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Luminance Contrast Calculator

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In Australia there are approximately 300,000 people who are either blind or vision impaired and this number is rapidly increasing with one person being diagnosed with a vision impairment that cannot be corrected by wearing glasses or contact lenses every 65 minutes. It has been estimated that by 2021 this number will increase to over 420,000 Australians.

Vision Australia defines vision impairment as simply meaning that a person has some degree of sight loss. Some forms of impairment may be treatable through corrective lenses however many eye conditions remain untreatable.

It is therefore important to ensure that a built environment is designed to assist and support those members of the community who have a degree of vision impairment. The Building Code of Australia (BCA), forming Volumes 1 and 2 of the National Construction Code require minimum ‘deemed to satisfy’ requirements for levels of luminance contrast to be provided to some building elements in an accessible path of travel, including tactile ground surface indicators (or TGSIs), stairway nosings, Braille signage, lift control buttons, glazing and doorways as well as accessible toilet seats. It is however important to remember that the BCA specifies a minimum requirement only and may omit other important finishes and surfaces outside those detailed in the BCA.

Luminance contrast is defined in Australian Standard 1428.1-2009 as ‘the light reflected from one surface or component, compared to the light reflected from another surface or component’.  It is not simply the difference in the colour contrast but the difference in the light reflective properties of each colour. 

Good selection of internal finishes with appropriate luminance contrast will assist people with low vision navigate through the built environment and help to identify features such as doorways and information signage – as well as hazardous areas such as stairway, ramps and areas with a danger of vehicle impact.

Luminance contrast between building elements is the difference in the amount of light reflected (or luminance reflectance) from a darker building element compared to the amount of light reflected from a second lighter building element.

Measuring Luminance Contrast

There are essentially two ways to measure the luminance contrast, in a laboratory or on-site, but both require the use of an expensive tristimulus colorimeter or spectrophotometer.  The equipment will measure the ‘Luminance Reflective Value’ of each surface.  Fortunately most reputable manufacturers of paint  will provide this information to designers and is often available on colour charts as an ‘LRV” value.
 
Equal Access Pty Ltd has developed an online Luminance Contrast Calculator tool to assist designers and certifiers check if two colours will achieve a minimum luminance contrast, which takes the hard work out of calculating the value yourself (and without having to decipher the Bowman-Sapolinski equation C = 125 (Y2 − Y1)/(Y1 + Y2 + 25)).  It simply requires the user to enter the two LRV values to determine the luminance contrast of the two colours.

To go to the website and download the App click here

 

This information comes from the website of Equal Access Pty Ltd

 


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