High definition O
When is lighting ‘ultra-efficient’? This term has been over-used, says Alan Tulla, but help is at hand via industry moves to offer guidance
ver the past couple of years, the phrase ultra-efficient lighting (UEL) has appeared in a great variety of documents. But it is most often used by people who
least understand what it might mean. The reason, I suppose, is that ‘ultra’ implies technical and cutting edge, and that if efficient lighting is a good thing, then ultra must be even better. It is well known that for ultimate energy efficient
lighting, we need the right light, in the right place, at the right time, provided by the right lighting system. This means having the right lighting scheme design for a specific place, installed and operated by the right lighting system. However, the term was widely assumed to be
product based, and not enough emphasis was given to user needs, good design, daylight or even simple measures, such as switching off a light when it wasn’t needed. There was a feeling among both designers and engineers that good lighting was being hijacked – on the one hand by simplistic energy regulations such as Part L of the Building Regulations, and LED (light emitting diode) manufacturers on the other. Part of the problem has been that everyone has
their own idea of what UEL actually means. Certainly, the phrase has been used by LED manufacturers to promote their products. The general idea is that LEDs are the next stage in lighting development and so the phrase UEL has been used to denote a further stage in
BSEN 15193 The BSEN 15193 standard was written in response to the Energy Performance of Buildings Directive (EPBD). The aim was to establish conventions and procedures for the estimation of energy requirements of lighting in buildings, and to give a methodology for a numeric indicator of their energy performance. It also provides guidance on setting notional limits for lighting energy derived from reference schemes. There is also advice on techniques for separate metering of the energy used for lighting that will give regular feedback on the effectiveness of the lighting controls. LENI (Lighting Energy Numeric Indicator) derives from this standard.
46 CIBSE Journal November 2010
President of the Society of Light and Lighting, Alan Tulla, has been working with SLL members to define ultra-efficient lighting
terms of efficiency. In addition – and forgive me if this sounds cynical – the phrase UEL sounds impressive when applying for government funding. The phrase is even beginning to appear in pre-qualification questionnaires (PQQs) and public tenders. It was this concern and a lack of clarification for all
parties involved that led to a clear definition of the term being sought, led by the Lighting Liaison Group (LLG). The LLG represents a number of lighting
organisations, including the Society of Light and Lighting (SLL), which have all been working together to try to define what UEL should mean. All parties agreed it was important to move to a wider, more inclusive definition. If such a definition existed, it would help lighting
bodies have a stronger, clearer voice in discussions on the subject with government. It would also create a consensus on what was really meant by the term, and would ensure we were all working on the same basis and clarify what was required. As a result, the LLG found that one of the most
important conclusions to emerge was that a product, by itself, cannot qualify as being UEL. For example, if a luminaire is switched on when it should be off, it has zero efficiency because it is wasting 100% of the input energy. Similarly, if it is giving 500 lux when only 250 is required, half the energy is wasted. And if it doesn’t respond to daylight, again it can waste energy. That is why only the lighting system itself can be
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