Factors determining discomfort glare are described and a general relationship between source luminance and size producing borderline comfort/discomfort (bcd) glare for an 'average' observer is given. The fundamental relationship is extended to the ease of a source displaced at an angle to the line of sight and to several sources. It is shown that glare effects from a number of sources may be combined by an appropriate function and good agreement is obtained between calculated and subjectively determined indices of sensation for a variety of lighting systems. Using the criterion of bcd the distribution of discomfort glare ratings (dgr) for over 200 observers and 41 experimental conditions was determined and a visual comfort probability (vcp) estimated. Percentage rations expressed in terms of vcp represent a figure of merit for the lighting system under consideration, thus relating dgr and vcp. In this research source and field luminances were measured in footlamberts and appropriate corrections are needed to the fundamental equation for index of sensation when SI units are employed. /Author/TRRL/

  • Availability:
  • Corporate Authors:

    ARRB Group Ltd.

    Vermont South, Victoria  Australia 
  • Authors:
    • Guth, S K
  • Publication Date: 1977-11


  • English

Media Info

  • Features: Figures;
  • Pagination: 7 p.
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00180016
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Monograph
  • Files: ITRD, TRIS
  • Created Date: Sep 27 1978 12:00AM