To ensure adequate consideration is given to the access requirements of people with disabilities, both the Building Code of Australia (BCA) and the Australian Standards (AS) outline design requirements for new building work. Particular attention is given to access requirements for people with sensory disabilities, including vision impairment.
To assist people with low vision, luminance contrast can be used as a design element to make specific building elements easier to identify.
What is luminance contrast?
Luminance contrast is the light reflected from one surface or component, compared to the light reflected from another surface or component.
Where is luminance contrast required?
AS 1428.1 Design for Access and Mobility refers to three specific areas which require the minimum luminance contrast value be achieved. These areas are:
- Toilet Seats
Stair treads are required to have a strip between 50mm-75mm wide installed across the full width of the path of travel. It may be set back from the edge of the nosing to a maximum of 15mm, and any change in level must comply with Clause 7.2 & Clause 7.3 of AS 1428.1 - 2010. Where the strip is not set back from the edge of the nosing, then any area of luminance contrast must not extend down the riser more than 10mm.
Doorways are required to achieve the minimum luminance contrast between:
- Door leaf and door jamb
- Door leaf and adjacent wall
- Architrave and wall
- Door leaf and architrave OR;
- Door jamb and adjacent wall
The minimum width of the area of luminance contrast is 50mm.
Toilet Seats must achieve minimum luminance contrast with the background, including the toilet pan or the wall/floor against which it is viewed.
What is the minimum luminance contrast and how is it measured?
Where two building elements are required to achieve sufficient luminance contrast, a minimum luminance contrast of 30% must be achieved. It may be necessary to test both elements in wet and dry condition.
To measure the luminance contrast between two surfaces, each surface is first tested to define its Luminance Reflectance Value (LRV) using either the laboratory test method, or the on-site test method.
Once the LRV’s for both surfaces are defined, the luminance contrast is found by putting the LRV’s into the following equations based on the relevant test method.