More cranes than ever before are appearing in our expanding skylines. In September, Manchester reached its highest number ever recorded with 64 cranes on site at schemes dotted throughout the ‘capital of the North’, with tall buildings soon to be scattered across the skyline. As a result, in the planning process these developments would have had to go through wind microclimate assessments.
Test, rebuild, test, rebuild, test. That’s the traditional and monotonous routine of assessing buildings in wind tunnels.
Invented towards the end of the 19th century, the UK has around 17 tunnels spread across 7 universities as part of the National Wind Tunnel Facility initiative. The tunnels are often used to test aerodynamics of planes, cars, as well as buildings, which means slots are in demand and costly.
Computational Fluid Dynamics, or CFD, modelling, which uses numerical analysis to predict movement, has reduced the demand for wind tunnel testing. However historically, for some, it was viewed as not being absolutely reliable and wind tunnels are still often used to verify predictions. Developments in software and processing speeds are changing that view though, and the advantages to programmes and budgets are clear.
A joint venture between engineering consultancy, Wardell Armstrong, and rights of light specialist surveyor, GIA, will see Wardell Armstrong’s wind microclimate software, which uses CFD, integrated with GIA’s VU.CITY 3D digital city models to create a new layer and provide accurate wind measurements.
The wind microclimate software was developed by Paul Evans, technical director of energy and climate change at Wardell Armstrong, who manipulated an open source piece of code to make it useful for modelling in an urban environment.
VU.CITY provides interactive digital city models aimed at those in planning or development into which users can import their own 3D model, placing proposals in context to assess their likely visual impact, gauging scale and massing. GIA currently uses VU.CITY to assess daylight and sunlight models and the wind service will sit alongside that.
Key to service is flexibility
The pair of companies hope the service becomes a more cost effective, viable alternative to wind tunnels whilst also speeding up the testing process and enabling designs to be updated more quickly to provide wind mitigation options.
Sam Wallis, managing partner of GIA, explained how for GIA this joint venture is a perfect fit: “We can bring our existing products and infrastructure together to form something that suits both our businesses really well. We’re excited about it because we feel like we can provide a really high standard service to clients without a high cost base that will lead to large fees.”
“CFD is being used alongside wind tunnels, however what we want to do is take CFD all the way through the process and we want to do it with local expertise and at a local base cost.”
Currently, if the development is already within an existing VU.CITY baseline model, clients can get reports instantaneously. If it’s not, it takes a couple of days to input and to run the model, 5-6 days to get the data and 1-2 weeks for reporting time.
“The key to this service is the flexibility because wind tunnels are very expensive and with them are fixed dates that can’t be moved,” added Sam.
Adrian Rigby, partnerships director at Wardell Armstrong, added: “This can be treated as a design tool in its own right, with this software any design amendment can be incorporated into the 3D model very quickly.
“There’s a limitation on the amount of data you actually get from a wind tunnel assessment because the data points amount to half a dozen to a dozen realistically. In a 3D computer model the number of monitoring points are effectively infinite.”
The service is available now and the cost varies depending on the size of the development.