Like the Phoenix rising from the ashes: HPP Architects not only designed a new extremely energy-efficient façade for the former Lufthansa high-rise building in Cologne. With extensive dismantling, refurbishment, and additions, they ensured that maxCologne has set new standards both ecologically and in terms of the design. The building ensemble makes the cityscape on the right bank of the river Rhine more attractive. The façade of the Schüco AWS 75 BS.HI series spans the two volumes, giving the complex a modern, architecturally appealing look.

Cologne’s Deutz district keeps on developing. Just a few years ago, press around the world reported on the neighbourhood on the right bank of the Rhine, because UNESCO had raised objections to the construction of five planned high-rises that would have obstructed views of Cologne Cathedral, a world heritage site. But even without the tall edifices, Deutz has managed to improve its image, thanks to various new buildings and refurbishment projects. In the spring of 2013 the maxCologne project, developed by HOCHTIEF Projektentwicklung GmbH, will be finished. The office complex consists of two building parts, the „LANXESS Tower“, named after the main tenant, and the „Rheinetagen“. Both are accessed via a central plaza. The ensemble is the result of the comprehensive revitalisation of the former Lufthansa headquarters, built based on the designs of the architect Johannes Mronz in 1967/1969 and 1978.

After Lufthansa moved out of the impressive complex with the golden windows and the horizontal arrangement in 2007, HPP Architekten won the restricted, one-phase façade competition in March of 2009.

The high-rise with its 22 storeys and height of 95 m (building dimensions: 55 m x 55 m) is a striking structure on the right bank of the Rhine that is visible from afar. The specialty chemicals company LANXESS will use the building
– the LANXESS Tower – with its 19 office floors as a new headquarters starting in the second half of 2013. Some 1,000 employees are expected to have new workplaces in the LANXESS Tower. The interior concept caters for transparency, teamwork, and a flexible working environment. The conference, seminar, and media rooms are equipped with state-of-the-art technology. The stringently adhered-to construction grid of 90 cm extends from the elements of the heating/cooling ceiling via the glass partition walls to the façade units.

The additions on the southwest and northeast side of the tower improve the efficiency of the space compared to the old high-rise and give the tower a striking shape. The entire building is accessed via a central core with seven elevators. Furthermore, a building-high recess on the south side makes it possible to naturally illuminate more space and thus more workplaces. The extensive glazing of the façade units promotes this concept and creates high transparency and a coherent overall appearance, befitting the building’s location.

The part of the building oriented towards the Rhine became an independent volume after the previously connecting base floor was removed. Of the 11 stories, 7 are conceived as pure office floors. The Rheinetagen were expanded considerably during renovation. To give the building a gentler cubature, the architects from HPP integrated the existing terraces into the building. On the upper floors, they were enlarged with the help of a steel substructure, and as a result now all of the floors have a common border towards the Rhine. Recesses in these terraces create exciting views between the terraces of the different floors.

The fact that the same vertical, room-high glazed façade units were incorporated for the envelopes of both buildings, and that both buildings are accessible via the plaza, reflects the close relationship between the two structures. The expansive glass façades (Schüco AWS 75 BS.HI as a special construction) unite the volumes architecturally and, moreover, are an integral part of the overall ecological concept. The façade units are triple glazed and attain a UCW value of 1.1 W/m2K. All of the rooms, including those on the upper floors of the high-rise, can be naturally illuminated and ventilated due to their two-shell construction, and the windows of the inner façade can be opened mechanically. Individually adjustable solar shading was integrated into the rear-ventilated space between the inner and outer layers of the façade to prevent the rooms from heating up and to ensure that the workplaces are glare-free. Other striking aspects of the design, apart from the verticality of the unitised façade, are the louvres of the ventilation units attached below and above, which make the building’s storeys discernible and discreetly give the façade a horizontal arrangement.

Back in February 2011, the maxCologne was awarded a gold pre-certificate by the German Society for Sustainable Building. The primary energy consumption is reduced due to the triple insulated glazing and the double shell of the unitised façade, less cooling energy is needed thanks to the integrated solar shading, and the floor plan enables the buildings to be naturally illuminated to a greater extent. Other important components of the energy concept include the temperature control of the building through the use of groundwater and the dust- and draught-free heating/cooling ceilings. Low-pollution, ecological materials were used for the revitalisation. A large part of the supporting structure of the buildings was retained despite the considerable construction measures, and the building material was reused whenever possible.