The much anticipated and long-awaited Acoustics, Ventilation, Overheating: Residential Design Guide (aka the “AVO Guide”) has been published by the Association of Noise Consultants. You can download a free copy from the Association of Noise Consultants’ website. At 26,500 words it provides a wealth of information. Read our Quick Start to the AVO Guide to get you going. We are co-organising, presenting and facilitating the launch event and workshop. We are now offering a CPD briefing on the details and implications of the AVO Guide. Publication of this ground-breaking guide follows the draft that was published in February 2018, industry consultation, and development of the Guide to respond to the consultation responses. The AVO Guide significantly improves the assessment of noise impact on occupants of new residential development; this enables development that is more sustainable and clarity for design drivers. The AVO Guide recognises that occupants may find a balance for their internal environmental conditions between noise, air quality and thermal comfort.
Noise and ventilation
The focus here is on sufficient ventilation as described in the Building Regulations’ Approved Document F to enable reasonable indoor air quality (IAQ). The amount of ventilation required to enable reasonable IAQ is typically much less than that required to prevent overheating. The distinction between ventilation to control IAQ and ventilation to mitigate overheating is vital to understanding the AVO Guide. The AVO Guide links suitable noise guideline levels to the various ventilation conditions – background ventilation, extract ventilation (in appropriate room types) and purge ventilation. It distinguishes between external transportation noise ingress and noise from building services, because occupants have different tolerances to different types of noise.
Noise and overheating
If you open a window it may get noisier inside but allow the room to cool down. How much noise should people tolerate in these circumstances? The AVO Guide establishes a principle of adaptive acoustic comfort. This principle assumes that people can tolerate higher noise levels (compared with annual average levels) where they have control over their environment – in this case with an opening window. The AVO Guide takes account of the extent of reliance on opening windows for thermal comfort to recommend suitable noise level guidelines. These guidelines differ for daytime and night time periods: people may open and close the windows to balance internal environmental quality (IEQ) conditions during the daytime, but not at night time when asleep. The AVO Guide considers noise annoyance as the acoustic constraint during the daytime, and sleep disturbance as the constraint for night time periods.
How was the AVO Guide developed?
We started publishing on the subject of Problems in residential design for ventilation and noise at the Institute of Acoustics conference in 2013. This work evolved and gained widespread acoustic industry support. The Association of Noise Consultants’ (ANC), chaired by Jack Harvie-Clark, proposed that the ANC develop an industry guide to address the problems. The AVO Group was formed in 2016, chaired by Anthony Chilton of Max Fordham. Apex are major authors of the AVO Guide: Jack Harvie-Clark took primary responsibility for writing Section 1 and Appendix B, and Nick Conlan was lead author for the section on Internal Ambient Noise Levels from Mechanical Services. We also made significant contributions to the other sections. Our paper Assessing noise with provisions for ventilation and overheating in dwellings was published in Building Services Engineering Research and Technology, and our paper How loud is too loud? Noise from domestic mechanical ventilation systems was published in the International Journal of Ventilation. Find out more about our work on the assessment of noise, ventilation and overheating here.
What happened before the AVO Guide?
Until now, the most common design approach has been to ignore the problem of interactions between thermal comfort and acoustic comfort. Our research showed that in 85% of planning applications, the noise assessment assumed that windows were closed to enable reasonable noise levels, while the overheating assessment simultaneously assumed windows were open to control overheating. There has hitherto been an absence of noise assessment when occupants rely on opening windows for thermal comfort. Occupants are forced to choose between acoustic and thermal comfort. The AVO Guide proposes a practical assessment and pragmatic approach to overcome this significant previous gap in guidance.
Workshop on the AVO Guide
The official launch of the AVO Guide is on 30th January 2020 at the Chartered Institute of Environmental Health, 15 Hatfields, London. This will be a full day event, with presentations in the morning and workshops in the afternoon. Attend the workshop to understand how to apply the AVO Guide in practice.