DUO² by UNStudio

DUO² by UNStudio: "

DUO and Tax Offices by UNStudio

Amsterdam architects UNStudio have completed a new headquarters for the Dutch national tax offices and the student loan administration in Groningen, the Netherlands.

DUO and Tax Offices by UNStudio

Called DUO², the 92 metre-tall building has a facade covered in horizontal fins to provide shade and reduce the need for artificial cooling.

DUO and Tax Offices by UNStudio

The project comprises 2,500 work stations, underground parking for 1,500 bicycles and 675 cars and a public park.

DUO and Tax Offices by UNStudio

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DUO and Tax Offices by UNStudio

Photographs are by Christian Richters/View unless stated otherwise.

Here are some more details from UNStudio:

UNStudio/ Ben van Berkel realizes with consortium DUO² governmental offices for DUO– Education Executive Agency & Tax Offices in Groningen

A greener approach to tall buildings in the post-iconic age – The Dutch tax office moves to one of Europe’s most sustainable offices

A new, 92 meter tall complex of soft, undulating curves marks the skyline of Groningen. This asymmetric, aerodynamic construction is set amidst small, ancient woodland, sheltering rare and protected species. The project includes the design, construction and financing of two public institutions; the national tax offices and the student loan administration. The commission from the RGD (National Buildings Service) includes, besides the architecture, the management and building maintenance and care of facilities and services for a period of 20 years. Accommodating 2,500 workstations, parking facilities for 1,500 bicycles and 675 cars in an underground garage, the building will be surrounded by a large public city garden with pond and a multifunctional pavilion with commercial functions.

DUO and Tax Offices by UNStudio

The architecture aims to present these institutions with a softer, more human and approachable profile. Tall buildings are generally associated with mid-twentieth century modernism. Their harsh, businesslike exteriors contain powerful, inaccessible-seeming strongholds. By contrast, the DUO and Tax offices deliberately cloak a commanding public institution in an organic, friendlier and more future-oriented form.

“We paid a great deal of attention to how people would move through the building. The office spaces are designed in such a way that they do not create simple linear corridors leading to dead ends, but instead each corridor has a route which introduces a kind of landscape into the building. You can take endless walks through the building, where there is a great deal of transparency, also towards the surrounding landscape.” Ben van Berkel

DUO and Tax Offices by UNStudio

Attainability; a mix of affordable and responsible – reaping material benefits of integral design and construction with a Design Build Finance Maintenance Operate Contract

The governmental office complex is built as part of a far-reaching form of public-private partnership (DBFMO) that is designed to effectuate on a more efficient use of public funds. The design, construction, financing, managing and maintenance of the building was hosted by one consortium consisting of Strukton, Ballast Nedam and John Laing. This consortium won the competition for the project on the basis of a combination of esthetic, technical and financial criteria. UNStudio, as the architect of the project, collaborated with Lodewijk Baljon for the landscape design, Arup for the engineering and Studio Linse as the interior advisor.

The life-cycle approach of a DBFMO contract requires that all relevant experts (designers, lawyers, installation specialists, financial specialists, facility specialists) are involved from the start of the project in order to find the best, most cost effective and environmentally-friendly solutions for the continued use and maintenance of the building. This working methodology stimulates not only creative and innovative ideas, but facilitates a reduction of total costs over the entire contract period compared to the traditional means of contracting. In PPP projects contracts are not awarded to the lowest bidder, but to the party with most effective solutions providing the best value for money.

DUO and Tax Offices by UNStudio

“In a PPP-construction you have to consider all the details concerning maintenance and the sustainable use of the building from the very early stages. It is a unique way to gather all the specialists and the end user around the table from the very outset of the project.”

Ben van Berkel

Exemplary sustainability

“The design contains numerous new innovations related to the reduction of materials, lower energy costs and more sustainable working environments. It presents a fully integrated, intelligent design approach towards sustainability.” Ben van Berkel

The project is one of Europe’s most sustainable large new office buildings. The RGD brief prescribed a future-proof building that couples flexibility and sustainability with an esthetic of sobriety. The architectural response to this has been to strive for an all-round understanding of the concept of sustainability, including energy and material consumption, as well as social and environmental factors. Thus the sustainability manifests itself in reduced energy consumption (EPC 0,74), as well as significantly reduced material consumption. Bringing back the floor heights from 3,60 m to 3,30 m resulted in a total reduction of 7,5 m. on the entire building, which also lessens the impact of the building on the surroundings. Both inside and outside the architecture generates a bio-climate that is beneficial to both humans and the local flora and fauna.

DUO and Tax Offices by UNStudio

All-round architectural sustainability: a sum of many parts.


