GUIDANCE | WORKPLACE LIGHTING WORK-LIGHT BALANCE The most influential guide to lighting the workplace has had its first update for a decade. Helen Loomes outlines the key changes L ighting design is going through a small revolution. The volume of the space is taking on as much importance as lighting the visual task, and the latest version of the most influential lighting guide in this area, EN 12464-1 Light and lighting Lighting of workplaces, is reflecting these changing times. Adopted into national standards in the UK in the autumn, as BS EN 12464-1:2021, this latest version appears a decade after the last revision. So, what are the key updates? The most obvious changes are to be found in the revised tables in Chapter 7 the list of specific lighting requirements. Here, there is a changed layout and additional considerations. As well as the previously required illuminance, which specifies the lowest maintained value in the activity area, there is now an additional, higher modified value, and requirements for mean cylindrical illuminance, walls and ceilings are specifically listed in the tables. The modified value enables the illuminance to be adapted to real tasks and activities. The aim is to create optimum visual performance and avoid errors at work by considering varying factors, including the age of the user. Increases in light levels refer to the scale of illuminance in EN 12665, which are levels at which the average person can detect visible change. In a brightly lit area, large changes in values are needed; in a dimly lit area, people can already perceive much smaller changes. These are not maximum and minimum values, however; rather, they are ranges to be considered. Increased illuminance is required if: The visual task is critical to the workow The correction of errors is costly Accuracy, higher productivity, or increased concentration are important The task is small or of low contrast The task is performed for an unusually long time The area has little daylight An employees eyesight is below the usual level of vision. If there are one to two additional requirements, an increase of one level should be made for example, from 500 lux to 750 lux. More than two additional requirements leads to an increase of two levels. Where the visual task requirements are lower, however, it is possible to reduce illuminance by one level, but this is a rarity. This change gives the lighting designer the ability to tailor the lighting to the actual needs of the user, and to make it more adaptable. The use of lighting control is, therefore, recommended: dimming means the 26 January 2022 www.cibsejournal.com CIBSE Jan 22 pp24-26 Workplace lighting.indd 26 23/12/2021 13:21