A systemic approach to lighting

By Stewart Langdown of Ceravision

As Part L of the Building Regulations continues to enforce improved energy efficiency in lighting, it’s now clear that future versions will do so through a more holistic approach. For example, as well as increasing the minimum luminaire efficiency, probably from the current 55 luminaire lm/W to 60 luminaire lm/W, it appears that the Lighting Energy Numeric Indicator (LENI) will be accepted as an alternative to the technology requirement in Part L 2013. Or the two may be used in conjunction with each other.

The important thing here is that the LENI also takes account of how the lighting is controlled, bringing it even closer to the realistic use of the lighting in the space. Many lighting pundits also believe that the LENI will become the de facto measure of efficiency in Part L 2016.

So what does this mean for the specifier involved in lighting design? I would suggest that it encourages, and facilitates, more of a ‘systems thinking’ approach that delivers better value to the end client. This is because it leads towards a solution that encompasses value for money, reduced cost of ownership, lower environmental impact and good lighting, rather than just focusing on the light source.

Of course, that’s easier said than done. For instance, we still tend to talk in terms of the light source when describing a particular type of lighting – LED lighting, HID lighting,  plasma lighting etc. There’s no doubt that this is very useful shorthand for communicating with each other, but we have to stop letting it dominate the specification.

For example, given the flurry of publicity surrounding light emitting diodes (LEDs) you could be forgiven for thinking that LED lighting is fast becoming the only game in town. But, while it is undoubtedly a very good light source in the right application (below 150W), it is certainly not a universal panacea. Unfortunately, there are attempts to use LEDs in quite inappropriate ways, to the detriment of the working environment.

This brings us back to the issue described above, namely that there is a tendency to think of the LED light source, rather than the LED lighting system. For instance, a badly designed luminaire with poor thermal management will prevent the LED light sources from performing at maximum efficiency – and shorten their life.

Lack of synergy

The same principle is true of most kinds of lighting, as the majority of luminaires are an assemblage of components from different manufacturers – lamps, control gear, reflectors, diffusers etc. They may be compatible with each other and capable of functioning together but they lack the synergies to enhance each other’s performance.

In addition, the quality of the lighting needs to be taken into account, such as avoiding excessive glare and achieving good colour rendering, as well as the way the lighting is controlled in relation to the way the lit spaces are used.

So when all of these influences are considered it’s clear that a more effective and productive approach will be to consider the whole package in the context of where it will be used. This can be illustrated by considering new plasma lighting systems that are now entering the market and how the characteristics of plasma lighting exemplify a ‘whole system’ approach in the hands of the right manufacturer.

High efficiency plasma (HEP) lighting will be less familiar to BSEE readers than many other light sources but the technology has been around for many years. It is only recently, however, that this technology has been packaged into a practical solution for a wide range of lighting applications.

The HEP system is an electrodeless lighting platform that consists of four integrated elements: a quartz radio frequency (RF) resonator and integral plasma burner (lamp); a transition unit (the system which couples the RF energy from the source into the resonator); an RF source in the form of a magnetron and an AC power supply.

The integrated burner and resonator contain an inert gas and metal halide salts. RF energy resonating within the lamp ionises the gas to form a plasma that combines with the metal halide to vaporise the metal halide salts, emitting an intense, bright light that does not need to be corrected with phosphors.

This bright white light has a colour rendering index (CRI) of up to 95 and the colour temperature can be adjusted by changing the chemical dosing to provide a range from 2,000K to 12,000K.

Furthermore, HEP lighting produces a compact, spherical light source that enables precise focusing of optics at the optimal point. This is in contrast to other light sources where the nature of the light source imposes limitations on the efficiency of the optical system.

As a result of this precision, HEP luminaires deliver an exceptionally high light output with no shadows from the lamp and can be supplied with a range of light distributions for different applications. The intensity of the light makes HEP ideal for applications requiring high light output that are traditionally served by HID light sources, such as high and low bay applications.

This design also means there are no wiring connections to the light source and no electrodes, thus minimising the risk of premature lamp failure.

The HEP combination of light source and optics brings real benefits for the end user. For example, it enables 300W light sources to deliver the same illuminance as 400W HID lamps – or to maintain the same illuminance with fewer luminaires. Either way, the installed electrical load is greatly reduced. HEP luminaires can also be dimmed to 30% of light output. Crucially, the dimming relationship is linear so that, for example, a 50% reduction in light output results in a 50% reduction in energy consumption (dimming of HID lamps is not linear and does not deliver the same energy savings).

Control performance

Keeping overall performance very much in mind, HEP lighting is also highly controllable, using RF technology to provide wireless communication between sensors and the control network. The control network uses Internet Protocol (IP) which can be accessed using a range of mobile devices such as smart phones and tablet computers. Each luminaire and sensor has its own IP address for highly flexible control, as well as monitoring of key parameters such as burning hours, light output over time and energy consumption. The system can also be used in conjunction with other IP-based technologies, such as RFID (Radio Frequency Identification) tagging.

So with HEP what we have is a lighting system that exploits the strengths of light source, luminaire and controls in the context of the application. As such it demonstrates the benefits of a ‘system thinking’ approach that reflects the actual performance of the lighting in situ, rather than the theoretical performance of a light source that may be impacted by other factors.

As with any lighting technology, HEP is particularly suitable for certain lighting applications and won’t be the best solution for others. And really, that’s the key point – choosing the best technology for each project.