Illuminance

Illuminance, often confused with luminous flux or intensity, is the amount of luminous flux incident on a surface per unit area. It quantifies how much light actually *falls* on a surface, impacting how bright that surface appears to the human eye. Measured in lux (lx) - one lux equals one lumen per square meter - it's crucial for understanding the visibility and visual comfort of a space. Factors affecting illuminance include the light source's intensity, the distance from the source, and the angle of incidence. Lower illuminance can lead to eye strain, while excessive illuminance can cause glare and discomfort. Its application is vast from architectural and engineering fields to even photography where it can be used to set aperture and shutter speed for different lighting scenarios.

Illuminance meaning with examples

• The interior designer meticulously calculated the illuminance levels throughout the office space. They ensured that areas dedicated to detailed tasks, like drafting and data entry, would have higher lux values than break areas. This was to provide adequate lighting without causing any eye strain. This careful management ensured that visual comfort and productivity remained optimal for employees.
• When assessing the effectiveness of a street lighting project, engineers primarily analyzed the illuminance provided by the new LED fixtures. They needed to ensure enough light reached the sidewalks and roadways, ensuring adequate illuminance levels for safety and visibility. They used specialized meters and calculations to measure the light levels and compared them against existing standards and regulations to make sure enough was provided.
• In photography, the photographer used an illuminance meter to measure the amount of light available in the scene. Based on the illuminance reading, the correct exposure settings - aperture, shutter speed, and ISO - were determined. Ensuring a balanced light exposure was crucial, helping to capture the image with the appropriate brightness, and without the problem of overexposure or underexposure.
• The research team studying the effects of light on plant growth measured the illuminance levels throughout the experimental greenhouse. They carefully controlled and monitored how much light, or illuminance, each plant received. They looked at the impact of varying intensities of light, or different lux values, on the plants' rate of growth and overall health and wellbeing. They analyzed the effect of a high illuminance vs. low illuminance on the success of the plants.