Public Lighting Recommendations

Abstract

Public lighting accounts for €56 million in public expenditure annually and is a major item in council budgets. A large proportion of the 480,000 units in the lighting stock are in need of replacement with more efficient luminaires in order to meet energy and carbon reduction targets. The following document is predicated on the assumption that LED lighting will be increasingly used for public lighting and aims to mitigate the negative effects within the constraints of the drive for energy efficiency and lower carbon production. It is important to point out, however, that in line with the recommendations of bodies such as the Institution of Lighting Professionals the greatest savings will be made by dimming lights or removing unnecessary lighting. This document outlines aspects of public lighting in relation to the installation of LED lighting and the desirability to reduce both light levels and the blue spectral component. LED technology is known to have positive outcomes in terms of economic and environmental aspects (including carbon dioxide reduction) and the replacement of older lanterns with modern full cut-off designs which reduce or eliminate light emission above or near the horizontal provide further gains. We suggest that besides the introduction of this technology and also “trimming and dimming” of lighting levels, the colour of the spectrum produced by LED installations and its relationship to the behaviour of human vision at low light levels should be considered when specifying and installing exterior lighting. Consideration of lighting colour and its impact can lead to a reduction in the level of lighting, its impact on the environment, and also potentially reduce human health effects such as sleep disruption. As we have closely followed UK practice in the past, we reference some recent developments, including reduced light levels as specified in BS5489 and also the forthcoming introduction of warmer colour LED lighting in residential areas. A large-scale statistical study of the effect of new lighting practices in England and Wales has detected no change in overall crime or traffic collisions due to restricted light levels and the introduction of white light. We recommend that luminaires with a correlated colour temperature (CCT) of 4000K operate at reduced lumen levels to take account of the increased blue light sensitivity of the human visual response. Such a reduction will lead to further energy savings as well as improved outcome environmentally. In keeping with developing UK practise we suggest that, as a general rule, LED luminaires with warmer colours (i.e., CCT values at or below 3000K) be specified for future installations. Finally, we recommend that pilot lighting schemes be tested in situ to verify the overall lighting design before rolling out more generally.