Part L: a battle for control

16 February 2012

The public consultation on the 2013 edition of Part L is finally out and the industry’s demands appear to have been heard. Lighting explains the proposals and tells you how to make sure they are implemented

The Department for Communities and Local Government has finally published its much-anticipated consultation document on changes to Part L of the Building Regs.

The process has been something of an emotional rollercoaster for the lighting industry and has sparked heated debate around the initial proposal to ratchet up the luminaire lumens per circuit watt ratio, which many felt was a crude measurement that failed to take into account how and when installations are used, the use of controls or natural daylight.

Lighting magazine has echoed calls from industry bodies such as the SLL, IALD, PLDA and LIA for the government to reconsider. At a top-line level, the campaign appears to have been broadly successful, although nothing has yet been enshrined in law. The introduction of the lighting energy numerical indicator benchmark, known as LENI, as an alternative to minimum luminaire lumens per circuit watt, is a major departure for the government, and one which was predicted by Lighting magazine in its November issue.

“The inclusion of LENI as an alternative to the less accommodating performance and efficiency requirements was a cornerstone of the industry’s approach to the consultation,” says John Gorse, technical marketing manager at Philips.

“Unwittingly the legislation could ultimately have driven the technology requirements to such a point that good and intelligent economic lighting was compromised. But the new proposals mean that in 2013 LENI could be used as a supplement or an alternative, rather than a replacement to the technology requirements.”

Elsewhere, the response to the consultation has largely been positive: “We are very interested in the inclusion of the LENI approach, along with the emphasis on controls,” says Kevin Theobald, president of the International Association of Lighting Designers. “These advances help to keep attention focused on the actual amount of energy a project might use and provide incentives for the design team.”

The Lighting Industry Association describes the inclusion of an option for LENI as a “positive proposal” in an initial response given ahead of a more thorough examination of the proposals.

“We were encouraged to see that the DCLG has included the option to use LENI to measure energy efficiency based on a lighting systems approach,” says Eddie Taylor, joint chief executive of the association.

PART L: THE PROPOSED CHANGES AT A GLANCE

● LENI included as an alternative to minimum luminaire lumens per circuit watt

● No allowance for daylight as a principal light source

● Minimum luminaire lumens per circuit watt increased from 55 to 60

● Increase in allowances for use of controls, ranging from a factor of 0.7 to 0.9

● Lighting to remain part of SBEM calculation

Daylight omission

Kevan Shaw, director of Kevan Shaw Lighting Design and a member of the Professional Lighting Designers’ Association, also welcomes the inclusion of LENI, although he is not entirely satisfied. “We have a kind of ‘LENI-lite’, in so far as it does not include daylight as a principal light source, as is intended by BS EN 15193,” he says.

The failure to include a calculation for the contribution to energy saving of pre-set lighting controls is also a significant omission for more complex lighting systems, he adds, while the fact that energy-saving lighting will be mandated in domestic buildings – including care homes – is a further disappointment.

Iain Macrae, head of global lighting applications management at Thorn Lighting, is largely pleased with how things have progressed. “Six months ago I expected just an increase in the demands for luminaire and lamp efficacy,” he says. “More recently I’d hoped we’d see a move fully to the LENI approach first included in BS EN 15193. As ever, we’ve met somewhere in-between. It is not ideal, but the regulations have made a significant step towards utilised energy, rather than installed load.”

Everything you wanted to know about LENI but were afraid to ask

Low energy exemplars

LENI is an index that describes the energy used by a lighting system over the course of a year, measured in kilowatt hours, per square meter, per year.

It is measured by monitoring the energy used by the lighting over a year and dividing this by the area being lit.
Calculating LENI is more complex. Practitioners need to know the total installed power, the area being lit and the number of hours that the light is required during the year.
Other factors include how much daylight is available in the space being lit, how often the space is likely to be empty and how the lighting control system reduces the energy used when full power is not required.
A fuller explanation can be found in BS EN 15193:2007 Energy Performance of Buildings. The new draft version of Part L uses a shorter and more approximate calculation.

Source: Peter Raynham, president, Society of Light and Lighting and board member of the International Association of Lighting Designers

New light sources

Alongside the inclusion of LENI is the proposal to increase the minimum number of luminaire lumens per circuit watt from 55 to 60. For some, there was relief this was not higher.

“We welcome a more restrained approach that doesn’t outpace the development capability of new light sources, such as LEDs,” says Gorse.

Shaw, however, warns that the 60 lumens per circuit watt efficiency target will not be achieved by many LED fittings and relatively few downlights with good dark light reflectors or effective wall wash optics.

“The danger is that we will be limited to using direct lighting luminaires with exposed lamps in many situations where we would rather use more controlled light distribution,” he says.

Alongside this was at least some acknowledgement of the impact controls can have on energy consumption, with the most generous allowances giving a factor of 0.7.

For Macrae, however, this doesn’t go far enough. “The controls factors in themselves are OK, but not realistic,” he says. “In a well day-lit office you do not need electric light for 87 per cent of the year and a control factor of 0.9 doesn’t reflect this.”

The proposals also confirm that lighting will remain part of the overall classification of the building as a whole, a move that was largely expected. This is something that splits opinion within the industry, with the IALD in particular expressing its disappointment.

Influence the debate

The consultation is, of course, an opportunity to further influence the debate. In the long term, however, there is hope that wheels are in motion which will eventually bring about further refinements of the next iteration in 2016.

“As it stands, the draft provides a good platform for all in the value chain, be it an end-user who just wants to understand the basic requirements to light a space, up to a lighting designer who wishes to take a holistic approach to both lighting and energy consumption,” says Gorse. “The industry should be pleased with its efforts and DCLG rightly praised for its response.”

Responding to the consultation document

The next step for the industry is to respond to the consultation document. The part of the document that includes the new lighting proposals can be found on page 125.

To respond to the new proposals click on Section Two – Annex B response form 2 and only answer those questions that apply to lighting. The most obvious question is number 42, on the issue of LENI, while number 59 provides an opportunity to provide additional information around particular issues.

Other questions which may be relevant include 34 and 35, and number 51 on improving as-built energy performance in non-domestic buildings.

The industry as a whole is keen for its members to take the opportunity to respond, to ensure gains made so far remain and address any remaining concerns.

“It is risky to assume your particular concerns will be addressed by associations or by the media,” warns Kevin Theobald, president of the International Association of Lighting Designers. “I would like to see individuals take the short time necessary to read through the questions and respond at least to the three or four that are most relevant to their concerns.”

“For once I think the DCLG has responded really well to our concerns, but it’s time for the industry to play its part, too,” adds Iain Macrae, head of global lighting applications management at Thorn Lighting. “If we want just LENI – and that would still be my preference – we need to make that clear. We have to study these proposals and make a sensible and meaningful response. The more of us that do that, the better.”