BS5489-1:2003 permits a reduced illuminance to be used for lighting in subsidiary roads when using lamps of high colour rendering index (Ra≥60) – these are widely known as white light sources. This technical report offers evidence for the advantages and disadvantages of using this trade-off between colour rendering and illuminance.

Can it be done? This is addressed by review of research – controlled laboratory studies and field trials – of brightness and visual performance under different light sources.

Should it be done? This is addressed through comparison of life-cycle costs for lighting schemes using high pressure sodium lighting and light sources meeting the ‘white light’ criteria.

Key features

• Examines both rigorously controlled laboratory data, and data from field studies which lose experimental rigour to gain context validity.
• It is recognised that the cost-benefit analysis will not suit all lighting engineers (variations in preferred light sources, column heights etc and prices) and thus a web site address is given for spreadsheet so that readers can repeat the analysis with their own preferred values.
• Field survey questionnaires are given, to encourage readers to carry out their own street lighting surveys and participate in the research.
• The report identifies situations where white lighting is, and is not, advantageous.
• Written by a panel including research and practitioners.