Specification · Colour
CCT and CRI for commercial spaces: offices, retail, healthcare and schools
Colour is where mixed-manufacturer packages show their seams. Pick it deliberately, write it completely, and check it on every alternate.
Short answer
Most commercial interiors in North America use 3000K to 4000K: around 3500K–4000K for offices, schools and healthcare work areas, 3000K–3500K for hospitality and many retail spaces. Specify CRI 80 minimum for general areas and CRI 90+ where colour matters (retail, healthcare exam areas, hospitality, art), plus R9 (saturated red) where skin tones and food matter. On linear runs, also specify colour consistency (for example, 3-step MacAdam) and keep one CCT per space across all manufacturers.
Key takeaways
- CCT sets warm or cool; CRI and R9 set how true colours look.
- 3000–4000K covers most commercial interiors; choose one per space.
- CRI 90+ with a stated R9 where colour quality matters.
- Colour consistency (MacAdam steps) matters most on long continuous linear runs.
- Check CCT, CRI, R9 and consistency on every alternate.
Three numbers, three different questions
| Metric | Question it answers | Typical spec |
|---|---|---|
| CCT (kelvin) | Does the light look warm or cool? | 3000K, 3500K, 4000K |
| CRI (Ra) | How accurately are colours rendered, on average? | 80 min, 90 min |
| R9 | How well are saturated reds rendered? | A stated minimum where colour matters |
| Colour consistency | Do fixtures of the same CCT match each other? | 2- or 3-step MacAdam |
Common choices by application
| Space | CCT | CRI | Notes |
|---|---|---|---|
| Open office | 3500–4000K | 80–90 | One CCT across the floor |
| Classroom | 3500–4000K | 80–90 | Pair with low-glare optics |
| Healthcare work and exam | 3500–4000K | 90+ with R9 | Skin tones matter |
| Retail sales floor | 3000–4000K | 90+ | Brand-dependent; merchandise colour |
| Grocery fresh areas | Product-specific | 90+ with R9 | Food appearance |
| Hospitality / dining | 2700–3000K | 90+ | Warm, dimmable |
| Back of house, storage | 4000K | 80 | Function first |
These are common practice, not requirements. The design intent of each project governs.
Why consistency matters more on linear
A row of linear fixtures or a long continuous run puts sources side by side, so small colour differences become visible as bands. Specify colour consistency (MacAdam steps) for linear runs, and avoid mixing manufacturers within one visible run.
Mixed-manufacturer packages
Most commercial packages combine products from several manufacturers: linear, downlights, wall washers, decorative. Their “4000K” may not look the same. To keep a space consistent:
- use one CCT per space across all types;
- specify the same CRI class for types seen together;
- ask for colour consistency data on each product;
- check CCT, CRI, R9 and consistency on every alternate (see or-equal substitutions);
- where it matters, ask for a sample of each product to compare side by side.
Beyond CRI
CRI averages eight pastel samples and can hide weak saturated colours. The newer IES TM-30 method gives a fidelity index (Rf) and a gamut index (Rg) and is increasingly used on demanding projects. If a spec lists TM-30 values, compare them as given.
How SuppLux helps
Send the fixture schedule and SuppLux’s AI matches every line to verified products, with the best alternative shown first, then turns the matched set into a quote and submittal package. See how to specify custom linear lighting or send a schedule.
Frequently asked questions
Is 4000K or 3500K better for offices?
Both are common. 4000K reads crisp and neutral and is typical in offices and schools; 3500K is a little warmer and often chosen for a softer, hospitality-like workplace. Consistency within the space matters more than the exact choice.
Is CRI 90 worth it?
Where colour matters (retail merchandise, food, healthcare, hospitality, art), yes. CRI 90 products typically use a little more power for the same light output. In back-of-house areas CRI 80 is usually adequate.
What is R9 and why does it matter?
R9 is the rendering score for a saturated red sample. It is not part of the general CRI (Ra) average, so a CRI 80 or even 90 source can still have a weak R9. It affects skin tones, food and wood.
What does 3-step MacAdam mean?
It describes how closely sources of the same nominal CCT match each other in colour. A smaller number means tighter matching; it is most visible on long continuous runs and in rows of fixtures.
References
Keep reading
- Guide · Specification How to specify custom linear lighting A step-by-step method for specifying custom linear lighting on commercial projects, covering application targets, mounting, optics, output, colour, run layout, voltage, drivers, controls and compliance, with a complete fixture schedule example. →
- Applications · Glare UGR below 19: specifying low-glare linear lighting for offices and classrooms What the Unified Glare Rating (UGR) measures, why UGR below 19 is the common target for offices and classrooms, why it is a property of the installation rather than the fixture, and how to specify and compare low-glare linear lighting. →
- Guide · Alternates How to get a lighting "or equal" substitution approved How to prepare a lighting substitution or value-engineered alternate that design teams approve, covering what to compare (photometrics, colour, electrical, dimensions, compliance), how to present it, and when not to substitute. →
- Custom linear lighting · Continuous runs Continuous linear lighting runs How continuous linear LED runs are built from joined sections, with L, T and X corners, feed points and drivers sized to the load. Custom continuous runs supplied across Canada with run layouts. →