Sustainability and energy reduction have steered the design of the facade, which contains technical installations that are tailored to be durable and cause minimal environmental impact. The facade concept integrates shading, wind control, daylight penetration and construction in fin-shaped elements. These horizontal fins keep a large amount of the heat outside the building, reducing the requirement for cooling.

Concrete core activation

Another technical feature of the building that contributes to its sustainable character is the combination of concrete core activation and underground long term energy storage. This appreciably reduces the demand for external energy sources.

Individual climate control for each workspace

Creating a healthy, energy efficient interior climate and employee workspace comfort was also an important element in the design. Plenty of natural daylight and adjustable heating, ventilation and access to fresh air for individual workspaces contribute to the comfort of the workspaces throughout the building.

The 11-th floor

A high pressure ventilation system with natural air inflow and outflow via main engineering shafts and the facade grills on the 11th floor reduces the need for artificial ventilation

DUO and Tax Offices by UNStudio

Future possibilities

In addition, the residual energy of the data center and offices can be used to heat the homes that will be realized in the future in the perimeter of the site.


And last, but not least, the building is designed so that it can be transformed into housing in the future without major structural modifications. Therefore, the locations of elevators, stairs and technical spaces have been carefully considered, and a structural grid of 1,20 m. has been deployed, rather than the conventional office grid of 1,80 m.


The inclusion of diverse passive and active environmental and energy efficient solutions has led to a building which is one of the most sustainable office buildings in the Netherlands.

Education Executive Agency & Tax offices, Groningen, the Netherlands, 2006 – 2011

DUO and Tax Offices by UNStudio


Client of the consortium:

Dutch Government Buildings Agency (RGD)

Client UNStudio:

Consortium DUO² (Strukton, Ballast Nedam, John Laing)

Program: Office building (phase A); underground parking (phase B); public city garden, pavilion (phase C)

DUO and Tax Offices by UNStudio

Building surface: 48.040m² offices, 21.000m² parking, 1.500m² pavilion

Building volume: 215.000m³

Building site: 31.134m²

Credits UNStudio:

UNStudio: Ben van Berkel, Caroline Bos, Gerard Loozekoot with Jacques van Wijk, Frans van Vuure, Lars Nixdorff and Jesca de Vries, Ramon van der Heijden, Alicja Mielcarek, Eric den Eerzamen, Wendy van der Knijff, Machiel Wafelbakker, Timothy Mitanidis, Maud van Hees, Pablo Herrera Paskevicius, Martijn Prins, Natalie Balini, Peter Moerland, Arjan van der Bliek, Alexander Hugo, Gary Freedman, Jack Chen, Remco de Hoog, Willi van Mulken, Yuri Werner, Machteld Kors, Leon Bloemendaal, Erwin Horstmanshof.

DUO and Tax Offices by UNStudio


UNStudio, architecture and interior

Studio Linse, interior

Arup, structure, installations

Lodewijk Baljon, landscaping

Buro van Baar, wayfinding

YNNO, internal logistics


DGMR, acoustics

EFPC, fire prevention

Ingenieursbureau Wassenaar, prefab structure

BTS Bouwkundig Tekenburo Sneek, drawing agency

ISS Nederland B.V, maintenance

Peutz, environmental technology

WUR (Wageningen University & Research centre), ecology

Strukton Bouw en Vastgoed, management and costing

Strukton Betonbouw, construction

Strukton WorkSphere, installations

DUO and Tax Offices by UNStudio


John Laing Infrastructure Limited, financial

RBC (Royal Bank of Canada) Capital Markets, financial

TCN SIG Real Estate Strukton Vastgoed, pavilion development

Allen & Overy LLP, legal

Sequoia, legal

RAIC 2011 Awards of Excellence

RAIC 2011 Awards of Excellence: "

OMS Stage / 5468796 Architecture © 5468796 Architecture

The Awards of Excellence recognize distinction in the field of architecture. Awarded categories include Green Buildings and Innovation in Architecture as well as the Architectural Firm Award which was given to Montgomery Sisam Architects. Members of the jury included: Peter Busby, Teresa Coady, Stephen Pope for Green Buildings and Enzo Gardin, Dan Hanganu, Gregory Henriquez for Innovation in Architecture.

Recipients and Honorable Mentions for 2011 Awards of Excellence following the break.

Durham Consolidated Courthouse / WZMH Architects © Shai Gil

Green Building:

OMS Stage / 5468796 Architecture © 5468796 Architecture

Innovation in Architecture:

  • OMS Stage / 5468796 Architecture (Art)

  • Mission 2050 / Baird Sampson Neuert Architects (Science)

  • North House: Responsive Envelope System / RVTR (Practice of Architecture)

  • Canadian Museum for Human Rights / Smith Carter Architects and Engineers, Antoine Predock Architect (BIM) – Honorable Mention

Manitoba Hydro Place / KPMB Architects © Paul Hultberg