Wind engineering matters for architects because the design of a building directly shapes the wind environment around it — for better or worse. A poorly oriented tower or an ill-placed opening can create dangerous gusts at street level, delay a permit application, or force expensive redesigns late in the project. Understanding how wind behaves around buildings, which assessments are legally required, and when to involve a specialist helps you make smarter design decisions from the start. The questions below cover exactly that.
How does wind behavior change around buildings?
When wind meets a building, it does not simply stop or pass around it smoothly. It accelerates, deflects downward, wraps around corners, and creates turbulent zones that can be far windier than the open surroundings. The shape, height, and orientation of a building determine where these effects occur and how severe they become.
A few patterns come up repeatedly in practice. A tall building that stands more than twice the height of its surroundings tends to push wind downward along its facade, creating strong downdrafts that hit the pavement directly in front of the entrance. Corner acceleration is another common issue: wind that splits around the sides of a building speeds up significantly at the corners, often making those spots uncomfortable or even unsafe for pedestrians.
The relationship between building height and street width also plays a role. When a building is tall relative to the street it faces, most of the wind gets channelled down into that street rather than passing over the rooftop. As a rule of thumb, a height-to-width ratio above 0.65 means most wind gets deflected over the building, while a ratio below 0.35 means most of it reaches street level.
Gaps between buildings, covered passages, and open facades facing the prevailing wind direction can all amplify these effects. Clusters of towers can actually protect each other — the so-called Manhattan effect — but only when height differences between neighbouring buildings stay within roughly 30%. When one tower significantly outstrips its neighbours, it creates downdrafts and corner flows that the surrounding buildings cannot shield against.
What wind studies are architects legally required to commission?
Whether a wind study is legally required depends on the country, the municipality, and the nature of the project. In the Netherlands, a pedestrian wind comfort assessment according to NEN 8100 is required when a building project is likely to affect wind conditions at street level — this typically applies to tall buildings, large building volumes, or developments in exposed locations. Municipalities can and do make this a condition of the permit application.
For projects in the UK, the Lawson criteria serve as the standard reference, and many local planning authorities — including the City of London and Leeds — have their own specific requirements for wind assessments as part of the Environmental Statement submitted with a planning application.
Beyond pedestrian comfort, structural wind loading calculations are required for facade design and load-bearing structures under Eurocode EN 1991-1-4. These are not optional: cladding contractors and structural engineers need them to sign off on the design. Wind tunnel tests are often used for this purpose, particularly for complex or irregular building shapes where standard calculation methods are insufficient.
If you are unsure which assessment applies to your project, the safest approach is to ask early. A wind engineering specialist familiar with wind engineering regulations in your target municipality can tell you exactly what is needed before you reach the permit stage.
What’s the difference between pedestrian wind comfort and wind loading?
Pedestrian wind comfort and wind loading are two separate types of wind assessment that answer fundamentally different questions. Pedestrian wind comfort asks: is the wind environment at street level safe and comfortable for people? Wind loading asks: what forces does the wind exert on the building structure and facade?
A pedestrian wind comfort study maps wind speeds at ground level around a building across a range of wind directions and speeds. The results are classified against a comfort standard — NEN 8100 in the Netherlands, Lawson elsewhere — and show which areas are suitable for sitting, walking, or passing through, and which areas exceed acceptable thresholds. The output typically includes colour-coded maps that can be submitted directly to a municipality or shared with a planning committee.
A wind loading study, by contrast, focuses on the pressures acting on the building envelope itself. It determines the forces that facades, cladding panels, fixings, and structural elements must be designed to withstand. This feeds directly into the structural engineering calculations and is needed for building approval regardless of whether a pedestrian comfort study is also required.
Some projects need both. A high-rise in a city centre, for example, will typically require a pedestrian wind comfort assessment for the permit application and a wind loading study to support the facade and structural design. These can sometimes be run in parallel to avoid delays.
How does a CFD wind simulation work in an architectural project?
A CFD (Computational Fluid Dynamics) wind simulation uses computer modelling to calculate how air flows through and around a building or urban area. It is the method of choice for large-scale assessments where a physical wind tunnel model would be impractical, and it produces detailed, spatially accurate results across the full site.
The process follows three main steps:
- 3D model construction: A digital model of the building and its surroundings is built from geodata and architectural drawings. Existing and approved buildings are included; details smaller than about one metre are omitted because they have a negligible effect on the results. A buffer zone of at least 250 metres around the core area ensures that wind enters the model realistically.
- Mesh generation: The air volume above and between buildings is divided into millions of small cells. Cell sizes vary from as fine as 0.25 metres near surfaces to several metres further away. The finer the mesh near building surfaces, the more accurately the simulation captures the velocity gradients that determine pedestrian-level wind conditions.
