lighting calculation principle

lighting calculation principle

(A) Understand the basic knowledge: lumen, Lux, etc

Fundamentally, lighting computing is about understanding the behavior of light. You need to know some key terms:

Lumens (lm) measure the total light output of a luminaire. Think of it as a "quantity" of light.

Lux (lx) represents the amount of light that hits a specific surface, i.e. the luminous flux per square meter. Imagine the sun shining on a table - how bright is it?

The Candela (cd) is a unit of light intensity in a given direction, like the beam of a flashlight.

Foot candle (fc, primarily used in the United States) is Lux's imperial equivalent, representing the luminous flux per square foot.

(B) Key formula

Let's start with the basics. To calculate illuminance (the amount of light falling on A surface) : E=Φ/A

Where E is the illuminance (Lux), Φ is the luminous flux (lumens), and A is the area (square meters).

This formula helps determine how much light is covering a particular area and is crucial for designing effective lighting solutions.

(C) illuminance and brightness: the difference between Lux and lumen

Take the flashlight, for example. Lumen will tell you how strong it is, but Lux will tell you how dispersed the light is across the surface. A high-lumen light bulb in a small room feels bright, but the same light bulb in a large room may feel dim.