Art Transplant

Forty years ago, Sheffield was seen as a city with a bright future, its prospects buoyed by its innovative approach to architecture and planning. Pevsner wrote of the ‘massive achievement of Sheffield from about 1950 onwards. No other English city except London can show so impressive an architectural record’. Ian Nairn was equally fulsome. ‘The buildings put up in the last ten years and projected for the next twenty are as interesting and exciting as all the older buildings in the city put together,’ he wrote in 1961. ‘Sheffield could be the boom town of the 1960s.’

Last year, Sheffield One, one of three new government-backed Urban Regeneration Companies, was launched with the prime purpose of regenerating not Sheffield’s rundown industrial fringes, devastated by the contraction of the steel industry, but the city centre which Pevsner and Nairn had so admired. In June, 2000, Koetter Kim was appointed as masterplanner for the central area – where 50% of Sheffield’s jobs are found. The achievements of the 1950s and 60s are now widely seen as a burden, with the drab commercial buildings of the period – Sheffield had suffered severe wartime bombing – no match for their Victorian predecessors and undoubtedly responsible in part for the city’s commercial decline. (As a retail centre, Sheffield lags way behind Manchester, Leeds and Nottingham.) The inner ring road constructed around the centre under the regime of J.L.Womersley (city architect 1953-63) is rightly regarded as an unmitigated disaster.

Pringle Richards Sharratt’s (PRS) recently opened Millennium Galleries is a prime component in the "Heart of the City" project intended to reinstate Sheffield as a major retail, cultural and leisure destination –office, retail and hotel developments are projected, linked by new public spaces. It is being promoted (more superlatives) as 'the most exciting and highest quality building to be built in Sheffield in the post-war period'. In 1996, with Terry Farrell then in the masterplanner’s seat, PRS , with engineer Buro Happold, was appointed to design the galleries and a linked winter garden, a covered public space to be built on part of the site of a bizarrely ugly (and functionally deficient) 1970s extension to Sheffield’s late Victorian town hall. Funding has come from the Millennium Commission, ERDF, English Partnerships, the local authority and a PFI initiative. The winter garden is set to open 'sometime in 2002' – demolition work on the town hall extension has not yet begun as a consequence of delays with the PFI funding. For the moment, visitors to the Ruskin Gallery, the westernmost of the run of new exhibition spaces which extends parallel to Surrey Street between the town hall and the Arundel Gate section of the inner ring road, have a view out not of a lofty, almost gothic space, crafted in timber, steel and glass, but of the crude egg-box facades of the Seventies monster. (Admirable glass panels by artist Keiko Mukaide do much to ameliorate its impact.) On Arundel Gate, PRS’s elegant glazed façade – the principal external expression of the building - is squeezed between a surviving Georgian town house (used as offices for the galleries) and the showy bulk of the Novotel.

The urban strategy behind PRS’s galleries and winter garden project is essentially anti-modernist – at least in the old Modern Movement, Pevsner/Womersley understanding of the term. The Millennium Galleries, say the architects, is not a freestanding object but ' a series of streets and spaces "mined" out of a dense bit of urban fabric'. John Pringle makes a comparison with the enclosed malls of Meadowhall, the 1980s out-of-town shopping centre which spelt near-ruin for central Sheffield: 'this is also a covered, enclosed space', he says, 'but it is true public space, where there is calm and, we hope, beauty'. He compares the complex to the networks of alleys and covered ways found in Mediterranean cities. Where the planners and architects of the 1950s, 60s and 70s went out of their way to ignore the regular grid of Georgian Sheffield – a surprising amount of which survives – PRS reconnects with the historic pattern.

The galleries take advantage of Sheffield’s steep slopes. The visitor – maybe an outsider, like me, having toiled up the hill from the station - entering from the eastern end, on Arundel Gate (now much tamed and not the impassable barrier it was), passes the restaurant, which opens out onto a new paved and planted square, and ascends by escalator or lift to the gallery level, exiting on grade at the western end or though a side door into Surrey Street. The undercroft contains education spaces, stores, staff accommodation and plant and is serviced via an underground service road created as part of the 1970s town hall extension project. None of the undercroft spaces is more than functional, though the education rooms benefit from the availability of natural light.

