Hearst Tower in New York

The design of this 182-metre-high office tower was the outcome of a dialogue between old and new structures. Situated near the south-west corner of Central Park, the block rises above a six-storey art deco plinth structure that was completed in 1928. Even in those days, the media mogul William Randolph Hearst had the idea of using this as the base for a high-rise block, and the appropriate structural measures were taken at that time. Almost 80 years were to pass, however, before this concept was implemented. The architects gutted the existing building down to the original sandstone outer walls, within which they created a spacious lobby, containing a lift area, a cafeteria and an auditorium, as well as mezzanine levels for meetings and special uses. The office storeys are served by 15 passenger lifts. Together with the two lifts to the mezzanine levels, they provide access to all parts of the building. In addition, there are two goods lifts. The new structure is raised above the lobby on reinforced concrete columns and linked with the historic plinth by a glazed strip. The office storeys, with a four-metre room height in most cases, provide space for 1,800 to 2,200 employees. The corner rooms, which are elsewhere commonly reserved for executives, are here available as staff areas and meeting points. The diagonal external members of the steel structure are visible in the facade in the form of triangulated frames that extend over four storeys. This efficient system helps to save roughly 20 per cent of the steel that would be needed in a traditional form of construction. The triangular bays of the grid are filled with low-E-coated glazing supported by a post-and-rail system. Recessed corners in the facetted surface lend the building a striking and memorable silhouette. The good energy standard of the tower should ensure a saving of roughly 25 per cent in comparison with conventional buildings. Water lost from the air-conditioning plant through evaporation will be replaced with rainwater, which will also be fed into a special pumping system to water plants and trees inside and outside the building. It is expected that captured rainwater will cover about half the watering needs.