Photo © Manos Meisen
Photo © Manos Meisen
Photo © Manos Meisen
Photo © Manos Meisen
Photo © Manos Meisen
Photo © Manos Meisen
Photo © Manos Meisen
Photo © Manos Meisen
Photo © Manos Meisen
Photo © Manos Meisen


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Am Wassermann 36, 50829 Cologne
Hiba Grundbesitz GmbH & Co.KG
CROSS Architecture / Benthem Crouwel GmbH
Project team
M. Sporer, S. Rullkötter, C. Wens
Building services
Zeiler & Partner Ingenieurgesellschaft mbH
Structural engineering
Ingenieurbüro Gerdes GbR
Building physics
ISWR Klapdor GmbH
Gross floor area
4,970 m²
2. Place PROM des Jahres 2009, DGNB Gütesiegel in Gold 2009, BREEAM Excellent

The Etrium is an especially power-saving and with lasting effect conceived office building with 150 workspaces according to the German passive house standards. The house fulfils completely all requirement criteria agreed by the German passive house institute. The compact, 3-storey body is based on a square plan with approx. 38-m edge length and an Inside lying, glass-covered atrium. It shows a very good relation of the outside surface to the heated building volume (A/V relation).

Building concept – The base is formed by two angles positioned face to face. They are stacked floor-wise and twisted in each case around 90 ° mutually. In this manner there originates the special interior space with the typical terraces. These subtend themselves on every floor and offer spaces for communication and informal use to the user.

Facade – The external covering of the highly insulated facade exists of a red cladding in which a surcharge of red, broken glass was trained. The glass granulate material allows the cubic body to radiate and glitter in the sun. By this material use the building is integrated harmonically in the site of existing red brick buildings but keeps it´s uniqueness. The facade clothing was applied in this form for the first time with a building project of this scale.

Atrium – The interior of the atrium is particularly treated: all surfaces of grounds, walls and covers receive surfaces from oak. The covers and walls are explained as acoustically effective wooden disguising, the floor coverings of the atrium and the terraces as a parquet layer. The interior thereby receives a special, comfortable and rather informal character. Plantbodies with Ficus plants and seat objects complement the choice of the materials.

Flexibility – The structure of the building admits varied user's scenarios. An in each case separate accessibility and renting of the single corners is possible. The house can be split in 6 separate unities of utilisation. In parallel all subdivisions up to a user of the whole building are also possible.

Corporate Identity – In the called flexibility the enterprise structure of Econcern can be shown as a holding company with the subsidiaries ideally: the enterprise group is built up from different firms which form together a whole – readable in the single corners of which the construction body consists. The clear adjustment on the central interior and the additional offer of the terraces to the atrium offer a spatial strengthening of the enterprise philosophy which bases community and communication strongly on the aspects.

Construction – Construction of the outer walls as weight-bearing ferroconcrete walls, inside skeletal construction with round ferroconcrete columns and flat concrete ceilings. The reinforcement occurs about the weight-bearing walls of the cores. The glass roof is explained as a steel frame construction from rectangle hollow profiles with high insulated glass-construction. The foundation occurs as a post foundation with ferro-concrete drilling posts (d = 90 cm).

Technical concept – Integral planning component of the house-technical draught is the central atrium which fulfils a determining exhaust air function and allows the exposure of the inside lying workspaces with natural daylight. The supply of the fresh air occurs about a ventilation system in connection with a highly efficient warm recovery. When required the ventilation air is preconditioned about the ground water, the postheating energy is made available by a ground water heat pump. About the guidance of the ventilation air by special aircanals within the concrete ceilings the masses of the construction body are activated and perform thus an essential portion to the space climate. The solar protection occurs about outside positioned solar control louvres with a daylight steering system in the upper third of the hangings. The whole lighting of the building is optimised on your efficiency and is linked up with movement and daylight sensors.

Sustainability – On account of the construction method in the passive house standard the energy consumption of the Etrium considerably differs in comparison to conventional office constructions. The need in heating warmth amounts to < 10 kWh in the year per square metre, the primary energy consumption is minimised on 116 kWh / m ² (including stream for the working equipment). An active heating system and chill system can be renounced for these reasons completely. The roof is additional equipped with a photovoltaik arrangement (34.2 kW) which offers with 30,000 kWh of solar energy a substantially contribution to the cover the rest power demand. An extensive green roof and the collection and use of rainwater are other components of the lasting, resources careful planning.

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