BDP, largest of the practices in our AJ 100 survey, has created a high-profile university teaching building, drawing on its in-house ability to integrate architecture, environment and structure While London Southbank University has been around in various forms for more than 100 years, the current name arose only last September as part of a 'repositioning project' to create a new corporate identity. Also contributing to that relaunch is the building of the Keyworth Centre, by BDP, part of a plan to create a clearer heart for the university. Located on minor streets adjacent to London's Elephant and Castle, there are already several large buildings belonging to the 17,000-student institution here, but little civic sense of an urban campus. The university aims to work toward this, especially by making Keyworth Street the campus spine, hopefully pedestrianised at some point in the future as part of a larger network of campus pedestrian routes.
Located on the site of a demolished podium-and-tower office, the Keyworth Centre is today a 'centre' mainly through providing teaching spaces that can be shared by all the university. At nine storeys (above ground) it is also something of a focal point among the existing lower-rise buildings. Closer-to, it makes a dramatic gesture to the street with a glazed face fronting an atrium that runs the full height and most of the width of the building.Within that space can be seen what are said to be the tallest timber building structures in Europe, two towers of meeting rooms and balconies on freestanding timber columns, set symmetrically either side of the atrium (see structure, page 32. ) Once inside the atrium, it can be seen that the facade is supported by timber props, and that behind the glazing's external metal cappings, the whole facade framing is a structural grillage of LVL (laminated veneer lumber). This timber is complemented by textured brickwork side walls to create a warm welcome. The lobby is double-depth on ground and first floor, providing a space for students to gather to use the large lecture theatres on the ground floor (one for 250, two for 120) and for university functions. It has already hosted a staff party. Above this double height setback, the south-west-facing atrium glazing is a source of daylight to teaching spaces on upper floors. These rooms have windows opening onto the atrium and those not shaded by the timber towers have colourful awnings under automatic and staff control.
Such drama is more than many university buildings customarily afford. Here it is part of the investment in 'positioning' (though like most education projects this one too has been subject to some cost trimming). Its quality partly reflects what project architect Chris Harding sees as a more recent trend among education clients generally: the increasing use of building quality to attract staff, students and researchers, in particular spending more on key spaces such as entrances and lecture theatres, and investing more in promoting social interaction in education, not just providing teaching spaces - rooms in the timber towers were partly seen as break-out spaces.
The typical floor plan, with rooms double-banked along a corridor, might suggest that the atrium is just attached to the front of a standard office-type block, but the presence of this volume permeates the building more fully than that. The timber towers continue the teaching floorspace, connected at the lift lobbies, providing mostly rooms and on a few levels, open balconies intended as lounge areas. (Their woodiness is mainly apparent on the outside; inside they are plaster-lined. ) The atrium dominates views from adjacent teaching spaces on all levels.
The transition from the warm timber/ brick welcome to the plaster/concrete/metal of the rest of the building is marked by steps up to security gates on the ground floor and the overhang of teaching spaces above them.
In materials an open stair marks the transition, steel framed but with timber treads.
To the rear of the building are further sidelit teaching rooms, typically for 25 students.
On a bright day they are usable without lights despite their 7m depth (though lights tend to be left on everywhere anyway, even in the atrium). All teaching rooms are clean-lined, plastered spaces, simple and flexible. Indeed some of this flexibility has been taken up since BDP designed the building. Rooms looking onto the atrium were to have been staff offices but have almost all become teaching spaces. On the second floor the run of offices has become a community skills centre, its north-easterly end room now its reception, with a glazed panel in the corridor wall increasing its openness; a move BDP would have liked to have introduced much more widely through the building.
The top two floors, with the top one cut back as a balcony, were at one stage considered as a home for the school of architecture.
In practice this top half-floor has become offices. The floor below is used as a crit space for architecture, though it does not provide permanent studio space for students. Instead they work mostly at home, a growing, budget-driven trend in schools of architecture.
The textured brickwork surfaces seen in the atrium continue on the exterior in the stair towers. Then brickwork runs plain around the rear of the building as quiet facades. A sweeping curved roof over the basement/ground floor main lecture theatre is repeated in the main building roof and again in covering the almost-outdoor cafe at the south-east end of the building. With tight views of these other facades from the streets, it is the atrium front that dominates as the set piece. It is successful as an essentially symmetrical composition, though somewhat compromised by the asymmetrical roof overhang to its right. This roof shape is a response to the asymmetry of the site.
