Consultation ongoing on draft updates to British standard for building acoustics guidance BS 8233

A draft of an update to BS 8233 is available, and consultation runs to 6th September 2025. This would be of interest to consultants, environmental health practitioners, policy makers, decision makers, planners and other stakeholders interested in noise in residential developments. So do take a look and respond, details here: British Standards Institution – Project

BS 8233 is a wide-ranging document which guides the sound insulation and noise reduction for buildings. It is a comprehensive handbook on acoustics, covering various considerations related to sound and noise in buildings. It provides a general overview of guidance for a large number of considerations while pointing to other documents to provide more thorough in-depth information.

It provides guidance on the planning and design of various types of buildings, including residential and non-residential structures such as hotels, offices, and industrial buildings. Specific design considerations and criteria are provided for each type of building as appropriate, and include things like control of reverberation, internal ambient noise levels and sound insulation.

While the current document is around 80 pages long and full of useful information, there is one section of guidance which is quoted more often than most of the document, which is Table 4. This sets out guidelines for indoor ambient noise levels for dwellings. These guideline noise levels are referenced in most planning applications and EIAs for residential development in England, either in an accompanying noise impact assessment or in planning conditions set by the local authority. Therefore, changes to this guidance in BS 8233 potentially have quite wide-ranging consequences, and this article will focus on that aspect of the draft.

A summary of the changes to this aspect of the guidance is described in the figure below:

Will the changes add or reduce complexity to planning residential developments and change some of the tried and tested practices that those involved in the planning process are used to?

This is important because if it is overly complex and difficult for people to understand, it’s either less likely to be used (perhaps in favour of current or older methods) or will add time and cost to the planning process. It’s also not an easy question to answer, and there will be differing opinions on it.

By removing L_Amax consideration, the draft guidance has the potential to reduce complexity and uncertainty associated with the use of this indicator.

Also, less complex is the method for determining a façade sound insulation requirement directly from the assigned sound exposure category (SEC). Though the more complex method of calculating façade sound insulation requirements to meet guideline internal levels remains in the draft as an alternative and may continue to be used, given the potential of this method to reduce the façade requirements and therefore cost and materials.

On the other hand, there is potential for greater complexity in the need to identify the dominant noise source and assess it accordingly.

There may be changes to planning policy and planning conditions, which would mean an initial added complexity. For example, maybe relating policy decisions to the SECs (e.g. noise is not considered a planning issue if the site is SEC I or II, or maybe planning permission may not be granted at SEC V etc.) or just replacing current references to the current BS 8233 internal noise levels with the new target transport mode specific internal sound levels.

There is a general level of added complexity which just comes from doing anything new and implementing changes. Survey data analysis methods will need updating to produce L_DEN, which is not commonly collected in England. Reporting methods and advice will need updating to the new standard, which takes quite a different approach to the current standard. Training will generally be required with consultants, environmental health practitioners, policy makers, decision makers, planners and other stakeholders who may be involved in the planning process, like residents.

In summary, in the long term, the changes might lead to lower or similar levels of complexity, but in the short term, to fully adopt the standard, there would need to be a lot of changes made, and education of those changes may take a while and add complexity to the process in the meantime.

Will changes improve or reduce acoustic standards for new residential developments?

So why make changes if it, at least in the short term, leads to added complexity? The motivation seems to be ideally to improve acoustic standards in homes and improve people’s health and well-being.

As the draft document states, “sound levels above health guideline levels are undesirable from a public health perspective as it has negative impacts on health and well-being, i.e. through psychological and physiological distress and disturbance of other biological mechanisms within the body.” So it is important to consider this when making recommendations on noise control in residential developments.

The World Health Organisation (WHO) produced the Environmental noise guidelines for the European Region in 2018, which sets out research on health impacts from different types of noise and their best estimates of recommended exposure levels for environmental noise to protect public health. These guidelines were produced after the current version of BS 8233, so it is argued that the guidance in BS 8233 needs to be updated to keep up with these recommendations.

As the draft standard and guidelines use L_DEN to describe noise levels and the current standard uses L_Aeq,16hr and L_Aeq,8hr and to an extent L_AMax,F, it is very difficult to determine whether the overall standard of acoustic comfort in a development will improve if the draft guidance is followed instead of the current guidance. These indicators are not directly comparable, and the relationship between them might change depending on the specific situation.

The draft standard does recommend a minimum façade sound insulation, which is not considered in the current standard, so there may be some improvement in relatively quiet environments, though this may also lead to unintended consequences.

The transport-specific internal sound level targets are substantially lower for Railway and particularly Aircraft compared to Road traffic noise. So, it seems likely that designing to these targets will produce greater levels of sound insulation than if designed to the current guideline L_Aeq levels. However, when dealing with these noise sources currently, other considerations, such as L_Amax may drive the design to a greater extent than the L_Aeq, so the result might end up similar.

In summary, it is arguable as to whether the use of the draft standard will lead to improved acoustic conditions. There is plenty of constructive discussion going on about it at the moment in the acoustics community as the consultation progresses. So, as mentioned above, you’re encouraged to read more about it and respond to the consultation. I look forward to seeing a final or updated version if/when it arrives!