The main gallery level is, however, an unusually satisfying, unfussy and truly modern succession of toplit spaces, 1500 sq.m. in area, which John Ruskin, with his loathing of pretension and empty display, might have approved of. They are formed as 11 bays on a 7.5 x 15m grid, with a series of rooms covered in exposed pre-cast concrete vaults – the finely finished concrete of the vaults, beams and posts creates the internal character of the building. In principle, the whole internal space can be reconfigured, opened up or sub-divided at will, though it is presently divided into five sections: a multi-purpose Long Gallery facing Arundel Gate, the Ruskin Gallery, the Craft and Design Gallery, the Metalware Gallery (showing products of Sheffield industry) and – the largest of the spaces – the 800sq.m. temporary exhibition gallery, which occupies five bays of the building. The first exhibition contains some remarkable treasures from the V&A - though this is not 'the V&A of the North' and the link with that troubled institution is far less close than was initially envisaged. (The Tate and National Portrait Gallery are the other partners in the project with the Sheffield Galleries and Museums Trust – the next visiting show brings works by Francis Bacon from the Tate)

The galleries will, inevitably, be compared with Kahn’s Kimbell for their calm dignity and skilful use of natural light but, as Pringle explains, they make use of a highly original daylighting strategy – light from a clerestorey level is bounced off reflectors set at the edge of the vault on to the white concrete. (The mix is calculated to give the vaults maximum reflective qualities.) The clerestorey itself is louvred to filter direct sunlight. Given PRS’s environmental interests, one expects (and gets) an innovative approach to energy and services. It helps that Sheffield – always a progressive place at heart – has its own 'green' district heating system (which burns refuse). Power from this source propels low velocity fans located in the raised office-style 'hypocaust' floor, introducing conditioned air which, absorbing heat from the sun, the lights and the visitors, is extracted at high level via a natural stack effect. The heavy concrete structure of the building acts, of course, as a thermal store, reducing the demand for mechanical heating and cooling. On top of the gallery vaults, there is a thick layer of insulation, with hard-wearing terne-coated stainless steel as the external covering. 'There’s not a lot to see', says John Pringle of the services, 'but there is a lot going on'. The discreet and elegant manner in which servicing is integrated into structure is one of the strengths of the scheme.

Like the forthcoming winter garden, the foyer space ('the avenue') which extends along the northern edge of the run of galleries, is a tempered but not conditioned environment. The use of double-glazed glass blocks and fritted glass will exclude glare and there are opening windows for hot weather. It is hoped that this space will become a public route, reinforcing the idea that the Millennium Galleries are not a destination but an incident in the city, a place where the passer-by may be drawn into the world of the Gloucester Candlestick (one of the V&A’s greatest treasures), the Sheffield cutlers, William Burges, the Kelmscott Chaucer, Japanese lacquer and Ettore Sottsass, to mention some of the wonderful things currently to be seen there, protected behind a layer of 4-ply plate glass. There is an admission charge to the temporary exhibitions, but all the other spaces are free.

The Millennium Galleries are seen as part of a regeneration programme, the key link in a new cultural quarter which includes the city’s Graves Art Gallery and the Crucible and Lyceum theatres, with the heavily populated campus of Hallam University nearby. The Graves is, however, stranded uncomfortably on top of the 1930s public library and the theatres are essentially evening places. In contrast, the Millennium Galleries are uncompromisingly democratic spaces, their prefabricated modular construction expressing their non-hierarchical character, which invite the public to enter, pass through or linger according to their inclinations. This non-prescriptive programme is in tune with the cultural thinking of New Labour and the Millennium Galleries are, in this respect, rather more radical than the more traditional 'destination' of Walsall.

