For most people, wind starts to feel uncomfortable at speeds above 5 metres per second (m/s) at pedestrian height, which is roughly 18 km/h. At that point, walking becomes noticeably unpleasant, hair and clothing are disturbed, and many people will actively avoid the space. Above 10 m/s, conditions become genuinely difficult for most outdoor activities. The exact threshold that counts as “acceptable” depends on what people are doing in a space — sitting still, strolling, or walking briskly all have different tolerance levels. The sections below break down how the main assessment frameworks define those thresholds and what drives the experience of wind comfort in practice.
What wind speed is considered uncomfortable for pedestrians?
Wind becomes uncomfortable for pedestrians when it exceeds 5 m/s at eye level (1.75 m above ground) with enough frequency to affect how people use a space. This is the threshold used in both the Dutch NEN 8100 standard and the internationally applied Lawson criteria. A single gust is rarely the problem — what matters is how often that speed is exceeded over the course of a year.
The reason 5 m/s is used as a reference point is practical: at that speed, most people experience noticeable disruption to their clothing and movement, and they begin to adjust their behaviour — speeding up, avoiding certain routes, or simply not using a space at all. Below 5 m/s, outdoor conditions are generally considered acceptable for most activities. Above it, acceptability depends on context: a busy pedestrian route through a city centre has different expectations than a rooftop terrace or a park bench.
It is also worth noting that perceived discomfort is not just about speed. Temperature, humidity, and solar radiation all play a role in how wind feels — a 5 m/s wind on a cold January morning feels very different from the same speed on a warm summer afternoon. That said, formal wind engineering assessments focus on wind speed exceedance as the measurable, standardised indicator.
What are the Lawson criteria and how do they classify wind comfort?
The Lawson criteria are a wind comfort framework widely used in the UK, Canada, and international projects. They classify outdoor spaces by activity type, each with its own wind speed threshold that should not be exceeded more than 5% of the time (roughly 438 hours per year).
- Sitting: wind speeds above 4 m/s should not occur more than 5% of the time
- Standing: threshold is 6 m/s, max 5% exceedance
- Strolling: threshold is 8 m/s, max 5% exceedance
- Walking briskly: threshold is 10 m/s, max 5% exceedance
- Uncomfortable: speeds above 10 m/s occurring more than 5% of the time
The logic behind the Lawson approach is that the acceptable wind speed scales with the activity: someone sitting still at a café terrace is far more sensitive to wind than someone walking purposefully through a transit hub. This makes the criteria useful for mixed-use urban environments where different zones serve very different purposes.
One practical limitation worth knowing: in dense urban environments with significant high-rise development, the Lawson thresholds can produce results that are more optimistic than what people actually experience on the ground. Research from Rotterdam, for example, showed that the Lawson method flagged only one location as uncomfortable, while several others were clearly problematic in practice. This is partly because the Lawson thresholds for most activities are higher than those used in NEN 8100. We apply the Lawson criteria for projects outside the Netherlands — including work in the UK, Gibraltar, and the Middle East — and always consider local context when interpreting results.
How does the Dutch NEN 8100 standard define wind comfort classes?
The NEN 8100 standard classifies pedestrian wind comfort based on how often wind speeds exceed 5 m/s at eye level (1.75 m). It uses five classes, from A (best) to E (worst), based on the annual exceedance probability of that threshold.
- Class A: exceedance less than 2.5% of the time (under 219 hours/year) — good for all activities
- Class B: 2.5–5% (219–438 hours/year) — good for walking, moderate for strolling
- Class C: 5–10% (438–876 hours/year) — acceptable for walking, poor for sitting
- Class D: 10–20% (876–1,752 hours/year) — moderate for walking, poor for most other uses
- Class E: more than 20% (over 1,752 hours/year) — poor for all activities
NEN 8100 is the standard used for permit applications in the Netherlands, and municipalities increasingly require a wind comfort assessment as part of planning submissions for new buildings — especially high-rise developments or large area plans. With over 21 years of experience conducting NEN 8100 assessments, we are familiar with how different municipalities interpret the standard and what they expect to see in a report.
One important detail: NEN 8100 does not distinguish between summer and winter conditions by default. In practice, this matters — wind hindrance is significantly worse in winter when trees have lost their leaves and wind speeds are higher. Producing separate seasonal maps gives a much more complete picture of how a space performs throughout the year.
What factors influence whether a wind speed feels acceptable?
Whether a given wind speed feels acceptable depends on activity, location, frequency, and season. The same 6 m/s wind can be refreshing on a sunny summer afternoon and genuinely unpleasant on a grey November morning. Assessment frameworks account for frequency and activity, but several other factors shape the real-world experience.
Activity type is the most direct factor. Someone sitting at an outdoor table is far more sensitive to wind than someone cycling or walking briskly. This is why both NEN 8100 and the Lawson criteria use activity-specific thresholds rather than a single universal number.
