An assessment on the limitations of the Unified Glare Rating (UGR) System - Comparison between Eastern and Western Subjects [ PDF

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(1)An Assessment on the Limitations of the Unified Glare Rating (UGR) System Comparison between Eastern and Western Subjects Odalea Melo testing, of the 31 subjects on the Goldmann. Introduction Several different systems for evaluating and. Perimeter. To the three remain experiments a. controlling discomfort glare have been evolving. new machine is created, the Glare Testing. independently in many countries and some have. Instrument.. been. officially. adopted. as. At first, the perimetry were tested from the. national. right eye because the time was an important. recommendations for Interior Working Places. The. Commission. Internationale. de. factor (the left eye could be mirrored for the. L'Eclairage, CIE report 117(1) introduces a new. Graphics.1 and 2). The. Unified Glare Rating (UGR) Method based upon. Lb 10 cd/m2 and 5 Isopters were selected from the. the existing Glare Index that is a practical. smallest and easiest to see, to the largest one. discomfort glare evaluating system for use in. (Isopters :I/1, I/2, I/3, I/4 and V/4, Table.1). To. interior lighting.. each subject, a period time given was 15 minutes.. The basic studies on discomfort glare were performed by Luckiesh and Guth. (2),. background luminance,. As for each Isopter the observer was asked to. 1949, and. look a fixed point in the. Hopkinson (3), 1963. Research has been carried out in efforts to. center of the sphere and. extend the applicability of the UGR formula. In. to stop the source light. the. psychological. when he was able to see. experiments were conducted to examine the. it. The source light is. sensitivity to a single glare source.. displaced from out off the. present. study,. successive. visual field to the center. The experiments and analyses are described. of the sphere.. here with the aim of elucidating the correlation between the UGR and the subjective glare rating,. Figure.1-Goldmann Perimeter. for Eastern and Western subjects.. Source Size No mm². Multiple Criterion Technique, same used by. 0 I II III IV. 1/16 1/4 1 4 16. Source Intensity Relative No. Brightness 1 0.0315 2 0.1 3 0.315 4 1 Added light intensity. Hopkinson, was implemented in this study.. V. 64. of 100 mililamberts. Methodology Thirty-one subjects aged between 20 and 40 were tested. Twenty-six of them were Japanese or Korean and five were from South America. The. Then, also a Single Criterion was conducted when. Table.1 Luminance ranges at the Goldmann Perimeter. a single standard is selected.. *1 mililambert= 0, 3142 cd/m2 (IES Lighting Handbook, 1984). In total, the 4 experiments presented here. The. were derived from 2 machines; the Goldmann Perimeter. (4). new. apparatus. consist. of. a. semi-spherical (66cm diameter) shelter covered by. (Figure.1) and the Glare Testing. white paper. The window (28x28cm) was cut from. Instrument (Figure.2).. the center of the sphere where a small hole was. At the beginning, the first experiment is. punctured. That location also relates to the line of. conducted to obtain the perimetry, the visual field. the observer’s vision. The lines on the white paper. 35-1.

