ECI Media

ECI helps Telstra reduce generator emissions!

Project overview

ECI worked with Transfield Services on behalf of Telstra to achieve both noise and exhaust pollution reduction at its Melbourne CBD Exchange Building. With the use of custom engineered acoustic solutions, ECI reduced the noise emissions from each generator at the exchange by 53 db(A). The total noise contribution from the generators at the boundary limit was reduced by a staggering 28 db(A). In addition, ECI achieved a 95% reduction in diesel exhaust emissions from the exchange’s stationary diesel generators.


The Telstra Exchange Building is located in Exhibition St in the heart of Melbourne’s CBD and is the country’s most important exchange. The list of customers relying on this facility for the smooth running of their day-to-day operations features many of Australia’s largest corporations, including major banks and airlines.

The exchange is approximately 94m high and is located on a property that is approximately 10,000m². In addition to Exhibition St on its western boundary, the exchange faces onto La Trobe Street (northern boundary), Burton Street (eastern boundary) and Little Lonsdale Street (southern boundary).

ECI were commissioned by Transfield Services on behalf of Telstra to conduct an engineering audit, with the goal of attaining acoustic compliance and reducing diesel exhaust emissions at the Telstra Exchange Building.

ECI was asked to gather and assess the data and determine an appropriate solution to address the existing MTU Detroit diesel generators on site. To safeguard the continual, uninterrupted operation of the Telstra Exchange Building, five of these generators take over immediately from any interruption to the mains power supply. Three of the generators were installed in 1992, while the other two were installed in 2005 and 2009 respectively. The noise and pollution created by these five generators is significant.

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The growth of Telstra’s flagship exchange over the last 30 years, and the resulting increased back up power generation requirements, meant there were a total of five diesel generators requiring noise and exhaust pollution mitigation to meet current EPA standards.

To further complicate matters, in recent years high-rise residential apartments had also been constructed around the location, and permanent residents now a mere 17 metres from the exchange. This has meant that the existing noise and exhaust emissions levels emitted from the installation required attention.

Successfully solving Telstra’s noise and pollution issues required specific, custom-built and installed equipment coupled with innovation, strategic thinking and a consultative approach.


This project featured a number of major challenges, each of which was smoothly and successfully negotiated by ECI. The major project challenges included:

  • Analysing the acoustic issues at the exchange was a complex process, as a number of sources contribute to the overall noise levels at various points along the building’s boundaries (eg traffic noise, pedestrian noise, noise produced at adjacent buildings etc).
  • Noise measurements indicated that there were significant low to mid level frequencies, all of which required very different approaches to solve the respective noise issues.
  • Built more than 30 years ago, the Telstra Exchange Building features a myriad of existing services including electric cabling, fire services, stormwater pipework and air handling equipment. Any installation of noise and pollution reduction equipment needed to effectively negotiate the vast labyrinth of existing services.
  • ECI needed to engineer a solution to keep within the manufacturers’ specifications of the diesel generators and integrate the appropriate acoustic measures into an existing 30 year old building, so as not to affect the operational performance of the exchange.
  • Any reduction in noise and pollution required equipment such as silencers and attenuators to be retrofitted into very compact spaces with significant accessibility issues.

ECI’s approach

ECI identified and prioritised the noise sources below to allow the maximum noise reduction to be delivered within the constraints of the project:

  • Exhaust stacks located in the courtyard approximately 17 metres from residential apartments
  • Air radiators located on the mezzanine level on the southern boundary
  • Intake air noise breakout from the basement car park affecting the eastern apartments
  • Discharge air noise breakout from the basement generators contributing to the overall noise level at the eastern boundary
  • Internal exhaust pipe work remediation to all five generators which included thermal expansion bellows, spring hangers, custom lobster back pipe work transitions and thermal insulation of exhaust pipe work and cable trays.
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Meeting EPA requirements

ECI’s acoustic testing and analysis process revealed that when all five of the exchange’s generators were running at full load (including their respective radiators), the noise level was 82dB(A) at the eastern boundary (directly below the City Gate apartments). This noise level at the exchange was 28dB(A) above Victorian Environmental Protection.

Authority’s (EPA) Noise Policy for Noise Emissions from commercial plant and equipment No. N-1 “Control of Noise from Commerce, Industry and Trade” (SEPP N-1) noise levels for the precinct. (Please see table.)

Key features of this policy are:

  • SEPP N-1 prescribes Noise Limits that are to be met at residential properties.
  • The method specified in SEPP N-1 for determining the noise limits takes into account the type of area in which the noise sensitive area is located, the time of day and the background noise level of the area.
  • For standby generators, the normal noise limits shall be increased by 10dB for the day period and 5dB for the other periods.

EPA noise limits table

Based on typical background noise levels measured in the CBD area, the SEPP N-1 limits applicable for normal and standby plant at this site will be as follows:

  Normal Plant Standby Plant
Day 7am-6pm (Mon-Fri) & 7am-1pm (Sat) 68 dB(A) 78 dB(A)
Evening 6pm-10pm (Mon-Fri)
1pm-10pm (Sat)
7am-10pm (Sun)
60 dB(A) 65 dB(A)
Night 10pm-7am (All days) 54 dB(A) 59 dB(A)

In the case of the Telstra Exchange Building, the critical residential noise receiving locations are the City Gate apartments to the northeast, approximately 17m from the standby generator exhaust stacks.


The five areas highlighted by ECI during the testing and assessment phase were each dealt with as follows:

Area 1: Courtyard Exhaust Stack remediation

ECI’s Super Critical SCS/A-450SP External Exhaust Silencers were fitted to each of the Telstra Exchange’s five diesel generators. ECI’s own EPA Cowl design was utilised to mitigate water ingress into the exhaust flue giving the exhaust system longer life. In addition, five custom Predator diesel particulate catalysts were incorporated into the external exhaust silencers. The total exhaust silencer package was then hidden from view by a visually unobtrusive façade enclosure, which was designed to blend into the existing building features.

