In June 2022, a host of new Building Regulations were introduced, considerably altering the development process for residential builds – notably Part O, which focuses on reducing the risk of overheating in new residential premises. Building Regulations Part O is accompanied by Approved Document Part O (or AD-O) – which provides a full guide to compliance. 

For a full overview of Approved Document O’s acoustic, thermal, and air quality requirements for residential developments, alongside advice on how to achieve compliance, read on:

 

Building Regulations Part O: A Basic Overview

Building Regulations Part O intends to minimise the occurrence of high indoor temperatures in new residential premises. Under it, residential buildings will need to balance mitigation requirements for:

• Acoustic design (a suitable level of internal ambient noise levels must be maintained).
• Thermal design (strategies to limit solar gains/measures to remove the excess heat from indoor environments must be implemented).
• Air quality design (the ingress of air pollutants in habitable rooms must be controlled).

 

Which Development Types Are Affected By Building Regulations Part O?

Building Regulations Part O applies to all new residential building projects submitted after 15th June 2022, encompassing dwelling houses, flats, institutional residential premises such as boarding schools, care homes, and student accommodations.

Please note that these rules do not apply to conversions or building extensions. Projects with a building notice or initial notice applied for before 15th June 2022 will be reviewed under previous Building Regulations, provided that works commenced before 15th June 2023.

 

Approved Document O: Methods of Demonstrating Compliance with Building Regulations

Approved Document O provides guidance on how to comply with Building Regulations Part O, and outlines measures for reducing the occurrence of high indoor temperatures. Testing typically consists of two steps – a baseline survey, and method-based testing.

 

Baseline Survey

In order to inform on the appropriate approach and the level of detail required to achieve compliance, a baseline environmental noise survey must be conducted at the development site as early in the process as possible. This is because the suitability of each test type can vary based on the development’s location, the units’ capacity for cross-ventilation, and the external noise levels that will affect bedroom façades during the night. 

Following said baseline survey, a 3D-noise (or acoustic) model should be produced to predict sound levels across the development site and establish the incident sound levels at each sensitive façade, helping determine appropriate mitigation measures and informing the energy/sustainability review. 

 

Testing Option 1: The Simplified Method

The simplified method is applicable if the development to be surveyed aligns with the requirements set out in AD-O. However, if the external noise levels in the area are too high, the more complex and accurate dynamic thermal modelling method should be employed.

If the simplified method is recommended following the baseline noise survey, Sound Solution Consultants and the instructed energy personnel will review the gathered data and establish the relevant method/approach for the development.

Following the competition of testing, the checklist found in the document’s appendix B can be submitted to Building Control to demonstrate compliance.

 

Testing Option 2: The Dynamic Thermal Modelling Method    

In contrast, the dynamic thermal modelling approach is mainly used where external sound levels require windows to remain closed at night and for complex buildings that require greater accuracy and design flexibility. This approach requires the instatement of an energy/sustainability expert, who will use CIBSE Thermal Modelling software (TM59) to accurately replicate the form of the building and map it against the potential overheating scenarios.

This tool can be used to work out the potential overheating risk in specific rooms and at specific times of the day.  It is also possible to model different mitigation methods and work out their efficacy, such as glass coatings, shading and shutters or blinds.

 

How Sound Solution Consultants Can Help You Navigate Building Regulations Approved Document Part O

As demonstrated above, approved Document Part O requires residential developments to adhere not just to design considerations for overheating, but existing stipulations under Part E (resistance to the passage of sound) and Part F (ventilation). 

Where each of these factors can affect the other, it is appropriate to consider these elements collectively. Baseline noise surveying must therefore take place in the earliest stages of the project both to assist in choosing the suitable approach (simplified or dynamic thermal modelling method), and to allow teams from the relevant disciplines to work together in providing appropriate overheating and mitigation solutions.  

Given the new regulations, all residential developments will now require an acoustic model to inform the thermal assessment. The complexity of this model will vary depending on the type and number of noise sources in the vicinity of the site. Our consultancy team is equipped to carry out comprehensive noise, air, and thermal assessments in compliance with Approved Document O, delivering a consolidated ‘Part O – Energy Report’ suitable for submission to Building Control.

 

Contact Our Consultants Today 

If you’re curious about how these new Building Regulations will affect your project or if you have any questions about Approved Document Part O, we are here to assist. Reach out to our expert acoustic consultancy team at Sound Solution Consultants. We can provide you with the information you need, help you understand your next steps, and guide you through the process of compliance.

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