Background
Market Square Limited commissioned Anderson Acoustics to conduct a noise impact assessment for a proposed change of use at 4 The Courtyard, Westerham, Kent.
The project involved converting commercial units into a single-family residential dwelling, including new windows, a roof terrace, and installation of air source heat pumps (ASHPs), solar hot water, and solar panels.
Challenge
The site is located off the High Street in a busy area of Westerham, adjacent to commercial premises and near residential receptors. The local authority required a comprehensive noise assessment to address several concerns:
- Potential noise disturbance from retained retail and mechanical plant;
- Proximity to a restaurant and other commercial activities;
- Ensuring sound insulation performance exceeded building regulation standards by at least 10dB;
- Assessing the impact of proposed ASHPs on neighboring residents;
- Demonstrating compliance with relevant standards (BS4142:2014, BS8233:2014, and Approved Document E).
What We Did
We undertook a detailed technical assessment, including:
- Site Survey & Layout Analysis: Mapped the site, nearby noise-sensitive receptors, and commercial premises. Identified key areas requiring enhanced sound insulation;
- Regulatory Review: Applied guidance from Sevenoaks District Council and relevant British Standards to set performance criteria for sound insulation and ambient noise levels;
- Sound Insulation Assessment: Evaluated separating floors and walls, recommending construction methods to achieve and exceed required sound insulation levels;
- Plant Noise Modelling: Used CadnaA 2023 software to model noise from the proposed ASHPs, considering site topography, building layout, and worst-case propagation scenarios. Predicted noise levels at the nearest residential windows, factoring in shielding from parapet walls;
- Internal Ambient Noise Assessment: Assessed internal noise levels, accounting for building services, external noise break-in, and ventilation system design. Ensured predicted levels met BS8233 guidelines for residential comfort.
Result
The assessment concluded:
- Proposed separating elements would meet or exceed the minimum standards of Approved Document E;
- Noise from the ASHPs would be inaudible at the nearest residential windows, with predicted levels well below thresholds for adverse impact – no additional mitigation required;
- Internal ambient noise levels would comfortably comply with BS8233:2014, ensuring a high-quality residential environment;
- Overall, noise was not identified as a barrier to planning permission for the development.
Project Progress
Sevenoaks District Council granted planning permission for the development on 28th February 2025.
