
Daylighting Performance Analyzer
Calculate daylight factors, illuminance, and visual comfort for code-compliant daylighting designs
What You Can Do
You can perform rapid daylighting performance analysis without simulation software, calculating daylight factors across work planes, predicting illuminance under CIE standard skies, and assessing glare risk using industry metrics. The skill cross-references building standards (IECC, ASHRAE 189.1, EN 17037, IES TM-12), identifies optimization opportunities for window sizing and orientation, and generates compliance documentation that supports design decisions with quantifiable data.
Features
computes DF% at multiple work plane depths accounting for site obstruction and sky component
estimates lux levels under overcast, partly cloudy, and clear sky conditions using CIE standard skies
evaluates annual sunlight exposure (ASE), daylight glare index (DGI), and useful daylight illuminance (UDI) ranges
tests window sizing, sill height, light shelf depth, and overhang dimensions to optimize performance
cross-references results against IECC, ASHRAE 189.1, EN 17037, and local energy standards
analyzes equinox and solstice conditions to predict daylighting availability across the year
generates defensible documentation with graphics, tables, and design narratives for presentations and submissions
identifies specific adjustments (reflectances, glazing properties, obstruction removal) to meet performance targets
Example Output
Example 1: Daylight Factor Report
- Work plane 5m from south facade: DF 2.3% (meets LEED EA Credit 1 threshold)
- Work plane 10m from facade: DF 0.8% (requires supplementary lighting)
- Recommendation: Install 1.2m light shelf at 2.5m height to increase deep-zone DF to 1.4%
Example 2: Glare & Visual Comfort Assessment
- Annual Sunlight Exposure: 45% of occupied hours exceed 300 lux direct beam (controlled by automated shading)
- Useful Daylight Illuminance: 62% of work hours fall within 300–3000 lux range
- Daylight Glare Index: maximum 24 (perceptible but acceptable; suggest 35° light shelf to reduce to <20)
Example 3: Code Compliance Documentation
- Building meets ASHRAE 189.1 daylighting requirements: 75% of regularly occupied spaces achieve ≥2% DF or 300 lux minimum
- Design exceeds IECC EA Option 2: daylighting contributes estimated 18% reduction in annual lighting energy
- EN 17037 assessment: spaces achieve "good" visual comfort classification in 78% of occupied hours
What's Included
- SKILL.md instruction file with analysis framework and standard references:
- Daylight Factor Calculation Template: spreadsheet-based quick estimator for multiple depths and orientations
- Illuminance Lookup Tables: CIE standard sky conditions, urban vs. rural site factors, and common glazing properties
- Glare Assessment Checklist: step-by-step UDI, ASE, and DGI evaluation with thresholds and mitigation strategies
- Code Compliance Matrix: IECC, ASHRAE 189.1, EN 17037 requirements mapped to performance metrics and documentation requirements
- Performance Report Template: formatted sections for executive summary, calculations, strategy comparison, and recommendations
Who It's For
- Daylighting Designers — optimize natural light strategies during schematic and design development phases
- Architects — verify code compliance and support sustainable design narratives without hiring specialized consultants
- Energy Engineers — quantify daylighting contributions to lighting energy reduction and integrated design decisions
- Building Science Consultants — perform rapid parametric studies and troubleshoot underperforming designs before detailed modeling
- Building Commissioning Professionals — assess actual daylighting performance against design predictions and identify adjustment opportunities
Best For
- Daylight factor calculations for work plane depths and orientations
- Illuminance level predictions under varying sky conditions
- Glare risk assessment and annual sunlight exposure analysis
- Window sizing and orientation optimization studies
- Building code compliance verification and documentation
- Light shelf, overhang, and reflectance parametric testing
- Seasonal daylighting performance modeling
- Client presentations and design narrative development







