1.   Introduction

1.1  Authorship

This guide has been prepared on behalf of the Department of Trade Industry (DTI) under the National Measurement Systems Acoustics Programme 2004-2007, managed by the National Physical Laboratory. Whilst this material has been prepared in consultation with the DTI, the views and judgements expressed in this guide are those of the authors and do not necessarily represent those of the DTI and NPL.

The document on which this guide is closely based has been prepared by Hoare Lea Acoustics.

The material contained herein has been approved and guided by a Project Board, with the following attendees:

Acoustics Group, National Physical Laboratory
AcSoft
Casella Stanger (now Bureau Veritas)
DTI (now BERR)
Environment Agency
Environmental acoustics
Hoare Lea
Institute of Acoustics

1.2  Purpose

This guide has been prepared for all parties who commission, undertake or use environmental noise predictions for commercial or industrial operations, of whatever type or scale, for which an environmental noise assessment may be required.

The guidance is directly relevant to predictive studies carried out in support of the following types of assessment:

• Pollution Prevention and Control (PPC) permitting
• BS 4142 and BS 9142 based investigations
• Planning condition compliance
• Development of site specific noise mitigation methodologies

The guide is intended to:

• Raise awareness of the utility of environmental noise prediction studies
• Raise awareness of the inherent variability of environmental noise fields, and the subsequent risk of incorrect assessment outcome that may result when attempting to utilise any objective rating method
• Provide an understanding of the types of potentially significant risks involved in using environmental noise predictions to inform decision making processes
• Promote the management of such risks from the outset of an investigation by adopting a structured approach to the design of prediction studies that recognises the relationship between variability, uncertainty and risk
• Raise awareness of the unavoidable practical, technical, and commercial limitations that prevail in all methods of noise assessment, and of the conclusion that limited assessment resources are best focussed on reduction of risk rather than of uncertainty
• Assist users to balance the risks arising from a restricted predictive study against other constraints and considerations, and thus identify instances where alternative assessment methods may need to be considered

Whilst this guide primarily addresses issues surrounding situation specific modelling for industrial and commercial noise immissions, the principles contained in it also have relevance for broader applications of environmental noise modelling.

1.3  Other sources of guidance

The uncertainties and challenges involved in large scale noise modelling have received considerable attention under European Union Directives that establish requirements for strategic noise modelling of transportation and industrial noise sources. However, this attention has been primarily focussed on the consideration of harmonised methodologies for strategic applications. In contrast, localised industrial and commercial noise issues require modelling techniques driven by different information requirements and constraints.

The principles contained in the guide share important synergies with BS 9142 (available from IEMA Publications) and the guidance produced under the NMS project on managing risks associated with environmental noise measurements (see Hoare Lea's project web page). An understanding of the guidance provided by these documents will be of assistance when the use of environmental noise predictions is being considered.
 
Other published sources of information on environmental noise prediction are listed in the document bibliography.

The advice contained in this guide should be read in conjunction with any other standards or codes of practice directly applicable to a given assessment. The advice is not intended to conflict with any existing standards, regulations or guidelines concerned with environmental noise assessment, and where any such conflict is found to exist, then users of this guidance should note that existing regulations take precedence. In the case of conflict with standards and guidelines, users will have to decide for themselves how best to proceed, but they should also provide a clear justification for any decisions made. It is permissible to deviate from non?statutory standards and guidelines where deviation can be justified by reference to the facts of any particular case.