Archives: Knowledge - Technical Resources

The recladding of high-rise buildings has become a major focus since Grenfell, with thousands of buildings across the UK undergoing works to replace unsafe (i.e. potentially flammable) façade materials. According to government figures (May 2025), over 1,700 buildings have been completed, more than 700 are in progress, and work has yet to start on almost 2,700 more.

The primary driver is of course fire safety. However, poorly considered changes to glazing, ventilation or cladding systems can create acoustic issues with the potential to result in claims and negative PR against developers, contractors and building operators undertaking the work. This scrutiny is likely to increase as Resident Engagement groups are given more power under the current legislation. 

This article outlines the key acoustic risks to assess when recladding, and how we are already helping our Clients achieve compliance and minimise their risk of PR issues and claims related to acoustic performance.

External Sound Insulation

High-rise buildings are often located close to major noise sources such as roads, railways, airports and industrial facilities. The design of the external façades — including glazing and ventilation — dictate internal noise levels. If the new systems have a lower acoustic performance than the existing systems, the noise levels in the building will increase as a result.

Planning requirements are often imposed to ensure this is considered, however, given the risk of negative PR and claims, an acoustic assessment of the proposed façade design is strongly recommended in any case.

Overheating and Thermal Comfort

Recladding typically improves a building’s thermal performance, reducing heat loss in winter. However, better insulation also increases the risk of overheating in warmer months, increasing residents’ reliance on open windows for thermal comfort and exposure to high noise levels.

To prevent problems, overheating assessments should be carried out alongside noise assessments, particularly for buildings close to significant noise sources. This ensures that both thermal comfort and acoustic comfort are protected.

Acoustic Separation Between Dwellings

In most cases, the sound insulation between dwellings (across separating walls and floors) is unaffected by recladding. However, buildings with curtain walling can present risks: sound may travel vertically or horizontally through the walling system, undermining acoustic separation between dwellings.

How Cass Allen Can Help

Cass Allen is already supporting clients with the design and specification of recladding systems. We add value by:

1. Undertaking site noise surveys to quantify risks
2. Reviewing cladding proposals to identify potential acoustic issues early
3. Making sure works do not introduce new or worse acoustic problems for residents
4. Helping achieve compliance with any relevant Building Regulations or planning requirements
5. Preparing clear acoustic specifications for recladding systems
6. Undertaking on-site acoustic testing of installed systems to demonstrate performance

Conclusion

Recladding programmes are rightly focused on fire safety. However, relatively inexpensive acoustic design assessments can protect developers, contractors and building managers against damaging PR and claims down the line.

If you are planning or already undertaking recladding works, call us on 01234 834862 or email mail@cassallen.co.uk to discuss your project and how we can help.

With the rising popularity of padel it is unsurprising that there is an ever-increasing demand for high quality courts on which to play, with many new developments now including them in their design.

Padel courts are beginning to appear in place of existing tennis courts, as well as both internal and external new locations across sports centres, spas, new residential developments, and smaller scale local padel clubs.

Padel, like tennis, revolves around the hitting of a ball over a central net, to be returned by an opposing player or team, but with the added element of squash, this can be done so through the rebounding of the ball on either the back or side walls of the court. With each hit and each rebound of the ball comes with it a very short sharp noise, with many of these noises in short succession making up a rally.

Unfortunately, due to this series of repetitive noises, padel games produce very distinguishable and high levels of noise, which has the potential to cause significant noise impact on surrounding occupants’ amenities if not assessed and mitigated correctly.

With our in house database of measured padel court noise and your proposed court locations we can use a calibrated, tried and tested modelling technique, to accurately predict the expected noise impact at the closest noise sensitive properties. Armed with this information, our team of specialists can provide you with bespoke mitigation design advice to aid in both the planning application, and the successful installation and running of your padel courts.

If you need assistance with this or any other leisure noise impact assessment, then please get in touch at: mail@cassallen.co.uk

In fact, many local authorities — including Cambridge, Bath and parts of London — are even revoking their Air Quality Management Areas (AQMAs) as pollutant levels fall below the statutory limits that underpin national planning policy.

Despite a great deal of scepticism, targeted measures such as the London ULEZ are working – alongside the benefits of cleaner vehicles, and the move away from combustion energy solutions for heating, and better urban design.

Does that mean Air Quality is now ‘sorted’? Not quite, and here is why:

• Compliance isn’t everything – new WHO targets and local authority policies mean a site might still be deemed unacceptable in health or planning terms.
• Councils are cautious – even where AQMAs are revoked, planning teams still request Air Quality Assessments, Mitigation Strategies, and Management Plans, in line with Local Plan policy and supplementary planning guidance.
• We know more about pollutants – even small amounts of brake and tyre wear can harm health and we can advise where this needs to be considered.
• Indoor air matters – we spend 90–95% of our time indoors, and home pollution is often higher than outdoors. BREEAM v7 now rewards projects for addressing indoor air quality.

