1. What is Daylight Factor?

Daylight Factor (DF) is a metric used in architecture and building design to quantify the amount of natural light available in interior spaces compared to the light available outside. It is expressed as a percentage and helps in assessing the adequacy of daylighting in buildings.

2. How Does the Calculator Work?

The calculator uses the Daylight Factor formula:

Where:

• \( Indoor Illuminance \) — Light level measured inside the building (lux)
• \( Outdoor Illuminance \) — Light level measured outside under unobstructed sky (lux)

Explanation: The formula calculates the ratio of interior illuminance to exterior illuminance, multiplied by 100 to convert it to a percentage.

3. Importance of Daylight Factor Calculation

Details: Daylight Factor is crucial for sustainable building design, energy efficiency, and occupant well-being. It helps architects and engineers optimize window placement, room dimensions, and material reflectivity to maximize natural lighting while minimizing artificial light usage.

4. Using the Calculator

Tips: Enter both indoor and outdoor illuminance values in lux. Ensure measurements are taken under consistent conditions (same time of day, weather conditions). Both values must be greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is a good Daylight Factor value?
A: Generally, a DF of 2-5% is considered adequate for most tasks. Values below 2% may require artificial lighting, while values above 5% may cause glare issues.

Q2: When should illuminance measurements be taken?
A: Measurements should be taken on an overcast day to eliminate direct sunlight effects, at the same time for both indoor and outdoor readings.

Q3: What factors affect Daylight Factor?
A: Window size and orientation, room geometry, surface reflectances, external obstructions, and glazing properties all influence Daylight Factor.

Q4: Are there limitations to this calculation?
A: The simple DF calculation doesn't account for direct sunlight, seasonal variations, or complex architectural features. More sophisticated daylighting analysis may be needed for comprehensive assessment.

Q5: How does Daylight Factor relate to building codes?
A: Many green building certifications (LEED, BREEAM) and building codes have specific Daylight Factor requirements to ensure adequate natural lighting in occupied spaces.