Find the prevailing wind from trees bent away from it, from snow drift patterns and from erosion on exposed soil, then shelter homes behind hills, tree lines or rock outcrops and place smoke, odour and fire sources downwind. A windbreak shelters a downwind distance of up to roughly ten times its height, so trees 8 m tall protect about 80 m.
Identifying the direction and seasons of the dominant wind at a site and arranging buildings, windbreaks and work areas around it.
Wind Is Named for Where It Comes From
A west wind blows from the west. See Wind Direction Reading for the on-the-spot method. The prevailing wind is the direction it blows from most often, and a site can have more than one: a cold winter wind from one quarter, a summer breeze from another. A building oriented to block one may face the other. The carrier is concerned with the dominant wind, which you identify by observing three clues:
- Tree growth patterns — flagged trees lean away from the dominant wind, with branches mostly on the downwind side.
- Snow drift patterns in winter.
- Erosion patterns on exposed soil.
What You Need
- A year of observation if possible — or a season plus local advice.
- A compass or sun reference — see Sun Methods.
- A notebook — direction, strength, season, time.
Method: Read the Clues, Then Lay Out
Step 1: Note the direction of each clue Walk the area and mark on a sketch map the direction each flagged tree, drift and erosion mark indicates. They should mostly agree.
Step 2: Separate seasons Ask which wind brings cold, rain, summer heat and smoke. Cold winter wind is the one to block; a summer breeze is often welcome, and the passive solar pages treat it as a cooling resource. See Passive Solar Building Design.
Step 3: Use natural shelter Place buildings on the lee side (downwind) of hills, tree lines or rock outcrops, as the carrier advises.
Step 4: Arrange work areas Orient the settlement so the prevailing wind carries smoke and odors away from living areas. Place workshops, forges and livestock downwind of the houses.
Step 5: Add windbreaks if the site lacks them Plant or leave tree rows across the wind, upwind of the buildings.
Worked Example
Windbreak guidance from agroforestry extension services gives shelter downwind of about ten times the barrier height, with the strongest shelter close to the barrier and a porous barrier working better than a solid wall. This is a general guide that varies with density and terrain.
- Tree row 8 m tall: 10 x 8 = 80 m of useful shelter.
- A house placed 20 m behind it (2.5 times the height) is well inside it.
- A house placed 120 m behind it is outside it.
Common Mistakes
- Forge upwind — sparks and smoke blow onto the roofs and houses.
- Windbreak too close — a tree can fall on a roof in a storm. Keep trees a full tree height away from buildings or remove weak ones.
- Judging from one calm day — wind is learned over seasons.
Safety
Wind carries fire
Thatch, timber and dry grass burn quickly in wind. Keep fires, forges and charcoal work downwind of buildings and stores, well apart from them, and keep a cleared strip between grass and buildings. See Fire Prevention in Settlements.
What’s Next
- Learn next: Sun Exposure & Shadows — the other half of microclimate
- Combine with: Cross-Ventilation Design — using summer wind inside the house