THE ARUP JOURNAL 3/1993 Front cover: Project Dragonfly. (Photo: Ken Newman) Back cover: THEARUP Holborn Bars. (Photo: Peter Mackinven) JOURNAL Vol.28 No3 Editor: 3/1993 David J. Brown Art Editor: Desmond Wyeth FCSD Published by Ove Arup Partnership Deputy Editor: 13 Fitzroy Street. Helene Murphy London Editorial Assistant: W1P680 Kris Buglear 3 'Future Assurance': The renovation of the Prudential Corporation head offices in The redevelopment London involved upgrading Alfred Waterhouse's celebrated of Holborn Bars building to modern standards without alteration to its listed interiors David Alling, Ken Coffin, and fa<;:ade , the comprehensive refurbishment of the remaining Ian McVitty, Patrick Morreau, Waterhouse buildings on the site, and the replacement of other Roy Wheeler structures there with 36 500m2 of new. high specification offices. 8 British Airways Ove Arup & Partners Cardiff office were design team leaders for Project Dragonfly the creation of this advanced maintenance facility for 747 jumbo Steven Luke jets at Cardiff Wales Airport. Considerable attention to environmental sensitivities was necessary in its planning, whilst the building itself 'llll!= ~~~~ilt;~' involved installing state-of-the-art specialist maintenance structures ~ as well as raising probably the longest continuous space girders in Europe. 16 Pescanova fish factory, Following the recovery of Namibia's fishing industry after the Liideritz, Namibia country's independence in 1990, the Spanish fishing group Barrie Williams Pescanova commissioned Arups to plan and design their new fish factory, plus causeway and jetty, at a bare rock site on the shore, north of the town of Luderitz. 20 The Oxyco development, Ove Arup & Partners Zimbabwe were principal agent and multi­ Harare, Zimbabwe disciplinary consultants for Oxyco Gases' new manufacturing, Lotte Reimer storage, and sales facility. Stringent safety precautions were incorporated in the design, in particular fire protection for handling and storing liquid petroleum gas. 23 Diisseldorf Tower Energy conservation was fundamental in Arup Associates' Alastair Gourlay competition entry design for this 20-storey office building, which Peter Warburton included solar collectors as well as carefully controlled natural Terry Raggett ventilation in its concept. 2 'Future Assurance': The redevelopment of Holborn Bars Architect: EPA Architects Ltd. David Atling Ken Coffin Ian McVitty Patrick Morreau Roy Wheeler Introduction Department as they. with Ove Arup & Part­ Holborn Bars is both the name and the ners as structural and building services engi­ location of the newly renovated and partly neers, DEGW as office planning consultants. redeveloped offices in London of the Pruden­ and Gardiner & Theobald as quantity sur­ tial Corporation . It has been their home since veyors, developed a scheme for discussion 1875, when the directors decided to move with English Heritage, the Victorian Society, west from Ludgate Hill to Holborn, where land other amenity groups, and the planning offi­ was available on what had once been a cers of the City of London and Camden Roman road from London, and which had Borough, in whose two jurisdictions the site again become a major thoroughfare with the lies. opening of Holborn Viaduct. Here, between The fundamentals of the scheme were to re­ 1876 and 1901 , the Prudential constructed, to tain those buildings identified by Cunning­ designs by Alfred Waterhouse and in stages ham as essential to Waterhouse's concept; dictated by site acquisition, the brick and ter­ and to demolish the 1930s building along racotta buildings which became a London Brooke Street. the relatively inferior 19th cen­ landmark (Fig. 1) . tury buildings at the rear of the complex During the 1980s, the Prudential again recog­ 1. Holborn elevation c . 1905. (keeping only one of the oldest - the 'Jewel' nized the need to change their premises. - a small building at the north-west corner). this time for efficiency rather than expansion. and two 1920s buildings on the far side of The piecemeal growth of the 19th century architectural quality of the various buildings Greville Street. which would be closed to 1 and some subsequent redevelopment (Fig . 