Luminous efficacy (also called lumen output ) is the amount of light produced and emitted by a light source, such as a lamp or fixture. It is measured in lumens (lm) and indicates how bright a light source is in terms of the total amount of visible light emitted. The more lumens, the more light is emitted by the lamp.
Importance of light output:
- Brightness : Light output determines how much light a lamp produces. This is the measure of the brightness of the light.
- Bulb Comparison : Comparing lumen output allows you to compare bulbs based on their brightness, regardless of the technology type (e.g., LED, incandescent, halogen, or fluorescent).
Lumen vs. Watt:
- Lumen indicates the amount of light a lamp produces.
- Watt indicates the amount of energy the lamp consumes.
It's important to understand that a high lumen rating doesn't always mean a bulb uses a lot of energy. For example, LED bulbs have a high lumen output (a lot of light) for relatively low wattage, while a traditional incandescent bulb requires much more wattage for the same light output.
Example:
- A standard 60-watt incandescent bulb produces approximately 800 lumens .
- A 9-10 watt LED bulb can also produce 800 lumens , but is much more energy efficient than an incandescent bulb.
Light output in practice:
- Low Lumens : For mood or accent lighting, such as a small night light, a low lumen output (e.g. 100-200 lumens) may be sufficient.
- High lumens : For general lighting in larger spaces, such as living rooms or kitchens, a higher light output is needed, for example 1500-3000 lumens depending on the size of the room.
Summary:
Light output (lumens) is a measure of how much light a lamp produces. It helps you choose the right bulb based on your desired brightness, while also considering energy consumption (watts).