29 November 2022
Following the new building regulation: Approved Document O, being enacted as of June 2022, Our Acoustic Air team supported clients by providing CPD Sessions to give an overview of the changes and help clients navigate this.
Now almost 6 months into these new regulation changes, our team have a wider understanding of the impact they are having on clients and projects in which the team are working on. So, to further support our clients, the Acoustic Air team have produced an easy-to-digest Q&A, providing information around this regulation.
What is Approved Document O?
Approved Document O (AD-O) is a new Building Regulation enacted on 15th June 2022, which considers the need to combat overheating in any new residential premises, including private homes, care homes, and student accommodations.
Overheating and Internal Acoustic Conditions in newly built residential accommodation is now of significant concern, which has seen the addition of AD-O coming into force. With global warming continuing to impact the UK and records summer temperatures in consecutive years, it has become apparent that more needs to be done to ensure that dwellings are comfortable from both a thermal and acoustics perspective.
The introduction of AD-O now requires overheating and Acoustics to be considered together. As a result, we are already seeing significant implications on the design of residential buildings.
Is AD-O a planning issue?
Currently, AD-O comes under the Building Regulations phase of a development site; however, when it comes to Acoustics, Building Regulations and Planning, it’s all very dependent upon the location within the country. For example, Approved Document E (Sound Insulation) is almost always only looked into at the Building Control stage. In contrast, Approved Document F (Ventilation) is almost always considered at the planning stage (albeit solely from a noise intrusion perspective).
Whilst not currently a planning issue, the Institute of Acoustics has highlighted that on low-risk sites where there may not be any planning concerns relating to Acoustics, the same site would have a significant probability of not satisfying the internal acoustic criteria in AD-O, meaning significant design and cost implications once on Site.
We recommend that consideration is taken at the planning stage to understand the implications to avoid problems coming to the fore at the Building Regulation stage.
If it’s not a planning issue, why should I consider it early in the process?
An early understanding of the impact that AD-O will have on your development will not only identify issues early on, so you can plan and adapt your development to comply, but commissioning early will significantly reduce the cost and delays that you will inevitably incur at construction/Building Control stage if your development doesn’t comply.
What implications can this cause if we leave AD-O to Building Control Stage?
As it is currently a Building Control regulation, if overheating issues are identified at sign-off, you may find your development having to stall to do your due diligence and, where required, implement mitigation measures. This may then impact build forecasts, additional construction work (for Louvers or Mechanical Ventilation) and additional costs that you have not previously considered or allowed for. In some instances whereby large louvres or Mechanical Ventilation is required, you would likely need to revisit the planning officers.
Do I only need to consider AD-O if the local authority considers noise to be an issue?
No, it is essential to note that any noise source which triggers a reading of 49 dB over a night-time 8-hour period or triggers ten events of 64 dB ore more in the same period will result in at least the front line of dwellings needing to undergo a process known as ‘Dynamic Thermal Modelling’ as the ‘Simplified Method’ of the Regulation will no longer be permitted to those dwellings.
As detailed in point 2.2.3.1 of the Institute of Acoustics response to the Regulation, ‘The assessment of noise in relation to this regulation is not limited only to sites where the Local Planning Authority consider noise to be an issue. Many sites where the Local Planning Authority did not consider noise to be an issue will nonetheless not comply with the noise level set out in this regulation’.
Can we ensure house types on the development satisfy AD-O regardless of external environmental issues?
Yes, if you use similar house types across all of your sites within the UK, it is possible to have a catalogue of results showing compliance through either the simplified method or the Dynamic Thermal Modelling method. Your house type would need to demonstrate compliance in all four orientations (facing north, south, east, and west). Should your Site have no environmental issues (external noise or Air Quality), then you could submit this to Building Control for compliance rather than work on a site-by-site basis.
Our team can help support your house types and seamless process through the Building Control stage by undertaking these assessments for you. This provides our clients with a file of all house types so that if there are no noise or air quality issues, they can submit the file that shows compliance at Building Control Stage.
Can I use calculations from one site and use them on another?
If there are external factors that would mean the Simplified Method is not viable, then no; unfortunately, due to external factors, changes in roads and orientation of sites, an assessment needs to be undertaken for each individual development. However, if house types remain the same from one site to another, our acoustics team will better understand your house types for future assessments, which may help reduce the timescales and costs if we already have a 3D model of the house on file.
Are you seeing many developments that don’t comply with AD-O?
Yes, around 90% of our noise assessments since June 2022 require mitigation strategies to support AD-O, even at lower risks sites, when considering the current ProPG document for Acoustics.
What mitigation measures have had to be put in place for these developments?
Following Overheating assessments, we have worked on various developments requiring various mitigation measures/strategies. The most common have required our clients to reconsider and amend their site plans to accommodate house and garden orientations. Some homes on these developments have needed to introduce acoustic louvres to allow the excess heat to escape whilst keeping windows shut. The acoustic louvre still allows sufficient airflow to satisfy the AD-O overheating criteria but reduces sound sufficiently to satisfy the acoustics criteria in AD-O. Both parts of the Regulation need to be complied with concurrently, so this is why it’s beneficial to have one team working on both parts!
For more significant measures where areas of the development are located within higher noise areas, our clients have had to include mechanical ventilation on a range of house types as the noise within these areas is too loud for open windows to act as the mitigation for excess heat, in some, but very few instances, cooling is also required. You can see more about potential mitigation options below:
Having to amend site layouts can have significant implications on development costs. Do you recommend undertaking assessments before a layout is produced?
Yes! With the implications that AD-O has on residential developments, undertaking an assessment as early as possible can help determine the overall impact and help you best design your development, identifying costs early and helping you maximise your development potential.
At the outline planning application stage, we typically undertake a quick assessment to let you know what percentage of your developable area would not comply with the simplified method of AD-O based on your indicative layout. This then helps inform further decisions at the detailed design stage.
Is your site affected by noise levels, and what approach do you need to take?
Why M-EC?
Our dedicated Acoustic Air team can assess and mitigate any potential issues in line with relevant regulations to ensure we meet the needs of all involved and maximise developable areas. We use the latest measurement technology and cutting-edge computer modelling programs to identify the noise and overheating issues for new and existing developments and specify cost-effective mitigation solutions.
back