A white-light descriptor, a rendering measure and a saturated colour scene answer different questions.
A white-light appearance and the way materials render under it are separate design decisions. For a commercial façade that also uses colour, define the everyday white scene and the saturated scenes individually rather than asking one descriptor to explain them all.
What correlated colour temperature describes
Correlated colour temperature, or CCT, relates a source's chromaticity to that of a Planckian radiator and is expressed in kelvin. It is a descriptor of the source's colour appearance, not the temperature of the fitting or a measure of brightness.
CCT is used within defined chromaticity limits. It should not be assigned indiscriminately to saturated red, blue or other coloured scenes far from the Planckian locus. For those scenes, establish the required colour and its appearance on the actual material.
What colour rendering asks
Colour rendering concerns how objects' colours appear under illumination relative to a reference. The conventional general colour rendering index, often written CRI or Ra, summarises a defined assessment; it is not a complete description of every material or saturated colour.
Two white-light sources with similar CCT can have different spectral distributions and rendering characteristics. Neither the CCT label nor a channel count establishes the other properties. Ask which measurement and operating state any quoted rendering result describes.
Keep the everyday scene attached to its evidence
For a normally white entrance or façade, specify the intended appearance and relevant rendering requirements for the selected configuration. Identify whether white comes from a dedicated source, a white channel or a multichannel mix.
Then consider the occasion scenes separately. A rendering figure or photometric file for one white-light state does not establish the output, spectrum or material appearance of every colour mix. Additional channels offer mixing choices; they are not, by themselves, measured proof of superior rendering.
Review representative materials
Bring the actual stone, coating, metal or landscape material into the assessment where practical. Record the agreed engine, scene, operating level and viewing conditions. A screen comparison is useful for communicating intent, but is not a spectral measurement or an installed material test.
Where information is unavailable, identify the open question rather than substituting a figure from a neighbouring model. Keep the selected optic and mounting in the review: distribution and viewing conditions also affect the architectural result.
Apply the distinctions to selection
Use the RGB versus RGBW guide to understand the white channel and the white-and-colour façade guide to frame the operating brief. Explore actual configurations through the colour selection.
For the technical record, keep the claimed metric, source document, revision and operating state together. The submittal templates provide blank fields rather than pre-approved product values.
Definitions and scope
The CIE definition of correlated colour temperature explains its chromaticity basis and applicability. The CIE lighting vocabulary provides the wider terminology for colour and rendering.
This guide explains how to ask the specification questions. It supplies no unverified CRI, CCT tolerance, spectral or colour-performance value for any Modaluce fitting. Bring the intended white scene and materials to a technical discussion.
Compare white scenes on representative material
Keep CCT, colour-rendering descriptors and the actual spectrum distinct. None alone describes every architectural colour task. Record which white state, source and material the evidence represents.
For a hypothetical pale-stone entrance, compare the planned ordinary-night white under consistent geometry and viewpoints before reviewing the occasion colours separately. Do not transfer a white-state rendering value to a saturated scene.
The companion example leaves observations and acceptance open. It is a method for a future review, not a claim of measured CRI, spectral superiority or installed colour accuracy.
Use the white-scene material review Excel workbook for the editable record, instructions, field guidance and fictional worked examples. The PDF companion provides a printable guide. All worked examples are fictional and are not project records, product-test results or accepted specifications.