Area 2: Radiator mezzanine level

ECI’s acoustic louvers were utilised to partially screen off the radiator mezzanine level open-air wall. The louvers and the acoustic lining of the radiator mezzanine northern and eastern walls provided the necessary air flow to the remote radiators and reduced the noise contribution to the courtyard area. The louvers’ external finish was also in line with the building’s overall colour palette.

Area 3: Basement car park

To control the noise emitted through this area, individually designed acoustic attenuators were installed to accommodate the existing services dominating this area. In this part of the installation, all penetrations leading up into the courtyard area were treated acoustically to ensure there was no noise breakout.

Area 4: Discharge air plenums

All of the five diesel generators’ air discharge ducts and plenums were acoustically lined and fitted with ECI’s range of acoustic attenuators. Each of these attenuators was individually designed and custom built to suit the existing building constraints. Additional lining of the number 5 generator internal plant room was completed to ensure there was no reverberated noise breakout.

Area 5: Internal exhaust pipe work

Due to the inclusion of new acoustic and emission control products and issues associated with previously installed pipe work, ECI calculated, designed and installed thermal expansion, pipe work spring hangers, custom pipe work transitions and upgraded the thermal insulation to be able to safely meet the demands of the exchange when operated at any time or duration.

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Throughout the entire project, ECI consulted clearly and continually, both within and external to the exchange, ensuring all stakeholders were informed and on-side during every step of the way. Before any work commenced, all components of the final design were independently audited to ensure the proposed works would achieve SEPP N-1 boundary noise limits for non essential operation of the basement generators (54 db(A) at site boundary).

Thorough planning, testing, design and execution

As part of the consultation and design process, ECI constructed a complete 3D model of the exchange plant rooms and external boundaries. This helped us ensure the components of the proposed works could be accurately deployed and safely installed into the tight plant room constraints, and avoided any major disruption to the exchange’s critical standby power capacity.

All of the diesel generators were extensively tested for their acoustic performance and compliance to the (SEPP-N1) noise limits. The new exhaust systems also received the same rigorous testing regime to ensure all of the engine manufacturers’ specifications were not exceeded.


The proposed retrofitting of exhaust silencers into the existing plant rooms was a major issue due to extensive and ongoing changes to ducting, cabling and installations over the years. Due to the extensive acoustic testing undertaken on the exchange, we understood that two out of the five generators produced significantly higher noise levels than the other three engines and required additional acoustic treatment in conjunction with the noise mitigation measures proposed in the courtyard area.

Thus, the existing internal silencers were removed and ECI constructed special, custom made oval units which not only improved the additional acoustic performance required for the project but also provided lower heat rejection to the existing plant room services and electric cabling. In conjunction with the proposed works ECI also redesigned the internal exhaust pipe work to achieve better exhaust gas flow, controlled thermal expansion and thermal performance.

Unique product – Predator Diesel Particulate Catalyst

ECI’s ability to solve the exchange’s diesel pollution problems was thanks to our patented product, the Predator Diesel Particulate Catalyst.

The Predator traps and then treats diesel particulate matter so that harmful fumes and emissions do not escape into our environment.

Installed on the external courtyard silencers at the exchange, the Predators reduced carbon monoxide (CO), odour-causing hydro carbons (NMHC) and particulate matter (PM) by a staggering 95%! In addition to the oxidation process of the particulate matter, the Predator also reduced total NO2 (NO x) by 15%!

The environmental dangers of particulate matter are well known. Similarly, because they are so small, diesel particulates can easily penetrate the lungs and contribute to a range of health problems. Reducing diesel particulate has assisted Telstra to meet its EPA obligations, as well as demonstrating its good corporate citizenship.

Results and Outcomes

The results of this project are nothing short of outstanding.

Noise pollution reduction

During overall acoustic testing at the end of the project, noise from the Telstra Exchange Building was not audible or measurable as the ambient environmental noise levels of 54 dB(A) were higher than the output of the diesel generators at 100% load!

Exhaust pollution reduction

The final emissions testing results for all of the basement diesel generators showed emissions reductions of 95%!

The incorporation of world’s best practice emissions control devices such as the Predator diesel particulate catalyst and custom-built ECI silencers and attenuators, have made the Telstra Exchange Building and adjoining residential and commercial precincts, better environments in which to work and live.

ECI’s project management excellence

Ultimately, ECI’s success at the Telstra Exchange Building was not just about our innovative products, their installation and application. It was our consultative approach and effective project management skills that underpinned our performance. For example:

  • All stake holders spent over 12 months diligently working through the issues, design process and the final project outcome so as not to impact the operational performance of the exchange and to minimise disruption to the external stakeholders adjacent to the proposed work site areas.
  • Over 300 hours was spent in the acoustic testing, design and consultation phases involving a number of parties including ECI, Transfield Services, Silcar and Telstra. This thorough process and the professionalism of all parties, directly contributed to the overall success of the project.
  • 1645 man-hours were spent executing each phase of the installation program within the exchange without any lost time injuries (LTI) or disruption to the exchange. This included five separate street closures and more than 40 hours of crane and rigging time to ensure all pieces were safely lifted and installed into position without incident.
  • For one of the most critical aspects of the installation, a timber template and custom lifting trolley was constructed to test the pathway and method of fitment of an internal oval silencer prior to the actual unit being hoisted into position, to ensure the safety of the personnel and integrity of the exchange.

Exhaust Control Industries P/L have for over 25 years been committed to the engineering, manufacturing and installation of the latest air and noise pollution reduction technologies to protect our urban environments.

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