A wind assessment for a mixed-use development helps you identify where wind conditions will be uncomfortable or unsafe for pedestrians, and gives you the design intelligence to fix those problems before construction begins. Mixed-use sites are particularly sensitive because they combine residential, retail, and public functions in one place — each with different comfort requirements and different levels of pedestrian exposure. The sections below answer the most common questions project managers and structural engineers ask when commissioning a wind assessment for this type of development.
How does a wind assessment change design decisions in mixed-use developments?
A wind assessment directly shapes decisions about building height, orientation, facade treatment, and the placement of outdoor functions. For mixed-use developments specifically, it tells you which ground-floor uses — a café terrace, a playground, a building entrance — can go where, and which layouts will create wind conditions that make those spaces unusable or unsafe.
The most impactful changes typically happen at the urban planning level. Clustering towers so they shield each other, limiting height differences between adjacent buildings to around 30%, and orienting streets diagonally to the prevailing wind direction rather than parallel to it — these are the interventions that prevent wind problems from emerging in the first place. Once the massing is fixed, it becomes much harder and more expensive to correct.
At the building level, a wind assessment informs decisions like where to set back upper floors, how deep a covered walkway needs to be to protect pedestrians, and whether a ground-floor arcade will actually shelter the people using it or simply redirect the problem to its edges. Setbacks are effective when they are at least 5 metres deep for a building of around 100 metres tall — a rule of thumb that comes directly from the kind of quantified analysis a wind assessment provides.
For retail and hospitality uses at ground level, the assessment also tells you where not to put terraces, entrances, or seating areas. Moving a terrace 10 metres around a corner can be the difference between a space people use and one they avoid. That kind of practical, location-specific guidance is what makes a wind engineering assessment genuinely useful rather than just a compliance document.
What wind comfort criteria apply to mixed-use developments?
In the Netherlands, the applicable standard is NEN 8100, which classifies wind conditions at pedestrian level into five categories from A (comfortable) to E (dangerous). For international projects, the Lawson criteria serve a similar purpose. The right standard depends on your project location and the requirements of the permitting authority.
What makes mixed-use developments more complex than single-use buildings is that different areas on the same site require different comfort thresholds. NEN 8100 distinguishes between activities such as sitting, standing, walking, and passing through — and each activity has its own acceptable wind class. A terrace or playground requires a stricter classification than a pedestrian through-route. This means a single development may need to meet several different comfort targets across its footprint.
The wind danger threshold under NEN 8100 is a wind speed of 15 m/s, with exceedance probabilities above 0.30% considered unacceptable regardless of context. Below that threshold, some wind hazard may be acceptable depending on the specific location and its use. Understanding where these limits apply on your site is exactly what the assessment maps out.
When in the design process should a wind assessment be commissioned?
The earlier you commission a wind assessment, the more value it delivers. Ideally, you bring in a wind assessment during the schematic design phase, when building massing and site layout are still being developed. At that stage, findings can directly influence the design without triggering costly revisions.
Many project teams wait until a permit application is imminent, which means the assessment becomes a compliance exercise rather than a design tool. If the results flag wind hazard at that point, your options for mitigation are limited to surface-level fixes — screens, planting, canopies — rather than the structural changes that would have solved the problem at its source.
A good approach for mixed-use developments is to run a preliminary wind assessment during early massing studies, then follow up with a more detailed study once the design has progressed. This two-stage approach lets you catch problems early and verify that your design responses have worked before you commit to final drawings. Wind problems discovered late in the design process consistently result in the most expensive and disruptive revisions.
What are the most common wind problems found in mixed-use developments?
The most frequent wind problems in mixed-use developments are corner acceleration, downwash from tall buildings, and channel effects between parallel building blocks. Each of these can turn an intended public space into somewhere people actively avoid.
Corner acceleration occurs when wind wraps around the edge of a building and speeds up. Ground-floor retail units and building entrances positioned at corners are particularly exposed. A building that is more than twice the height of its surroundings significantly increases the risk of this effect.
Downwash happens when wind hits a tall facade and is deflected downward to street level. Towers in otherwise low-rise neighbourhoods are common causes. The area directly adjacent to a tall building can experience wind speeds well above 3 m/s even on days that feel calm elsewhere on the site — a pattern confirmed by urban wind studies, including research conducted in Rotterdam.
