PART L1A/L1B

PART L1A/L1B relates to lighting for domestic use. 

L1A referring to new dwellings and L1B to existing dwellings.  

At least 75% of fittings must be low energy. Reasonable provision requires either 1 energy efficient fitting per 25m² or 1 in 4 fixed luminaires.

The lamp holder used must be such that it can only accept energy efficient lamps that achieve greater than 40 lumens output per circuit Watt. Fluorescent and compact fluorescent fittings would meet this standard. Halogen and GLS lamps are highlighted in the guidelines as non compliant.

Fixed external lighting should not exceed 150W and be controlled so it automatically switches off or can only accept lamps with efficacy >40 lumens/Watt.

PART L2A/L2B

PART L2A/L2B refers to buildings other than dwellings. 

L2A referring to new buildings and L2B to existing buildings, with over 100m² of floor area.

PART L2A relates to new buildings other than dwellings,
with over 100m² of floor area.

A minimum average lamp efficacy of 50 lumens/circuit Watt for general lighting.

A minimum average lamp efficacy of 22 lumens/circuit Watt for display lighting.

Exceptions are emergency lighting and specialist process lighting.

Note:

It is not necessary for individual luminaires to meet 55 luminaire lumens per circuit Watt, giving the designer flexibility to use a mix of technologies that average 55 lm per circuit Watt.

Circuit Watt is the actual power consumption for the luminaire which will include lamp and  control gear if applicable or installed load. 

Lighting controls should be used to optimise available daylight and switch off lighting when  not required.
Display lighting should be in dedicated circuits that can be switched outside the displays usual function.