You can reduce wind turbulence around high-rise buildings by combining smart urban planning, thoughtful building design, and targeted mitigation measures such as setbacks, aerodynamic facades, and strategic vegetation. The most effective approach starts at the planning stage, before a single brick is placed. Once the building is up, your options narrow significantly, and fixing wind problems becomes far more expensive.
The sections below answer the most common questions about wind turbulence around tall buildings, from what causes it to what you can do when a wind assessment flags a hazard.
What causes wind turbulence around high-rise buildings?
Wind turbulence around high-rise buildings is caused by the way tall structures force fast-moving air from height down to street level. When wind hits a tall facade, it has nowhere to go but down. This downwash creates strong, unpredictable gusts at pedestrian height, particularly at building corners, in passages, and around entrances. The effect is made worse when a building is significantly taller than its surroundings.
A useful rule of thumb: a building more than twice the height of its immediate surroundings is likely to create wind problems. The geometry of the surrounding streets matters too. A street running parallel to the dominant wind direction acts as a channel, accelerating airflow along its length. Gaps between buildings, covered passages, and open facades on the windward side all amplify this effect.
Squares and open plazas are particularly vulnerable. When more than 25% of the windward facade of a building opens onto a square, the risk of wind nuisance increases sharply. This is why wind behaviour cannot be assessed building by building alone. The relationship between a building and everything around it determines what happens at street level.
Which design features reduce wind turbulence most effectively?
The most effective design features for reducing wind turbulence are setbacks, aerodynamic facade shapes, and strategic building clustering. These work at the source of the problem rather than treating symptoms after the fact. Measures applied later, such as screens or planting, are less effective and harder to implement well.
At the urban planning level, clustering towers so they shield each other is one of the most powerful tools available. This is sometimes called the Manhattan effect. The key is keeping height differences between adjacent buildings within 30%, so that wind is not funnelled down a steep step between a tall and a short structure. Streets should be oriented perpendicular or diagonally to the dominant wind direction, not parallel, to prevent channelling.
At the building level, the following measures are ranked by effectiveness:
- Setbacks: Stepping the building back at intermediate floors interrupts the downwash. A setback needs to be at least 5 metres deep for a building of around 100 metres to have a meaningful effect. Note that the roof level of a setback sits directly in the downwash and is not suitable as usable outdoor space.
- Aerodynamic facades: Rounded or tapered facades guide wind around and past the building rather than pushing it straight down. This reduces corner acceleration and downwash significantly.
- Covered walkways and galleries: These protect pedestrians directly. A minimum depth of 5 metres is needed for a building of around 100 metres. The area immediately beside the gallery, however, receives no protection.
- Canopies: Less effective than setbacks. They shift the downwash to the canopy edge rather than eliminating it.
- Wind screens: Redirect local airflow but accelerate wind at their edges. They can also affect sightlines and perceived safety.
At street level, vegetation, raised edges, and sunken seating areas can improve comfort. Deciduous trees lose their leaves in winter, which is exactly when wind speeds are highest, so they work better as a comfort measure than a safety measure.
How does CFD simulation identify wind turbulence problems early?
CFD (Computational Fluid Dynamics) simulation identifies wind turbulence problems by building a detailed 3D model of the building and its surroundings, then running virtual airflow calculations across multiple wind directions. This makes it possible to spot problem areas, such as corner acceleration, downwash zones, and channelling effects, before construction begins.
The process starts with a 3D model built from geodata, incorporating existing and approved buildings. The air around and between the buildings is divided into a computational mesh of cells, with the finest resolution close to surfaces where airflow gradients matter most. The simulation then solves airflow equations for each wind direction, typically 12 directions across two seasons.
The output is a set of colour-coded maps showing wind speed and comfort classification at pedestrian height. These maps make it straightforward to pinpoint where conditions fall outside acceptable limits and to test design changes before committing to them. For large-scale studies, this is the only practical method. A physical wind tunnel cannot replicate a city district at full detail, but a CFD simulation can.
Running the simulation early in the design process means that setbacks, facade adjustments, or changes to building orientation can still be incorporated without costly redesign. Wind problems discovered late, after planning permission has been submitted or construction has started, are far harder and more expensive to resolve.
What is the difference between a wind comfort study and a wind loading study?
A wind comfort study assesses how wind conditions at pedestrian height affect the usability and safety of outdoor spaces. A wind loading study calculates the forces that wind exerts on a building’s structure and facade. These are two separate assessments with different methods, outputs, and audiences.
A wind comfort study looks at the probability that wind speeds at eye level exceed a threshold over the course of a year. In the Netherlands, this is governed by NEN 8100, which classifies locations from A (comfortable) to E (unacceptable) based on how often wind speeds exceed 5 metres per second. For international projects, the Lawson criteria serve the same purpose. The output is used by urban planners, architects, and permit authorities to evaluate whether outdoor spaces are fit for their intended use, whether that is sitting, strolling, or through-traffic.
