Light at the end of the tunnel

The Department of Communities and Local Government (DCLG) recently published its consultation document outlining changes to the Building Regulations, including Part L and its aim to conserve fuel and power. Alastair Ramsay, Sustainable Development Manager for Legrand, explains why it provides lighting control manufacturers real grounds for optimism.

Prior to the publication of the new Part L consultation document there seemed to be a consensus of opinion that far too much emphasis was being placed on reducing energy consumption through lamps and luminaires. In contrast, it was widely agreed that nowhere near enough attention was being paid to the potential savings offered by the widespread adoption of better lighting controls.

Today though, we find ourselves with a consultation document that, should its contents survive as currently proposed, delivers real optimism for those championing the cause of lighting controls.

Firstly, as the energy/carbon limit targets for buildings are being further reduced, lighting energy measures will have to come to the fore. The reason for this is that the measures that have been used traditionally, such as glazing, insulation and biomass boilers, are very much operating at their optimum levels and so will simply not be able to deliver the additional energy reduction.  Meanwhile, lamps and luminaires will not deliver the kind of savings necessary while also maintaining the quality of lighting and meeting other legislative lighting requirements such as those advised by BS EN 124641 (Lighting of Work Places). Instead there will need to be a new reliance on lighting controls and management systems.

Secondly, the Guidance Notes now offer far better advice on the energy benefits of lighting control, and in fact are weighed more in favour of controls over manual switching. And when you take a quick look at the headline figures, and the potential savings these systems deliver, you can see why.

Emphasis on dimming

Lighting accounts for 20% of the annual electricity consumption in non-residential buildings in the UK every year, a figure that equates to 15.2million tonnes of CO2 at a cost of £3.6billion. Even the most basic of absence detection installations will in most cases save a minimum of 30% of this energy, and therefore cost, by automatically turning off lights when a space is unoccupied. And the more sophisticated the installation, the greater the savings – regularly up to 60%. That minimum 30% saving equates to an astonishing annual saving of 4.56 million tonnes of CO2 or £1.08billion.

The Part L consultation also places an increased emphasis on dimming, including the case of maintained illuminance. This is aimed at eliminating the energy wasted by specifying initial lighting output levels above those required – a common practice that takes into account the expected declining light source performance over time.

Finally, the full and proper introduction of LENI (Lighting Energy Numeric Indicator) as an alternative way of accounting for lighting energy use will give a more realistic method for lighting designers to use. And what’s more it’s a methodology that lighting designers and specifiers are already familiar with.

In my opinion LENI will undoubtedly play the most important role in delivering significant energy savings from lighting. Most notably as a means of ensuring designers can deliver good quality lighting which is fit for purpose – something that to date has proved extremely difficult to achieve within the SBEM modelling methods. 

Focus on lighting

SBEM is designed to model a whole typical building, but does not fully reflect the true benefits derived from installing lighting controls, an issue that was highlighted in the recent consultation documentation on the Green Deal which said: “Our concern is that, even with the improvements to the SBEM methodology we are putting in place, the Green Deal Assessment will not be equipped to consider in detail how a whole system (e.g. a lighting control system) might be designed in a non-domestic property to maximise savings. It would therefore be likely to lead to routine underestimation of the level of savings that could actually be made ……”

Additionally, although SBEM assumes presence and lux controls in its modelling of the target building, plus the inclusion of automatic dimming controls in day lit areas, this is not recognised and hence has resulted in lighting controls not being routinely adopted into buildings.

The result is that even simple levels of lighting control are often omitted, even in new build projects, as a result of value engineering. This situation has been accentuated by the ease with which more static measures, such as insulation, have been implemented instead.

In contrast, LENI is fully focused on lighting. EN 15193 specifies the way in which it is calculated and while the formula does appear complex, when broken into its individual parts it is relatively easy to appreciate. 

The various parameters, including occupancy patterns and target lighting levels for the spaces being considered, are input and the final calculation then generates an energy use figure per annum per square metre. For regulatory purposes, and as proposed in the Part L consultation, this calculated energy use is compared against a table giving a maximum target based on planned occupancy rates and target lighting levels.

In practice, specifiers and designers will rarely be faced with wrestling with the formula as they will use lighting design software that incorporates the LENI calculation, the results of which will be output as part of the standard reports.

Making progress

The proposals outlined in the Part L consultation don’t guarantee the uptake of lighting controls in new buildings, but the increased prominence given to LENI and the improved guidance in the Guidance Notes will certainly play a major role in encouraging a far greater uptake in use.

Furthermore, if these elements are also introduced into the calculations of the Green Deal’s Golden Rule this will give a kick start to tackling the hugely inefficient lighting schemes in our existing buildings.

Whatever the final content of Part L, it does feel like we are making progress and that the situation will soon exist where the gap between the type of lighting technology most designers talk passionately about, and the type of technology being installed and used in buildings across the country will begin to vanish.

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