Lighting Uniformity

Lighting uniformity refers to the evenness of illumination across the work area, floor and walls respectively. Uniform lighting is particularly important for work areas.If the lighting is uneven, the eyes of the occupants make involuntary adjustments for the different lighting levels while trying to stay in focus, creating undue stress and fatigue

The standard EN12464-1 specifies an additional design criterion to discourage excessive non-uniformity. In purely mathematical terms, lighting uniformity is the ratio of minimum to average illumination for a given area. The minimum illuminance uniformity is called UO. In the case where the uniformity requirement UO is 0.6 and the illuminance requirement for the work area is 300 lux, the illuminance at any point in the work area will be a minimum of 180 lux.

The daylight distribution in a room with windows will normally be rather uneven which can be perceived as stimulating and positive as long as it does not reduce the comfort and the ability to read boards or screens.
In case of uneven distribution, sun screening might be used to control lighting uniformity.

The main direction of the light affects our ability to see the depth, form and texture of an object or person and thus influences our capability to estimate the distance. The total directionality of incident light is very important when three-dimensional objects need to be recognised as such.

Uniform lighting coming from “all” directions, such as indirect lighting, does not produce shades and as a result, makes visible objects look flat. This kind of lighting is called diffuse lighting. Direct lighting causes shadows and can cause details to disappear. In general, the best lighting is a mix of diffuse and direct lighting.

Designers can choose from a variety of reflector types for LED illumination with different reflector forms, reflector colours, and lamp position; all impacting light evenness. Furthermore, lenses can be used to achieve different light qualities e. g. frosted lenses create more uniform illumination but decrease the brightness. It is important to weigh up all the options before committing to a lighting choice

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