Acoustic ambitions for a better built environment – part 3.


Planet-conscious design.

In parts 1 and 2, we discussed how acoustic design that keeps schtum, the sectors and building types where acoustics should shout loudly.

But how might acoustic design help to deliver high-performance buildings which directly address the need for planet-conscious outcomes? Firstly, as far as high-performance buildings are concerned, planet-conscious design can broadly be classified into three main areas:

  • Energy and carbon
  • Material resource
  • Biodiversity

Controlling both sound and vibration to acceptable levels in the built environment generally requires some form of physical intervention, and any physical intervention will have associated with it some degree of material resource usage, and the potential for embodied carbon. Some physical interventions also have associated with them the potential to be directly responsible for operational carbon.

One common example of an intervention with both embodied and operational carbon is the inclusion of in-duct acoustic attenuators, commonly used to reduce a ventilation system’s fan noise to acceptable levels in the rooms served by those systems. However, one consequence of an acoustic attenuator’s ability to reduce sound energy is the introduction of additional resistance to air movement, thereby increasing the electrical energy required by the fan(s) driving the system.

Depending on the electrical carbon intensity at the time, increased energy consumption by fans equates directly to increased carbon emissions.

There is then also the energy used to manufacture, deliver and install each attenuator, plus the embodied carbon in the materials used.

Another common example of a physical intervention includes the specification of additional materials in partition, floor and façade make-ups to enhance their resistance to the transmission of sound and vibration. Again, this involves the manufacture, delivery and installation of additional construction materials, plus the associated embodied carbon of those materials.

A bold balance
An acoustically high-performing building is one which strikes the appropriate balance between delivering the acoustic performance required for positive human outcomes and the resultant environmental impacts from the design interventions required to achieve those outcomes. This need for balance may well lead to an interesting shift in the approach to acoustic performance specification. To further elaborate, it is commonly accepted that a difference of 3 dB is subjectively the smallest perceptible change in sound level under practical, real-world conditions.

The question therefore needs to be asked as to what environmental benefits a potentially imperceptible relaxation in target sound criteria of 1 dB, 2 dB or even 3 dB could have through a reduction in the required performance of any sound and vibration control intervention. These environmental benefits would result from the savings in materials/energy required to implement lower-performing interventions. Individual gains may only be small, but cumulatively the benefits could be significant, especially when considered on a global scale.

Added to the above is the prospect that compliance-led acoustic design based solely on the specification of target dB criteria may, of itself, be moving into a new era.

This change will emerge from the previously mentioned research into soundscape design and our greater understanding of the subtleties of human reactions to the characteristics and context of the sound environments to which they are exposed.

In part 4, we consider the rapid advances in building technologies that give rise to future possibilities…

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