At Cass Allen, whilst still helping you to gain planning approval, our focus is shifting to demonstrating that developments actively support health and policy ambitions. This means:

• Navigating diverse local and regional guidance to meet planning requirements.
• Designing air quality positive strategies for planning gain.
• Future-proofing projects against tightening guidance regarding fine particulate matter.
• Building mitigation packages that satisfy planners before objections arise.

If you’re planning, designing or managing a site in 2025 and beyond, air quality is not just a box to tick — it’s an opportunity to enhance both community wellbeing and your project’s performance, reputation, and long-term value.

If you’d like us to review an upcoming scheme or help shape a mitigation strategy, just reply to this email — we’re always happy to talk through options.

In this article, we set out how our involvement with the redevelopment of a historic site in north London helped manage noise, dust and vibration emissions and keep the project continuing smoothly. Our role has been to manage these impacts effectively and maintain compliance for this landmark scheme which is delivering hundreds of affordable dwellings and a community support centre for vulnerable people.

A robust monitoring and management strategy was developed to address the site’s complex urban setting alongside the client and local authority. Deploying real-time dust, noise, and vibration monitoring at four locations — including site boundaries and off-site receptors — to track emissions continuously and provide clear evidence of compliance with the local authority’s planning conditions. Additional attended monitoring was carried out during activities with higher potential for emissions, such as mechanical breaking during demolition.

Since our involvement began in late 2022, continuous monitoring and regular liaison with the Local Authority’s Environmental Health Team have enabled the project to keep progressing in compliance with the planning conditions. The project is due to complete in 2028, with our monitoring strategy being reviewed and updated in line with each phase of work to keep the project on track.

By working closely with the project team and the council’s Environmental Health Team, Cass Allen’s proactive approach secured a Section 61 consent for construction works following demolition — and we continue to renew this on a rolling 6-month basis as the project progresses. Our real-time monitoring, attended checks, and clear fortnightly reports have provided confidence for the council, assurance for residents, and the evidence needed to keep this ambitious project moving forward.

How We Can Help
Cass Allen are trusted specialists in environmental monitoring, offering:

• Baseline surveys before works commence
• Installation and management of real-time noise, dust, and vibration monitors
• Remote data access and alert systems for site teams
• Regular reporting to clients, contractors, and authorities
• Support in responding to complaints or regulatory queries

If you’d like to discuss how we can help manage environmental impacts on your current or future projects, please get in touch — we’re here to support you at every stage.

The acoustic design of rooms can play a crucial part in determining how effectively spaces can be used.

This is most obvious in spaces such as music venues or theatres, where the acoustics of the space is often a primary design focus. However, good acoustic design is also important for other acoustically sensitive buildings such as educational, commercial and medical facilities.

Designing Better Sounding Spaces

With the latest room acoustic modelling software, Cass Allen can build a room virtually and then simulate how sound behaves inside it. We can try different materials and constructions to see how they affect things like clarity, loudness, and echo. This means we can fix problems before anything is built, saving time and money. You can even hear what a space will sound like before it’s built — a virtual preview of the room’s acoustics.

Reverberation untreated

Treated

From improving speech intelligibility in offices and classrooms to making music sound amazing in a concert venue. The below images show CATT modelling to simulate the reverberation control within a lecture theatre.

If how your development sounds is important to you then get in touch and we would be pleased to help you get it right.

We are pleased to introduce the newest addition to the Cass Allen team – the Nuemann KU 100 microphone. It’s an anatomically correct pair of ears on a head with two microphones used for binaural recordings.

Binaural recordings are a method of audio recording designed to capture sound in a way that replicates the human experience of hearing – so that when played back through headphones the listener feels as though they’re immersed in the space where the recording was made and able to locate the position of the sound sources around them.

We will be carrying out some binaural recordings over the next few weeks and months to capture various ‘soundscapes’. We will post some examples on our website and link to them in our next update so you can have a listen. Watch this space!

P.S. we currently looking for the best name for our new recruit – ideas on a postcard/email please with a prize for the best suggestion! mail@cassallen.co.uk

Cass Allen recently assisted on a challenging new development in Cornwall where it was necessary to assess the air quality and odour impact of an agricultural use on residences in terms of air quality and odour.

The Challenge
The project came with two major considerations related to a livestock calf rearing building in close proximity to dwellings and ecologically significant areas:

• Odour risks for residents.

• Air quality impacts on residents and nearby Sites of Special Scientific Interest (SSSIs).

A robust desktop-based solution was essential to establish the potential impact on air quality and odour from the livestock building.

The Solution
Odour. Using a source–pathway–receptor approach, combined with detailed weather data, we demonstrated that the risk of nuisance odours at the dwellings was negligible.

