1. What is the BESS Daylight Factor?

The BESS Daylight Factor is a metric used in architectural design to quantify the amount of natural light available in interior spaces. It represents the ratio of interior illuminance to exterior illuminance, expressed as a percentage.

2. How Does the Calculator Work?

The calculator uses the BESS Daylight Factor equation:

Where:

• \( Average Illuminance \) — The average light level measured inside the space (lux)
• \( External \) — The simultaneous external illuminance under an unobstructed sky (lux)

Explanation: The equation calculates what percentage of available external daylight reaches the interior measurement point.

3. Importance of Daylight Factor Calculation

Details: Daylight Factor calculation is essential for sustainable building design, ensuring adequate natural lighting, reducing energy consumption for artificial lighting, and creating healthier indoor environments.

4. Using the Calculator

Tips: Enter both average illuminance and external illuminance values in lux. Measurements should be taken simultaneously under overcast sky conditions for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What is a good Daylight Factor value?
A: Generally, a DF of 2% is considered the minimum for adequate daylighting, 5% is good, and above 5% is excellent for most tasks.

Q2: When should measurements be taken?
A: Measurements should be taken under overcast sky conditions to eliminate direct sunlight effects and ensure consistent results.

Q3: How many measurement points are needed?
A: For accurate average illuminance, multiple points should be measured across the space following standard grid patterns.

Q4: Are there limitations to Daylight Factor?
A: DF doesn't account for direct sunlight, building orientation, or seasonal variations, making it most reliable for overcast conditions.

Q5: How does DF relate to building standards?
A: Many green building certifications (LEED, BREEAM) have specific Daylight Factor requirements for credit achievement.