A wind loading study calculates peak wind pressures on facades, cladding, and structural elements. This feeds directly into structural engineering calculations and is used by facade contractors and structural engineers to specify the right materials and fixings. The inputs, methods, and norms involved are entirely different from those used in a comfort study.
Both studies can use CFD or wind tunnel methods, but they answer different questions. A project may need one or both, depending on its scale, location, and the requirements of the permit authority.
When is a wind study legally required for a high-rise project?
In the Netherlands, a wind study is required when a building project is likely to affect pedestrian wind conditions, particularly for high-rise buildings, large area developments, or projects in exposed locations. Municipalities increasingly require a wind comfort assessment as part of the permit application, especially in cities with active wind policies such as Rotterdam and Amsterdam.
The NEN 8100 standard is the applicable norm for wind comfort assessments in the Netherlands. It sets out the classification system, the meteorological inputs, and the acceptable limits for different types of outdoor activity. A permit authority may require a study to demonstrate that conditions in public spaces around a new development meet the relevant class for their intended use.
There is no single national rule that specifies exactly when a wind study is mandatory. In practice, the trigger is often the municipality’s own policy, the scale of the development, or a specific concern raised during the planning process. Projects involving buildings taller than their surroundings, developments near open water or exposed areas, and large masterplans are most likely to require a study. For projects outside the Netherlands, the Lawson criteria are widely used in the UK and internationally, and local planning authorities set their own requirements.
The safest approach is to commission a wind engineering assessment early, before the permit application is submitted. This gives you time to act on the results and avoids the situation where a missing study holds up the process at a critical moment.
What can be done when wind assessment results show a hazard?
When a wind assessment identifies a hazard, the response depends on where you are in the design process. If the building is still in design, adjustments to the layout, facade, or surrounding urban form can resolve most problems. If construction is already underway or complete, the options are more limited and typically involve local mitigation measures.
Under NEN 8100, a wind hazard is defined as a location where wind speeds above 15 metres per second are exceeded more than 0.30% of the time. This is considered unacceptable. Between 0.05% and 0.30%, a hazard is classified as a limited risk, which may be acceptable depending on the location and function of the space.
The most effective responses, in order of preference:
- Redesign at building level: Adjust setbacks, reorient the building, modify the facade profile, or reduce the height of the most exposed section.
- Urban form changes: Add or reposition adjacent buildings to provide shelter. This is most feasible in masterplan situations where multiple buildings are being designed together.
- Covered walkways or galleries: Provide direct protection for pedestrians in the most affected areas.
- Wind screens or barriers: A practical short-term measure, though they accelerate wind at their edges and have visual and social drawbacks.
- Vegetation: Effective for comfort improvement but not as a primary safety measure. Seasonal variation limits its reliability.
- Functional relocation: Moving entrances, terraces, playgrounds, or seating away from the most exposed spots. Sometimes a shift of just a few metres is enough to move from an unacceptable to an acceptable classification.
The Rotterdam pilot study carried out by the municipality and Actiflow showed that some of the most serious wind hazard locations in the city, including areas near the Erasmusbrug and the Lloyd Tower, are the result of design decisions made without sufficient attention to wind at the planning stage. The lesson is consistent: addressing wind at urban planning scale is far easier than fixing it building by building after the fact.
How Actiflow helps you reduce wind turbulence around high-rise buildings
We have been working on wind assessments for high-rise buildings and area developments since 2005, with over 21 years of experience in the Netherlands, Belgium, the UK, and beyond. We know the NEN 8100 norm inside out and apply the Lawson criteria for international projects. Our team understands both the technical side and the regulatory requirements of specific municipalities, which means our reports hold up under scrutiny from permit authorities.
Here is what we offer:
- Pedestrian wind comfort assessments using advanced CFD simulations, producing colour-coded maps that you can submit directly to municipalities or share with clients and planners.
- Wind loading studies for facades and structural elements, tailored to the needs of facade contractors and structural engineers.
- Large-scale area assessments, including city-wide studies of the kind we carried out for Rotterdam, covering districts, masterplans, and complex urban environments.
- Early design advice, so that wind problems are identified and resolved before they become expensive to fix.
- Fast turnaround: for regular clients, we set everything aside and start the next day if needed. Our internal automation continuously reduces delivery times further.
- Clear, visual output: colour-coded maps and graphics that make complex airflow patterns easy to present to clients, planners, and permit authorities.
Curious how we can help with wind turbulence around your high-rise project? Feel free to 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 us and our background in fluid dynamics consultancy.