Five years into its history, Pringle Richards Sharratt has produced a major work, though one which is intentionally unmonumental and clearly one element in a regeneration strategy rather than a grand-slam Bilbao-style gesture. (Branson Coates’ Pop Music Centre, now closed, was a cut-price attempt at the latter.)

But it is the winter garden, phase two of the practice’s grand projet, which could be the key move in breaking the stranglehold of Meadowhall and reanimating the city centre. If other new developments in Sheffield take their cue from Pringle Richards Sharratt’s restatement of civic and cultural values, the city, with its real assets of landscape and community, could be on the road to real renaissance.

Structure

The exposed precast concrete gallery structure is multi-functional, forming the finished surfaces, contributing to the thermal stability of the carefully conditioned gallery spaces and creating a reflective surface for distributing natural light, as well as supporting building loads.

The Leeds office of Buro Happold designed the precast concrete roof vaults (which span 15m across the gallery spaces) in pairs of 28 tonne units which are stitched together on site.

The gallery spaces are controlled to narrow temperature and humidity parameters. Displacement ventilation provides required conditions in the lower space where artefacts are located. Upper levels are allowed to fall outside these conditions, reducing volumes of air required and energy use.

Thermal mass

Exposed structural concrete surfaces - roof vaults, gutters, columns and adjacent ducts - provide thermal mass, assisting in stabilising the gallery environment. Their high heat capacity prevents sudden fluctuations in temperature though occupants, exhibits, lighting heat loads etc.

Fair face concrete

The Gallery finishes are exposed precast concrete. Upper levels are precast elements with permanent precast concrete formwork for insitu concrete columns. Back of house areas at the lower level are constructed in insitu concrete. The concrete roof vaults were formed in steel moulds, with other elements cast in timber moulds. The vaults were cast in two halves, allowing exposed surfaces to be cast face down into moulds. Cast surfaces were shot blasted to create a lightly textured finish.

Precast vaults design

The 5.6m wide roof vaults span 15m, are supported corner columns with a stainless steel tie preventing the folded plate spreading. There are no ties across the vault within the span. Because a complete vault forms a very efficient structural component the compression and tension forces in the apex and eaves (respectively) are not large. The vault overall depth is around 1.4m, with span to depth ratio around half that of a typical beam in a structure. The vault shell thickness was thinned to 80mm, reducing overall units weight for handling and erection. Stiffening ribs expressed on the vault under sides provide additional out of plane stiffness. Bottom edges of the vaults are in tension, acting as beams. While reinforced concrete can carry tension forces, development of surface cracks needed considering. The low vault span to depth ratio led to low strains in the concrete edges and though careful detailing of the reinforcement, small crack widths. The problem of calculating crack widths in concrete is not straight forward, due to the non-linear behaviour of the material over time, known as "creep". Concrete carries on deflecting under load over time. In evaluating deflections and consequently crack widths, this behaviour changes the distribution of forces between steel and concrete and the strains in the concrete over time.

A spread sheet programme developed to solve the behaviour of the vault, calculated long and short term behaviour. It was established that crack widths could be adequately controlled using normally detailed reinforced concrete. However, Dutch contractor Hibex was concerned about development of cracks, particularly during manufacture, and opted to post tension vault reinforcement.

Light reflectivity

Diffuse light is required for gallery spaces. Concrete surfaces were formed in white concrete with specially selected sands and aggregates. These were exposed shot blasting, creating a high light reflective surface. The clerestory windows, in conjunction with a light shelf at gutter level, bounce light onto the vaults and thus into the gallery.

