Lighting

Gloucestershire County Association for the Blind

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People with visual impairment require clarity from a lighting system. Reflection, glare, shadows and large variations in lighting levels generate visual confusion and, in some cases, discomfort.

reflection: can be minimized with the careful use of non-reflective finishes on internal surfaces

glare: can be reduced by the thoughtful positioning of lights out of the line of vision

glare from daylight (sun): can be tackled with adjustable blinds or by re-arranging furniture

shadows: can mask hazards. They can be avoided by increasing the level of ambient light and ensuring spotlights are not used on their own

feature lighting (e.g. downlighters): should be located where they will not cause shadows

large variations in light levels: which requires swift reactions from the eye should be avoided. Any change in lighting levels should be gradual

Lighting often fulfils secondary functions, for example:

gives directional guidance in a corridor illuminated by a series of lamps mounted longitudinally on the ceiling

highlights potential hazards, such as staircases. Lighting should be designed to function successfully in both directions of travel without causing shadows and offer adequate contrast between treads and risers. Glare and reflection should be minimized

Task lighting is essential for the individual management of lighting levels according to work requirements and an individual's needs.

adjustable fittings with compact fluorescent lamps can be used. This type of lamp ensures that the surface temperature of the lamp remains low even after long periods of operation, allowing the user to work in close proximity to the lamp

increasing the size of the task by 25% is equivalent to increasing the level of illumination by 100%. It may be more cost effective to increase the task size than to invest in replacement lamps and fittings

the contrast of the task details is also important

different coloured work tops can often be a useful method of achieving a suitable task contrast, e.g. reversible black/white work tops

where task lighting is in operation, background lighting must be sufficient to allow the user's eyes to adjust, without experiencing any discomfort, from the high level of lighting s/he is using to the background level

in offices where VDUs are being operated, guidance contained within CIBSE Lighting Guide 3 should be followed

offices areas can often appear gloomy even though levels of illumination meet CIBSE guidelines because all emitted light from lamps is directed downwards and the ceiling is under-illuminated. Careful use of indirect lighting can be helped to prevent this. The ceiling may become a distraction if over-illuminated.

Ultimately, the flexibility of a lighting system will depend on the ability to control it

rheostat (dimmer switches) can be used to control levels of illumination

multiple lamps in light fittings, each governed by a separate switch, can also be used to enable a lighting system to be controllable

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Lighting Considerations

[ Lighting ]

The lighting needs of people with visual impairment can vary enormously. Some may require higher levels of illumination, while others may experience sensitivity to increased levels of illumination. FLEXIBILITY is the key to successful lighting design that can accommodate these factors.

Visual Confusion