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Green facade of the citigroups' data center in Frankfurt am Main; Green facade of the citigroups' data center in Frankfurt am Main;

Citibank Data Center, Frankfurt am Main

Sustainable, resilient data centre design: meet the world's first LEED Platinum certified data centre

Engineering sustainable, energy-efficient data centres is the next design frontier for built environment consultants worldwide. As the key processing hubs behind the global rise of cloud computing, data centres consume a huge amount of energy to manage and maintain the data that powers our daily lives. So how do you design a large-scale, sustainable data centre without compromising its operations and reliability?

With more than 25,000m² of total floor space, Citibank’s Frankfurt am Main Data Center was Citigroup's largest data centre outside the USA at the time of its opening in 2012. Beyond its sheer scale, the data centre is also a leading example of sustainable data centre design. Engineered to consume 30% less energy than a conventional data centre, this energy and resource-efficient showcase project was the first ever data centre to secure a Platinum LEED certificate.

Citigroup appointed Arup to design and deliver the project, including consulting on the site selection in Europe, general planning, LEED certification, contract management, site supervision during construction and commissioning.

Sustainable data centre design: a new architectural language

Arup’s multi-disciplinary approach was central to the seamless adoption of an integrated sustainability strategy. Our engineers calculated energy use at initiation of the design process, which informed the building orientation, spatial configuration, and mechanical systems; and has generated cladding and façade shading systems that respond to solar orientation.

The architectural design is aligned with this: despite its functional geometry, Arup created a modern, human-friendly data centre featuring a high-tech workplace with large open spaces, landscaped gardens and an iconic green wall.

The offices feature natural day lighting and ventilation via glazed façades, with external timber louvres made of white oak, designed to contrast with the metallic external façade of the technical facility. The functional and aesthetic aspects as well as their CO2 balance and later reusability played a decisive role in the selection of all materials. Disguising the full volume of the data hall, the iconic green wall features indigenous plants and is fully irrigated by harvested rainwater. The wall, measuring some 55 m by 12 m high, complements the extensive green roof and helps maintain a constant building temperature throughout the year while reducing thermal gain in the summer months.

Project Summary

11MW computing power

10,000data centre space

25,000gross floor area


Resilient, energy-efficient infrastructure design

The data centre meets the highest requirements in terms of supply security. The innovative and consistently planned technical infrastructure for secure and economical operation enabled a “quantum leap” in the energy efficiency of data centres in 2012 and, with a PUE (power usage effectiveness) value of < 1.2, is still one of the most efficient data centres in the world today. We designed the data centre hall partitions precast as concrete wall panels with predefined and co-ordinated services penetrations, providing additional security while contributing to the hall’s thermal inertia.

Innovative problem-solving with state-of-the-art tools

Working closely with the client, we developed an innovative concept for a safer, more economical supply, a cooling system that does more than 70% without chillers and a reverse osmosis concept for recycling cooling tower water that makes the use of chemicals almost superfluous and reduces water consumption by 30%.

To validate our own planning variants, we used tools such as CFD (Computer Fluid Dynamics) air flow modelling and failure probability simulations to guide the decision-making process together with the client, enabling the development of groundbreaking solutions. Our solutions were developed in the interaction of architecture, building physics and technical building equipment and are characterized by particularly high quality, sustainability and cost-effectiveness.

Working with Citigroup, Arup has succeeded in creating an innovative and high-quality design. When completed, Citigroup's new European data centre will be a global example of energy efficiency and sustainability. ” Bernd Günnewig Project Manager Citigroup Germany

From "Go for Gold" to "Platinum“

Sustainability has always been a central aspect of our planning. The goal of LEED Gold certification was ultimately exceeded with the world's first platinum certification of a data centre. In Germany, the Citibank Data Center was the first building ever to receive LEED certification.

Following the commissioning of the data centre, Arup has remained closely associated as a partner for all subsequent conversion and expansion measures, supporting Citigroup with energy monitoring and operational optimization.