The methods of calculating average luminance contained in this Guide cover various open bottom apertures as well as flat and drop lensed units, including units with multiple openings in the light emitting area. The candela values of interest are obtained by means of IES techniques for relative or absolute photometry, and are not obtained from field measurements in application. Note: Average luminaire luminance is not a reliable indicator of either direct or reflected glare due to potential luminance non-uniformity.
The averaging of data from spot luminance measurements obtained with luminance meters or high resolution imaging systems is not within the scope of this document. This calculation is based solely on the candela values obtained by goniometric measurement of the luminaire and the luminous projected area.
All light sources, for which there are current standards for luminaire photometry, are covered by this Guide. These include incandescent, fluorescent, high intensity discharge (HID), low pressure sodium, and LED sources.
Nomenclature and Definitions
General method of calculation of average luminance (Calculated)
Annex A - Representative Area Formulas Reference (not all-inclusive)
A.1 Circular Luminaire Opening (Open Bottom or Flat Lens)
A.2 Circular Luminaire Openings with Drop Lenses (Truncated Cone)
A.3 Square or Rectangular Luminaire Openings (open bottom or flat lens)
A.4 Square or Rectangular Luminaire Openings with Drop Lenses
A.5 Spherical Lens
References (for Annex A)