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The proposed changes to Part L are part of the government’s drive to cut energy use and carbon emissions. The new Part L will also incorporate the European Energy Performance of ÐÇ¿Õ´«Ã½s Directive (EPBD). Among other things this includes requirements for a method for calculating the energy performance of buildings; and performance standards for new and existing ones.

As far as lighting is concerned, the directive states in its annex: ‘The methodology of calculation of energy performances of buildings shall include at least the following aspects:

… (e) built-in lighting installation (mainly the non-residential sector)’.

It goes on to recommend that the positive influence of natural light be taken into account, where relevant.

The directive has important implications for the way in which new buildings may comply with Part L in the future. Currently compliance with Part L is often achieved by the elemental method. This considers individually the performance of each aspect of the building, including lighting.

Under the provisions of the directive, the energy performance of the whole of a new building will have to be calculated, so a predicted carbon emissions method would become the standard way to comply. This predicts the performance of the whole building and compares it to a reference building that complies with the elemental method.

This type of method sums emissions from a range of building energy uses, not just lighting. So it is possible to have less efficient lighting, provided energy savings are made in heating or cooling that outweigh the extra lighting related carbon emissions. This could have implications for the role of lighting. On the one hand, in some buildings lighting may be seen as a minor energy consumer and designers may not pay much attention to it, preferring to concentrate on limiting heat loss, for example, as a way to ensure compliance. On the other hand, it is often easier to make energy savings in lighting towards the end of the design process, so designers may see energy efficient lighting as a suitable way to upgrade a building that may otherwise be non-compliant.

For small extensions, or refurbishment of existing buildings, it would usually be possible to achieve compliance using an elemental type approach as at present. This could for example include having to show that lighting in an extension was reasonably energy efficient.

Domestic buildings

For interior lighting in new dwellings, the proposal is that lighting calculation be part of the dwelling carbon emissions rate (DCER), linked to the SAP rating calculation procedure. Details of the proposed calculation can be viewed on www.bre.co.uk/sap2005/. It includes a credit for fittings that can only take energy efficient lamps such as compact fluorescent lamps. Under the proposed Part L it would be normal to provide these, but gives no recommended minimum number.

Under the new proposals, only complete luminaires (including lamp, control gear and an appropriate shade or diffuser or other device for controlling the output light) would count as low energy. In the 2002 Approved Document, sockets without a lamp or shade complied, but with the new proposals this would no longer be the case. There has been some concern among sectors of the lighting industry that it is easier for new householders to remove a compact fluorescent lamps sockets and replace it with less efficient tungsten lighting.

The DCER is also likely to give a credit for daylighting, based on window area, glazing type, and external obstruction. So if a new dwelling had good daylighting and a number of low energy fittings, this would give it a lower DCER rating and make it easier for it to comply with the proposed requirement.

External lighting is not proposed to be included in the DCER calculation. Instead the Approved Document gives an extra recommendation, similar to that in the 2002 guidance. External lighting would comply if it went out when not required at night (for example if it had a presence detector that turned the light on for a limited time). It would also comply if it could only be used with energy efficient lamps, such as compact fluorescent. A new recommendation sets out a maximum power of 150 W per luminaire.

For offices and non-domestic buildings Part L proposals require reasonable provision to minimise carbon emissions due to lighting.

For existing homes, the proposals mainly cover lighting in new extensions, and where there has been a material change of use (for example conversion of a non domestic building into dwellings). For interior lighting a way to comply would be to include a number of complete fittings that can only take low energy lamps. The recommended number is related to the area of the extension rather than the number of rooms as in 2002. This gives a fairer approach for open plan dwellings. For new external lighting on an extension, the guidance is similar to that for new dwellings, although here there is an additional recommendation that external lighting automatically extinguishes when there is enough daylight.

Commercial buildings

For offices and other non-domestic buildings, Part L proposals require reasonable provision to minimise carbon emissions due to lighting. However there is no detailed guidance on the type of lighting. Instead it is proposed that the building should meet a carbon dioxide emissions target - a set percentage improvement on a notional building complying with the 2002 ADL2. The calculation of emissions is to be developed; for lighting, it may use techniques being developed by a CEN committee (TC169 WG9). These are likely to include the effects of lighting controls and daylight.

The notional building is to have the same design illuminances and display lighting provision as the actual building. It is proposed that it have a general lighting efficiency for all buildings of 3·75 W/m^2/100 lux. This is similar to the 2002 recommendation for offices but without including the full benefits of lighting controls, and better than the 2002 recommendation for other buildings. Display lighting in the notional building is to have a lamp efficacy of 15 lm/W, as in the 2002 Approved Document. If this approach is adopted it is likely to be less strict than 2002 on lighting in daylit offices and factories, but more strict on lighting in other building types without daylight, particularly those with architectural lighting that does not contribute to a work plane illuminance.

As in the 2002 Approved Document, replacing the lighting systems in an existing building counts as controlled work and comes under the ÐÇ¿Õ´«Ã½ Regulations. The recommendations in the Approved Document also apply to material changes of use and small extensions (it is proposed that large extensions be treated in the same way as new buildings). The proposals do not currently state how much of the lighting needs to be changed before approval is required; this issue needs to be addressed to avoid the need to notify trivial alterations like changing a couple of luminaires.

Here the proposed guidance is similar to that in the 2002 Approved Document though there are some important differences. For office, storage, industrial, and educational and hospital buildings, lighting would comply if on average it had an initial luminaire efficacy of not less than 45 luminaire lumens per circuit Watt (an increase from the 2002 recommendation of 40 lm/W). The luminaire efficacy includes the light output ratio of the luminaire and corrections for type of lighting control, as well as the efficacy of the lamp and ballast. The corrections for lighting control are proposed to be less generous than before, with no exemption for the first 500 W of lighting.

The proposals for guidance on general lighting in other building types, and display lighting, are similar to those in the 2002 Approved Document. The proposed recommendations on lighting control also follow a similar pattern. Local switching (either manual controls or absence detection) would comply, although the definition of a local switch is proposed to be altered to reduce the maximum distance from switch to fitting. Alternatively the guidance in BRE or Action Energy documents can be followed.

Conclusions

New ÐÇ¿Õ´«Ã½ Regulations proposals have been put forward which aim for a 25% improvement in carbon emissions on the 2002 Part L. For existing buildings, including extensions to dwellings and lighting replacement in other types of building, the proposals are similar to those in the 2002 Approved Document, though with some important changes.

In new buildings, however, the recommendations are centred around a whole building carbon emissions calculation, of which lighting forms a part. This could have important implications for the way energy efficient lighting is designed into new buildings. In some buildings the designer might prefer to concentrate on improving the envelope performance by including more insulation and better performance windows. In other buildings designers might wish to concentrate on the building services and efficient lighting will be seen as a good way to meet the targets. The detailed approach depends on the structure of the calculation methods, currently being developed.

Paul Littlefair is principal lighting consultant at the ÐÇ¿Õ´«Ã½ Research Establishment.

• This summary is only intended to provide an overview of the proposed changes and is in no way definitive. The Part L consultation document is available from the ODPM web site www.odpm.gov.uk. The proposals are not formally agreed at this stage and are subject to change taking account of response to the public consultation and the views of the ÐÇ¿Õ´«Ã½ Regulations Advisory Committee and others. The new Part L is scheduled to be issued later this year. This paper was produced as part of the research programme of the ÐÇ¿Õ´«Ã½ Regulations division of the ODPM.