Illuminating the public realm – the importance of public lighting The application of lighting


Standards and guidance European CEN Standards EN BS 13021 ‘Street Lighting Requirements’ in conjunction with BS 5489 ‘Code of Practice for Road Lighting’ set the performance requirements for the majority of public realm areas. These are supplemented by a range of National Guidance documents such as the Technical Reports produced by the Institution of Lighting Professionals.


The observer will be aware that existing public lighting uses a range of different coloured light sources – orange, gold, white etc. These are chosen to give a balance between providing visual information to the user (colour rendering and colour temperature) and energy efficiency.


Colour rendering This describes how closely the colours of surfaces illuminated by a particular lamp type compare to their appearance when lit by daylight. The colour rendering index (Ra) is measured on a scale from 0 to 100.


Examples of colour rendering under different light sources**


Colour temperature White light sources (such as the metal halide example shown above) and Light Emitting Diodes (LEDs) are also referenced by their colour temperature, which is a measure of the warmth/coolness of the light source. Those used in public lighting come in three colour temperatures: warm at 3,000K, neutral at 4,000K and cold at 5,600K. The higher the colour temperature the higher the efficacy of the LED; however, as the temperature increases so does the coldness of the light. The colour temperature also directly affects the ambience of the area being lit; using a cool colour temperature source will make an area feel cooler


thus encouraging people to pass through it, whereas a warmer colour temperature may increase the use of an area.


Coloured light Coloured light can be used to enhance features, monuments and buildings within the urban landscape to create interest and focus.


Westminster City Council and Institution of Lighting Professionals


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