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What the lux?

A short glossary of terms and technicals to help you decipher all that cryptic jargon

Lighting Measurements:

  • Lux (lx) - A measure of the amount of light that falls on a surface

  • Lumens (lm) - A measure of the total amount light emitted by a light source

  • Watts (W)- A measure of the amount of energy used by a light source to produce light

  • Kelvin (K)- A unit of measurement used to describe the color temperature of a light source

  • Color Rendering Index (CRI) - A measure of a light source's ability to accurately reproduce colors compared to natural sunlight

  • Efficacy (lm/W) - A measure of the amount of light emitted by a light source for every watt (W) of power used

Types of Lighting:

  • Ambient Lighting - General lighting used to provide overall illumination in a space

  • Task Lighting - Lighting designed to provide focused illumination for specific tasks, such as reading or cooking

  • Accent Lighting - Lighting used to highlight or accentuate a particular object or area in a space

  • Downlight - A type of light fixture that directs light downward

  • Uplight - A type of light fixture that directs light upwards

  • Backlit - Illuminating something from behind creating depth and drama

  • Indirect Lighting - reflecting light off a surface to light a space or subject rather than shining light directly onto it reducing glare and diffusing the light

  • Pendant Light - A type of light fixture that hangs from the ceiling and typically has a single light source

  • Chandelier - A decorative ceiling-mounted light fixture with multiple arms or branches for holding bulbs or candles

  • Sconce - A wall-mounted light fixture that provides mostly decorative lighting

  • Track Lighting - A type of lighting system where multiple light fixtures are attached to a track, which can be adjusted to direct light in different directions

  • Strip Lighting - using LED strip in an aluminium extrusion to create a continuous strip of light often used under shelves, over benches, and mounted high along walls to uplight a ceiling

  • Surface Mount - light fittings that are mounted onto a surface without being recessed or suspended

  • Flush Mount/Recessed - light fittings that are mounted flush to a surface, usually by recessing into the surface

  • Inground - a light fitting, usually exterior, that is recessed into the ground or floor to provide uplighting

  • Treadlight - a small wall or step mounted light fitting that sits just above the floor or path to offer enough illumination to safely navigate at night

Common Acronyms:

  • LED - Light Emitting Diode, a type of lighting technology that uses less energy and lasts longer than traditional bulbs

  • RGB - Red Green Blue, used to refer to LEDs that can change colour

  • RGBW - Red Green Blue White, colour changing LEDs with a dedicated white LED

  • BC - Bayonet Cap, the base of a light bulb with two prongs that is inserted with a push and a twist (also referred to as B22)

  • ES - Edison Screw, the base of a light bulb with a thread that is inserted by screwing (also referred to as E27)

  • CFL - Compact Fluorescent Lamp, often called 'tornado' or 'spiral' lamps, more efficient than incandescent but made obsolete by LED

  • IC-F (IC/IC-4)- Indicates that the fitting (usually a recessed downlight) can be covered by insulation

  • CA90 - Indicates that the fitting (usually a recessed downlight) can have insulation abut the side of the fitting but not cover it

  • Non-IC - the fitting cannot be covered or abutted with insulation (these are only allowed in commercial buildings in NZ)

  • SSL - Solid State Lighting, another term for LED

  • CTC - Close To Ceiling or surface mounted ceiling lights

  • IP - Ingress Protection, accompanied by two numbers to indicate the level of protection from water and dust, etc.

  • TCO - Total Cost of Ownership, how much a light fitting will cost you

Common Terms:

  • Luminaire - another name for a light fitting

  • Lamp - another name for a light bulb

  • Incandescent - traditional light bulbs that use a tungsten filament that glows white hot to produce light (Fun fact: these are less than 5% efficient with more than 95% of the energy being used released as heat)

  • Fluorescent - a form of lighting that uses mercury vapor in a tube to produce light through fluorescence, much more efficient than incandescent bulbs but being replaced with LED

  • Halogen - a form of incandescent lighting that uses halogen gas inside the bulb to increase the lifespan and allow for smaller form factors, higher operating temperatures, and greater efficiency than standard incandescent bulbs

  • Driver - the power supply for an LED light source, can output a constant voltage or a constant current depending on the requirements of the LED

  • Transformer - the power supply for an extra low voltage incandescent lamp such as a 12 volt halogen

  • Ballast - the power supply for a fluorescent light source

  • Beam Angle - the angel with which light emanates from a light source, expressed in degrees, eg: 15°, 30°, 60°, 180° (Fun fact: beam angle is measured from the center of the light cone to the point where the intensity of the light has decreased by 50%)

  • Ceiling Rose - the part of a pendant or ceiling light that mounts to the ceiling, also acting as a junction box for the wiring connection

  • Negative Detail - a recess or lip that hides the light source, can be built into the buildings structure or applied after with the use of a pelmet or extrusion, used extensively with LED strip lighting

  • Diffuser - a material that light is shone through to soften the light and increase it's spread

  • Retrofit - the replacement of older fittings with newer

  • Zero Clearance - fittings that have been tested and proven to be safe to install against flammable building elements such as beams and other timber elements

  • Glare - excessive light that acts to cause visual discomfort and obscure vision

  • Flicker - the phenomenon where the flickering of an LED light source is of a low enough frequency that it is visible to the naked eye, usual appearing as lines on a camera screen when viewing low frequency LED lights

Less Common Terms:

  • Hue - the colour of light being displayed

  • Saturation - the intensity of the colour of light being displayed (from pure to washed out)

  • Brightness - the overall intensity of the light (the colour does not change as the brightness changes)

  • MacAdam Steps - indicates the consistency of light output of the LEDs across a range of fittings, the lower the number of steps the more closely each fitting will be in brightness and colour (2-3 MacAdam Steps is imperceptible to the human eye, 5 or more and you will likely notice the difference if two fittings are side by side)

  • Binning - the testing of LEDs during the production process to group similar light outputs and colour temperatures to ensure greater consistency in final products

  • Dichroic - a surface coating on the reflector of a halogen lamp that projects the visible light spectrums forward while dispersing the non visible infrared and ultra-violet radiation

  • Heat Sink - a passive piece of material, usually a metal such as copper or aluminium, that is used to draw heat away from heat generating components such as LEDs and other electronics

  • DALI/DSI/DMX - protocols for controlling individual light fittings on the same circuit by giving them all their own addresses illuminating the need to cable them all seperately

  • Photopic Lumens - the light registered by the cones of the human eye, active in bright conditions

  • Scotopic Lumens - the light registered by the rods of the human eye, active in low light conditions

  • Lumen Maintenance - the ability of an LED light source to maintain it's light output over time, often expressed as L70, L80, etc. indicating that after the advertised lifespan the light output should be 70%/80%/etc. of the original output

  • Specular Reflection - the reflection of intense light on a shiny reflective surface, often appears as a bright spot on shiny surface

  • Troffer - a square or rectangular light fitting designed to be installed in a standard suspended ceiling

  • Finial - in lighting the finial is the decorative piece found at the bottom of a chandelier or pendant, usually a small sculptural knob of crystal or metal

  • Gallery - a metal skirt that attaches a glass or metal shade to a standard lamp holder


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