Engineers use four main wind comfort criteria to assess how wind affects people in and around buildings: the Lawson criteria, the NEN 8100 standard, the Davenport comfort scale, and the Eurocode wind loading standard (EN 1991-1-4). The first three focus on pedestrian comfort, while Eurocode deals with structural wind forces. Which one applies to your project depends on the country you are working in, the type of assessment required, and whether you need a comfort study or a structural loading analysis. Below, we break down each criterion and explain when to use which.
How do wind comfort criteria differ from wind loading standards?
Wind comfort criteria and wind loading standards measure completely different things. Wind comfort criteria assess how wind conditions affect people at street level — whether a location is pleasant to sit, walk through, or stand in. Wind loading standards calculate the forces wind exerts on a building’s structure and facade, which engineers use to design cladding, connections, and load-bearing elements.
In practice, a building project often requires both. The comfort assessment tells you whether pedestrians in the surrounding public space will experience acceptable wind conditions. The loading assessment tells your structural engineer whether the facade and frame can withstand the forces the wind puts on the building. These are separate studies with separate outputs, and confusing the two is one of the most common misunderstandings we encounter in early project conversations.
For comfort assessments, the relevant standards are the Lawson criteria, NEN 8100, and the Davenport scale. For structural loading, Eurocode EN 1991-1-4 applies. Wind engineering consultants typically advise on which combination of studies your project needs before any simulation work begins.
What are the Lawson criteria and how are they applied?
The Lawson criteria are a set of wind comfort thresholds used to classify outdoor spaces based on the activity they are intended for. Developed in the UK, they define acceptable wind speeds for activities ranging from sitting in a cafe terrace to walking briskly through a city square. Each activity category has a threshold wind speed that should not be exceeded for more than a set percentage of the time.
In practice, the Lawson criteria work by comparing the predicted wind speed at a location — typically at pedestrian height of around 1.75 metres — against the activity taking place there. A location classified as suitable for sitting must meet a stricter threshold than one classified for walking or cycling. If the predicted conditions exceed the threshold for the intended use, the design needs to be adjusted.
The Lawson criteria are widely used in the UK and on international projects where no national standard prescribes a specific method. Cities such as London and Leeds reference them directly in their planning guidance. If you are working on a project in the UK, Gibraltar, or other international locations, the Lawson criteria are almost certainly the right starting point. We apply them regularly for projects across the UK and further afield, using CFD simulations to generate colour-coded comfort maps that planning authorities can review directly.
What is the NEN 8100 standard and when does it apply?
NEN 8100 is the Dutch national standard for assessing pedestrian wind comfort and wind hazard around buildings. It applies to projects in the Netherlands and is the legally prescribed method for permit applications involving wind assessments. If your project requires a wind study as part of a Dutch building permit, NEN 8100 is the standard you need to meet.
NEN 8100 classifies wind conditions into five classes (A through E) based on the probability that wind speed at pedestrian height exceeds 5 m/s. Class A means the exceedance probability is below 2.5%, which is acceptable for all activities including sitting. Class E means the probability exceeds 20%, which is unacceptable for any activity. The standard also defines a separate wind hazard threshold: if the probability of wind speeds exceeding 15 m/s is above 0.30%, the location is classified as dangerous and intervention is required.
The meteorological input for NEN 8100 assessments must come from the NPR 6097 dataset, which covers the period 1963 to 2002 and is the legally prescribed wind climate reference for permit procedures in the Netherlands. This is an important detail: using a different dataset may produce a technically valid result, but it will not satisfy a Dutch municipality reviewing your permit application. With over 21 years of experience working with municipalities across the Netherlands, we know exactly what format and level of detail local authorities expect.
What is the Davenport comfort scale used for?
The Davenport comfort scale is one of the earliest systematic frameworks for classifying pedestrian wind comfort. It defines seven wind speed categories — from calm to storm force — and links each to a description of how people experience those conditions. It is used primarily as a reference framework in research and early-stage design discussions rather than as a regulatory standard for permit applications.
