An appropriate level of general lighting is between 350 and 450 LUX. These levels of lighting can be achieved by the use of any of the following types of fluorescent lighting.
Many people with impaired vision have difficulty in visually adjusting to the change from lighter to darker areas. To reduce this problem, lighting should be equally diffused throughout a building. Open areas should be free of patches of light and shadow, and there should be equal levels of lighting between one area and the next. Corridors, staircases, lifts, storerooms, lavatories and offices should all be of similar LUX levels.
Foyers and entrances need a level of lighting which takes account of the increased adjustment time people with vision impairment usually require moving from artificial indoor lighting to natural daylight. For this reason, foyer lighting levels may need to be increased, particularly if the foyer entrance is on the side of the building facing the sun. The shade cast by a canopy over a door will also provide a helpful transitional zone between interior and exterior lighting. To avoid glare and visual distraction, overhead lighting should be recessed in such a way that light sources are not visible. Diffusers help eliminate glare problems.
Daylight
Daylight is an important source of light, but it should be monitored so that it does not produce areas of glare. Windows can create glare that may require the installation of blinds or outside awnings.
Staircases are best enclosed by walls rather than by external glazing and windows. Corridors should not end with a large window or other sources of artificial or natural light. Skylights, if used, should be fitted with effective diffusion devices and not create patches of light.
Reflection
When selecting interior surfaces, the degree of potential reflection from light sources should be considered. Highly reflective surfaces on tiles, linoleum, glass, concrete, polished wood and metal can create a reflection that may impair vision functioning. For this reason, matt finishes are generally preferable to gloss finishes.
Direction of light sources
Light sources should be placed so that they do not shine directly into the eyes. Strip lighting over kitchen benches and similar benches should be concealed.
Fluorescent tubes placed beside mirrors in bathrooms or wash rooms should also be concealed. External spotlights or floodlights placed on or near the ground to illuminate a pathway or steps must not dazzle the pedestrian. These fixtures must be positioned so that all of their illumination is directed towards the feature that needs to be highlighted, for example, steps within a path.
Colour
Lighting and colour must work in combination with each other. People with impaired vision depend upon a high quality of light and this usually involves some increased general level of illumination. However, over-bright illumination can “wash out” colours and reduce them to whites, greys and blacks. A well-designed lighting scheme should allow sufficient light to highlight the difference between light and shades of colour. Colour perception is also detrimentally affected by excess glare from direct or reflected natural and artificial light sources.
Design elements that provide potential danger should be eliminated or modified.
Floor and stair surfaces should be constructed of non-slip material throughout.
Last modified: Wednesday, 19 October 2011, 8:29 AM
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