Why is Luminance Contrast important

  • September 19, 2014
  • Bruce Bromley

Impaired Vision

There are over 300,000 people in Australia who are blind and/or have impaired vision. This number is constantly increasing, as one person is diagnosed with irreversible vision impairment every 65 minutes. Unfortunately, most of these cases can not be corrected by wearing glasses or contact lenses. By 2021, it is estimated that the total number of blind or vision impaired people in Australia will increase to over 420,000.

According to Vision Australia, vision impairment is defined as “any person who has some degree of sight loss”. While many eye conditions and forms of impairment remain completely untreatable, some forms of vision impairment can be treated by wearing corrective lenses.

Building an environment that is designed to support the community of people with vision impairment is an important step for Australia. The Building Code of Australia and the National Construction Code call for a minimum required amount of luminance contrast levels in many buildings and building elements such as travel path or accessway. This includes installing ground surface indicators in an accessible pathways, installing staircase nosings in multi level buildings, adding Braille on all signage throughout the building, adding lift control buttons on all evacuation chairs and elevators, and installing accessible toilet seats. An important factor to remember is that the BCA only specifies the minimum required amount of luminance contrast levels and can easily omit other important finishes that are not detailed in the BCA.

According to Australian Standard, luminance contrast is defined as “the light reflected from one surface or component, compared to the light reflected from another surface or component”. This is not referring to the difference in colour, but rather the difference of the light reflective properties of each colour.

By having a vast selection of internal finishes with the appropriate levels of luminance contrast, those with vision impairment will be able to easily navigate through the environment of the building and surrounding areas. They will be able to easily identify doorways and read all the proper signage. They will also feel safer when travelling through more hazardous areas such as a staircase, ramps, and those areas that have a high chance of vehicle impact.

Luminance Contrast of Building Elements

The luminance contrast of building elements is referring to the actual difference in the amount of light reflected from a darker building element in comparison to the amount of light reflected from a second lighter building element.

The minimum required levels for all doors, doorways, and circulation space in the doorways need to have a minimum of 30% luminance contrast between the following:

● door leaf and door jamb
● door leaf and adjacent door
● architrave and wall
● architrave and door leaf
● door jamb and adjacent wall

In regards to the above pairings, the minimum width of the luminance contrast must be at least 50mm wide.

Visual Indicators on Glazed Doors

All of the contrast lining on the glazed doors must contain a minimum of 30% luminance contrast from a viewing angle by the floor surface or any surface that is within a 2m radius of the actual glazing on the other side.

Stair Nosings

Each stair tread must contain a strip at the nosing of no less than 50mm and must not exceed 75mm deepness across the entire width of the travel path. This same strip must also be placed back a maximum distance of 15mm from the front of the nosing. This strip must also contain at least 30% luminance contrast from the background, where the luminous contrasting strip fixed to the surface of the tread.

Toilet Seat

Each toilet seat must contain the minimum luminance contrast levels of 30% against the background.

Tactile Ground Surface Indicators

There are many different types of tactile ground surface indicators. The following are the most well known and most often used:

Integrated Tactile Ground Surface Indicators

This series of tactile ground surface indicators are defined by using a pattern of the same colour and the same material as the surface that is underlying. These integrated tactile ground surface indicators that use the same colour must contain the minimum requirements of 30% luminance contrast across the entire area.

Discrete Tactile Ground Surface Indicators

This series of tactile ground surface indicators are individually installed and are not apart of a group. The tactile ground surface indicators must contain the minimum requirements of 45% luminance contrast across the entire area.

Composite Tactile Ground Surface Indicators

This series of tactile ground surface indicators are constructed by using two separate colours or materials. There is a raised surface that should have a section that contains the minimum requirements of 60% luminance contrast, including a diameter of 24mm to 25mm.