3) on it . Dr Cunningham's report makes fas­ extend the site northwards to Beauchamp had created problems which they now sought cinating reading, but space does not permit Street (Fig. 2). In architectural terms, the two to address. Chief among these were the more than a summary of his main con­ key issues were how to join new to old, and variety of floor levels and tortuous com­ clusions: that previous piecemeal growth how to achieve an exterior which neither munications between the various buildings; allowed the possibility of sectional redevelop­ clashed with Waterhouse nor imitated him. ment. but not at the expense of Waterhouse's the inefficiency of the floor plans; standards The first was resolved by retaining the original of heating, cooling and ventilation inappro­ overall concept of a fac;:ade to Holborn lightwells with their white glazed brick walls, priate for the 20th (let alone the 21st) century; backed by a sequence of courtyards. This, adding glazed roofs to convert them to atria, and the total absence of provision for the and the detailed recommendations of the and so articulating the junctions between information technology essential to oper­ report, formed the basis of the planning con­ retained buildings and the new development. ate such a diversified financial services cept adopted by the Prudential Architects The atria thus became major architectural organization. spaces, detailed and finished with granite Gaining the objective 2. Site map. and marble on the columns and, in the circu­ The Prudential's goal was straightforward: a lar main atrium. a sweeping spiral staircase modern office building of at least the same with a 5~ tonne granite sphere (the 'Kugel'), floor area on the same site - a simple rotating on a film of water, to act as a focal enough objective, but not easily achieved point. For the external elevations, the archi­ when the outmoded buildings are listed tects adopted a vocabulary of proportion, Grade W and designed by one of the great detail and material that echoed Waterhouse: names of Victorian architecture. Total demo­ granite panels mounted on frames integral lition and redevelopment was out of the ques­ with windows. cornice. and other details. Two tion, nor did the Prudential consider it: the colours were used, the lighter above, and the buildings had become a symbol of the com­ elevations were stepped back to make the pany. to be conserved and modernized as far building appear less imposing (Fig. 4). as possible. Nonetheless it was evident that. This scheme, which left the main frontages to whatever the scope of the works proposed, Holborn and Leather Lane restored but un­ gaining the necessary listed building and changed, was the basis of extensive dis­ planning consents would require careful cussions with English Heritage and others. preparation. and was granted planning permission in As a first step, the Prudential commissioned December 1988. At this stage, the Prudential Dr Colin Cunningham, a recognized authority retained EPA Architects to carry the project on Waterhouse and his work, to prepare a forward to detailed design and see it through brief history of the site and an appraisal of the to completion. 3. The site from the south-west, 4. North-west corner new buildings, before redevelopment. showing stepping of fai;ade and colours. 3 5 . The completed redevelopment. from the north-west Thus the Holborn Bars development com­ prised three distinct areas (Figs. 5, 6): • the 9000m2 Holborn frontage - described by Cunningham as the 'Flagship' of the Prudential - to be renovated and heated and air-conditioned to modern standards with­ out. as far as possible, alteration to its listed interiors • the remaining Waterhouse buildings (24 OOOm2) to be stripped internally and refur­ bished as 'shell and core' • 36 500m2 of new buildings to be con­ structed to a high specification and com­ pleted as 'shell and core '. Although it was anticipated that some build· ings would be occupied by the Prudential, separate lettings in the future were a possibil­ ity and so. for that purpose. the new scheme was designed so that each block could if necessary function independently, with its own (or a shared) entrance and core. Thus the complexities of circulation were resolved. The engineering issues For the structural engineer the principal issues particular to Holborn Bars were the condition and load-carrying capacity of the existing buildings, the effects on them of the new con­ struction, and the alterations needed to install the new services. The strategy for building services was crucial. Discussion with English Heritage and the planners revealed that space for rooftop plant would be severely restricted, so to avoid using office quality accommodation for ser­ vices installations. basement locations were Key: considered. The subdivision of the develop­ ment into three possibly differing tenancies suggested that each block be provided with its own plant, though considerations of outlay dictated that centralized chiller. boiler, and water storage systems be provided in a base­ ment plantroom below the new building at the northern end of the site. A 1.5m deep basement level building ser­ vices trench provides the distribution route between the central plantroom and the numerous services risers located throughout the complex. With the centralized