“Very proactive and extremely helpful, especially with technical queries. I would not hesitate to recommend and will certainly be using them again in the future.”



Under CDM2015 regs we have found CASS ALLEN to exercise a level of professionalism and due diligence which is second to none. We would therefore definitely recommend CASS ALLEN as our preferred acoustic consultant, for all of our projects.’


SF - Taylor Wimpey South Thames

“I was very pleased with their technical knowledge and professional approach when dealing with a very awkward purchaser as well as the local authority.”


JH, Telford Homes

“Cass Allen went above and beyond to help with the Acoustic planning performance and conditions regarding the Greenwich Creekside project…”


LM, Capita plc

“Good comprehensive reports and advice at all design stages. Very flexible and professional, provided attendance at acoustic cladding tests at short notice.”


DF, Berkeley Homes

“Cass Allen have assisted us on a number of our projects. I’ve been impressed with their thorough and professional approach.”


MT, Lark Energy

AVO Guide Launched

The Acoustics, ventilation and overheating residential design guide (AVO Guide) was officially launched at the end of January. A copy of the guide can be found here.

The document provides guidance on the importance and interdependence of acoustics, ventilation and thermal comfort in the design of good quality residential development.

The guidance helps developers and Local Authorities avoid the situation where openable windows are relied on for the control of overheating, but closed windows are needed for the mitigation of external noise; the outcome being that residents are forced to choose between high internal temperatures or high internal noise levels.

This overheating problem has become more common over the last 10-15 years due to changes to Buildings Regulations encouraging energy conservation (i.e. keeping heat in). The issue is made worse by the move towards developments with larger areas of glazing and less thermal mass and the “heat island” effect in built-up areas.

For noisier sites where windows need to be kept closed most of the time, the control of overheating can be difficult and many of the mitigation measures require consideration early in the design process. These include changes to fenestration, orientation of dwellings, ceiling heights, roof design and solar shading etc.

Research by the AVO Guide authors showed that many planning applications still include energy assessments that rely on open windows in summer and noise impact reports that rely on closed windows. This is resulting in developments with overheating issues and it is also creating problems for developers who are struggling to then comply with overheating or acoustics related planning conditions.

Most of the above overheating mitigation measures will not normally be possible within the constraints of a planning consent and this can result in an overreliance on mechanical ventilation (e.g. MVHR) and low-g-value glazing.

With the release of the guide we expect to see more Local Planning Authorities requesting ‘AVO assessments’ as part of planning applications to show that this issue has been considered from the outset. This will help ensure better quality developments and more upfront clarity on design costs and risks for developers.

If you would like to discuss how the new guide affects you or if you need a noise impact assessment for your development then please don’t hesitate to give us a call.


Get in touch

We hope you’ve enjoyed browsing our website but if you have any questions feel free to call us to talk through any acoustic issues you may be facing on your projects. The best person who can help with specific queries can be found here.