Building acoustics is the science of controlling noise in buildings. This includes the minimisation of noise transmission from one space to another and the control of the characteristics of sound within spaces themselves.
Building acoustics is an important consideration in the design, operation and construction of most buildings, and can have a significant impact on health and wellbeing, communication and productivity.
Poor sound insulation performance is an issue that plagues much of our hosing stock, both new and existing.
Noise between dwellings – Sound Insulation – is controlled by Building Regulations - 2014 (Part E) which sets these minimum thresholds of performance:
DnT,w >56dB (Airbourne)
LnT,w <59dB (Impact)
However, it is probably fair to say that regulations somewhat lag behind expectations and even achieving the minimum performance can result in subjectively poor sound insulation. For instance, the regulations were not designed to deal with modern surround sound systems or gaming activities or even working from home!
Retrofitting solutions can be expensive so it’s always better to tackle the issue early in the design process.
For larger developments circulation spaces also require acoustic treatment and external amenity spaces are important criteria regardless of the scale of the development – see Noise Ingress.
Commercial & Leisure
Many commercial activities have potential acoustic issues, some of which may be dealt with at the planning stage and some at design stage. Noise issues however may not manifest themselves until after a complaint is received.
Environmental noise modelling may be needed to predict the impact that a new activity may have on nearby residents. Good acoustic design can help prevent noise breakout from an activity and also manage the noise within spaces.
Hotels for instance are concerned about their clients’ experience but also on the impact events may have on the nearby community. Architectural acoustics therefore plays an important role but so to does environmental noise impact assessments.
Similarly, sport stadiums, skateboard parks, playgrounds etc may all have an adverse impact on their communities which should be assessed at the planning stage.
Gyms often operate within or beside residential buildings. They open early and Airborne and Impact noise/vibration needs careful control to prevent disturbance.
Outdoor music events, while may not be regular occurrences, require specific noise control and monitoring schemes.
Generally, various guidance like BS4142 exists to advsie on planning and controlling noise from all of the above however, great care should be taken that the incorrect guidance is not prescribed.
The design and construction of school buildings should provide acoustic conditions that enable effective teaching and learning. As has been proven by research, noise and
poor acoustic design has a detrimental effect upon pupils’ academic performance and teachers’ vocal health.
The Department of Education and Skills’ Technical Guidance Document TGD021 sets out performance standards including:
- Indoor Ambient noise levels from external sources such as traffic
- Building Services noise levels
- Sound Insulation performance between spaces
- Reverberation & Sound Absorption in rooms and corridors
The world is changing fast especially the places where we work and how we use them. Workplaces were traditionally a mixture of open-plan and private offices, but increasingly remote communication is a key factor which demands careful consideration of room acoustics to be effective. Break-out spaces, huddle areas and hangouts also pose particular acoustic problems.
Speech intelligibility within a room, sound insulation between spaces, building services noise and external noise ingress all need consideration. Indeed, speech privacy can be a particularly sensitive matter for some professions including law and medicine.
The key role of the acoustician is to set appropriate design goals for the client and then ensure that products and constructions are robust enough to meet them.
Guidance form BS 8233 suggests that a good indoor ambient noise level within cellular office spaces should be in the range of 40 to 50 dB LAeq with meeting rooms and executive offices in the range of 35 to 40 dB LAeq. The minimum level of sound insulation generally required between two offices is in the order of DnTw 38dB and where privacy is important this rises to around 48dB.
When dealing with external noise sources such as traffic, acceptable noise thresholds that should be achieved for bedrooms, living rooms and external areas are set out in BS 8233. This covers both day-time and night-time periods and an increasing number of local authorities now require developers to prove that these thresholds will be met.
The methodology of ProPG should be followed to assess the noise environment within the vicinity of a proposed development. For this, a site survey may be required although occasionally data from Noise Maps may be used in the scoping exercise. This quantifies the risk of noise being issue and informs if a detailed Good Acoustic Design statement is required.
Good Acoustic Design – or Intelligent Acoustic Design as we like to call it – will ensure the occupants will not be adversely affected by noise. It typically includes a detailed sound insulation scheme for the dwellings (including facade, roof, glazing and ventilation specifications) and possibly advice on the layout and orientation of the proposed scheme.
Acoustic Design should add value to a project and it is important that the sound insulation scheme does not over-specify the performance criteria of the various elements.
A revised design goal could be considered if an enhanced performance is needed. This can aid marketing of a development and reassure potential purchasers, particularly near busy roads.
"The good news is that Intelligent Acoustic Design unleashes the potential of even the noisiest of sites."
Irish Builindg Regulations - Part E (Noise)