(2) indicate the positions of the source (in degrees).. had been more easily determined by the subjects in. To obtain the illumination of the visual field (the. the. background luminance) an incandescent lamp. luminance was 10, 30, 100 and 300 cd/m2 and. was placed above the head of the observer and a. source size was 5, 10, 20 and 40 mm diameter at. shield was used. Through the white paper the. positions of 0°, 10°, 30°, 45° and 60° on the line of. observers could evaluate. sight. The procedure was also the same as in the. the sensation from the. previous. optic fiber lamp (5mm. determining the luminance correspondent to a. diameter).. required degree, the source brightness is decreased. To make control of. previous. experiment.. experiment.. The. After. background. the. subject. the. and leaves the subject to the adaptation field. That. environmental conditions,. procedure is conducted to avoid fatigue and the. the use of a dimmer was. experimenter to change the position of the source. very important.. and start again. Therefore, the sources were. Figure.2- Glare Testing Instrument. displaced on the line of the vision from 80° (in a horizontal plane) to 0° (which represents the. Incandescent. fixation point); and 15 minutes were the time used. Fiber optic lamp. lamp Ranges of. Size of the source. luminance adopted. No.. ! cd/m²". (mm) #5. 10$300. to each sample (Table.7).. Possible. In the fourth and last experiment, a. ranges of Solid angular. luminance. "#$teradian" 0.00018. 0$300000. comparison. ! cd/m²". #10 #20. 0.00072 0.0029. 0$27000 0$10000. #40. 0.012. 0$8000. between. the. results. from. the. Goldmann Perimeter and the Glare Testing Instrument was conducted to show the curves of sensitivity to glare and the curves limiting the. Table.2 Luminance ranges and limitations on the Glare Testing Instrument. visual field (Table.4, Table.1, Graphics.1 and 2).. In the second experiment, the Multiple. Background Luminance Source size Source （mm） Lb#cd/!" position. Criterion Scale, the observer’s were asked to. 10. assess discomfort from the 4 recognized criteria: R.. !5. 0°∼360°. Source intensity (cd/!" s1. s2. s3. s4. s5. 1500. 2400. 4500. 24000. 70000. Table.4 Glare source positions. G. Hopkinson Glare Criteria, Table.3. Glare Category. Degrees of. Lb 10 cd/m² 5 WEST ISOPTER +GLARE (0° represents the line of sight). Observer's reaction. discomfort glare Just Perceptible. 1. I am aware to the glare. Just. 2. I am aware to the glare. Acceptable Just. even it does not bother me 3. Uncomfortable Just Intolerable. 90° 105°100° 90° 120° 80° 135° 70° 60° 150° 50° 40° 30° 165° 20° 10° 0° 180°. I am aware to the glare and starts to bother me. 4. I can not keep looking. 75°. 45° 30° 15° 0°. 195°. Table.3 The Multiple Criterion Scale. 345°. 210°. 330°. 225° 240° 255°. The source size was 5mm diameter (!. 60°. 315° 300° 285° 270°. =0,00018 sr) and at positions of 0° and 30° on the. I1. I2. I3. I4. V4. line of sight (0° represents the fixation point).. s1. s2. s3. s4. s5. The background luminance was 10 and 30. Graphic.1 Average about the visual field and glare source. cd/m2 (Table.5, next section).. positions, 5 WESTERN. As for the third experiment, the single criterion was selected, Just Acceptable, because it. 35-2.