Urban geometry plays a major role in how wind behaves at street level. Key design factors include:
- Building height relative to surroundings — a building more than twice as tall as its neighbours significantly increases the risk of wind problems at ground level
- Street width-to-height ratio — narrow streets with tall buildings channel and accelerate wind
- Open facades on windward sides of squares — if more than 25% of the windward edge of a square is open, wind hindrance increases substantially
- Gaps between buildings or through-passages aligned with the dominant wind direction — these create pressure shortcuts that drive fast airflow through at ground level
Vegetation and microclimate also matter. Trees can reduce wind speeds locally, but they lose their leaves in winter — exactly when wind speeds are highest and comfort matters most. Temperature, solar radiation, and humidity all affect perceived comfort too, even if they are not part of the formal wind speed classification.
When does wind become a safety hazard rather than just a comfort issue?
Wind crosses from a comfort issue into a safety hazard when speeds at pedestrian height exceed 15 m/s with sufficient frequency. At that point, people can lose balance, and the risk of accidents increases significantly. Both NEN 8100 and the Lawson criteria include separate danger thresholds distinct from their comfort classifications.
Under NEN 8100, wind danger is assessed based on the exceedance probability of 15 m/s at eye level:
- No risk: exceedance below 0.05% (under 4.5 hours/year)
- Limited risk: 0.05–0.30% (4.5–26 hours/year) — sometimes acceptable depending on location
- Dangerous: above 0.30% (more than 26 hours/year) — unacceptable
The Lawson framework uses slightly different thresholds: speeds above 15 m/s occurring more than 0.025% of the time pose a risk to vulnerable people, and speeds above 20 m/s at the same frequency are considered dangerous for everyone.
In practice, dangerous conditions tend to occur at specific hotspots rather than across an entire development. Exposed locations near high-rise buildings — particularly where downwash from tall facades reaches ground level — are the most common problem areas. Bridges and riverfront locations are also vulnerable, as wind can travel unobstructed over water and accelerate significantly. During storms like Eunice in February 2022, the 15 m/s danger threshold was exceeded at multiple locations across Rotterdam, including bridge decks and areas directly adjacent to high-rise buildings.
How is pedestrian wind comfort measured and assessed in practice?
Pedestrian wind comfort is assessed by measuring or simulating wind speeds at eye level (1.75 m above ground) across a site, then comparing the results against the relevant comfort standard — NEN 8100 in the Netherlands, or the Lawson criteria for international projects. In practice, CFD simulation (Computational Fluid Dynamics) is the most common method, though physical wind tunnel testing and on-site measurements are also used.
A CFD simulation builds a virtual model of the building and its surroundings, then calculates airflow patterns for multiple wind directions and speeds. The results are presented as colour-coded maps showing wind comfort classes across the entire site — making it straightforward to identify problem areas and communicate findings to clients, planners, and permit authorities. You can explore more about CFD simulations and what goes into building an accurate model.
The inputs needed to get started are relatively straightforward: a 3D model or detailed drawings of the building and its context, local wind climate data (wind rose), and clarity on which standard applies. From there, the simulation process produces results that directly feed into design decisions — whether that means adjusting building setbacks, adding canopies, or repositioning entrances and outdoor seating areas away from the windiest zones.
For large-scale projects, the same methodology scales up to cover entire city districts or masterplan areas. The Actiflow team has carried out assessments ranging from individual high-rise towers to city-wide wind studies covering areas several kilometres in diameter.
How Actiflow helps with pedestrian wind comfort
We carry out pedestrian wind comfort assessments for architects, developers, structural engineers, and municipalities — from early design stages through to permit submission. Whether you need an NEN 8100 assessment for a project in the Netherlands or a Lawson-based study for a development in the UK, Gibraltar, or elsewhere, we apply the right framework for your context and deliver results that hold up under regulatory scrutiny.
Here is what working with us looks like in practice:
- Assessment method advice: we tell you upfront which standard applies, what level of detail is needed, and whether a quick scan or a full CFD study is the right fit for your project stage
- CFD simulations with clear visual output: colour-coded wind comfort maps and graphics you can share directly with clients, planners, or permit authorities — no translation required
- Seasonal analysis: separate summer and winter results where relevant, giving a complete picture of how a space performs year-round
- Design feedback: practical recommendations when results show wind problems — adjustments to building geometry, setbacks, canopies, or landscaping that actually fix the issue
- Speed and flexibility: for regular clients, we set everything aside to start the next day if needed; internal process automation keeps turnaround times short without compromising quality
Curious how we can help with pedestrian wind comfort? Contact us — we would be happy to discuss your project and help you find the right approach. You can also find out more about our team and background on our about us page.
