Building Regulations point to growth of LED lighting
Mike Simpson explains the requirements of the new Part L for lighting — and suggests that there is too much focus on installed load rather than energy used. He would like to see more emphasis on control.
Successive Governments have placed energy policy at the heart of their manifestos, and since the agreement of the Kyoto Protocol there have been legally binding targets for countries to reduce carbon emissions. These have been backed up by local legislation designed to help achieve the UK’s target of reducing carbon emissions by 80% by 2050.
Reducing carbon is also good economics since the UK is now a net importer of energy. Within this decade we may well face shortages as we de-commission old power stations and wait for new ones to come on line. Greening our supply and changing people’s habits are long-term solutions. Using the existing energy supply more efficiently is something we can do now.
Buildings account for 50% of our energy use, so it is not surprising that there is constant pressure to reduce demand in this sector. In 2006 the revised Part L of the Building Regulations was targeted to reduce energy in buildings by 28%. In October this year (2010) the revised Part L should take a further 25% off that value, pushing us towards the goal of a net zero-carbon buildings by the end of the decade.
Lighting is a significant user of energy in buildings, and using currently known technology could deliver up to 40% savings. For commercial buildings the Part L target value of light output from a luminaire has been raised from 45 to 55 lm/W (circuit), averaged over the whole building.
This requirement pushes upwards the need for efficient light sources and luminaires. A lamp with an efficacy of 80 lm/W and a luminaire with a light output ratio of 70% would just about hit this mark.
New LED technology is also hitting overall efficacies in excess of 65 lm/W (circuit), making it a contender to replace conventional solutions in complying with Part L. With the projected increase in efficacy of LED technology, we expect that in five years 70% of new lighting sold could be LED-based and deliver greater energy savings than today’s solutions.
There is also discussion about whether the lighting levels set in current codes are too high. These were set in the days when the task was a pencil on a piece of white paper. Do we need the same level of light when most office tasks are screen based? Moving to task lighting with a reduced overall ambient level is another way to ensure light is only used when it is needed.
One of the problems with Part L is that it focuses on installed load rather than energy used. We know that introducing lighting controls can make a big saving on energy use. Simply switching off when there is sufficient daylight or when no one is around can reduce the effective installed load by 60%. This is far greater than the current allowance made for lighting control in the latest Part L. We therefore need to replace the current system with one that fully takes account of the actual use of lighting, rather than simply what is installed, if we are to reach our goal of zero-carbon buildings. EN 15193 is the European standard for Energy Performance of Buildings and offers a comprehensive method of evaluating the lighting energy load.
Greening our homes will be a greater challenge, with 15% of the energy used going on lighting. For the home we have seen the Part L requirement for lamp efficacy rise from 40 lm/W to 45 lm/W and the number of lighting points with this efficacy rise from 25% to 75%. This means new-build or major refurbishments cannot use traditional tungsten-halogen lamps as the main form of lighting.
For general lighting in homes, we have the compact fluorescent lamp, whilst for more directional lighting new LED lamps can replace the traditional MR16 reflector lamp. Indeed it is predicted that the compact fluorescent lamp will be relatively short lived as a technology, with our homes being totally lit with LEDs by 2030, reducing the energy load due to domestic lighting by 90% compared to 2008 levels. Unfortunately tackling the domestic heating load will not be so easy or offer the same quick paybacks.
One of the big challenges is how to ‘green’ the existing building stock. Of the buildings we have in 2010, 70% will still be around in 2050. Unless significant changes are made to the fabric of existing buildings, lighting offers the single best solution for real reductions in energy consumption.
Mike Simpson is technical and design director with Philips Lighting.