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Part L tightens lighting efficaciesFebruary 2011

The lighting requirements of Part L of the Building Regulations have tightened.

Minimum efficacies have improved across the board. The requirements applying to lighting efficacy also moved from Approved Document L2A (ADL2A) to a new, second-tier document, Non-Domestic Building Services Compliance Guide (NDBSCG). For general lighting in office, industrial and storage areas, values are expressed in terms of luminaire lumens per circuit-watt. The new values are 55 lm/W, compared with 45 lm/W in the old Part L.

For general lighting in other areas, and display lighting, efficacy is expressed in terms of lamp lumens per circuit-watt. The values have risen from 50 lm/W to 55 lm/W, and 15 lm/W to 22 lm/W respectively. The design of the luminaire is not included.

The new values also apply when lighting is provided or extended in an area greater than 100 m2. This has to be reported to Building Control.

Increasing the installed capacity of lighting may trigger a consequential improvement to other building systems. For example, a lighting system that is extended into a previously unlit space will need to meet the relevant minimum efficacy, prompting a need to make other energy efficiency improvements, such as insulating hot water pipes or fitting occupancy sensors.


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