- Post-processing and visualisation: Raw simulation data is processed into maps, colour-coded by wind speed or comfort class. These outputs can be tailored to what planners, architects, or permit authorities need to see — comfort maps, ventilation potential, pollutant dispersion, or wind energy yield, all from a single simulation run.
The wind data feeding the simulation comes from meteorological records. In the Netherlands, the NPR 6097 dataset (required for NEN 8100 permit procedures) and the more recent DOWA dataset are both used, depending on the purpose of the study. Both produce comparable wind roses, with the strongest and most frequent winds coming from the southwest.
Our CFD simulation approach uses OpenFOAM with an SST k-omega turbulence model — a well-validated combination for atmospheric boundary layer flows. The colour-coded output maps are designed to be directly presentable to clients, planners, and permit authorities without requiring a fluid dynamics background to interpret them.
When in the design process should architects involve a wind engineer?
The earlier, the better. Involving a wind engineer at the concept or schematic design stage gives you the most room to act on the findings. At that point, changes to building orientation, massing, setbacks, or the placement of entrances and public spaces are still straightforward. Once the design is fixed and a permit application is in preparation, options narrow significantly.
Wind problems are almost always easier and cheaper to solve at the urban planning or massing level than at the building detail level. A strategic setback, a change in building orientation, or the clustering of towers can eliminate a wind hazard entirely. Adding a canopy, a screen, or landscaping after the fact is less effective and more expensive — and sometimes not enough.
A practical approach is to commission a quick scan or expert opinion at the early design stage to identify any obvious risks, then follow up with a full CFD assessment once the design is sufficiently developed. This two-stage approach keeps costs proportionate to the level of certainty needed at each phase.
For projects with tight permit timelines, it also helps to know that turnaround time matters. Explore the full range of wind assessment services available before committing to a consultant, and confirm that they can deliver within your project schedule.
What happens when wind assessment results show a hazard?
When a wind assessment identifies a hazard — meaning wind speeds that exceed the safety thresholds defined by NEN 8100 or Lawson — the project does not automatically stall. It means the design needs to be adjusted, and there is a clear hierarchy of measures to work through.
The most effective interventions happen at the level of the building volume itself:
- Setbacks: Stepping the building back at lower floors reduces the downdraft reaching street level. A setback needs to be at least 5 metres deep for a building of around 100 metres tall to be effective. Note that the roof level of a setback itself sits in the downdraft zone and is not suitable as a terrace or usable outdoor space.
- Facade orientation: Avoiding the widest facade being perpendicular to the prevailing wind direction reduces the pressure difference that drives downdrafts and corner flows.
- Aerodynamic shaping: Rounded or tapered facades guide wind around the building rather than pushing it downward. This is more effective than adding screens or canopies after the fact.
- Covered walkways and galleries: These protect pedestrians directly beneath them, but the area immediately outside the covered zone gets no benefit.
- Landscaping: Trees, hedges, and shrubs can improve comfort, but they are not a primary safety measure. Deciduous trees lose their leaves in winter — exactly when wind speeds are highest.
If the hazard is at a specific location such as a building entrance or a public square, sometimes a small repositioning of that function is enough. Moving an entrance 10 metres around the corner can make the difference between a dangerous and an acceptable wind environment.
The important principle is that wind hazards are much harder to fix at the detail level if they were not considered at the urban planning level first. That is why early involvement of a wind engineer is not just convenient — it is genuinely cost-effective.
How Actiflow helps with wind engineering for architects
We work with architects, project managers, and developers at every stage of the design process — from a quick expert opinion at concept stage to a full CFD assessment ready for permit submission. With over 21 years of experience and roots at Delft University of Technology, we know both the technical side and the regulatory requirements of municipalities across the Netherlands, Belgium, the UK, and beyond.
- Pedestrian wind comfort assessments according to NEN 8100 (Netherlands) and Lawson criteria (UK and international), with colour-coded maps suitable for direct submission to planning authorities
- Wind loading studies for facades and structures, in line with Eurocode EN 1991-1-4
- Large-scale CFD assessments for area developments and masterplans — including city-wide studies such as the one we carried out for the city of Rotterdam
- Early-stage quick scans to identify wind risks before they become costly design problems
- Fast turnaround without compromising report quality — for regular clients, we can start the next day if needed
- Clear, visual output that you can share directly with clients, planners, or permit authorities
Curious how we can help with wind engineering for your project? Contact us — we would be happy to discuss your project and help you find the right engineering solution. You can also find out more about our team and background on our about us page.
