Useful Lighting Terms

Accent Lighting

Lighting that focuses its output in a narrow beam, drawing attention to specific decorative features or objects, making them stand out from their surroundings. Accent lighting is also useful in gallery or high-end retail applications, where it can be used to draw attention to specific pieces, or products to provide visual hierarchy.

Ambient Light

Light which emanates in all directions to provide a blanket illumination without emphasise on any one object. This can be provided by a glowing light source such as a large lamp shade, daylight or other large flat light sources.

Amp (ampere)

Measurement unit for the flow of electric current. In lighting installations, wiring and protections are calculated based on the amperes drawn by the lighting circuits, as well as their rated voltage.

Angle of Light

Angle between the orientation of a light source and the viewing direction. For example, the angle of light is 0° when looking at a downlight directly from below and increases progressively as the viewer steps away from it.

The term is commonly used in theatrical lighting, to describe the angle between the stage lighting direction and the viewer’s line of sight.

Architectural Lighting

Architectural lighting is the essential lighting which illuminates a building structure and is integral to the design and construction of the building. Typically, this is simple in both form and function.

Beam Angle

Also known as beam spread, the beam angle is a value that describes the downward light cone emitted by a lighting fixture with a reflector. The beam angle is measured between the downward direction, where the lamp provides maximum lighting intensity, and the direction in which intensity drops to 50%. In other words, a lamp with a large beam angle spreads light into a wider cone.

Candela (cd)

The measure of directional light – Unit of luminous intensity of a light source in a specific direction. Also called candle.Technically, the radiation intensity in a perpendicular direction of a surface of 1/600000 square metre of a black body at the temperature of solidification platinum under a pressure of 101,325 newtons per square metre.

Colour Temperature

A standard of measuring the characteristics of light, measured in degrees Kelvin.Lower numbers indicate a warmer colour temperature (more red)Higher number indicate a cooler colour temperature (more blue)

Cool White

White light that is characterized by a cooler or blue colour tone. The term is generally used for lighting with a correlated colour temperature (CCT) of around 4000-6500K.

 CRI – Colour rendering Index

The measurement from 0 to 100 percent indicating how accurate a light source is at rendering colour when compared to a reference light source. The higher the CRI, the better the colour rendering ability. Light sources with a CRI of 95+ are considered good at colour rendering

DALI

Acronym for Digitally Addressable Lighting Interface, a communication protocol for lighting automation.

Diffused Light

Light produced by an extended surface, either directly or through reflection. Diffused light provides a uniform and soft distribution that minimizes shadows.

Dimmable

Adjective used to describe a lamp or fixture whose lighting output can be modulated (reduced/increased) with a dimmer.

Dimmer

A device that regulates the lighting output of a lamp by controlling the power supplied. Dimmers can be used to make indoor environments more customisable and personal and are also useful to save energy. It is important to note that not all lamps are compatible with dimmers, and incompatible types may cause damage.

Dimmer switches

Also referred to as light transformers are electrical devices that are used to change the voltage of a circuit to make the light dimmer or brighter.

Downlight

A compact lighting fixture that directs its output downward, hence its name. Downlights can be recessed, surface-mounted or suspended as a pendant.

Decorative Lighting

Decorative wall lights, chandeliers, table/desk lamps, floor standard lamps.

Driver

A piece of electronic equipment that transforms an alternating mains supply voltage into either a lower constant voltage (CV) or direct current (DC) that is appropriate for LED lighting. Some LED products have a built-in driver, while others require one to be connected externally.

Flood

A broad beam of light, less directional and intense than a spot.

Footcandle (fc or ftc)

Unit of light intensity, measured in lumens per square foot. The brightness of one candle at a distance of one foot. Approximately 10.7639 lux.

Halogen

Type of lamp in which a tungsten filament is sealed in a clear capsule filled with a halogen gas.

Incandescent

Incandescent lamps produce heat by heating a wire filament sealed within a glass bulb filled with argon gas until it glows. The glow is caused by the filament’s resistance to the current and is called incandescence.

Incident Light

Light seen directly from a light source (lamp, sun, etc).

Infrared Light

A type of electromagnetic radiation, invisible to the human eye (i.e., beyond the visible spectrum) with a wavelength of 700 to 1050 nanometres.Infrared emits a radiant heat which like ultraviolet light is particularly damaging to delicate pigments and natural materials.

Fortunately, our LEDs, do not emit this section of the light spectrum.

Kelvin

The measurement of the warmth/tone of light. Lower values are towards the red end of the spectrum and higher values are towards the blue end of the colour spectrum

Layering Light

A lighting design approach where several types of lighting are combined to achieve a specific ambience or mood. Layers can include ambient, accent lighting, task lighting, decorative lighting

LED

Acronym for light-emitting diode, a solid-state component that emits light when connected to electric current. LED lighting represents the state-of-the-art in the industry, outclassing most other types of lighting in terms of energy efficiency, design flexibility and colour of light available.

Lens

Lamp or luminaire component that has the goal of focusing the lighting output so that the desired light distribution pattern is achieved.

Light Scallops

An effect created from a spot light or down light which is located to close to a wall without adequate light dispersion. Typically, this is an undesirable effect.

