RECOMMENDED ILLUMINANCE LEVELS FOR VISUAL TASKS IN BUILDINGS
Keywords:
Visual performance, illuminance, recommendation, ThailandAbstract
Illuminance recommendations in Thailand have been adopted from western standards’documents. Using the adopted illuminance standards for Thai people is questioned. Themain objectives of this paper are to compare the visual performances of Thai people andwestern people under different lighting quantities and to suggest appropriate illuminancelevels to perform various visual tasks for Thai people. The final part of the study comparesthe study’s results to the existing lighting recommendations and legislation standards inThailand. Firstly, the visual performances of 36 subjects of various ages were tested in thelighting laboratory with the same method used in the original research by Weston (1945).The visual task used in this experiment was finding the directions of Landolt rings ondifferent charts under 6 illuminance levels (5, 22, 86, 345, 1,380, and 5,510 lx). Landolt ringsizes of 4.5, 3.0, and 1.5 min of arc and contrasts of 0.97, 0.56, 0.39, and 0.28 were included.In the second part, the obtained illuminance levels were then tested for satisfaction underreal situations. The results showed that the average visual performance scores of Thaisubjects were lower than those found by Weston. However the recommended illuminancelevels obtained from the study were similar to the ones of Weston in every task group.When comparing the recommended illuminance levels with Thai legislation, theilluminance criteria in legislation in Thailand were relatively lower. When considering thesatisfaction test, the illuminance levels of the Illuminating Engineering Society of NorthAmerica were relatively low compared to the test results.
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