Acoustic Implications of Approved Document O

The new Building Regulations Approved Document O (AD-O) primarily focuses on avoiding overheating in new homes. However, it also introduces internal noise criteria for bedrooms at night, above which open windows cannot be used to remove excess heat.

This will mean many new residential dwellings will be required to use an alternative means of providing relief from overheating in bedroom areas (i.e. other than open windows). This will lead to more complex and potentially energy intensive overheating design solutions in homes and this is likely to affect the vast majority of new residential developments to some degree, even when located in what are considered to be ‘quiet’ locations.

There is also uncertainty as to how the AD-O acoustic requirements will be enforced and what will be required to demonstrate compliance. Mat Hyden, who leads our acoustics team, is one of the authors of a new guidance document that will provide a methodology for demonstrating compliance with the acoustic requirements of AD-O. Mat has provided his top tips below for identifying and addressing the design challenges that the new AD-O will present. These tips will help reduce design complexity, avoid unexpected project costs and reduce the risk of problems gaining Building control approval.

✔ Top tips

  • Make sure your advice is up to date. Guidance and requirements are evolving quickly and your consultant needs to be fully up to date.
  • Get acoustic advice early – the vast majority of residential developments will require a noise assessment to support planning. This will allow early consideration of noise constraints and identify where it may or may not be possible to rely on windows as part of the project overheating strategy.
  • Give detailed consideration to the impact of plot layout and orientation of rooms (AD-O noise criteria only apply to bedrooms at night).
  • Reduce overheating as far as reasonably practicable using passive means other than open windows (solar shading, glazing design, building orientation etc).
  • Consider using buildings or structures with less sensitive facades to provide ‘acoustic screening’ and reduce noise levels incident on other building facades containing bedrooms or more sensitive spaces.
  • Engage with building control early in the project to discuss their understanding and expectations in relation to overheating and noise. Getting early agreement of what is required to demonstrate compliance can avoid risky commissioning testing and costly, difficult to implement mitigation measures.
  • Where bedrooms are dual aspect, it may be possible to use the ‘quiet’ facade to provide the required opening window areas.

× Things to avoid

  • Do not wait until later in the design of a building to consider noise impacts. This is likely to affect most developments to some degree and often solutions will have a significant impact on the design of the building both architecturally and from a building services perspective.
  • Do not assume because your site is subjectively ‘quiet’ this is not an issue. If a residential development includes sensitive facades within 10 to 15 metres of an internal road, access road or other traffic route, there is a significant risk you will not be able to rely on open windows.
  • Do not assume that if there are no noise related planning conditions / requirements that this is not an issue. 

New regulations

Download the key takeaways below 

Leading Minds webinars

Mat Hyden led a webinar on the Acoustic Implications of Approved Document O as part of our Leading Minds webinar series. View the series programme below where you can watch this webinar, as well as many others on a range of development topics.

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