Published 2026-10-29 · 2 min read
How to orient a house to the sun and size the overhang
The same house, rotated 90 degrees on its plot, can have very different heating and cooling bills. Orientation costs nothing if you decide it early and a lot if you fix it later with air conditioning. The examples below are for the northern hemisphere; south of the equator, swap north and south.
Where each room goes
- South: living and dining. Sun all day in winter; in summer, with the sun high, an overhang shades them easily.
- East: bedrooms and kitchen. Morning sun is gentle and wakes you up; by evening these rooms are already cool.
- West: be careful. Afternoon sun is low and hot in summer — hard to shade with an overhang. Use external blinds or trees.
- North: bathroom, pantry, hallway, stairwell, garage. Steady light, no heat gain.
How high the sun gets
At noon, the sun's angle above the horizon is easy to work out: 90° minus your latitude, plus 23.4° at the summer solstice, minus 23.4° at the winter one.
At 45° N: summer 90 − 45 + 23.4 = 68°, winter 90 − 45 − 23.4 = 22°. At 51.5° N (London): 62° and 15°. That large gap is exactly what a well-sized overhang exploits.
Sizing the overhang on the south side
The overhang should shade the window in summer and leave it clear in winter. Its depth is the height from the bottom of the window up to the underside of the overhang, divided by the tangent of the summer angle.
- Window bottom 1.5 m below the overhang, at 45° N: 1.5 / tan 68° = 1.5 / 2.48 ≈ 0.6 m.
- A 60 cm overhang fully shades that window at summer noon.
- In winter, at 22°, its shadow drops only 0.6 × tan 22° ≈ 24 cm down the glass — the sun comes in almost unobstructed.
- On east and west faces an overhang does not help: the sun is too low. Use shutters, external blinds or a pergola with climbers.
Check the shadows before you build
In GrafitGo's architecture editor, the time-of-day slider in the top bar moves the sun from sunrise to sunset and the shadows move with it. You quickly see which face is in the afternoon sun and whether a tree or the neighbour's house shades your terrace.
It is an approximation — a summer day, with no exact latitude — good for a first impression. For the overhang depth, use the formula above.
What if the plot will not let the living room face south?
Put the big windows on the side closest to south and add rooflights or a high window. Up to about 30° off south makes little practical difference.
Does orientation matter for a well-insulated house?
Yes. In a well-insulated house, winter sun through south windows can cover a noticeable share of the heating, and summer overheating becomes the main issue — exactly what the overhang solves.
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