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Acoustics and HVAC – our health and productivity depends on it

From a HVAC perspective, at times we tend to neglect acoustics. In theory, any noise issues should be eliminated already when making the blueprints for the HVAC system, and if everything goes right, the system is designed, dimensioned and installed in a way that doesn’t cause disturbing noise. But in reality, there may be miscalculations and faulty installations. Even if everything works at commissioning, as refurbishments are made and tenants change, the acoustic environment may not be satisfactory any more. Since we do not measure the sound in rooms continuously – the way we often do with temperature – the feedback instead tends to arrive in the shape of tenant complaints about noisy indoor environments. But there are ways to avoid this.

What is acoustics and why it’s important?

People spending time inside a building are, obviously, affected by the conditions within. The term Indoor Environmental Quality (IEQ) refers to the quality of a building’s environment related to the health of occupants within it. IEQ is determined by many factors including air quality, humidity, thermal comfort, lighting and acoustics. The latter factor is more important than many people tend to think, and should always be considered in building projects.

Acoustics, in the case of buildings, refer to the soundscapes of the interior spaces. What is considered “good” acoustics is dependent on the purpose of the space; an auditorium and an office aim for different acoustics, likewise a hallway compared with a bedroom.

A major goal for acoustics engineering is reducing the impact of unwanted sound, i.e. noise. Spending extended time in spaces with poor acoustics, being exposed to noise pollution, can have adverse effects on health. Research shows that over time noise can potentially cause tinnitus, heart problems and sleeping disorders. Noise and bad acoustics also affects productivity; in one study looking at academic environments, productivity rose by 0.7 percent for every 1 dB lower noise level.

acousticimageUnderstanding acoustics

Loudness of the noise is an important factor. However, reducing noise pollution is not as simple as only reducing the levels of the sound. There are a number of other sound qualities that influence how much people are affected by noise. A number of building regulations lists one or more crucial factors related to sound and acoustics that need to be considered in order to achieve high IEQ in a space. The most common are:

  • Service noise – from ventilation, hydraulics etc.
  • Exterior sound
  • Reverb time – i.e., time to fadeout
  • Floor impact – sound from spaces above or below the room
  • Acoustic separation – sound from adjacent rooms on the same level
  • Speech intelligibility – i.e. the easiness or difficulty of hearing speech
  • Sound masking – actually adding background sound to increase comfort
  • Vibrations

In Green building rating tools, schemes and standards, Service noise (often combined with exterior noise as internal noise level) and acoustic separation are the most common regulations.

Best practices to avoid acoustic problems

In order to achieve good acoustic characteristics in the course of a building project, the following points should always be considered.

  • The acoustic classification standards must provide clear and verifiable demands.
  • Acoustics data must be available from suppliers of key building components, such as HVAC equipment. Also, designers have to be familiar with the products and their associated risks.
  • Producers and suppliers of key building components must have tested their products towards international standards, providing correctly calculated and designed specifications to the project.
  • Entrepreneurs must have relevant mounting and installation instructions available, to avoid potential hazards.
  • The controllers have to be supported by standardized measurement and calculation methods listed in the sound classification standard.

As mentioned above, from a HVAC perspective, the first step towards better acoustics indoors is to make sure the system is designed in a way that doesn’t cause unnecessary noise, and that the noise incurred is efficiently eliminated. But it’s also important to be able to simulate what happens if the system is changed during its lifetime. Here there are some helpful digital tools available.

A good place to start is Swegon’s Room Unit Design software, which makes it easy to verify that the HVAC products in the room are supplying the right amount of air, while maintaining a good acoustic environment. It’s also possible to export BIM files to transfer the calculated data for further use in Revit or MagiCAD.

As a complement, Swegon’s Acoustic Design software is a great help in calculating and estimating sound levels also in the ducting, as well as configuring and selecting acoustic products to eliminate any noise problems.

In short – there are many ways to improve the acoustic environments that surrounds us, and doing so will provide tangible health, productivity and comfort benefits.