colour comparison can look different at another scene. |
When selectable CCT is involved
Selectable or tunable white fittings need the setting written beside each note. A schedule that says "selectable CCT" but does not state the commissioned setting leaves the colour note open to drift. A site note can stay compact if it notes the scene, setting and surface together.
| Situation | Better note | Boundary |
|---|---|---|
| Switchable CCT downlight | Selected kelvin setting, room zone and date checked. | Does not prove CRI/Ra, glare or lux. |
| Tunable-white scene | Scene name, CCT setting, dimming state and surface being judged. | Another scene can have a different appearance. |
| Replacement group | Old and new CCT/CRI markings plus room or display zone. | Wattage and fitting shape still need their own note. |
| Mixed old and new fittings | Adjacent-zone CCT and CRI/Ra comparison. | Does not decide whether output or beam spread matches. |
| Daylight-mixed space | CCT/CRI for electric light plus daylight condition note. | Daylight colour changes through the day. |
For before-and-after comparisons, keep the colour line beside the lux meter before and after notes only when the same scene, surface and daylight condition are visible. If a colour setting and a lighting level both changed, write both changes rather than making the lux difference carry the colour explanation.
Next-page checklist
The comparison page should decide which supporting page to open next. It should not turn every colour question into a single all-purpose page.
| Need | Supporting page | What stays out |
|---|---|---|
| White-light appearance | Colour temperature table | CRI/Ra, output, glare and energy. |
| Colour rendering cue | CRI ratings table | CCT, lux, beam spread and load. |
| Schedule field separation | Luminaire markings table | Design acceptance or substitution approval. |
| Combined colour note | Colour quality notes table | Universal appearance guarantee. |
| Room appearance choice | Warm white vs cool white | Colour rendering and measured-light proof. |