(3) The Lb 10 cd/m² 26 EAST ISOPTER +GLARE. 75°. importance of locating glare sources on the line of sight, where the difference in the visual field is not as large as in the vertical plane. A comparison. 330° 315° 300° 285°. between the Isopters and glare source positions shows that they have similar curves of sensitivity.. 270° I3 s3. Western. below of the line of sight). These results show the. 345°. I2 s2. and. difference appears (about 17°, 9° above and 8°. 0°. 195°. I1 s1. Eastern. plane (4°), but for the vertical plane a great 60° 45° 30° 15°. 210° 225° 240° 255°. of. subjects shows a slight difference on the horizontal. (0° represents the line of sight) 90° 105°100° 90° 120° 80° 135° 70° 60° 150° 50° 40° 30° 165° 20° 10° 0° 180°. perimetry. I4 s4. The Multiple Criterion Technique indicates. V4 s5. that the correlation with UGR scale and the scale Graphic.2 Average about the visual field and glare. adopted in the experiment have a good agreement.. source positions, 26 EASTERN. The results from the Single Criterion, Just Acceptable, show that Western subjects are more. Correlation between UGR method and the. tolerant to glare than Eastern subjects. As for the Single Criterion (UGR-15~17), a difference about UGR units between Eastern and Western subjects is shown on Table.8.. subjective appraisals The UGR Formula: & 0.25 L2ω # UGR = 8 log $ ' P2 ! % Lb " Where:. Glare. Source. Criterion. Lb = background luminance (cd/m2), the average background. 1Just Perceptible. luminance of the luminous parts of each luminaire in the. 3Just Uncomfortable. by the luminous parts of each luminaire at observer’s eyes (sr); P = the Guth position index for each luminaire (displacement from. 0°. 2Just Acceptable. 10. 5787 (17 )* 7822 (17 )* 13386(23 )* 21953(24 )*. 4Just Intolerable. !5. 33660(30 )* 56742(30 )*. 1Just Perceptible. 3856 (11 )* 5271 (10 )*. 2Just Acceptable. 30. 9026 (17 )* 10676 (15 )*. 3Just Uncomfortable. 24248 (24 )*29631 (22 )*. 4Just Intolerable. 41549 (27 )*58143 (27 )*. (*UGR value). 13 – 16 – 19 – 22 – 25 – 28. Where high values indicate more discomfort glare and low values indicate low discomfort.. Glare sensation adopted. Correspondent. in the experiment. UGR value. 1. 10∼13. 2. 15∼17. 3. 22∼24. 4. 27∼30. The UGR Limitations: The UGR System is limited to source sizes from 0,0003 to 0,1 steradian, subtended at the eye. Table.6 Glare sensation adopted in the experiment and respective UGR value. in a uniform background luminance (0,0003 sr as an incandescent lamp seen from about 10m; 0,1sr, a 1m2 luminaire seen from about 3m).. UGR scale. Source size !5 ("=0,00018sr). Results and Conclusion The difference in sensitivity to discomfort glare between countries and cultures is a very important point. Even if it is difficult to investigate these. Lb10cd/m² Lb10cd/m² Lb30cd/m² Lb30cd/m². 40 37 34 31 28 25 22 19 16 13 10 1. -. 0° 30° 0° 30°. 2. 3. 4. differences which involve factors of sensitivity and. Glare sensation adopted in the. also the language, it is important to be careful. experiment. when. translating. 30°. 2892 (13 )* 4038 (12 )*. Table.5 The Multiple Criterion Scale. the line of sight).. The UGR Scale:. Average source intensity (cd/m²). (mm). luminance of the field of view excluding the glare source; L = the. direction of observers’ eyes (cd/m2); ! = the solid angle subtended. Lb. Size (cd/m²). scales. and. working. with. Graphic.3 The Multiple Criterion Scale (0° represents the fixation point). subjective appraisals.. 35-3.

