SOLAR GEOMETRY · COOPER 1969 · NOAA METHODOLOGY
Sun zone tool
Pick a reference city or enter your latitude. The tool returns peak sun elevation at the winter and summer solstice, day length across the year, and the louvre tilt that geometrically blocks direct noon sun for a 195 × 100 mm bioclimatic louvre profile. Use it for pergola siting, RAL palette decisions linked to summer heat load, and louvre automation thresholds.
Range −60 to 70. Use a positive value for the Northern hemisphere.
| Month | Noon elevation | Day length | Louvre tilt at noon |
|---|---|---|---|
| Jan | 16.2° | 7.9 h | 74° |
| Feb | 24.2° | 9.6 h | 66° |
| Mar | 34.7° | 11.5 h | 55° |
| Apr | 46.9° | 13.7 h | 43° |
| May | 56.3° | 15.5 h | 34° |
| Jun | 60.8° | 16.6 h | 29° |
| Jul | 59.0° | 16.1 h | 31° |
| Aug | 51.3° | 14.5 h | 39° |
| Sep | 39.7° | 12.4 h | 50° |
| Oct | 27.9° | 10.3 h | 62° |
| Nov | 18.3° | 8.4 h | 72° |
| Dec | 14.1° | 7.4 h | 76° |
METHOD
Solar declination follows Cooper 1969: δ = 23.45° × sin(360°/365 × (n + 284)) where n = day of year. Solar elevation at noon: α = 90° − |φ − δ| where φ = latitude. Day length follows from the sunrise hour angle H₀ = arccos(−tan φ × tan δ). The recommended louvre tilt is the minimum angle that blocks direct noon irradiation given the louvre depth-to-spacing ratio; a 195 × 100 mm Luxa Sereno profile achieves full noon shade for any sun elevation.
Outputs are computed values for clear-sky geometry, ignoring atmospheric refraction (≤ 0.5° near horizon) and local terrain. For thermal comfort modelling under variable cloud cover, combine these geometric values with regional irradiance data (PVGIS, Meteonorm).