There is an existing body of research into noise, vibration and wind regime concerns associated with urban wind turbines demonstrating the detrimental effects of these topics on the energy yield potential and therefore financial worth of an installation. Much of the research has focused on wind regime assessment and optimum roof top placement via CFD modeling offering generalised guidelines showing a potential for wind power to contribute towards lowering London's CO2 emissions. Unfortunately, without benefiting from appropriate planning assessment, a number of early urban turbines failed and have risked irreversibly tarnishing the concept.
Hitherto no studies have been specifically conducted on the urban potential of building integrated wind turbines. As integration is bespoke, typically determined by the architecture, it is unknown whether existing guidelines for roof mounted wind turbines could be directly applied. It is probable that each installation would merit its own assessment and analysis procedure.
This study aims to investigate the differences between roof mounted and building integrated turbines in terms of assessment, operation and urban potential. In response to these differences it is intended to demonstrate how a successful installation can be achieved.
Comparisons between two urban sites, one smaller, roof mounted HAWT and one larger, building integrated HAWT have been made via noise, vibration, CFD and atmospheric data recorded and analysed over two years to build a comprehensive understanding of the inherent urban issues.
The prospect of successfully situating an urban turbine is complex in nature and considering the high installation costs and high level of design and engineering required to do so it is imperative that their energy yield provide a satisfactory return on investment and efficient supply of power without adversely impacting upon the surrounding environment or themselves.
This study concludes that a multifaceted approach is necessary to achieve an efficient building integrated turbine, comprised of: (i) accurate local noise surveys to establish the local acoustic environment to inform acceptable turbine operating ranges, (ii) specific noise modeling of manufacturer provided data or, where none is available, acoustic testing of the proposed turbine across all applicable wind speed ranges, (iii) comprehensive vibration assessment, not only of the turbine tower/system but also of the turbine housing and any lower residential floors to ensure no natural frequencies will be excited and to prevent any vibration transmission via appropriate mounting, isolation or damping where necessary, (iv) the acquirement of site specific wind data to inform architectural design, turbine selection and placement. If monitoring at hub height is not possible it has been found that it may be acceptable to monitor in close proximity and then extrapolate the results using CFD analysis and wind profile methods, (v) CFD modeling of the surrounding topography, the turbine mount and/or enclosure. These areas are discussed with potential areas of noise and vibration control and turbine optimisation, specific to the case studies, investigated.
Further to the aforementioned study an investigation into a new method of assessing noise and vibration levels associated with average anemometry recorded wind speeds has been presented so as to attain average levels per wind speed bin without being skewed by impulsive gusts.