All you need to know about foot candles
When it comes to designing efficient and well-lit spaces, understanding foot-candles is essential. Foot-candles are one of the most widely used units of measurement in the lighting industry. They play a crucial role in determining the right amount of illumination needed for different areas, from commercial offices to industrial warehouses.
This guide will explain everything you need to know about foot-candles, including how they are calculated, recommended lighting levels for different spaces, and how Energy Design Engineers (EDE) can help optimize your lighting design.
What Is a Foot-Candle?
A foot-candle (fc) is a unit of measurement that indicates how much light falls on a one-square-foot surface from a uniform light source. It is commonly used in lighting design to measure the brightness or illuminance of a space. Unlike lumens, which measure the total light output from a source, foot-candles measure the light that actually reaches a surface.
Key Concept:
1 foot-candle = 1 lumen per square foot.
Why It Matters:
Designing a space with the correct foot-candle levels ensures visibility, safety, comfort, and energy efficiency. For instance, warehouses may require only 10-30 foot-candles, while educational facilities like classrooms may need 40 foot-candles to provide sufficient light for reading and writing.
How to Measure Foot-Candles
To measure foot-candles, lighting professionals use a device called a light meter. The meter is placed on the surface where the light is measured, and it calculates how much light is actually reaching that point. The reading is displayed in foot-candles (fc).
Simple Formula for Foot-Candles:
Recommended Foot-Candle Levels for Different Areas
The Illuminating Engineering Society (IES) has established recommended foot-candle levels for various spaces. Below is a list of common areas and the recommended foot-candle levels:
Warehousing & Storage
| Area | Recommended Foot-Candles | Range |
| Bulky Items (Large Labels) | 10 fc | 5 – 15 fc |
| Small Items (Small Labels) | 30 fc | 15 – 30 fc |
| Cold Storage | 20 fc | 10 – 30 fc |
| Open Warehouse | 20 fc | 10 – 30 fc |
| Warehouse with Aisles | 20 fc | 10 – 30 fc |
Commercial Office Spaces
| Area | Recommended Foot-Candles | Range |
| Open Office | 40 fc | 30 – 50 fc |
| Private Office | 40 fc | 30 – 50 fc |
| Conference Room | 30 fc | 20 – 50 fc |
| Restroom | 18 fc | 7.5 – 30 fc |
| Break/Lunch Room | 15 fc | 5 – 20 fc |
Educational (Schools)
| Area | Recommended Foot-Candles | Range |
| Classroom | 40 fc | 30 – 50 fc |
| Gymnasium (High School) | 50 fc | 20 – 100 fc |
| Gymnasium (College) | 80-125 fc | 30 – 150 fc |
| Auditorium | 7.5 fc | 3 – 10 fc |
| Corridor | 25 fc | 10 – 40 fc |
Industrial/Manufacturing
| Area | Recommended Foot-Candles | Range |
| Assembly (Simple) | 30 fc | 15 – 60 fc |
| Assembly (Difficult) | 100 fc | 50 – 200 fc |
| Component Manufacturing (Large) | 30 fc | 15 – 60 fc |
| Component Manufacturing (Medium) | 50 fc | 25 – 100 fc |
How Foot-Candle Levels Impact Workplace Efficiency
Providing the right foot-candle levels can directly impact visibility, safety, and productivity in the workplace. Here’s how:
• Safety: Insufficient lighting can lead to workplace accidents. For example, low lighting in warehouses can make it difficult for forklift operators to see obstacles.
• Productivity: Proper lighting can improve visibility, allowing employees to complete tasks more quickly and with greater accuracy.
• Energy Efficiency: By using LEDs and sensor-based controls, businesses can achieve the appropriate foot-candle levels while minimizing energy waste.
How to Achieve the Right Foot-Candle Levels
Achieving the appropriate foot-candle levels requires a mix of proper light fixture selection, fixture placement, and lighting controls. Here’s how Energy Design Engineers (EDE) can help:
1. Lighting Audit: Conduct an on-site analysis to determine the required foot-candle levels for each space.
2. Lighting Design: Calculate how many fixtures, bulbs, and sensors are needed to meet the target foot-candle levels.
3. Technology Upgrade: Replace outdated fluorescent or incandescent lighting with energy-efficient LEDs.
4. Use Controls: Install dimmers, occupancy sensors, and daylight sensors to automatically adjust lighting levels.
Tools and Devices for Measuring Foot-Candles
To maintain the correct light levels, lighting designers use several devices, including:
• Light Meters: Measure the intensity of light on a surface.
• Lighting Control Systems: Allow for remote control of light levels, enabling you to maintain optimal foot-candle levels in real time.
Frequently Asked Questions (FAQ)
1. What is the difference between lumens and foot-candles?
• Lumens measure the total light output from a source, while foot-candles measure the light that actually reaches a surface.
2. How many foot-candles do I need for a warehouse?
• Most warehouses require 10-30 foot-candles, depending on the size of items being handled and whether aisles are present.
3. How do I measure foot-candles?
• Use a light meter to measure the intensity of light on a specific surface in foot-candles (fc).
4. Can LED lights provide the right foot-candle levels?
• Yes! LED lights are fully capable of achieving the required foot-candle levels for any commercial, industrial, or educational facility.
Why Work with Energy Design Engineers (EDE)
At Energy Design Engineers (EDE), we specialize in providing energy-efficient lighting solutions that meet IES-recommended foot-candle levels for commercial, industrial, and educational spaces. Our experts conduct on-site audits, design energy-saving lighting plans, and install solutions that ensure optimal brightness, safety, and energy savings.
Key Services We Offer:
• Lighting Design and Optimization
• LED Retrofits to Meet Foot-Candle Standards
• Installation of Smart Lighting Controls
Contact us today to schedule a consultation and discover how EDE can help you achieve the proper foot-candle levels for your business or facility.