Wednesday, September 06, 2006
The American code
Building codes in the U.S., for instance, aim to protect occupants from exterior and interior sound sources. To deal with exterior noise the codes usually require measurement of the exterior acoustic environment in order to determine the performance standard required for exterior building skin design.
The architect and the acoustical scientist can arrive at the best cost effective means of creating a quiet interior (normally 45 dBA). The most important elements of design of the building skin are usually: glazing (glass thickness, double pane design etc.), roof material, caulking standards, chimney baffles, exterior door design, mail slots, attic ventilation ports, etc.
There are two ways in which sound can be generated within buildings. Firstly, airborne sound travels through walls or floor/ceiling assemblies due to either human activities in adjacent living spaces or from mechanical noise within the building systems. Mechanical systems are elevator systems, boilers, refrigeration or air conditioning systems, generators and trash compactors. Walls or ceiling assemblies have to meet certain performance standards to achieve the desired level of quietness.
Secondly, it can arise from transmission through the building itself, like the footfall of occupants. This type of noise is somewhat more difficult to abate, but consideration must be given to isolating the floor assembly above or hanging the lower ceiling on resilient channel.