Air Quality: Initial screening with the SCAIL-Agriculture model flagged potential nutrient nitrogen impacts that could harm protected sites. Working closely with Natural England, we carried out a full dispersion modelling assessment to dig deeper taking into account nearly 300 local planning applications to assess potential cumulative impacts.

After rigorous assessment and open dialogue with Natural England, we provided the robust evidence needed to keep the project on track — balancing air quality and odour considerations arising from the proximity of the agricultural and residential uses.

The Result
The risks were managed and funding was secured. This was a great example of how timely environmental assessment keeps construction moving while safeguarding the environment for generations to come.

If you or any of your colleagues require any Air Quality or Odour assistance on your sites, then please contact mail@cassallen.co.uk

The Act also places a strong emphasis on competence and accountability among professionals involved in building design and construction. As a leading consultancy in urban design acoustics, Cass Allen has already had the opportunity to assist with a large number of submissions and we have noted a few challenges that have been a common thread through all of them:

Amount and Detail of Reporting Evidence Required

The majority of Gateway 2 Submissions that have been submitted are still under review by the relevant authority and yet to be decided or have any feedback provided. The amount of evidence required to successfully demonstrate compliance with any of the Building Regulations is therefore somewhat unknown. Cass Allen has however tailored our submissions in line with feedback we have been able to gather alongside our extensive experience in Building Regulations Approved Document E, and we are confident in our approach for our clients’ developments.

Timing of Submission

The Gateway 2 process has required significantly more information regarding the final detailed design and selection of materials for developments at a much earlier point in the design process. This has placed pressures on commercial and design teams to produce a co-ordinated developed design faster than ever before. Our response to this particular challenge has been to ensure that acoustics design considerations are presented and finalised as early as possible to allow the rest of the design team complete the designs in time for submission.

Company Experience and Technical Evidence

The BSA places great emphasis on companies to prove their relevant experience. Any designer must therefore be above to demonstrate not only that they have the qualifications to be carrying on the assessment but also that the assessment itself can be backed up with evidence. Our approach is to base our assessment on our 20+ years experience in Approved Document E as well as over 25,000 on-site sound insulation tests. As well as forming a reliable foundation for the advice we provide, this archive of test data also provides the strongest possible evidence to demonstrate compliant designs for Gateway 2.

This article describes the latest proposed changes to BS8233, which is the British Standard used for informing the acoustic design and planning of new residential buildings. The final version will likely change significantly, so nothing yet for developers to worry about, and we will keep you updated with future articles.

BS8233 is currently being updated and early drafts outline a new approach for the acoustic design of residential properties (well new to the UK at least).

The current revision of BS8233:2014 provides recommended internal noise levels and these recommended levels are frequently relied upon by Local Planning Authorities (LPAs) to ensure that suitable internal noise environments are provided in new residential development.

Planning applications for new residential development in urban areas or areas near to significant noise sources (roads, railways, airports, etc) will normally require noise impact assessments demonstrating that BS8233 recommended internal noise levels will be achievable, and compliance with the levels are often also secured via planning conditions.

For example, a typical planning condition might read as follows:

Prior to above ground works, a scheme of noise and vibration attenuation shall be submitted to and approved in writing by the Local Planning Authority to achieve the habitable room standard for residential properties as detailed in BS8233:2014. The approved noise and vibration attenuation measures shall thereafter be retained and maintained in working order for the duration of the use in accordance with the approved details.

It is normally possible to achieve the BS8233 recommended levels at all but the very noisiest sites through careful design and appropriate acoustic treatments (e.g. acoustically upgraded glazing and ventilation to habitable rooms).

The new proposed approach is very different and seeks to replicate the approach of other European countries. Instead of targeting specific internal noise levels, the likely quality of internal noise levels would be assessed based on measured external noise levels.

The aim of this proposed change, as far as we can tell, is to align BS8233 with the results of large-scale studies on the effects of noise on health and wellbeing, which are generally conducted by comparing health indicators with external noise levels.

This new approach would likely have significant implications for developers, particularly those that specialise in schemes in noisier areas (which includes most of Cass Allen’s Clients). The new approach would likely indicate that these schemes are unfavourable from an acoustics perspective, and we would be concerned how LPAs may respond to this information (we regularly see less experienced Environmental health teams propose to reject good schemes based on even slightly unfavourable acoustic assessments).

Given the potential implications, the proposed new approach has prompted significant backlash from the Acoustics Consultancy community who are asking whether the current revision of the standard requires such significant revision (“if it ain’t broke…”). Those concerns have been articulated back to the British Standards Institution (BSI) and we are expecting to see significant changes in the next revision.

Therefore, nothing for developers to worry about yet but we will of course keep you updated.

If you have any questions or would to discuss your recent development challenges please don’t hesitate to get in touch with the Cass Allen team.