Summary
- ADC3 is the third building planned at Nabiax's Alcalá de Henares campus.
- The project represents investment approaching €800m and is intended to add up to 100MW of IT capacity progressively through 2029.
- The groundbreaking occurred on 18 September, outside this run's core sourcing window.
Nabiax has started construction of the next major phase of its Alcalá de Henares data centre campus near Madrid, with the ADC3 project intended to progressively add up to 100MW of IT capacity through 2029.
The cornerstone ceremony took place on 18 September, before DataCentral’s current 48-hour sourcing window, but the project remains a material capacity development. Regional and local reporting puts investment in the expansion at close to €800m.
ADC3 will be the third building at the Alcalá campus. Nabiax already operates data centre infrastructure on the site, meaning the expansion is not a speculative greenfield proposal but an enlargement of an established Spanish colocation location.
The project comes as Madrid continues to absorb a large share of Spain’s new data centre investment. The city benefits from dense connectivity and a growing cloud and colocation ecosystem, but the scale of the development pipeline is increasing pressure on the electrical infrastructure needed to turn planned capacity into operational megawatts.
One campus, much larger electrical demand
Passing 100MW of IT capacity changes the scale at which a data centre campus interacts with the surrounding energy system. IT capacity excludes at least part of the facility overhead required for cooling and other building systems, so the electrical connection supporting the complete campus must be larger than the quoted server load.
Expansion also places more pressure on electrical distribution inside the site. Additional transformers, UPS capacity, standby generation or alternative backup technologies, and medium- and low-voltage distribution all have to be integrated without compromising the resilience of the operational estate.
That becomes particularly difficult where construction takes place beside live data halls. New phases have to be energised, commissioned, and connected while existing customers remain in service.
Nabiax’s current public portfolio states 36MW of IT power across its facilities, which gives an indication of how material the Alcalá programme is relative to its existing footprint. The new development is therefore not simply another data hall but a significant step up in the company’s installed capacity.
Cooling will be equally central. High-density deployments make thermal design one of the largest differences between new and older halls, and ADC3 is expected to use closed-loop cooling rather than relying on continuous water consumption for heat rejection.
Madrid’s capacity pipeline
Spain’s data centre market has attracted increasingly large projects, but announced capacity needs to be separated from commissioned supply. Construction programmes can run over several years, while grid works, planning, equipment lead times, and customer deployment determine how quickly a completed shell becomes revenue-generating IT capacity.
That distinction is particularly relevant for projects quoting campus-level end states. The planned 100MW addition is an eventual build-out target through 2029, not an indication that the whole amount becomes available when the first ADC3 construction package is completed.
The project nevertheless adds another large block to Madrid’s committed development pipeline. Nabiax already has an operating presence, an established campus address, and construction under way, giving ADC3 a more advanced status than projects still seeking land or early planning approval.
The immediate delivery test is now physical: building, energising, and commissioning the new infrastructure while maintaining the operational standards expected from the existing campus. In a market where grid access increasingly decides which announced projects become usable capacity, construction is only one part of the programme.
