Noise Impact Assessments: What are they and why do we need them?

Noise can be defined as an unwanted or disturbing sound that affects the health, productivity and well-being of people as well as having an impact on the existing environment including animals. Continual exposure to loud noise could result in high blood pressure, heart disease, sleep disturbances, and stress across all age groups, especially children.

What is a Noise Impact Assessment?

Noise Impact Assessments (NIAs) consist of a series of detailed noise surveys, which are often required for a variety of planning applications. These are requested by Local Planning Authorities (LPA), in particular by Environmental Health Officers (EHOs), in order to establish the environmental noise impacts of existing and proposed developments. An NIA will typically involve an assessment of the existing noise sources and comparison of the predicted noise level generated by the proposed development. NIAs are generally requested by an LPA due to concerns arising from noise exposure to prospective or existing noise sensitive properties.  

Typical focus of NIAs:

  • Transport noise (Road, Rail, and Aircraft) to proposed noise sensitive developments (BS8233:2014);
  • Noise from new fixed plant at existing residential receptors (BS4142:2014);
  • Noise from existing commercial units upon proposed noise sensitive developments (BS4142:2014);
  • Noise due to road traffic generated by the development (Change in Ambient).

Focusing on a BS8233:2014 assessment, the aim is to set out appropriate internal and external noise levels for Bedrooms, Living Rooms, Dining Rooms and Gardens for the day time (07:00 – 23:00) and night time (23:00 – 07:00). It also provides guidance on the design of sound insulation for buildings and methods of achieving appropriate noise reduction for new build dwellings and refurbished dwellings undergoing change of use.

Noise modelling is imperative in the work that we do. Noise models are created, through using state of the art CadnaA software, which can accurately predict noise levels, and how they propagate over a site. Figure 1 demonstrates how, through the use of colours and bands, we can effectively demonstrate to clients the feasibility of a site, which is an integral part of a Noise Constraints Assessment. Noise Constraint Assessments are often used at the infant stage of a large development, whereby the assessment can inform developers of potential constraints and take these into consideration through the design phase. A variety of noise sources can be inputted into the noise map, from transport (Figure 1) to single source output (Figure 2) which can significantly effect the propagation of the noise. Cadna also has a 3D function (Figure 3), which can be particularly useful in high rise blocks or buildings with large facades, where noise levels can vary significantly.

Why do developers need a BS8233 Noise Assessment?

When developing a residential property, school, healthcare facilities or hotels (or any other premises that could be defined as noise sensitive), if the development site is near to  transport noise such as a road or railway then it is likely that the Local Authority will request a BS8233 noise survey to be undertaken to ensure that appropriate internal and external noise levels can be achieved to guarantee the amenity of the future occupants. BS8233 sets the following noise criteria:

How is a BS8233 noise survey conducted? 

The aim of a noise survey is to gain a baseline measurement of the noise environment within the vicinity of your proposed development. Once the noise environment has been defined, the potential noise impact on residential dwellings can be assessed. The level of noise impact is analysed according to BS8233:2014 to ensure the future occupants will not be adversely affected by noise.

  • We will carry out an noise measurements to establish the noise levels across the development site. Measurements can include for road, rail and aircraft noise and could be attended or unattended depending on the source;
  • We calculate the predicted noise levels at the façade of the development as well as within the external amenity areas due to the existing sources;
  • We recommend appropriate mitigation measures to protect the external areas;
  • We will calculate the internal noise levels to allow the provision of appropriate glazing and ventilation specifications as required; and
  • We will provide a technical report which is submission to your local authority to support the planning application.

What will be in the Noise Impact Assessment report? 

The purpose of the technical report is to outline to the Local Authority how ‘Good Acoustic Design’ has been implemented in the design of the development to ensure appropriate control measures are being installed. The noise survey report will outline the following:

  • Detail of the proposed development and the existing area including any noise sources surrounding the site;
  • The surveying method that has been used to assess the noise incident on site, including monitoring locations, monitoring dates and times, the equipment used, calibration details, and weather conditions ;
  • A summary of the results including the LAeq and LAMax, fast in accordance with the BS8233:204 requirements.
  • An assessment of the noise level results in accordance with BS8233:2014
  • Mitigation measures required to protect the amenity of the future occupants including calculations of the expected noise reduction from the sound insulation scheme.

What Mitigations measures can be expected from your noise report?

The report will aim to apply all reasonable noise control measures to ensure the internal and external noise requirements of BS8233:2014 can be achieved. It is always preferable for noise to be controlled at source, however this is not always feasible. The following mitigations measures can be applied:

  • Natural corridors and distancing from the existing sources;
  • The orientation and internal layout of the proposed Buildings;
  • Acoustic Barriers and Bunds;
  • Acoustic Glazing; and.
  • Alternative Ventilation Schemes.

Why do NIAs matter?

Noise can have an effect on health, wellbeing, productivity and the natural environment. Noise is considered to be any unwanted or disturbing sound that affects the health and well-being of humans and other organisms. Noise pollution impacts millions of people on a daily basis. Exposure to loud noise can also cause high blood pressure, heart disease, sleep disturbances, and stress. These health problems can affect all age groups, especially children. Many children who live near noisy airports or streets have been found to suffer from stress and other related issues, such as impairments in memory, attention level, and reading skills.

Cities have become the epicentre of this type of pollution, which, is severely damaging to humans . So much so that the European Environment Agency estimates that noise is responsible for 72,000 hospital admissions and 16,600 premature deaths every year in Europe alone. (Noise — European Environment Agency (europa.eu). In the UK alone, cities take up 8% of the land whilst accounting for 54% of the population. As cities expand larger and urban populations grow, the problem of noise pollution will only get worse, and thus the focus upon mitigating all forms of noise pollution will become ever more prevalent and important.

How can Omnia help?

Omnia has extensive experience of producing NIAs for a number of clients, with varying sized developments. We’d be happy to assist you in any upcoming projects or enquiries you may have, and look forward to working with you.

If you’d like Omnia’s help with your project, contact us to speak to one of our team.