City of London planners have introduced strict rules on all new tall buildings to combat the effect of potential wind tunnels at street level
The City of London Corporation has published tough wind microclimate guidelines for new developments over 25m tall as part of a bid to boost conditions for sitting, walking and cycling in the Square Mile.
Reports by pedestrians of powerful gusts in the capital’s financial district have been commonplace in recent years, coinciding with the upward growth of the City’s skyline. In 2015, unexpectedly strong winds around the base of the Walkie Talkie made the headlines, prompting the City at the time to demand ’independent verification’ of developers’ wind studies.
Under the new 25-page guidelines, developers proposing a tower more than double the height of surrounding buildings should carry out both wind tunnel testing and computational fluid dynamics assessment. This requires separate independent consultants following firm guidelines – and where results differ, an ‘experienced wind engineer’ should be brought in to find out why.
A colour-coded grid for defining wind conditions is published as part of the document, classifying breezes as acceptable for ‘frequent sitting’ or ‘walking’ for example, and ending with ‘uncomfortable/unsafe’. Mitigation measures will be required for conditions that fall short of the intended use of the area.
The City of London Corporation’s Planning and Transportation Committee chair, Alastair Moss, said: ‘With the number of tall buildings in the Square Mile growing, it is important that the knock-on effects of new developments on wind at street-level are properly considered.
‘These guidelines mark another significant step that the City Corporation is taking to put cyclists and pedestrians at the heart of planning in the Square Mile, prioritising their safety and experience.’
New London Architecture chairman Peter Murray said the City had been cracking down on the wind effects of new proposals on a case-by-case basis for a few years.
‘It’s right that architects pay more attention to street comfort when the City is putting such focus on improving conditions for pedestrians and cyclists,’ he said. ‘The Corporation’s Transport Strategy is first class and architects should respond to it.’
Jason Hawthorne, co founder of VU.CITY
There’s actually no excuse for new buildings in London to be built that don’t address the microclimate at ground level. Gone are the days when physical models had to be created and days booked in the wind tunnel. Using highly accurate digital modelling combined with computational fluid dynamics can quickly identify issues with wind meaning proposals can be adapted in real time to find solutions and prevent costly mistakes.
Other areas of London – and other cities – will also need to address this. With planning biased to developing clusters of tall buildings, the wind effects felt in The City could be common place in Croydon and Blackfriars, for example. And with some 17 schemes currently requiring CFD analysis across Manchester, Salford and Liverpool the Tall Buildings Wind Effect is now an essential part of the planning process falling under the EIA (environmental Impact Assessment).
High rise definitely has a role to play in the future of our cities, and using technology will enable this development to take place and still create spaces that are pleasant for everyone to use.