(4) UGR scale. Lb 10 (cd/m²) E26+W5. Lb #cd/!". size#mm". 0%. 10%. 30%. 45%. 60%. 10. &5. 3752(14)* 3054(18)* 1530(18)* 8989(31)*. 10409(20)* 2686(17)* 1395(17)* 5130(25)*. 13577(19)* 3205(18)* 1709(16)* 2078(22)*. 11774(17)*. 15127(16)* 4756(21)* 2353(12)* 2806(19)*. 7815(16)* 4355(16)* 3169(19)* 2839(23)*. 12377(18)* 4589(16)* 2974(18)* 2530(23)*. 13813(17)* 5766(15)* 2930(18)* 2840(23)*. 23474(18)*. &10 &20 &40. 7680(15)* 3066(19)* 3424(24)*. 30903(17)* 8284(13)* 3384(20)* 3668(25)*. &5. 12734(13)*. 21937(17)*. 40454(20)*. 29436(19)*. 38856(21)*. &10. 7099(14)* 3751(14)* 4436(20)*. 7632(13)* 3645(14)* 3304(19)*. 11081(14)* 3740(11)* 3882(16)*. 9611(11)* 3624(9)* 4725(15)*. 10580(9)* 4579(8)* 4485(13)*. &5. 7863(10)*. 39268(15)*. 65942(18)*. 27375(18)*. 29000(19)*. &10. 10128(15)* 6195(22)* 4858(26)*. 12464(16)* 5859(24)* 5173(27)*. 15948(17)* 4372(22)* 4259(24)*. 20074(18)*. 20515(17)* 7955(27)* 3041(20)*. !10. &5. 30. !20 !40. 100. 0°. 10°. 30°. 45°. 60°. Source luminance and respective source position on the line of the sight. &10 &20 &40. !5. 40 37 34 31 28 25 22 19 16 13 10 7. Source. &20 &40. 80°. Source position on the line of the sight (degrees). 300. &20 &40. Graphic.4 The Single Criterion Scale、Lb 10 cd/ m2 (Just Acceptable - UGR scale 15 ~ 17) Average of 31 Subjects, Eastern and Western. 3488(19)* 1971(14)* 1794(19)*. 3700(19)* 4987(23)*. *UGR value. Table.7 The Single Criterion Scale. (Just Acceptable ~ UGR scale 15 ~ 17) Average of 31 Subjects, Eastern and Western. UGR scale. Lb 30 (cd/m²) E26+W5 !5. 40 37 34 31 28 25 22 19 16 13 10 7. !10. Lb. Source. !20. #cd/!". size. !40. 10°. 30°. 45°. 60°. 30°. East West. East. 45°. West. 60°. East West. East West. 13. 16. 24. 15. 23. 15. 19. 15. 17. 17. 18. 16. 18. 15. 21. 13. 24. 11. 30. !20. 18. 18. 17. 18. 15. 16. 13. 15. 10. 15. !40. 23. 39. 21. 39. 20. 23. 18. 20. 17. 21. !5. 15. 16. 18. 19. 17. 17. 17. 19. 16. 18. !10. 16. 17. 15. 17. 14. 17. 14. 16. 12. 14. !20. 19. 19. 17. 19. 15. 22. 14. 24. 12. 28. !40. 22. 24. 21. 24. 19. 27. 17. 31. 15. 34. !5. 11. 15. 15. 19. 18. 22. 23. 15. 27. 14. !10. 11. 16. 10. 17. 10. 18. 9. 13. 6. 11. !20. 9. 18. 9. 18. 8. 14. 7. 11. 5. 10. !40. 16. 24. 13. 24. 13. 20. 11. 19. 9. 16. !5. 8. 13. 12. 18. 17. 20. 20. 16. 25. 14. !10. 13. 16. 16. 20. 15. 22. 14. 26. 9. !5. 16. !20. 26. 18. 29. 18. 34. 10. 38. 1. 43. 10. !10. !40. 31. 21. 33. 21. 34. 15. 33. 14. 32. 7. 30. 100. Graphic.5 The Single Criterion Scale, Lb 30 cd/ m2. Lb 100 (cd/m²) E26+W5. UGR cscale. 10°. West. 16. Source position on the line of the sight (degrees). 300. !20. Table.8. !40. UGR. value. for. Just. Acceptable. criterion. (UGR-15~17) to Eastern and Western subjects. References 0°. 10°. 30°. 45°. 60°. (1) CIE Technical Report 117:”Discomfort Glare in Interior. 80°. Source position on the line of the sight (degrees). Lighting”, 1995.. Graphic.6 The Single Criterion Scale, Lb 100 cd/ m2. (2) M. Luckiesh and S. K. Guth, Brightness in Visual Field at Borderline. Lb 300 (cd/m²) E26+W5. UGR scale. East. !5. 80°. 40 37 34 31 28 25 22 19 16 13 10 7. #mm " !10. 10. 0°. UGR value and respective source position on the line of sight 0°. 40 37 34 31 28 25 22 19 16 13 10 7. Between. Comfort. and. Discomfort. (BCD),. Illuminating Engineering Society, Vol. XLIV, No. 11, p. 650, !5. 1949.. !10. (3) R. G. Hopkinson: “Architectural Physics: Lighting”, 1963. !20 !40. (4) G. W. Tate, Jr., M.D., Principles of Quantitative Perimetry: Testing and Interpreting the Visual Field, 1977. (5) CIE Publication No.55: “Discomfort Glare in the Interior Working Environment”, 1983.. 0° 10° 30° 45° 60° 80° Source position on the line of the sight (degrees). (6) IES Lighting Handbook, Illuminating Engineering Society,. Graphic.7 The Single Criterion Scale, Lb 300 cd/ m2. 1984. (7) CIE DS 008.1/E: “Lighting of Indoors Working Places”, 1999.. 35-4.

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