Wind speed changes with height, exposure, and nearby structures — this tool estimates shelter effect, pressure load, and outdoor comfort levels.
| Activity | Threshold (m/s) | Current Speed | Status |
|---|
| Force | m/s Range | Description | Likely Effects at Pedestrian Level |
|---|
| Height (m) | Wind Speed (m/s) | Dynamic Pressure (Pa) | Beaufort Force |
|---|
| Distance from Windbreak | Reduction % | Speed Remaining (m/s) |
|---|
| PET (°C) | Category | Perception | Stress Level |
|---|---|---|---|
| < 4°C | Very cold | Extreme cold stress | Very strong |
| 4–8°C | Cold | Cold stress | Strong |
| 8–13°C | Cool | Moderate cold stress | Moderate |
| 13–18°C | Slightly cool | Slight cold stress | Slight |
| 18–23°C | Comfortable | No thermal stress | None |
| 23–29°C | Slightly warm | Slight heat stress | Slight |
| 29–35°C | Warm | Moderate heat stress | Moderate |
| 35–41°C | Hot | Strong heat stress | Strong |
| > 41°C | Very hot | Extreme heat stress | Very strong |
Why Wind Comfort Deserves the Same Design Attention as Sunlight
Ask someone why they never use a particular outdoor seating area and the answer is often simply that it always feels windy there, even though wind rarely appears anywhere on a rendered design visual or planting plan. This guide explains how wind comfort is actually assessed and calculated, bringing the same rigour to it that designers routinely give to sunlight and sightlines.
Why wind speed increases with height and open exposure
Wind speed near the ground is significantly slowed by friction against the ground surface itself and by obstructions such as buildings, trees, and general urban clutter, meaning wind speed increases progressively with height above ground and with reduced surrounding obstruction, which is precisely why a rooftop terrace or an exposed plaza edge experiences meaningfully higher wind speeds than an equivalent sheltered courtyard at ground level, even on an identical day with identical regional wind conditions. This relationship between height, surrounding terrain roughness, and wind speed is exactly why a design that feels comfortably sheltered at ground level cannot simply be assumed to feel the same way once the same layout is proposed for an elevated or more exposed location, and needs to be reassessed specifically for that location’s actual exposure conditions.
How a windbreak’s sheltering effect is estimated
A windbreak, whether a dense hedge, solid fence, or building form, reduces wind speed downwind of itself, and the degree and extent of that sheltering effect depends on two main factors, the windbreak’s height, since a taller windbreak shelters a proportionally greater downwind distance than a lower one, and its porosity, meaning how much wind is allowed to pass directly through it rather than being forced up and over it. Counterintuitively, a completely solid, non-porous barrier is often not the most effective windbreak design, because it tends to create strong, turbulent eddies immediately downwind as deflected air rushes back down to ground level, whereas a moderately porous barrier, such as a hedge or a slatted screen allowing some airflow through, generally produces calmer, more genuinely sheltered conditions over a greater downwind distance than an equivalent height of completely solid barrier.
Calculating wind pressure load on structures
Any freestanding structure exposed to wind, whether a pergola, screen, or freestanding wall, experiences a wind pressure load that has to be resisted by its structural design, and this pressure is calculated from the local basic wind speed for the site’s region, adjusted by factors accounting for terrain roughness and the specific structure’s height and exposure, following the methodology set out in the Eurocode 1 wind actions standard. This calculated pressure then has to be resisted by the structure’s own design, meaning a lightweight pergola or screen proposed for a genuinely exposed, elevated, or coastal location needs meaningfully more robust structural design than an identical-looking structure proposed for a sheltered, low-lying, inland courtyard, even though the two structures might look visually identical in a design drawing.
Understanding the urban canyon and venturi effect
Where buildings of similar height are positioned closely together, particularly where a gap or passage runs perpendicular to the prevailing wind direction, wind can accelerate noticeably as it is forced through that constricted gap, an effect commonly referred to as the venturi effect, and this is a genuine and well-documented cause of uncomfortable, sometimes hazardous ground-level wind conditions in dense urban schemes, even in locations where the general regional wind climate is otherwise unremarkable. Identifying where a proposed building layout is likely to create this kind of accelerated wind corridor, simply by looking at gaps and passages aligned with prevailing wind direction between buildings of broadly similar height, is a useful early design check well before any formal wind microclimate study would typically be commissioned.
Translating wind speed into a genuinely useful comfort measure
Raw wind speed figures in metres per second or kilometres per hour are not always intuitive on their own, which is exactly why wind speed is commonly cross-referenced against the internationally recognised Beaufort Scale, a scale running from zero to twelve that translates wind speed into observable, familiar effects, such as leaves beginning to rustle at a fairly gentle force, versus umbrellas becoming difficult to use at a considerably stronger force. Combining an estimated wind speed with the specific activity intended for a space, since sitting still requires calmer conditions to remain comfortable than standing, which in turn requires calmer conditions than simply walking through a space, produces a genuinely useful comfort classification that communicates far more design-relevant information to a client than a raw wind speed figure alone ever could.
Disclaimer
The information and any results referenced on this page are provided for general educational and early design purposes only, referencing general principles from the Eurocode 1 wind actions standard and the Beaufort Scale. This is not a certified wind microclimate study, wind tunnel assessment, or structural wind loading design. For planning submissions requiring formal wind microclimate assessment, or for structural elements exposed to significant wind loading, consult a qualified wind engineer or structural engineer.