CHP Noise Surveys Explained by NOVA Acoustics Ltd

LEEDS, U.K. - Sept. 29, 2014 - PRLog -- For those with an interest in acoustics (we assume that to be the case if you’re currently reading this!), it is often enlightening and occasionally enjoyable to gain an insight into how certain Noise Surveys within the industry can be tackled. There are many varying methodologies within the acoustics industry; we wanted to share with you a recent Noise Impact Assessment we undertook which, though initially challenging, was ultimately a rewarding experience that resulted in a happy client and some nice-looking pictures…(if you like that sort of thing!)

The Proposal:

The client commissioned NOVA Acoustics (http://novaacoustics.co.uk/) to assess the suitability of a site for the installation of two Combined Heating & Power (CHP) plants and wood-drying storage unit. In order to perform this Noise Impact Assessment (http://novaacoustics.co.uk/acoustic-surveys/noise-impact-assessment/), the typical background noise present at the proposed site would need to be measured. Following this, noise-modelling would be used to calculate the expected noise impact that the CHP plants and wood-drying storage unit would have on the nearest Noise Sensitive Receptor (NSR). All work carried out for this Noise Survey would need to comply with BS4142:1997:’Method for rating industrial noise affecting mixed residential and industrial areas’ (http://shop.bsigroup.com/ProductDetail/?pid=0000000000011...). This provided the Noise Impact Assessment with the following objectives:

Determine the existing noise climate
Assess the likely noise impact from the proposed CHP plants and the wood-drying and storage building on the neighbouring dwellings (NSRs)
Detail the proposed attenuation/design necessary to protect the amenity of the occupants of the neighbouring sensitive receptors (NSRs)

The Site:

The proposed Noise Impact Assessment was to be undertaken on a site which was formerly a farm. The site contained a mixture of traditional farmhouse buildings and newer builds which were used as offices. Also onsite were large grain storage facilities; these were to be converted into the wood-drying storage units. One CHP plant had already been installed onsite, with a view to install the second in the near future. Also onsite were residential properties. These would be the NSRs. All of which can all be seen in the picture below:

The Methodology:

A four-day environmental Noise Survey was undertaken at the site. The location was chosen for its representative nature and accessibility; this is labelled as ‘background measurement position’ in the picture above. The monitoring equipment was located on the first floor of a building at a distance of 1 metre from the facade. The measurement period covered both a weekend and two weekdays to give as representative a measure as possible. All measurements were performed using CESVA sound level meters.

Also measured was the engine of the already-installed CHP plant (which was running at 100% output). This was measured at various positions which are labelled A-E in the picture below.

In typical NOVA Acoustics ‘above & beyond’ style, measurements were even made by climbing onto the roof of the CHP plant to ascertain the noise made by the engine exhaust (position E in the above picture).

Measurements of a fan to be located in the wood-drying storage unit were also obtained. This can be seen in the picture below.

Finally, the attenuation of these measurements at the NSRs was calculated using a noise-modelling package.

The noise-modelling package that takes into account numerous geometric variables to provide an accurate prediction of the noise expected at a certain point. Pictures of what this clever little software package working can be seen below.

The Result:

After all the modelling had been completed, the results were analysed according to BSR4142.

This suggested that, based upon the values extrapolated during the modelling process, complaints would be ‘likely’ from the NSRs.

The Recommendations:

Following our arrival at this result, NOVA Acoustics were then able to recommend suitable modifications to the site-proposals in order to reduce the noise arriving at the NSRs.

Following this Noise Survey, we recommended the installation of an acoustic fencing around the CHP plants; with sound attenuators for the inlet duct of also being proposed.

To ensure that our recommendations would be suitable, these too were inputted into the noise-modelling software. A picture of this process, showing the proposed CHP plants and acoustic fences (in green) can be seen below.

So, there we have it. One of the many jobs where NOVA Acoustics were able to help a client make sound (no pun intended) investments thanks to their Noise Impact Assessment. These will help to ensure that the development does not cause anybody problems or attract complaints – saving time, money and hassle in the long-run. Visit http://www.novaacoustics.co.uk for more information.