A building’s basic utilities include electrical service, lighting, plumbing, heating/cooling and air handling systems. Of these utilities, air handling and plumbing are the two that present more wide ranging for possible noise and vibration problems, with the air handling distribution system being the more dominant. Acoustical consultants can contribute noise and vibration solutions in the design process, significantly reducing future problems.
Noise From Pipes
Plumbing systems can produce and transmit noise throughout a building. A metal pipe, as well as the fluid within the pipe, are good conductors of sound, and there was a time when tenants of old buildings would communicate with the building superintendent by banging on their radiator. This was a signal that they wanted more heat, and the banging could be heard ten floors below, in the boiler room. The musical group The Pointer Sisters immortalized this method in their song, “Banging On The Pipes.” Sometimes a building’s plumbing produces noise of its own, and this is almost always due to pipes that are not securely mounted or acoustically isolated at the point of attachment to the building walls or floors. A residential acoustic consultant can help design a plumbing system that is quiet and free of vibration and will stay that way for decades to come.
A Long Metal Box
An HVAC system is basically an acoustic transmitter that also happens to carry air. The ductwork is typically constructed of what amounts to long metal boxes, which are acoustically reverberant and do an excellent job of conveying noise. They push air into rooms and draw air out of rooms, all through these hollow metal structures. Devices like ceiling and stove exhaust fans send their airflow, noise, and vibration through the ductwork, potentially creating significant disturbances in many rooms along the way. In the case of office, commercial and institutional buildings, the HVAC ductwork is shared between multiple rooms, creating a potential “speaking tube” transmitter of sound between separate rooms.
Typically, the smaller the duct size, the more air noise that is generated due to the higher air velocity. The best way to push air into a room is through a large duct. This method moves a large volume of air more slowly and tends to produce less air noise. But small ductwork is less expensive, so contrary to recommendations from residential acoustic consultants, many residential buildings have smaller, noisy ducting. The same is true for the size of the air registers and vents – smaller ones tend to produce more air noise.
Isolating and acoustically decoupling a building’s utilities are the key to reducing noise and vibration. Acoustic consultants in Toronto are always finding ways to include these solutions in a building’s design. Floor mounted pieces of machinery can be carried or “floated” with vibration isolators, to decouple them from the floor. Ceiling mounted devices can be carried on vibration isolation hangers instead of rigidly mounted, to decrease the noise and vibration transmission. Ductwork can be fitted with acoustical silencers or interior sound absorbing linings as well as external lagging that minimize sound levels.
Acoustical consultants play a critical role in the design process of new construction. By using state of the art, cost effective measures, noise and vibration can be minimized and in many cases, prevented entirely.