In the 1980s and '90s, many of our projects were in Oxford and Cambridge colleges, on sensitive sites in conservation areas, next to listed buildings and monuments. Today, we are working on similarly sensitive sites in London conservation areas, but the requirements of the clients are radically different.
At St John's College, Oxford, the Garden Quadrangle was built 10 years ago on a site surrounded by the college's collection of buildings and gardens developed between the 17th and 20th centuries. The college required the architecture of permanence, buildings which would allow flexibility of use within individual spaces, but would otherwise remain unaltered for decades, if not centuries.
At Paternoster Square, we are building next to St Paul's Cathedral in the heart of the City. The building contains 21st century work space and dealer floors, facilitating maximum flexibility, with the ability to be refitted to suit changing working arrangements. The commercial necessity is to build offices and shops with a capital value more than five times the Garden Quadrangle, but constructed in half the time and with a fraction of the life expectancy. The building must, however, fulfil the onerous demands of its urban context; like St John's it has to achieve a stature of permanence worthy of its setting while responding to the client's very different aspirations.
Architecturally, there is a continuity of language and compositional themes in the two buildings. Both use exposed precast concrete together with masonry, lead and glass, but technologically they are worlds apart. At St John's, precast concrete was used to make huge loadbearing elements forming large-span domed structures over a sunken 'underworld' containing an auditorium and dining room. The massive structure was exploited for its ability to regulate the internal environmental conditions.
At Paternoster, precast concrete offered a method of prefabrication whereby the envelope could be panellised and installed on a steel frame, in structural bay-sized units with glazing pre-installed. Speed of construction demands that as much work as possible is carried out off site. Roof plantrooms are craned in pre-assembled, the lead roof has been prefabricated and delivered in sections. Apart from the concrete floor slabs, there are no wet trades above ground level.
In contrast, the Garden Quadrangle used hand laid brick and stone, constructed in the tradition of its older neighbouring buildings by craftsman on site.
In this way the two buildings illustrate a concern running throughout our work, which is to reconcile the pragmatism of construction, appropriate to different buildings, with architectural ideas which are specific to client and place, drawing on wide ranging historical precedents.