Description

A primary concern of the modernisation and extension of Hamburg Süd’s office building was to preserve as far as possible the appearance of the listed building while also comprehensively renovating the building and improving its energy efficiency. The Hamburg Südamerikanische Dampfschifffahrts-Gesellschaft KG, or Hamburg Süd for short, has a history stretching back 450 years. In 1964, Cäsar Pinnau designed and built a modern office complex for the shipping company, the second largest in Germany, on a war-damaged site on the edge of Hamburg’s old town. Pinnau’s design for the shipping company drew inspiration from two famous buildings in New York, SOM’s Lever House and Ludwig Mies van der Rohe’s Seagram Building, both high-rise buildings with glass façades detached from the primary supporting structure. Pinnau’s high-rise in Hamburg has open-plan offices and – like the Lever House – rises above a lower, two-storey block containing the entrance lobby and casino, among other things. The western end of the ensemble of buildings comprises a six-storey end building with further offices.

After half a century of use, it was time for a fundamental renovation and expansion of the now listed headquarters. In consultation with the conservation authorities, the old buildings were stripped down to the loadbearing structure and re-clad and refitted in accordance with modern technical and energy requirements. The skyscraper and end building were fitted with new curtain-wall-type façade elements comprising storey-high façade elements with inner and outer windows separated by an air gap. The inner leaf includes a triple-glazed ventilation casement while the outer has a ventilated baffle plate mounted in a lightweight metal frame that also serves as fall protection. Between the inner and outer panes, aluminium slatted blinds have been incorporated where they are protected against wind and weather. Thermally insulated panels with opaque glazing cover the ends of the floor slabs, creating the impression of an unbroken glass façade in both the tower and end building. A shadow line between the glazing bead and the unchanged frame profile serves as an air supply and exhaust channel as well as for smoke extraction from the twin-leaf façade elements. The low, connecting building was also re-clad, albeit with a single-leaf, triple-glazed façade. The new twin-leaf affected the proportions of the end building, requiring slight adaptations, and the outer dimensions of the high-rise tower likewise increased by 23 cm on each side. In order to remain as true as possible to the original proportions of the building, despite the 46 cm extra width, the window profile intervals were increased by 1.5 cm each compared to the original. For the high-rise, which has an extra storey at the top, the concrete columns of the original structure required additional reinforcement.

Next to the end building, KSP Jürgen Engel Architekten erected a new seven-storey office building with a central atrium as a heated foyer. Here the twin-leaf façade comprises openable window elements, that are only double-glazed due to the reduced sound insulation and thermal insulation requirements to the atrium. While the new building refers to the existing complex, its horizontal subdivisions set it apart as a distinct building element.

In accordance with the client’s specifications, all modernisation measures in both new and old sections conform to the climatic and energy requirements of new buildings. To keep the new building and the end building cool in summer, two cooling units were installed as part of the HVAC facilities in the lower ground floor of the end building. As in the high-rise building, the offices are equipped with metal cooling elements in the ceiling grid of the suspended ceiling. Both the old building complex and the new building are equipped with mechanical ventilation systems as a partial air conditioning system. Two central heating systems with two heat generators (local and district heating) ensure that the offices are pleasantly warm in winter. Various different systems are used to achieve this. In addition to exposed heating surfaces in the individual and open-plan offices, the foyer and technical rooms, three other systems are installed in the old building: air heating with an induction unit for the conference rooms and the restaurant, air heating with a fan convector for the group offices and heated air conditioning. The second central heating system likewise supplies the end building and the new building with the same combination of three systems in the offices.

The rooftop extension was subject to several stipulations: the height and positioning of the installations on the roof of the newly constructed 15^th floor for the Executive Board had to be exactly in line with the specifications of the previous installations on the 14^th floor. The roof now houses the ventilation system for the upper office floors, above which are recooling units for the cooling units of the high-rise and for supplying the cooling elements in the ceilings as well as the induction units, which were installed together with roof-mounted central shafts, a façade access system and an elevator overtravel. For design reasons, the base of the recooling plants could not exceed a height of 1080 mm; the reduced intake clearance ensures a sufficient recooling capacity up to an outside temperature of approx. 32°C.

The new, expanded headquarters of the shipping company provides space for some 800 employees. The staff have spacious workplaces with excellent views over the city, the canals and the harbour. The carefully renovated, historical entrance hall with its marble floors and unaltered 1960s ambience has lost none of its original charm.

Originally published in Bauwelt 17.2017, pp. 52-57, abridged and edited for Building Types online, translated by Julian Reisenberger

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