AirTrunk details A$4.3bn Mickleham data centre in federal filing

At a glance

• AirTrunk values its planned data centre at 45 Donnybrook Road, Mickleham, at A$4.3 billion, according to documents published for federal environmental assessment on 4 November 2026.

• The campus would have seven data centre buildings, each built and commissioned before work starts on the next, over about 10 years.

• AirTrunk says the site will connect to the grid through a new Donnybrook terminal station, with a planned 132kV supply, and the buildings will use dry air chillers.

• AirTrunk is offering A$26.5 million for local education, skills and sport, and A$200 a year off power bills for eligible nearby households through Origin Energy.

• Public comments on the federal documents close on 18 November.

AirTrunk has put a A$4.3 billion value on the seven-building data centre campus it plans at Mickleham, in Melbourne's north, in environmental documents published on 4 November for federal assessment.

The documents estimate about 1,605 construction jobs a year over a build of about 10 years, and AirTrunk is offering A$26.5 million for local education, skills and sport. The National Environmental Protection Agency is assessing the plan, with public comments open until 18 November. Victoria's planning minister decides the state permit after the 28 November state election.

The 67-hectare site at 45 Donnybrook Road sold for a reported A$350 million, with AirTrunk named as the buyer by Real Estate Source in July. A state planning application for seven data centre parcels went in on 1 July. Our July story asked whether Mickleham was the second Melbourne campus AirTrunk announced in December 2025, and the federal documents now give it the MEL3 name.

Mickleham is AirTrunk's third Melbourne campus

On AirTrunk's own figures, the Mickleham site has more than seven times the land of either of its existing Melbourne campuses. The developer is AirTrunk MEL3 Pty Ltd, as trustee for the AirTrunk MEL3 Land Trust, and its parent is AirTrunk Australia Holding, according to the documents.

AirTrunk MEL1, in Melbourne's west, sits on 8.8 hectares with a total capacity of more than 185MW, according to AirTrunk. AirTrunk MEL2, in the north-west, was announced in December 2025 with more than 354MW on an 8.07-hectare site with a 66kV feed. The Mickleham study area covers 67.1 hectares, with a planned 132kV supply. Across Australia, AirTrunk plans to invest a further A$75 billion over the next decade.

Mickleham is about 31km north of central Melbourne, on land zoned for industry and classed by the state as future significant industrial land. Our national capacity outlook lists it among Melbourne's campuses in planning.

Seven buildings go up one at a time over about 10 years

AirTrunk plans to build and commission each of the seven buildings before starting the next, over about 10 years. The first of two construction stages covers early works, bulk earthworks, building foundations, roads and services. It includes a switchyard beside the site's conservation area, and the second stage builds the seven data centre buildings.

Development covers 57.9 hectares of the site, with a 4.89-hectare conservation reserve and a 4.29-hectare tree reserve. AirTrunk's project page gives a total gross floor area of 935,730 square metres. AirTrunk will tender for a construction contractor once the federal approval is in, according to the construction environmental management plan.

Power comes through a new Donnybrook terminal station

AirTrunk says the site will connect to the Victorian transmission network through a new Donnybrook terminal station, with a planned 132kV supply. The environmental documents describe a substation being designed by AusNet on its land to the south of the site. The connection to the site's switchyard runs about 300m past the property boundary, and AusNet will build the supply works during the first construction phase.

AirTrunk will fund the grid connection through upfront contributions and ongoing network charges, according to its project page. Dry air chillers will cool the buildings, with no water used for cooling in normal operation, according to AirTrunk. Across its portfolio, AirTrunk reported a PUE of 1.32 and water usage effectiveness of 0.89 litres per kilowatt-hour in FY2025, the documents say.

AirTrunk offers nearby households A$200 a year off power bills

AirTrunk's documents estimate about 1,605 full-time equivalent jobs a year during construction. At full occupation they count about 1,680 ongoing full-time equivalent positions, direct and indirect. AirTrunk's project page puts the figure at more than 1,000 ongoing local jobs. An Urbis assessment in the documents puts the project's direct and indirect contribution to the Victorian economy at about A$547 million a year over the 10-year build.

AirTrunk is offering A$26.5 million for community infrastructure, subject to approvals. The package includes A$15 million for education and training facilities in the Mickleham area, A$6.5 million for a Victorian Skills Partnership to support the electrical and technical workforce, and A$5 million for local sport and recreation.

Eligible nearby households would get A$200 off a standard yearly electricity bill through Origin Energy, backed by a community battery, under an agreement AirTrunk is still finalising. AirTrunk offers the same scheme at the Kurri Kurri campus it is planning in the NSW Hunter.

AirTrunk will hold drop-in sessions at Mickleham North Community Centre on 17 and 18 November, and a webinar on 23 November. AirTrunk puts the nearest home more than 400m from the site.

Victoria's planning decision waits for the new government

Federal assessment began in 2023, when the site was planned as the Fusion Business Park, and the project was declared a controlled action for threatened species and communities. On 31 August 2026 the National Environmental Protection Agency accepted a variation that changed it to a single-use data centre. Comments on the documents go to AirTrunk until 18 November, before the federal decision.

The state application sits in the Development Facilitation Program, and Hume City Council has authorised the site's rezoning and asked the planning minister to approve and gazette it, the documents say. Victoria entered caretaker mode on 3 November, so planning decisions now pass to the government formed after the 28 November election.

The project would clear about 2.1 hectares of critically endangered native grassland, including a 1.7-hectare patch that also counts as a protected wetland, and nine Matted Flax-lily plants would be moved, the documents say. AirTrunk is finalising agreements for offset sites at Shelford and Mininera in western Victoria. On the documents' offset calculations, the two sites would secure more than the required offset for each community, an overall gain of 243 per cent. Management of its 4.89-hectare conservation reserve would pass to Hume City Council after two years.

What to watch

• The federal decision. It follows the comment period, which closes on 18 November.

• The state permit. Victoria's next government decides the planning application after the 28 November election.

• The community sessions. AirTrunk meets residents at Mickleham North Community Centre on 17 and 18 November.