Acoustic Barriers for Data Centres

Australia’s dependency on data has long been on an upward curve. Thanks to driverless cars, 5G, the IoT, the Cloud, IP telephony and now the boom in e-commerce and remote working driven by COVID-19 restrictions, our data centre industry is about to enjoy another dramatic expansion. We already have some of the largest data centres in the world and there are major new constructions underway, especially in Canberra and Sydney, but also new builds in Melbourne and Perth. NextDC, Equinix, Digital Realty, CDC and Macquarie are among the biggest investors.

IT entrepreneur Bevan Slattery recently reported that an “absolute rush” of people moving to the Cloud has seen capacities spike 50-100% with a 100-200% increase expected in the near term: “major clouds are scrambling to grab every available [megawatt] of capacity available and locking up future builds”. Equinix reported a 40% surge in internet exchange traffic that started before coronavirus restrictions even came in. They are currently building a new 9,225 cabinet data centre in Sydney – their sixteenth in Australia.

Costly problems

Australia’s emergence as an IT powerhouse is great news but data centre builds face some serious practical problems. They need to be close to the urban centres that need them and to the international cables that communicate to the outside world. One of the biggest problems they create for those nearby urban areas is noise.

Data centre noise is generated by generators, air conditioning and thousands of cooling fans; processors have them, enclosures have them, and room air conditioning adds more. Somewhere, often outside and unshielded by the walls of the building, HVAC equipment, chillers and backup generators are running night and day.

Inevitably, noise leads to a variety of problems inside and outside the facility; employees can suffer hearing damage, properties lose value, neighbours lose sleep and local government goodwill can begin to evaporate. Specific consequences can include high employee turnover, compensation claims and opposition to planning applications.

Moving new centres further away from the cable networks they need and the cities that need them raises costs and degrades performance. That is a headache for an Australian industry that is growing almost four times faster than predicted. Future opportunities are immense, but only if we solve the noise problem.

Some costs are less apparent. Research has proven that employees are less productive in noisy environments: it is literally hard to think. They don’t enjoy their work and turnover rises. When good network engineers are hard to retain, salaries have to rise. Even the equipment exhibits issues. Noise and vibration reduce the lifespan of expensive hardware and cause higher read/write latency in hard disc arrays.

In Australia, both central and state governments can define noise abatement policies, but the main bodies of legislation – the 1986 Environmental Protection Act and 1997 Environmental Protection (Noise) Regulations – were drawn up before most data centres existed. They set tiers of acceptable noise that assume peak levels are not continuous – something extremely difficult for an industry that operates continuously. The industry needs to act quickly or risk impairing its future growth.

Indoor noise control

By focusing exclusively on IT benchmarks, managers often miss acoustic engineering opportunities. For example, server fans could run slower if there was better water cooling but the cost of modifying every server retrospectively is significant. Some centres try noise cancellation equipment, but again this is a retrospective solution addressing single sources of noise. Replacing entire servers and disk arrays with larger ones simplifies the problem but leads to more capacity redundancy, increasing the ratio of noisy equipment to data throughput.

The main source of noise internally is the ventilation system, but If you redesign ductwork and vents for quieter airflow, you risk impairing the cooling efficiency. Acoustic tiling and soft carpets can make significant improvements but there are still drawbacks such as disruption during installation and space lost to tiles and partitions.

One of the most cost-effective internal improvements is the installation of acoustic doors and windows such as IAC Acoustics Noise-Lock® range. In addition to access and viewing points, acoustic absorption to reduce reverberation and lower the overall noise level should be a core part of any internal design specification.  While they improve the comfort and safety of employees inside the building, external noise mitigation measures are necessary as well.

Outdoor noise containment

Indoor noise control is needed to protect employees and comply with occupational health regulations, but it rarely stops enough noise from escaping the building. IAC Acoustics recommends acoustic barriers as the cheapest, quickest and most effective way to contain this noise.

There are a host of individual noise reduction improvements you can make, but IAC Acoustics always adopt a cost/benefit approach from the outset in order to maximise the improvement per dollar, while minimising time and inconvenience. With 70 years of experience, IAC Acoustics have the knowhow and products to deliver unbeatable results.

Externally, the main sources of noise are the air handling apparatus and generators. A 3MW data centre generator is hardly compact; along with their containers they weigh about 60 tons and there may be several of them.

Their loud growl isn’t the only problem; they are prone to emit troublesome frequencies. Distant neighbours frequently complain about penetrating ‘whining’ noises. The surrounding landscape can focus the problem in one place while it is inaudible in another, so to tackle it you have to begin with CadnaA noise mapping and then tailor solutions with a specific noise mitigation strategy.

IAC Acoustics have patented numerous sound-absorbing technologies and have products available off-the-shelf, but every solution is tailored for the site, the landscape, the neighbours and of course the plant’s access requirements. The installation of acoustic barriers rarely causes any disruption to data centre operations and as a modular design can be relocated if you change the way you use your site.

HVAC chillers and rooftop air handlers are often a challenge. They need free airflow so you can’t fully enclose them.  Acoustic louvres and attenuators can be integrated into the HVAC system specification and barrier or enclosures for additional noise mitigation.

Design is the key to success

On an existing site, IAC Acoustics begin with an acoustic survey, but If you are planning a new build, acoustic design should be an element in your plans from the outset. It is better to design a plant room correctly in the first place than have to try mitigating the problem after it is built. Addressing and planning to treat the source is the most effective strategy and has preferable cost implications. IAC’s modular acoustic enclosures are far lighter in construction, often more effective, and definitely easier to adjust in the future over fixed structural builds in concrete.

Your ideal solution must also incorporate provision for fire safety, energy conservation, operational access and sufficient airflow and all these things have to work with your acoustic solution. That is why you need our highly skilled acoustic engineers with the experience of delivering a holistic noise control solution.

The number and size of Australia’s data centres is seeing fantastic growth and it is far from over. New demand generated by new digital technologies has barely begun, and each will generate spin-off technologies that need more bandwidth and more data centres with more racks, generators, compressors, ductwork and cooling systems.

Let IAC Acoustics help you meet current and future noise regulations, secure the goodwill of local communities, and provide comfortable workplaces that will attract and retain the talented staff you need.

Jay Owen.