The Lighting Effectiveness Factor (LEF) is a measure of the efficiency and effectiveness of a lighting system , taking into account the amount of light actually used for the intended task . It is often used to evaluate the performance of a lighting application by looking at the ratio of light produced to the actual illumination utilized .
1. How is the Lighting Effectiveness Factor calculated?
The LEF is calculated as the ratio of the amount of light illuminated (lux) on the work plane to the total light output (lumens) generated by the system.
📌 The higher the LEF, the more effective the lighting system in using the generated light energy.
2. Factors that influence LEF
| Factor | Influence on LEF |
|---|---|
| 🏢 Reflection of surfaces | Light surfaces reflect more light and increase LEF. |
| 💡 Type of lighting | LED lighting has a higher LEF than traditional incandescent bulbs due to higher efficiency. |
| 🏠 Layout of the room | Spaces with an open layout often have a higher LEF, because light can spread well. |
| 🧹 Maintenance of luminaires | Pollution and dirt reduce LEF by scattering light. |
| 🌡 Ambient temperature | Higher temperatures can reduce the efficiency of some lamps, lowering the LEF . |
📌 The LEF helps to measure the actual effectiveness of a lighting system in different environments.
3. Applications of the Lighting Effectiveness Factor
| Application | Why is LEF important? |
|---|---|
| 🏢 Office lighting | Helps maximize lighting efficiency for productivity and energy savings. |
| 🏪 Shop lighting | Ensures that lighting effectively highlights products without wasting energy. |
| 🏗 Industrial lighting | Improves light distribution for safety and working comfort. |
| 🌍 Public lighting | Increase the effectiveness of street lighting for energy savings. |
📌 LEF is especially important when designing sustainable and energy-efficient lighting systems.
4. How can the LEF be improved?
🔹 Use energy-efficient lamps such as LEDs for higher light output with lower energy consumption.
🔹 Keep fixtures clean through regular maintenance to reduce light loss due to contamination.
🔹 Use reflective materials in the space to optimally utilise light and increase LEF.
🔹 Optimize lighting layout to maximize light distribution and reduce dark spots.
📌 Improvements in fixtures, lamps and maintenance can significantly increase LEF, leading to more efficient energy use and better lighting.
💡 In short:
The Lighting Effectiveness Factor (LEF) is a measure of the efficiency of a lighting system , indicating how much of the generated light energy is effectively used for the intended illumination. A high LEF indicates an effective system with optimal light distribution and less waste .