Glare

Glare

Glare is the discomfort, and sometimes, the disability, caused to the human eye due to the presence of very bright surfaces and/or contrast in the field of vision. Glare is (to an extent) subjective and depends a lot on a person’s age, quality of sight, and adaptability to certain environments. Glare and its related effects are defined extensively in Australian Standards. Glare cannot be ‘measured’, but can be calculated using complicated formulas and software.

July 19, 2021

Effects of glare:

·       Squinting and eye fatigue  

·       Annoyance and inconvenience  

·       Decreased visual comfort  

·       Colour distortion

·       Poor depth perception

·       Reduced quality of vision  

·       Glare and decreased safety go hand in hand

How to calculate glare:

·       Indoor electric glare is calculated and reported as UGR (Unified Glare Rating). It’s a logarithmic scale and the values range from 10 to 30—with 10 being the least glary space where no discomfort is caused and 30 being the most glary space where disability glare is being experienced. UGR takes into account three things: The background brightness of walls, ceiling and surfaces; the bright portions of the luminaire; and the luminaire position relative to the observer.

·       Outdoor electric glare is calculated and reported as GR (Glare Rating). It’s a logarithmic scale and the values range from 10 to 90—with 10 being the least glary space where no discomfort is caused and 90 being the most glary space where disability glare is being experienced.GR takes into account two things: The bright portions of the luminaire and the luminaire position relative to the observer.

The brightness of a luminaire or a source is dependent on its size and light output. Hence, with LEDs, glare is very important and critical, because a tiny light source produces a high amount of light.

Ways to reduce glare:

·       Shield the source

·       Use deep-set fittings

·       Use diffusers

·       Use matt surfaces

·       Select proper beam angle

·       Use dimming

·       Remove the luminaires from your line of sight

For the same amount of light output - luminaires b, d and f will appear less glary than a, c and e.