Lighting Terms

LUMEN

For a long time, the term was “candles.”

Today, we use “lumens” to describe the amount of light emanating from a light source,

but it still refers to the amount of light generated by candles. The number of lumens

corresponds directly to the same number of candles, so that more light = more candles = more lumens.

 

 

 

 

 

Colour Rendering Index (CRI)

Lighting affects the way colours appear, called Colour Rendering Index. It measures light quality. It has a range of 0 to 100. The CRI can only be assessed by reference to another light of the same color temperature.

 

 

 

 

 

 

 

Colour Temperature

Lights have different colours, measured by temperature, called Kelvins and described as warm, neutral or sources. Typically, the lower temperatures reference the warm end of the scale.

 

 

 

 

 

 

 

Design Lifetime

 

How long a bulb will last, with normal use, depending on the type of light. LED’s have the longest life as much as thirty years, and are more expensive, while incandescents are much less expensive, but only last a year or less.

 

 

 

 

 

 

Luminous Efficacy

Measured in lumen output per unit power input (watt).

Efficacy = lumen / wattage

Incandescents = 12.8 lm/W

Halogens = 14.4 lm/W

Compact Fluorescents = 45 lm/W

LEDs = 68 lm/W

 

 

 

Beam Angle

Measured in calibrated degrees a beam angle of a light source’s radius. The beam angle is calculated when its lux level drops to half of the intensity of the centre beam (see diagram). Beam angles are typically 15, 30, 45 and 60 degrees.

 

 

 

 

 

 

 

Lux

Dictated by Australian standards, this measurement refers to the brightness of a light in a space. Lux meters are available to determine lighting levels and evaluate the energy efficiency of lighting designs.

1 lumen psm = 1 lux.

1 lumen psf =1 foot candle.

 

 

 

 

 

Daylight Harvesting

With a daylight harvesting sensor, your LED lights are automatically dimmed to maintain a consistent light level, depending on the amount of light needed in the space throughout the day.

 

 

 

 

 

 

 

Dimming ability

Dimmable lights allow light to be adjusted to the right brightness. Emitting different intensities, for different occasions, can alter the atmosphere of a space.

Depending on the amount of light they can create defines if a dimmer switch can be applied.

 

 

 

 

 

 

Gimbal

A light that is gimbaled rotates on an axis and allows the direction of the light to be adjusted to a certain degree. Gimbals are useful if you need the light to be projected in a certain direction, i.e. if light needs to point down a hallway or highlight a picture.

 

 

 

 

 

 

 

Watt

The amount of electrical power consumed by a lamp or light fixture is determined in “watts”. One watt is equal to the power dissipated by 1 ampere of electrical current flowing across a resistance of 1 ohm . Typically a standard halogen incandescent bulb operates at 50 watts. LED’s, on the other hand, can be just as bright while using about a quarter of the watts.