| | | UGR Values for determination of direct glare The "Unified Glare Rating (UGR)" method was developed by the CIE (Commission International de the Eclairage) to have to have a universal standardized system for evaluating glare. This method is based upon on a formula similar to that of the British Glare-Index system. Unlike Sollner's diagrams, which give evaluations to the glare of each single fitting, the UGR formula was studied and developed to judge glare generated by an entire and complete lighting system. With this objective in mind, the formula considers the luminance of every installed fitting and the luminance of the walls or ceiling where they are installed with respect | | |
| | | to positions where an observer would normally stand. The diagram shows two UGR values for a standard room. The first refers to a transversal view with respect to the fittings and the second to a longitudinal view. They are absolute values related to the rated flow of the lamps installed. We took a standard location into consideration. 8 H length and 4 H width. The spacing of the fittings in both directions is S=0,25 H. reflection index: ceiling 70%, walls 50%, floor 20%. H=height of the light fitting above the eye of the observer. | | |
| | | DIN 5040 According to this standard, the photometric classification of light fittings is composed of one letter and two numbers (A60, for example). The letter (A,B,C,D,and E) identifies the percentage of light flux emitted in the lower and upper hemispheres. The closer to letter A, the higher the percentage of flux emitted in the lower hemisphere. The numbers that follow identify, respectively, the flux toward the work surface and the flux toward the ceiling in a typical standard configuration. | | UTE C71-121 The photometric classification of the light fittings is composed of the output in the lower hemisphere followed by a letter, plus the output in the upper hemisphere followed by another letter (for example: 0,50D+0,24T). The letters range from A to J and they represent the percentage of light flux within set solid angles, while the presence of letter T indicates that part of the light flux is emitted into the upper hemisphere. | | CIBSE The photometric classification of the light fittings is divided into ten categories (BZ1.....BZ10). The category indicates the percentage of light flux emitted into the lower hemisphere which directly reaches the work surface in a typical configuration. For this reason the classification is also related to the location index. For instance, the fittings classified as BZ1 emit higher quantities of light flux onto the work surface than fittings identified BZ2 -10 | | |