The technical details on Part L are now with us and I am slowly getting my head around them. One of the things that stands out is that we now need to refer to supplementary documents and, in particular, to one called the Domestic Building Services Compliance Guide.
Buried away on p 123 of this document is the guidance on lighting, and lo and behold, it’s changed significantly from the guidance in Part L 2006.
What did Part L 2006 call for?
• for 1 in 4 light fittings to be low energy, or for 1 every 25m2
• for all these fittings to be dedicated fittings (no bulb switchovers later on, matey)
• 40 lumens per circuit-watt or better as the definition of low-energy. Almost all fluorescents and some LEDs will meet this.
How does Part L 2010 differ?
• it asks for 3 in every 4 outlets to be low energy
• but it relaxes the requirement for the fittings to be dedicated, meaning that people will be free to switch over to any old bulb after the building is finalled
• the new efficiency threshold is increased to 45 lumens per circuit-watt.
What it means in effect is that it will be extremely difficult to floodlight rooms with halogen downlighters, but much easier for people to ditch all the energy saving bulbs which remain hugely unpopular with consumers. In effect, all the developer has to do is to design a traditional lighting scheme with no dedicated fittings at all, and just put energy saving bulbs in everywhere. Or, for the really skin-flint developer, no bulbs at all.