The Floor Cavity Ratio (FCR) is a measurement in lighting design that describes the geometric relationship between the floor and surrounding surfaces of a space. It helps calculate how light is reflected within a space , specifically from the ceiling and walls to the floor.
1. How is the FCR calculated?
The Floor Cavity Ratio (FCR) is calculated using the following formula:
whereby:
- = the height of the floor cavity (distance from the work surface to the floor)
- = the width of the room
- = the length of the room
📌 What does this formula mean?
- A higher FCR means that a larger portion of the light is absorbed by the floor.
- A lower FCR means that more light is reflected indirectly by the walls and ceiling.
2. Why is the Floor Cavity Ratio important?
✅ Determines the lighting efficiency → How much light actually reaches the floor.
✅ Helps with light reflection calculations → For even lighting in offices, shops and industrial buildings.
✅ Influences energy efficiency → The higher the FCR, the more important floor reflectance becomes.
✅ Essential for indirect lighting → For ceilings and walls with high reflection values, the FCR can help to achieve optimal light distribution.
📌 In lighting design, the FCR is a crucial parameter to determine how light is distributed in a space.
3. Applications of the FCR
🏢 Offices and workplaces → Optimal use of light reflection for energy savings.
🏪 Shops and showrooms → Good lighting at floor level for product presentation.
🏗 Industrial halls and warehouses → Efficient lighting minimizes dark areas on the work floor.
🏡 Residential Lighting → In open spaces with plenty of natural light, FCR helps determine how artificial light is distributed.
📌 Architects and lighting designers use the FCR in combination with the Room Cavity Ratio (RCR) and Ceiling Cavity Ratio (CCR) for a complete lighting analysis.
💡 In short:
The Floor Cavity Ratio (FCR) helps analyze how light is reflected within a space , specifically how effectively light reaches the floor. It is used in lighting design for offices, shops, industry, and architecture to achieve optimal light distribution and energy savings .