The roof follows the eastern site boundary, while the building below comes only part of the way forward and is hardly visible from the front. Only the ground floor cafÚ fully follows the site boundary like the roof, but this is less distracting than the overhang, reading more like a separate building, the sort of juxtaposition of low and high structures often found in established urban areas.
Using a conspicuous curved roof requires that there is no rooftop plant, as did the planning permission. All major plant is in the basement. Pursuing a low energy strategy has involved integrating environment and fabric (the capital cost of plant accounts for some 25 per cent of the budget). Natural ventilation was explored but there was concern over future flexibility of the building and the heat generation of IT equipment. The building is mixed mode, combining natural and mechanical ventilation, adding some cooling in summer and heat recovery in winter.
The atrium drives stack effect ventilation, helped when needed by slow-speed running of the smoke extract fans at the top of the atrium. Powered air supply to teaching spaces is delivered through raised floors acting as plenums and extracted through high level slots in partitions; ceilings are slatted rather than suspended. Base air distribution is by builder's work ducts integrated into the architecture rather than the more expensive conventional fabricated ducting. Lighting is metal halide plus fluorescent straight tubes and compacts. Choice of finishes is part of the lighting scheme, as is focusing light on the walls, not just the working plane, to light people's interaction not just head-down study.
Integration of disciplines does not, of course, demand a multidisciplinary practice but such offices create opportunities - that BDP has taken here.What could have been a slab block has become richer both for its immediate users and the university. And with its high-profile atrium it manages something few higher education buildings achieve, namely giving some animation to the street, some signs of life from within.
The main entrance facade of the Keyworth centre comprises a glazed curtain walling system supported by a grid of structural timber members. The glazed wall extends the full height of the building, more than 33m, and is about 31m in width, enclosing an atrium.This space forms the social heart of the building and houses the timber 'pod' rooms and terraces used as break-out spaces.
The atrium is framed by two structural concrete cores, each containing two lifts, which form the peripheral supports to the vertical edges of the timber grid structure.
The structural steel roof provides horizontal positional restraint to the top edge of the wall through sliding connections, which ensures no vertical load is imparted to the wall due to roof deflection, and similarly that the wall does not impose vertical load onto the roof cantilever. The vertical columns of the structure take all gravity loading directly to the foundations.
Wind loading on the facade is resisted by the two-way spanning action of the timber grillage with its peripheral edge supports and intermediate timber props.The props are positioned to maintain a maximum unsupported area of wall of 7.5m x 7.5m. They spring from both the main RC superstructure which traverses the atrium space at high level, and the timber pods which sit behind the facade.The lateral loads on the building from the props are all transferred back into the stiff structural elements of the main part of the building, either directly or by diaphragm action of the floor plates.
The structural timber members of the grid are formed of laminated veneer lumber, a high-strength form of laminated timber comprising 3.2mm-thick veneers of Norway spruce or Scots pine, positioned on every mullion and transom position (which are at 2.5m and 1.84m centres respectively).
The combination of the efficient two-way spanning design and high-strength timber means that the member sizes were restricted to a depth of 360mm and are typically 90mm wide.
Each horizontal or vertical grillage member was designed as effectively continuous. At mullion-transom intersections, continuity was provided by moment connections formed using proprietary concealed fixings, 'Shearlocks', designed and provided by the fabricator, Cowley Structural Timberwork.
Where higher stresses were induced in the vertical members due to the combined bending over props, wind load and compression from dead load, member sizes were increased on a 7.5m module to 360mm x 180mm.
The timber pods and terrace areas within the atrium space were arranged in two towers of six levels each, set either side of the atrium space, adjacent to the lift cores.These structures are supported vertically by two 300mm-diameter glue-laminated timber columns within the atrium space and also take support from the lift cores directly. Their timber floor structures at each level from second floor through to the seventh are constructed in an LVL beam arrangement which forms a horizontal 'A'frame in order to transfer wind load from the facade wall, via the props, into the main stability elements of the building.
Within the A-frame arrangement, timber filler joists span between the main structural beams to form the structural floor deck. Around the perimeter of each floor, a deep beam was provided to conceal the raised floor voids, which act as an air plenum.
Building Design Partnership