The SLL Code for Lighting

The Society of Light and Lighting (SLL) and its predecessors, the Lighting Division of the Chartered Institution of Building Services Engineers (CIBSE) and the Illuminating Engineering Society (IES), have published recommendations on lighting practice since 1936. From the beginning, these recommendations, called Codes for Lighting, have all contained details of the illuminances required for use in different applications together with qualitative guidance on how to implement these recommendations. Over the years, as the understanding of how lighting conditions can affect visual performance and cause visual discomfort has increased, additional quantitative lighting criteria have been added, notably those concerned with the level of colour rendering required and with limiting discomfort glare. For many years, the IES Code for Lighting was the de facto standard for lighting provision in the United Kingdom. However, in 2002, the Committee for European Standardisation (CEN) took on the task of providing lighting recommendations, and, since then the British Standards Institution has adopted the CEN recommendations for use in the United Kingdom. As a result, there are now a range of British Standards that specify the quantitative lighting requirements for a wide range of applications. Consequently, the role of the SLL Code for Lighting has shifted from being the only source for quantitative lighting recommendations to being a guide on how to interpret the British Standard recommendations and how to implement them in practice. This edition of the SLL Code for Lighting takes the changes in lighting guidance a step further by a process of separation and concentration. The separation involves moving the details of vision, lighting technology and lighting applications into another publication, the SLL Lighting Handbook. The concentration occurs because this SLL Code for Lighting provides information on three fundamental matters of relevance to lighting practice. These matters are: A summary of what is known about the effects of lighting on task performance, behaviour, safety, perception and health as well as its fi nancial and environmental costs. A compendium of all the lighting recommendations relevant to the United Kingdom with suggestions as to how these should be interpreted. This compendium covers recommendations for both interior and exterior lighting in normal conditions. A detailed description of all the calculations required for quantitative lighting design. While it is a fact that, today, most lighting calculations are done using software that simply implements the fundamental calculations described here, without knowledge of these calculations, it is diffi cult to assess the meaning and merit of the results produced by software.