04Sun
Where the sun falls, any day of the year
Pick a day and an hour to see where the sun falls and where the house, the neighbours and the trees cast their shade. Below the model: hours of sun on the terrace and in every room.
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Sun path
Through the year
Hours of direct sun on day 21 of each month. Shading: louvres at 60° and blinds up.
| Month | Day length, h | Terrace with shading | Terrace without shading | Living room | Study | Bedroom 2 | Bedroom | Bedroom 3 |
|---|---|---|---|---|---|---|---|---|
| January | 8.9 | … | … | … | … | … | … | … |
| February | 10.5 | … | … | … | … | … | … | … |
| March | 12.2 | … | … | … | … | … | … | … |
| April | 14.1 | … | … | … | … | … | … | … |
| May | 15.6 | … | … | … | … | … | … | … |
| June | 16.2 | … | … | … | … | … | … | … |
| July | 15.6 | … | … | … | … | … | … | … |
| August | 14.1 | … | … | … | … | … | … | … |
| September | 12.3 | … | … | … | … | … | … | … |
| October | 10.5 | … | … | … | … | … | … | … |
| November | 8.9 | … | … | … | … | … | … | … |
| December | 8.2 | … | … | … | … | … | … | … |
How it is calculated
The sun's position comes from the NOAA algorithm (after Meeus), accurate to a hundredth of a degree, in local time including summer time. Every 10 minutes a ray is cast towards the sun from a grid of points on the window glass and the outdoor areas, to see whether anything blocks it.
Each room counts its best-lit window, weighted by how much of the glass is in sun: a window a third in sun for an hour counts as a third of an hour.
Shade comes from the roof, the reveals, the louvres and blinds as set, the neighbouring houses, fences, trees (in leaf in summer) and the terrain. The high summer sun reaches only a strip of glass under the overhang, which is why south-facing rooms get little direct sun in summer and plenty in winter.