Linear Lighting

Multiple LEDs (light-emitting diodes) aligned in a single linear strip and used for creating uninterrupted lines of lighting. These can be either directional or dispersed dependent on either the use of a lens or a diffuser respectively.

Louver

A translucent or opaque screen that blocks direct visibility of a light source and eliminates glare.

Low Voltage Track

a track that functions at a low voltage supply using a step-down transformer.

Lumen (lm)

Unit of light flow or luminous flux. The output of artificial lights can be measured in lumens. The amount of light a light source/bulb emits – brightness.

Luminaire

A complete and functional lighting fixture. A luminaire includes the lamp, internal wiring, reflectors, lens and any additional components required to deliver light. This can also include the driver/transformer

Luminance

The brightness of an object or surface, as perceived by human eyesight from a specific direction. Luminance is measured in candelas per square meter (cd/m2). It is important to note than luminance changes depending on the viewing angle, and high luminance values are a direct cause of glare.

Lux

The amount of light that hits what a light source is illuminating. This is the most important measurement in terms of artwork and is essential for pigment and material conservation 

Lux (lx)

Unit of illumination equal to one lumen per square metre. The metric equivalent of foot-candles (one lux equals 0.0929 footcandles). Also called metre-candle.

Lux hours

Lux hours is the number of hours that an object is exposed to an amount of light (measured in lux) and summed over the course of a year.

There are maximum recommended light levels for particular objects e.g. oils, works on paper, perishable objects, fabrics, natural materials, delicate pigments – see diagram.

Metal Halide (MH)

A subtype of HID (high intensity discharge) lamp that produces its lighting output by stimulating vaporized metal-halide compounds, hence its name. Like old mercury vapour lamps, MH lamps are commonly used in outdoor and industrial setting due to their high output, lamp life and energy efficiency.

Ceramic metal halide is a subtype of MH lamp, where the arc tube is made from a ceramic material instead of quartz glass. This improves the colour rendering index of the lamp.

Neutral White

White light that is characterized by a neutral colour tone. The term is generally used for lighting with a correlated colour temperature (CCT) of around 3000-3500K.

Pin-spot

A controlled, narrowly-focused beam of light typically emitted from a small “pin” sized hole or small aperture downlight

Photometry

The measurement of light and its properties.Measurements can include lux, lumens, candela, beam angle etc.

Recessed Lighting / Recessed Fixture / Recessed Luminaire

Also known as a down light, recessed lighting fixtures or luminaires are installed into openings in a ceiling/soffit and appear as if the light is shining from a hole.

Reflected Light

Light seen after having bounced off a surface.

Retrofit

A replacement lighting system upgrade to an existing lighting infrastructure, generally with the goal of improving energy efficiency, performance, colour rendition, safety etc.

Saturation

The resulting “colourfulness” when objects are exposed to a light source, compared to that resulting from natural lighting. If the colours appear more intense, the light source saturates them; on the other hand, if colours are dulled, the light source desaturates them.

A higher colour rendition typically improves colour saturation and therefore the vibrancy in which objects are viewed.

Sconce

A wall-mounted lighting fixture, which generally has a decorative lighting purpose.

Spot

A controlled, narrowly-focused beam of light.

Strip Light

Flexible, dynamic and customizable, LED strip lights can be made to lengths and mounted almost anywhere, according to a project’s requirement.

Track Lighting

Lighting configuration where several fixtures are mounted on a common track, which provides them with power and allows each of them to be oriented in a different direction.

Tungsten

Light from an ordinary light bulb containing a thin coiled tungsten wire that becomes incandescent (emits light) when an electric current is passed along it. Tungsten colour temperature is around 2800K to 3400K. It is also known as incandescent light.

Ultraviolet Light

A type of electromagnetic radiation, invisible to the human eye (i.e., beyond the visible spectrum) with a wavelength of 10 to 380 nanometres.

Ultraviolet light is especially damaging to delicate pigments and natural materials. Fortunately, our LEDs, do not emit this section of the light spectrum.

Up Lighting

Lighting method where an object or surface is lit from below, with a luminaire that directs its output upward. The applications of uplighting are generally decorative, such as up lighting a sculpture or an architectural archway.

Voltage

The electric potential difference between two contacts. Voltage drives electric current through lighting fixtures and other appliances.

Wall Grazing

Lighting effect where a wall is illuminated at a close offset so that irregular surfaces are emphasised. This effect is best on rough surfaces such as those built from stone or exposed brick.

This is a similar effect to wall washing, however with wall washing the offset from the illuminated wall is greater thus the texture of the wall is flattened, rather than enhances.

Wall Washing

Lighting effect where a wall is illuminated so that surface irregularities are minimized, it appears smoother.

The opposing lighting effect is wall grazing whereby the texture is emphasised.

This lighting effect is ideal for large art murals and tapestries.

Warm White

White light that is characterized by a warmer yellow to orange tone. The term is generally used for lighting with a correlated colour temperature (CCT) of around 2700K.

Watt

Measurement unit for the electric power (P) consumed by a lighting fixture, or any other appliance that runs with electricity.

A Watt is the sum of the voltage (V) multiplied by the current (A).

Watts to Lumens

To convert watts to lumens, multiply the power (P) value, denoted in watts (W) by the luminous efficacy (η) in lumens per watt (elm/W).