In practical wind engineering today, the Davenport scale has largely been superseded by more detailed criteria such as Lawson and NEN 8100, which are tied to specific activities and exceedance probabilities. However, the Davenport scale remains useful for communicating wind conditions to non-technical audiences. Its plain-language descriptions — such as “wind felt on face” or “difficulty walking against wind” — make it easier to explain comfort implications in early design workshops or client presentations without immediately diving into exceedance statistics.
Which wind comfort criterion should be used for a specific project?
The right wind comfort criterion depends on three factors: the country where the project is located, the type of planning or permit process involved, and the stage of the design. There is no universal standard that applies everywhere, so choosing the correct criterion is one of the first decisions in any wind assessment.
- Projects in the Netherlands: Use NEN 8100. It is legally required for permit applications and the only standard Dutch municipalities will accept.
- Projects in the UK: Use the Lawson criteria. London, Leeds, and most other major UK planning authorities reference Lawson in their wind assessment guidance.
- International projects without a national standard: The Lawson criteria are the most widely recognised international benchmark and a safe default choice.
- Early design or feasibility stage: A qualitative desk study or quick scan using Davenport-based descriptions can be enough to identify risk areas before committing to a full assessment.
- Structural design: Eurocode EN 1991-1-4 applies regardless of country for facade and structural loading calculations.
When in doubt, a brief consultation with a wind engineering specialist will save time. The choice of criterion affects not just the methodology but also the meteorological input data, the reporting format, and whether the outcome will be accepted by the relevant authority. Getting this wrong early means redoing the work later. You can find an overview of the full range of CFD simulation services we use to run these assessments on our website.
How does a wind comfort assessment use these criteria in practice?
A wind comfort assessment takes the relevant criterion and applies it to simulated or measured wind data at pedestrian level around your building or development. The process starts with building a 3D model of the site, running CFD simulations or wind tunnel tests across multiple wind directions, and then post-processing the results into a comfort classification map.
For a NEN 8100 assessment, the simulation calculates the exceedance probability of 5 m/s at 1.75 metres height for each location on the site. Those probabilities are then mapped against the five-class system, producing a colour-coded plan that shows which areas meet the standard and which do not. For a Lawson assessment, the same simulation data is compared against the activity-specific thresholds for each zone of the public space.
The output is a set of maps and a written report. The maps show comfort classes across the site using a colour scale — typically green for acceptable, yellow for marginal, and red for problematic. These visuals are designed to be shared directly with architects, planners, and permit authorities without requiring any background in fluid dynamics to interpret. Where results show wind hazard or comfort problems, the report includes design recommendations: adjustments to building orientation, the addition of setbacks, canopies, or wind screens, or changes to the planned use of affected areas.
The earlier in the design process you run this assessment, the more options you have. Wind problems identified at concept stage can be solved with relatively minor design changes. The same problems identified after planning approval are far more expensive to address. More background on how wind studies fit into the broader design process is available on our website.
How Actiflow helps with wind comfort assessments
We carry out pedestrian wind comfort assessments for projects across the Netherlands, Belgium, the UK, and internationally — applying NEN 8100 for Dutch permit procedures and the Lawson criteria for UK and international projects. Our team of engineers combines over 21 years of experience in wind engineering with direct familiarity with the regulatory requirements of municipalities and planning authorities.
- Full CFD assessments conforming to NEN 8100, Lawson, and other applicable standards, with colour-coded maps ready for submission to permit authorities
- Wind tunnel testing for facade pressure, structural loading, and complex building geometries
- Quick scans and desk studies for early design stages, helping you identify wind risks before committing to a full assessment
- Large-scale area studies, from individual high-rise buildings to city-wide masterplan assessments like the one we carried out for the city of Rotterdam
- Clear, visual reporting that you can present directly to clients, planners, and municipalities without needing to explain the methodology
- Fast turnaround — for regular clients, we set everything aside to start the next day if the project timeline demands it
Curious how we can help with your wind comfort assessment? Contact us and we will be happy to discuss your project and help you find the right approach. You can also learn more about us and how we work.
