As Acoustic Consultants the weather and its accurate forecast is a significant element to our work. Poor weather and their forecasts results in unreliable noise survey data.
We are regularly asked by clients what are your timescales and our response when environmental noise surveys are within the scope of works are for example 7 days however this is dependent on weather conditions.
In an ideal world we would monitor 24hrs a day, 365 days a year and in all weather conditions. Unfortunately this is not always possible and it’s not because we don’t want to standing in the cold and rain! The purpose of this article is to inform our clients and other who share an interest in what weather conditions you should monitor under, why you should monitor under these conditions and the potential adverse effects of monitoring in unsuitable conditions.
For reliable data noise surveys should be undertake under the following conditions:
- Dry with no rain.
- Temperatures above freezing with no significant variation.
- Wind speeds of below 10 miles per hour.
The ideal weather conditions for noise surveys are sunny skies and no wind, however living in the UK days like these are few and far between!
To ensure we are monitoring under correct conditions we use a range of weather forecasting sites such as The Met Office, BBC, Weather Underground etc however these sites are not always 100% reliable and as such for the long term surveys we deploy weather stations to ensure the data we obtain is correct.
Why should we monitor under these Conditions?
Noise monitor should be undertaken under these conditions first and foremost to ensure you obtain accurate noise data and secondly to ensure you are following the methodology of the British Standard you will be using for your assessment, such as BS4142:2014 and BS7445:2003 etc.
For a residential scheme where you addressing the noise impact of external noise on the development adverse conditions would result in a more onerous noise assessment. This in effect would result in additional mitigation and cost to the client. When addressing external noise the most significant factor is generally high wind speeds as this affects the low end of the noise spectrum. However, rain, cold and wet roads also have an adverse effect on the assessment.
For a plant noise assessment for example it will result in a less onerous assessment, however it would not follow the methodology of BS 4142 and as such may not be considered acceptable by the local authority. In addition if an application went to appeal the baseline noise data is unlikely to be accepted without further evidence (additional surveys) to verify its accuracy.
As such it is of a benefit to a client to ensure noise monitoring is undertaken in ideal conditions. At Acoustic Consultants we have a high number of modern outdoor sound level meters (Class 1) and weather stations to ensure that we can quickly deploy to numerous sites once the weather forecast is suitable.