Light Quality & Visual Comfort Selector
Choose suitable colour temperature, colour-rendering, consistency, flicker and glare-control requirements for your space. Answer a few practical questions to create a clear lighting-quality brief or compare declared product specifications.
Selection recommendation
Your light-quality requirement
UGR is an installed-project result. A luminaire statement or standard table does not verify the actual room, layout, reflectances, observer positions or viewing directions.
Requirement brief
| Specification | Recommendation | Entered value | Status |
|---|
Verification checklist
What this selector assesses
Each metric describes a different part of lighting quality.
CCT
The appearance of white light, expressed in kelvin.
CRI, R9 and TM-30
Different measures and indicators of how colours are rendered.
SDCM
Initial colour consistency between nominally matching light sources.
PstLM and SVM
Metrics used to assess flicker and stroboscopic visibility.
UGR
Discomfort glare for an installed arrangement under defined conditions.
Important distinction
These metrics are related, but they are not interchangeable or one combined quality score.
Light quality and visual comfort questions
What is the difference between CRI and colour temperature?
CCT describes whether white light appears warmer or cooler. CRI describes aspects of how object colours are rendered compared with a reference light.
Is CRI 90 always better than CRI 80?
CRI 90 is useful where colour appearance matters, but the correct specification depends on the task, other colour metrics, efficiency and the complete lighting design.
What does R9 mean?
R9 is a special CRI index for a saturated red test colour. It is useful as a screening value where reds, food, skin, wood or artwork matter, but it does not describe every colour.
What does SDCM mean?
SDCM expresses chromaticity consistency. Lower declared values indicate tighter initial colour matching between nominally similar light sources.
What are PstLM and SVM?
PstLM is a short-term flicker metric and SVM evaluates stroboscopic visibility. Check declared values under the relevant operating and dimming conditions.
Can UGR be calculated from a luminaire datasheet?
A datasheet or UGR table may support a calculation, but actual project UGR also depends on room geometry, reflectances, luminaire positions, photometry and viewing direction.
Is UGR ≤19 required for every room?
No. It is commonly specified for regular office work, while the applicable target depends on the activity, project and governing workplace requirements.
Does a diffuser guarantee low glare?
No. Diffusion can reduce visible brightness contrasts, but glare also depends on luminance, source area, shielding, position, background and viewing direction.
Can two lights with the same CCT look different?
Yes. Chromaticity tolerance, spectrum, colour consistency, optics, surfaces and surrounding light can all influence their appearance.
Why does the colour preview differ from the real light?
A screen emits its own limited spectrum and is affected by calibration and ambient light, so on-screen colour cues are illustrative only.
Selection recommendation
Your light-quality requirement
UGR is an installed-project result. A luminaire statement or standard table does not verify the actual room, layout, reflectances, observer positions or viewing directions.
Requirement brief
| Specification | Recommendation | Entered value | Status |
|---|
Verification checklist
What this selector assesses
Each metric describes a different part of lighting quality.
CCT
The appearance of white light, expressed in kelvin.
CRI, R9 and TM-30
Different measures and indicators of how colours are rendered.
SDCM
Initial colour consistency between nominally matching light sources.
PstLM and SVM
Metrics used to assess flicker and stroboscopic visibility.
UGR
Discomfort glare for an installed arrangement under defined conditions.
Important distinction
These metrics are related, but they are not interchangeable or one combined quality score.
Light quality and visual comfort questions
What is the difference between CRI and colour temperature?
CCT describes whether white light appears warmer or cooler. CRI describes aspects of how object colours are rendered compared with a reference light.
Is CRI 90 always better than CRI 80?
CRI 90 is useful where colour appearance matters, but the correct specification depends on the task, other colour metrics, efficiency and the complete lighting design.
What does R9 mean?
R9 is a special CRI index for a saturated red test colour. It is useful as a screening value where reds, food, skin, wood or artwork matter, but it does not describe every colour.
What does SDCM mean?
SDCM expresses chromaticity consistency. Lower declared values indicate tighter initial colour matching between nominally similar light sources.
What are PstLM and SVM?
PstLM is a short-term flicker metric and SVM evaluates stroboscopic visibility. Check declared values under the relevant operating and dimming conditions.
Can UGR be calculated from a luminaire datasheet?
A datasheet or UGR table may support a calculation, but actual project UGR also depends on room geometry, reflectances, luminaire positions, photometry and viewing direction.
Is UGR ≤19 required for every room?
No. It is commonly specified for regular office work, while the applicable target depends on the activity, project and governing workplace requirements.
Does a diffuser guarantee low glare?
No. Diffusion can reduce visible brightness contrasts, but glare also depends on luminance, source area, shielding, position, background and viewing direction.
Can two lights with the same CCT look different?
Yes. Chromaticity tolerance, spectrum, colour consistency, optics, surfaces and surrounding light can all influence their appearance.
Why does the colour preview differ from the real light?
A screen emits its own limited spectrum and is affected by calibration and ambient light, so on-screen colour cues are illustrative only.