Local authorities generally require the impact of proposals to be assessed against the existing background noise levels. These usually have to be measured over a 24-hour period.

For new plant installations, allowable noise emissions are usually set to a maximum level of 5 to 10dB below the minimum 24 hour background noise level.

All sound tests are undertaken in accordance with BS EN ISO 140 and results are calculated according to the method given in BS EN ISO 717 required by part E of the building regulations, Ecohomes and the Code for Sustainable Housing.

At the planning stage of a project, whether it be residential or commercial, an environmental noise impact assessment is required by the local authority.

Standard Number BS EN ISO 140-1:1998

Title Acoustics. Measurement of sound insulation in buildings and of building elements. Requirements for laboratory test facilities with suppressed flanking transmission

Standard Number BS EN ISO 717-1:1997

Title Acoustics. Rating of sound insulation in buildings and of building elements. Airborne sound insulation