AS 1428.1-2009 PWD Code.pdf

AS 1428.1—2009                                 100




                                          APPENDIX B
                THE MEASUREMENT OF LUMINANCE CONTRAST BETWEEN
                              BUILDING ELEMENTS
                                          (Informative)

       B1 GENERAL
       This Appendix sets out two methods for measuring the luminance contrast between
       building elements—in a laboratory or on-site.
       Where it is necessary to achieve sufficient luminance contrast between building
       elements, this can usually be achieved by using very dark or very light materials.
       The luminance contrast is achieved by measuring the luminous reflectance of the
       first building element and comparing it with the luminous reflectance of the second
       building element , as set out in Paragraphs B3 and B4 or B5.

       B2 LUMINANCE CONTRAST REQUIREMENTS
       Luminance contrast between building elements is the difference in the amount of
       light reflected (luminance reflectance) from the 1st building element compared to
       the amount of light reflected from the 2nd building element.
       The first building element has to have a minimum luminance contrast of 30%
       compared to the amount of light reflected from the second building element.
       It may be necessary to test both elements when wet and dry.
       The test to be conducted may be carried out in the laboratory and on-site, and for
       published results to then be compared.

       B3 MEASUREMENT OF LUMINANCE CONTRAST—LABORATORY
       B3.1 General
       This Paragraph sets out a method for measuring the luminous reflectance of
       building elements. The method is carried out with reference to a standard light
       source, which is an inherent feature of suitable colorimeters and
       spectrophotometers.
         NOTE: Some buildings materials manufacturers do publish luminous reflectance values
         for each of their products.
       This test method is not suitable for measuring the luminous reflectance of
       translucent materials or illuminated objects. It is less applicable where the
       measured surface is not uniformly coloured.
         NOTE: The method specifies colorimeters and spectrophotometers that are widely
         available.
       B3.2 Instrumentation
       A tristimulus colorimeter, or spectrophotometer with a diffuse illumination/normal
       viewing (d/o) geometry, is used with CIE Standard Illuminant D65. The instrument
       has to be capable of measuring absolute CIE for Y xy to be calculated. The
       measured luminous reflectance is defined by the tristimulus value Y. The
       chromaticity coordinates x and y provide an indication of the colour.




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