Lumen Pro 2 — Validation
CIE 171 validation — daylight calculation accuracy
What this validation covers
The daylight calculation engine of Lumen Pro 2 was validated against the analytical reference values of CIE 171:2006 — “Test cases to assess the accuracy of lighting computer programs” (the CIE standard used worldwide to verify daylighting software). Eight test cases are covered, split into four series:
- 5.9 — daylight factor under a 1×1 m and a 4×4 m roof opening (CIE general sky type 1)
- 5.10 — the same roof openings fitted with glazing (transmission 0.88)
- 5.11 — daylight factor through a 2×1 m and a fully-open 4×3 m vertical facade opening
- 5.12 — the same vertical facade openings fitted with 6 mm glazing (transmission 0.88)
All calculations use CIE general sky type 1 (overcast sky) and a 100% white diffuse BSDF (0 roughness) on the internal surfaces. The daylight factor is calculated at calculation points A to N plus the extended grid G’ to N’ and compared with the analytical reference values.
Test overview
| Test | Opening | Glazing |
| 5.9.3.1 | 1×1 m roof opening | — |
| 5.9.3.2 | 4×4 m roof opening | — |
| 5.10.1.1 | 1×1 m roof opening | glazing (T 0.88) |
| 5.10.1.2 | 4×4 m roof opening | glazing (T 0.88) |
| 5.11.3.1 | 2×1 m vertical facade opening | — |
| 5.11.3.2 | 4×3 m vertical facade opening | — |
| 5.12.3.1 | 2×1 m vertical facade opening | 6 mm glazing (T 0.88) |
| 5.12.3.2 | 4×3 m vertical facade opening | 6 mm glazing (T 0.88) |
CIE 171 validation result
The calculated daylight factors closely match the analytical reference values of CIE 171:2006 across all eight test cases. The full report contains the per-point comparison table, the accuracy indicators (MAE, RMSE, relative deviation) and the reference-versus-Lumen graphs for every test.