Matthew Lovell, Buro Happold

Tender date: November 1997
Start on site date: 1 March 1999
Completion date: 4 April 2001
Contract duration: 109 weeks
Gross floor area: Gallery 4594 m2 (including kiosks and plant room mezzanine). Leader House 394 m2
Form of contract: JCT Standard form of Management Contract 1987 Edition
Total Cost: Gallery £12,780,000. Leader House £354,600

Credits
Client: Sheffield City Council, Sheffield Galleries Museums Trust
Architect: Pringle Richards Sharratt Architects: John Pringle, Penny Richards, Ian Sharratt, Douglas Oyugi, Basil Kalaitzis, Adam Blacker, Joanne Metcalf, Valerie von Truchsess, Therese Degermark, Tim Gledstone
Project Manager: Sheffield Design & Property?
Quantity Surveyor: Sheffield Design & Property?
Structural & Services Engineer: Buro Happold?
Fire and Access Consultant: Buro Happold FEDRA?
Acoustic Consultant: Arup Acoustics
Lighting Consultant: Bartenbach LichtLabor/ Ingenieurbür Martin Klingler?
Exhibition Designer: Jasper Jacob Associates, Ralph Appelbaum Associates
Glass artist (Ruskin Gallery): Keiko Mukaide
Winter Garden Landscape Consultant: Weddle Landscape Design
Planning Supervisor: Sheffield Design & Property?
Management Contractor: Tilbury Douglas Construction
Leader House refurbishment: Graham Stuart Construction

SUBCONTRACTORS AND SUPPLIERS

retaining wall piling Stent Foundations; mini piles Van Elle; earthworks Moorhead Excavations; substructure Hewlett Civil Engineering; in situ concrete, blockwork walls Graham Stuart Construction; precast concrete structure Hibex BV; precast concrete erection Klomp BV; structural steelwork JP Fabrications; roof coverings, rooflights Kelsey Roofing Industries; Terned stainless steel roof suppler Eurocom Enterprise; single layer roof membrane supplier Flag UK; roof glazing Coxdome; external glazing and lift shaft enclosure Soliver Waregem; Aluminium framed glazing RC Systems; bolted glazing Structawall, Glas & Metaal Engineering; automatic sliding doors Geze UK; glass blocks and terrace GBW; glass block supplier Solaris; glazed blockwork Astraglaze (Forticrete); external louvres Western Avery; mechanical and electrical services NG Bailey; passenger and goods lift, dumb waiters Independent Lifts; scissor lift RS Stokvis; escalators Schindler; internal glazed screens In House Design; raised access floors Atlas Access Floors; raised floor tile suppler Tate Access Floor System (Alumasc Interior Building Products); ventilation louvres Glidefield; joinery Sheffield Direct Services; architectural metalwork Beeley Fabrications; spiral staircase Albion Design; glass balustrades Sovereign Stainless Fabrications; security grilles Troax (UK); sliding/folding partitions Panelock, Alco Beldan; dry lining partitions, washrooms JDM Contracts; plasterboard supplier British Gypsum; floor finishes Q Flooring Systems; floor tiles Quarella (Concord Tiling); WC wall tiles Ezarri – Shackerley Holdings; shower tiles Buchtal (UK); sanitary fittings, WC accessories GroheDal, Armitage Shanks, Keramag, Hewi, Laufen, Duravit, Ideal Standard, Warner Howard, Amwell Laminates; ironmongery supplier Lloyd Worrall; ironmongery manufacturer FSB Allgood; lock supplier ASSA; decorations Foyle & Kirk; floor paint Hesselberg Barrikade; window cleaning equipment HCL Safety; clerestory blinds Screenline (UK); internal blinds Levolux AT; external works Sheffield Direct Services; gallery fitout Graeme Ash Shopfitters; plaster and render Horbury Building Systems; sealants PJ Sealants; track lighting Concord; light fittings iGuzzini, Artemide, Erco, Thorn

WINTER GARDEN SUBCONTRACTORS

demolition Controlled Demolition Group; substructure Hewlett Civil Engineering; laminated timber structure Merk Holzbau; roof and wall glazing J&W Haran; roof glazing system supplier Vitral UK; roof access system Clow Group; winter garden planting Rentoikil Tropical Plants

Link: Architects Journal 26th April 2001

© Architects Journal 2001