Lighting Glossary

Ambient Light – General illumination that comes from all directions in a space, without a visible source.

Brightness – How the eye perceives light; affects pupil size and visual comfort.

Colour Appearance – The perceived colour emitted by a light source, described as warm, intermediate, cool, or cold.

Colour Temperature (CCT) – Measured in Kelvin (K); indicates the “warmth” or “coolness” of a light source. Common ranges:

• 2200K – Very Warm white
• 2700K – Warm White
• 3000K – White
• 4000K – Cool White
• 6000K – Daylight

RGB / RGBW / RGBWW – Red, Green, Blue and White. This is a multiple channel LED strip that allows the uses to combine primary colour LEDs in a mixture of output to create different colours of the spectrum.
Colour Rendering (CRI) – Ability of a light source to reveal the true colours of objects. Measured by the Colour Rendering Index (Ra), from 0–100. LEDs are typically Ra 80–85, though Ra 95 is available at a premium.

Contrast – Subjective perception of brightness differences between areas viewed simultaneously.

Glare (UGR) – Discomfort or impaired vision caused by excessive brightness or contrast in the field of view.

Scallop – A light effect created by distribution when a luminaire is close to a surface, often used decoratively.

Wall Wash – Even light distribution designed to illuminate a wall; a signature element in many Moth Lighting designs.

Spot – Narrow beam used to highlight a specific object.

Flood – Wide beam providing broad, even illumination.

IoT (Internet of Things) – Devices connected to the internet for monitoring or control.

Illuminance – Amount of light falling on a surface per unit area, measured in lux. Varies from:

• 0.2 lux – Moonlight
• 500 lux – Office lighting
• 100,000 lux – Bright sunlight

Luminance – Measured brightness of a luminous or illuminated surface, in cd/m².

Lux – SI unit of illuminance; 1 lux = 1 lumen per square metre.

Lumen – Total visible light emitted by a source (luminous flux).

Luminous Efficacy – Efficiency of a light source: luminous flux produced per watt of power consumed (lm/W). Key for Part L compliance.

LOR (Light Output Ratio) – Percentage of light emitted by a luminaire compared to its total source output. Designers must verify for compliance.

Luminous Flux – Total light emitted by a source per unit time, measured in lumens.

Luminous Intensity – Amount of light emitted in a specific direction, measured in cd or lm.

Task Lighting – Localized lighting to increase illuminance for reading, desk work, or theatre tasks.

Uniformity – Ratio of minimum illuminance to average illuminance over a specific area.

Switching – Type of control powering a lighting circuit.

Dimming – Adjustable light output from 0% to 100%.

Circuit – Group of lights connected via one cable; may be separate from other circuits.

Channel – Circuit linked to a breaker or control system.

Chromaticity – Degree of deviation of an LED’s colour; defined using MacAdam ellipses (SDCM) per CIE 1964. Scale: 0–10.

CTT (Correlated Colour Temperature) – Measurement of colour tone preserved from warm white (≤3000K) to cool white (≥4000K).

MacAdam Steps – Tolerance of colour variation (SDCM):

• 1–3 Step: Minimal variation; suitable for museums, galleries, offices, retail, healthcare.
• 4 Step: Common in fluorescent lighting.
• 5 Step: Acceptable outdoors; noticeable only on bright surfaces.

ECA (Enhanced Capital Allowance) – Government scheme supporting energy-efficient lighting investments.