Glossary

Lumen/ Watt is a ratio expressing the luminous efficacy of a light source. The symbol used for lumen/ watt is Lm/w.

A lumen is the unit of luminous flux which expresses the total light emitted by a light source. The symbol for lumens is lm.

A semiconductor that when energised emits blue light. LEDs usually incorporate a phosphor layer to change the colour characteristics to white light at various colour temperatures (CCT).