Passive Design
Designing the building and the spaces within it to benefit from natural light, ventilation and even temperatures.
Noise Control in the Building Envelope
Sound-attenuating walls, roofs, windows and doors can be used to block sources of noise. They’re expensive in new homes, but harder and even more expensive to retrofit to existing ones.
Two types of noise may need to be dealt with:
- airborne sound passing through gaps and openings
- structure-borne sound from impact or vibration.
Sound-attenuating external walls
External walls facing the source of external noise should be of as heavy construction as possible. They should have no windows or doors – or, if windows or doors are unavoidable, they should be sound attenuating. All gaps should be sealed. Effectively dealing with intrusive noise can be expensive. It is also difficult to remedy a noise problem once a building has been completed.
- External sound envelope (fibre cement cladding)
A high-density sheet cladding, with sealed joints, thermal insulation, and sound attenuating interior lining. This will provide sound reduction at moderate cost, using lightweight construction.
- External sound envelope (brick veneer)
A brick or concrete masonry veneer, a rigid air barrier, thermal insulation, and sound attenuating interior lining is an expensive option using heavier weight construction. It will provide effective sound reduction.
- External sound envelope (concrete masonry)
An high density sheet cladding installed over battens, interior strapping and thermal insulation, and sound attenuating interior lining provides an expensive option using heavyweight masonry construction. It will provide a very effective sound barrier.
Sound-attenuating roofs
It is difficult to build heavy mass into roofs. Only in extreme circumstances, such as under the flight path of planes at low level, would a concrete slab roof be justified. Other options, in which ceiling construction forms an integral part of the sound attenuation system, include:
- Bitumen-impregnated underlay to long-run profiled metal roofing – this is a low-cost option and will help to reduce rain noise, but significant noise is still transferred through the fixings
- Concrete or tiles – this is a moderate cost option using heavy construction; it will reduce the impact noise of rain and hail but, because of the gaps, airborne noise will tend to penetrate
- Long-run profiled metal roofing with plywood underlay, thermal insulation, a sound attenuating ceiling, no rooflights, and the roof vented on the side away from the source of noise – this is a moderate cost option using lightweight construction; it will provide effective sound reduction.
Sound-attenuating external windows and doors
Windows
A problem with sound rating windows is that if they are opened for ventilation all sound rating effectiveness is lost. In some cases, windows may only need to be closed for some of the day for example rush hour or during school time.
If ventilation cannot be obtained through opening windows facing away from the source of noise, the only option may be to introduce ducted, fan-powered ventilation or air conditioning.
Options for sound-attenuating external windows include:
- glazing with noise-reducing laminated glass – this is an expensive option that provides significant sound reduction; generally the window can’t be opened; this option can be retrofitted
- fitting additional glazing to the window reveal – this is an expensive option that provides a noticeable sound reduction when all windows are closed; it is most suitable for retrofitting; a sliding version is more suitable for cleaning and is needed for opening the outer window.
External doors
Sound-attenuating doors should:
- be of solid core construction
- have no glazed panels or have sound-stopping laminated glass
- have brush, foam or rubber seals all round.