Authors: Dr Kevin Kelly is head of electrical services engineering, Dublin Institute of Technology and James Thomas Duff, Arup and PhD student, Dublin Institute of Technology
Recent changes to the SLL Code for Interior Lighting (2012) are affecting lighting design in Ireland, the UK and internationally. Lighting design is one of the fastest-changing areas in engineering at present. Interior lighting design has evolved significantly in recent years, due to changing technology and demands for reduced energy.
New recommendations change previous demands for equal illuminance across an entire space and make new recommendations for qualitative metrics and distribution of light, combined with demands for control and energy efficiency.
Increased demands for more daylight linked to improved lighting control are increasingly leading to more holistic design with the need for architects, engineers and facilities managers to work more closely to provide a holistic solution. Light-emitting diode (LED) lamp technology is expected to be a €65 billion industry by 2020, with this technology improving at an exponential rate.
But LEDs can be expensive and are not without problems. This is an exciting and challenging time for the lighting industry. We are challenged to provide holistic robust solutions that maximise the benefits of new technologies, whilst protecting our clients from poor-quality lighting products and installations.
CURRENT GUIDANCE AND ITS LIMITATIONS
In Ireland, the UK and many other parts of the world, the foremost authority on interior lighting is the Society of Light and Lighting (SLL), previously named the Illuminating Engineers Society and founded in 1911 . It has set guidance for the industry since 1936 and writes a wide variety of design guides for the lighting sector, which are widely adopted throughout the world.
The SLL’s Code for Lighting and accompanying Lighting Handbook provide a summary of lighting standards and offer further qualitative guidance, which combines to provide a comprehensive text on lighting. In recent years, the European Committee for Standardisation (CEN) has also set standards for all countries in Europe. Although there are many standards, in the foreground are EN 12464 Lighting for Workplaces and EN 15193, the Energy Performance of Buildings Directive.
In EN 12464, minimum requirements for lighting are laid down for both interior (part one) and exterior (part two) lighting. EN 12464 specifies many quantitative criteria, but the most prominent are maintained illuminance, uniformity, colour rendering index and unified glare rating :