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  Key points

  • A simple model was built from our noise source library
  • Noise levels on site and at nearby houses were accurately predicted
  • The site layout and building construction were optimised using the model
  • Noise contours were predicted using CadnaA software

     


  


Power station
Noise propagation modelling

The brief

Coupland Bell was asked to provide technical support for a tender for a power station project.  Far field noise at the nearest house was a key concern. For our client’s bid to be successful, it would be necessary to show a thorough understanding of the noise sources on the proposed development and how they could be adequately treated.

The brief was to develop a numerical model leading to predictions of the far field noise.  The predictions would be used as part of the Planning application and sufficient background evidence would have to be supplied for the Planning authority to complete its Due Dilligence process. 

The model would need regular updates, to keep pace with the site design and would be used to select acoustic treatment.




 


Spreadsheet model

Coupland Bell has developed a library of noise source data for power stations over the years.  This was used to build a simple spreadsheet model of the entire power station.  It included the interior of the power halls, transmission through doors and breakout from ducts.  Various receptor positions that were of interest to the

Planning authorities were included.
Initial predictions were straightforward and showed how the noise limits imposed by the Planners could be achieved.  The model was constantly updated as the layout of the proposed site was changed, for engineering reasons. 

The noise predictions were then used to influence the site layout and optimise the screening of plant.  


An embankment around the project was planned and its screening effect was included in the model.  The construction of the buildings was optimised, based on the acoustic transmission loss necessary to meet the far field requirements.  This allowed accurate cost estimates to feed into the bid.







CadnaA model


The bid was successful and our client was awarded the construction contract.  The Planning authorities asked to see predicted noise contours for the whole area surrounding the development. 

Coupland Bell built a noise propagation model using CadnaA software.  This confirmed the validity of the spreadsheet model, to within 1 dB(A).


Noise contours were predicted, within the site boundary and out to the nearest residential properties.  The contours within the boundary were useful for confirming that the contract maximum of 80 dB(A) would not be exceeded, where items of plant were closely spaced. 

The CadnaA model also confirmed that although the earth bank would provide local screening, it would not justify lower specification acoustic treatment to the buildings, because of the need to maintain limits at the first floor windows of distant houses.










Confidentiality


To protect the confidentiality of this project, an example model was built.  All of the images in this case study are from the example, rather than the real project.




Coupland Bell Ltd, The TechnoCentre, Puma Way, Coventry, CV1 2TT tel: (+44) 01926 863563 - email: web_enquiry@couplandbell.com

West Midlands engineering consultancy generating new concepts for our clients, solving unusual mechanical design problems, finite element analysis, noise, stress and vibration analysis. We specialise in renewable energy, wind turbines, marine, gas turbines, R&D and technology licensing.