IRC halogen lamps are sources where the central halogen burner has been coated with an infra-red coating (hence IRC). This reflects the infra-red energy back onto the tungsten burner, which means it heats up and becomes more efficient as much of the reflected heat energy is turned into visible light.
The UGR method (Unified Glare Rating) is an international index presented by CIE, the international lighting research body, in its publication 117 and is used to evaluate and limit the psychological direct glare from luminaires. Contrary to previous methods where the glare was rated using the luminance values of a single luminaire, this method calculates the glare of the entire lighting installation at a defined observer position.
Colour gamut is a measure of how colourful a scene will appear under a given light source. Sources with a high colour gamut generally make objects appear brighter and more colourful.