Luminaire lumens
Approved document L, Conservation of Fuel and Power, Volume 2: Buildings other than dwellings, 2021 edition incorporating 2023 amendments, defines luminaire lumens as: ‘Equal to (light source lumens light output ratio) and represents the output of the luminaire. Light output ratio (LOR) is the ratio of the output of the luminaire at stated practical conditions to that of the lamp(s) contained in the luminaire under reference conditions.’
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