User:Sjr/Sandbox
From WikiLectures
Joint lighting[edit | edit source]
- Joint lighting is the simultaneous lighting of an area with both artificial lighting and daylighting.
- This type of lighting is much more favorable than complete artificial lighting as it includes a number of the natural spectra of daylight.
- Even good artificial light is inadequate as a substitue for daylight.
- Joint lighting has the advantages of both day light ( spectral composition, variability) and artificial light ( adequate intensity).
- Obviously a higher concentration of daylighting than artificial lighting is preferable.
- Mixing ratio of daylight and artificial lighting should be at least 1:1. At a ratio of 1:5 and less, the test results differ very little from results obtained in artificial lighting only.
- Measurement and evaluation of the joint lighting is not easy. It consists of a constant component and a large amount of variability and spectral composition.
Glares (dazzles)[edit | edit source]
- Difficulty seeing in the presence of bright light such as direct or reflected sunlight or artificial light such as car headlamps at night
- Can be caused directly by a light source, or by its reflections on surfaces with a higher reflection factor.
- Glare is caused by a significant ratio of luminance between the task (that which is being looked at) and the glare source.
3 types[edit | edit source]
- Dazzle by critical brightness:
- Direct sunshine - The eyes cannot adapt and the person cannot see well.
- Critical value of brightness ranges from 200 000 to 1 000 cd.m -2.
- Transitory dazzle:
- Due to sudden change of brightness. - going from inside to bright outside. The eyes takes some time to adapt.
- There is a sudden change in brightness of the visual field at a rate greater than 1:100
- Dazzle by contrast:
- When there are surfaces of various brightness. The eye cannot adapt to both and a dazzle occurs e.g. bulb fiber on wall.
Glare reduction[edit | edit source]
- Glare can be reduced using a number of methods:
- Sunglasses - polarized sunglasses are designed to reduce glare caused by light reflected from surfaces such as water - used mostly by fly-fishers.
- Some cars include mirrors with automatic anti-glare functions.
- Anti-reflective treatment on eyeglasses reduces the glare at night
Bibliography[edit | edit source]
- BENCKO CHARLES UNIVERSITY, PRAGUE 2004, 270 P, V, et al. Hygiene and epidemiology. Selected Chapters. 2nd edition. Prague. 2008. ISBN 9788024607931.
