UGR with interval number represents 10 to 30, the greater the number according to indoor light makes most people feel uncomfortable direct glare. For example UGR19 represent 65% of the people inside the space does not have real feel have glare interference, but the remaining 35% of the people will feel the light cause discomfort to the line of sight.

Easy to imagine the situation for everybody, you can clearly explain the relationship between these factors produce the glare of results to people. If you walk at night in a street lamps not completely dark, suddenly has a front lit the lamp of the car to you. You will soon feel caused by two beams of light glare and temporary blindness, makes you harder to see road. But if the same situation occurs in sunny summer night, the stars and the open headlight car to you again, this time what your eyes feel uncomfortable is far lower than the previous situation. Although the car headlights don't have any change, but on the degree of glare you feel is different because of the brightness of the background environment have head. The other user's location and the line of sight must also be taken into consideration. If the lamps and lanterns is beyond the scope of the line of sight of the man, he/she isn't affected by glare.

Certain regulations for regions such as the office, library, for example, ask its lighting UGR must be considered. Lighting design professionals can use the international commission on illumination CIE defined glare rating scale. 117-1995. The table to simplify the complicated formula, in order to check the design case of cloth lamp and lamp whether meet the UGR regulations.

However, LED light, scale limits need special attention. The UGR value is in the standard space calculation single kind of lighting glare. The standard space often with party a's place and environment has very big disparity. According to glare rating scale formula, reflection coefficient is 20%, the highest floor wall between 30% and 50%, floor between 50% and 70%. We often see in the building of the white wall or ceiling reflectivity is 75% to 90%, but has not been considered in scale in the formula. Another limitation is parallel or vertical scale observers can only with the position of lamps and lanterns, but fewer in the lamps and lanterns of diagonal position. In addition, the scale calculation of rectangular space, don't consider other shapes. Lamps and lanterns of each have their own UGR scale, but the actual situation of space often have more than one of lamps and lanterns, how to integrate different lamps and lanterns of UGR is a problem.

Common to the lamps and lanterns manufacturer UGR values such as UGR < 19 is written in the product description. Best giving the UGR obtained other relevant parameters, such as in the space of 4 h / 8 h, reflection coefficient 20% floor, wall and ceiling 50% and 70%, and so on.

In general, the LED light UGR form will appear in DIALux report, more details of the analysis can also use the DIALux UGR calculation point or UGR surface to calculate.