Channel effects arise when streets or gaps between buildings run parallel to the prevailing wind direction, accelerating flow through those corridors. In mixed-use developments, these channels often align with the pedestrian routes that connect different parts of the site — exactly the spaces where comfortable conditions matter most.
Plazas and open courtyards with more than 25% open facade on the windward side also tend to concentrate wind, making them uncomfortable for the outdoor seating and social activity that mixed-use developments depend on to succeed.
How does CFD simulation compare to wind tunnel testing for a mixed-use project?
For most mixed-use developments, CFD (Computational Fluid Dynamics) simulation is the more practical choice. It handles complex urban geometries, allows rapid design iteration, and produces detailed spatial results across the entire site. A physical wind tunnel test requires a scale model and is better suited to individual buildings or smaller masterplans where physical accuracy is the priority.
CFD works by building a detailed 3D model from geodata, dividing the surrounding air volume into millions of computational cells, and simulating airflow across multiple wind directions. The results are processed into colour-coded maps that show wind conditions at pedestrian level across the full site. For a large mixed-use development with multiple buildings, public spaces, and ground-floor uses, this spatial overview is directly actionable for design teams.
Wind tunnel testing remains valuable when you need physical validation of a specific building form, or when a regulatory authority specifically requires it. In practice, the two methods are sometimes combined: CFD for the broader site study and wind tunnel testing for a particularly complex or sensitive element of the design.
Both methods are accepted under NEN 8100 and the Lawson criteria. The choice depends on the scale of your project, the stage of design, and what the permitting authority expects. Our CFD simulation approach uses OpenFOAM with an SST k-omega turbulence model and meteorological input from KNMI datasets, producing results that meet the requirements of Dutch permit procedures.
What outputs does a wind assessment report include for a mixed-use site?
A wind assessment report for a mixed-use development typically includes colour-coded wind comfort maps, wind classification results per zone, an explanation of the assessment method used, and practical design recommendations. The maps show wind conditions at pedestrian level across the site for multiple wind directions, with each area classified against the applicable comfort criteria.
For a mixed-use site, the most useful outputs are:
- Pedestrian comfort maps showing NEN 8100 or Lawson classifications across the full site footprint
- Wind speed contour plots for specific wind directions and reference heights
- Zone-specific assessments for areas with different use requirements — terraces, entrances, play areas, through-routes
- Mitigation recommendations with a clear hierarchy from urban planning interventions down to landscape measures
- Before-and-after comparisons when design changes are tested during the study
The visual quality of these outputs matters as much as the technical content. A report that can be presented directly to planners, clients, or permit authorities without translation saves time and reduces friction in the approval process. Colour-coded maps that clearly show which areas meet the required comfort class and which do not are far more useful in a planning meeting than tables of numbers.
How Actiflow helps with wind assessments for mixed-use developments
We specialise in wind assessments for exactly the kind of projects described in this article — developments where multiple building types, outdoor uses, and public spaces sit side by side, and where getting the wind conditions right matters for both comfort and regulatory approval.
- We have over 21 years of experience with wind assessments in the Netherlands, Belgium, and internationally, and we are familiar with the specific requirements of municipalities across these regions
- We apply NEN 8100 for Dutch projects and the Lawson criteria for international ones — and we advise you on which standard applies before the study begins
- Our CFD simulations produce detailed, colour-coded comfort maps that you can share directly with clients, architects, and permit authorities without additional interpretation
- We work across the full scale range, from individual high-rise assessments to city-wide wind studies like the comprehensive study we carried out for the city of Rotterdam
- We are known for our speed and flexibility — for regular clients, we can start the next day if the project requires it, and our internal automation continues to reduce delivery times
- We provide a single point of contact from intake to final report, staying close to your project throughout
You can find a full overview of our wind engineering services and other fluid dynamics expertise on the Actiflow website. Curious how we can help with a wind assessment for your mixed-use development? Feel free to contact us. We would be happy to discuss your project and help you find the right engineering solution. You can also learn more about our team and background on our about us page.
