Wind and Pedestrian Comfort

IN2 uses advanced wind modelling to assess wind speed, direction and turbulence caused by new developments, particularly in exposed or dense urban environments

We model how proposed massing, landscape and local wind climate interact at pedestrian level, then work with the design team to develop mitigation before submission. The result is a scheme where entrances, streets, balconies and roof terraces perform as intended, and a technical evidence base your planning consultant can defend at committee.

This service matters most on tall, exposed or dense urban schemes, where down-draughts, funnelling and turbulence around taller buildings can undermine public realm and private amenity space that the rest of the design has worked hard to deliver.

When does a UK planning authority ask for wind assessment?

There is no single national wind standard in the UK. The National Planning Policy Framework sets the general expectation that development achieves a high standard of amenity for existing and future users, and individual local planning authorities interpret that requirement through their own policies, design guides and case-by-case judgement at pre-application or validation stage.

A wind assessment is commonly requested for:

• Tall buildings and high-density schemes, particularly where they introduce a step change in height against the surrounding context.
• Sites in exposed locations or areas with a strong prevailing wind climate.
• Proposals with potential for wind tunnelling, funnelling or down-draughts between blocks or through gaps at ground level.
• New streets, pedestrian routes, public squares and building entrances.
• Private balconies, communal courtyards, roof gardens and roof terraces.
• Schemes that sit beside an existing public realm or change how people move through a site.

Requirements vary by local planning authority. Confirm the expected scope and methodology with your planning consultant and the relevant authority at an early stage, ideally before the massing is fixed.

What standards and methods apply?

Lawson Comfort Criteria

IN2 uses the Lawson Comfort Criteria to interpret predicted pedestrian-level wind conditions. The method combines local wind speeds with the frequency of different speeds and directions across the year, rather than judging a space against a single worst-case result.

The resulting comfort classifications relate wind conditions to the activity expected in each location:

• Sitting for private balconies, communal courtyards and roof terraces.
• Standing for entrances, bus stops, window-shopping areas and public amenity spaces.
• Strolling for general pedestrian routes and internal walkways.
• Business walking for city-centre streets where people are moving through rather than lingering.

This helps the design team confirm whether a space suits its intended use and where mitigation is needed. A safety or distress check can be added where the project brief or the local planning authority requires it. Lawson is an established industry assessment methodology, not a statutory standard, so the applicable criteria should be agreed with the planning team and, where necessary, the authority.

CFD modelling and wind-climate data

Computational Fluid Dynamics models how air moves around the proposed and surrounding buildings across a range of wind speeds and directions, predicting local velocities, pressures and flow patterns across the site.

IN2’s wind-analysis workflow combines:

• Three-dimensional massing models, typically in SketchUp or Revit format.
• CFD simulations using SimScale or Phoenics/Flair, as appropriate to the project.
• Regional wind-climate data from the Global Wind Atlas, developed by the Technical University of Denmark and the World Bank Group.

The Global Wind Atlas gives a useful regional baseline for wind speed and directional frequency, but it doesn’t remove the need for project-specific judgement about terrain, nearby buildings, surface roughness and modelling assumptions. Where site measurements or other local data are available, these should be factored into the assessment basis.

For early masterplanning, a wind-rose review and qualitative appraisal can flag locations that need more detailed modelling later. For planning-stage schemes with potentially material effects, detailed CFD or another appropriate method (including wind-tunnel testing) may be required. BRE Digest 520, Wind microclimate around buildings, covers wind flow around buildings, mitigation options and assessment methods including CFD and wind-tunnel testing, and is a useful reference for UK practice.

What does the assessment cover?

The assessment boundary and level of detail are set by project stage, site context and the specific planning question. Depending on the brief, IN2 can assess:

• Existing and proposed building massing, including relevant surrounding buildings.
• Wind speed and direction across the site and adjacent public realm.
• Turbulence, down-draughts, funnelling and localised high-velocity areas.
• Entrances, footpaths, streets, courtyards and public open spaces.
• Private balconies and terraces.
• Communal amenity areas, roof gardens and roof terraces.
• The effect of localised screening, boundary treatments and landscape proposals.
• Alternative massing or mitigation options during design development.

Results are converted into annualised comfort classifications so the assessment reflects how often conditions actually occur, not just the worst wind direction on the worst day.

This service covers external wind microclimate and pedestrian comfort. Structural wind-load design, airport operational wind assessments, dispersion studies and internal natural-ventilation analysis are separate technical questions. Flag these to IN2 early if they’re part of your brief, so they can be scoped separately.

How IN2 integrates wind analysis into design

IN2 works iteratively with the architectural and landscape teams to catch problems early and test proportionate responses, rather than treating wind as a late-stage compliance check.

1. Review the planning question and site context. Confirm project stage, local planning authority expectations, intended uses, assessment boundary and available wind-climate information.
2. Build or review the three-dimensional model. Check building heights, massing, balconies, roof forms, entrances and landscape features that could materially affect airflow.
3. Run the airflow simulations. Test a suitable range of wind speeds and directions and review predicted velocities, pressures, turbulence and flow patterns.
4. Assess intended activities. Apply the agreed Lawson criteria to relevant ground-level, public-realm and amenity locations.
5. Test mitigation and design changes. Review massing adjustments, localised screening, landscape treatments, planting, balustrades and the arrangement of seating or amenity areas.
6. Update and communicate the findings. Reassess important design changes and give the planning and design team clear results and recommendations.

What you’ll receive

Deliverables depend on the planning brief and project stage. A typical package includes:

• A description of the site, proposed development, surrounding context and assessment assumptions.
• The wind-climate basis, including relevant speeds, directions and frequency information.
• Three-dimensional CFD outputs showing airflow patterns and predicted local velocities or pressures.
• Wind-comfort maps or tables for entrances, routes, public spaces, balconies and external amenity areas.
• Lawson comfort classifications matched to the intended activity in each assessed location.
• Identification of areas that may need design changes or mitigation.
• Practical recommendations for massing, screening, landscape, planting and amenity-space layout.
• Updated analysis of agreed design options where iteration is part of the brief.
• Clear figures and explanatory text to support coordination with architects, planners, landscape architects and the wider planning submission.

It all starts with a plan. Contact us today to chat about Wind and Pedestrian Comfort for your next project.