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Wild at heart

aj building study: At the Wetlands Conservation Centre at Slimbridge, Gloucestershire, ECD Architects combined existing facilities and new build to create an environmentally friendly building which sits happily in its context

The naturalist Sir Peter Scott, who founded the Wetland Centre at Slimbridge, Gloucestershire, in 1946, was indisputably a visionary. During the last half century, the pace of development in this country has rapidly accelerated, so that two thirds of Britain's estuaries are currently reckoned to be under threat - the recently inaugurated Cardiff Bay Barrage, for example, has destroyed the breeding grounds of large numbers of waterbirds.

The Wildfowl and Wetlands Trust (WWT), which Scott founded, now has nine centres - the latest is set to open this year on former reservoir land at Barnes, West London - but Slimbridge remains its largest and most important site. The completion of ECD Architects' Wetlands Conservation Centre equips Slimbridge to deal with large numbers of visitors (170,000 in 1998 and soon likely to top 200,000), providing the standard of facilities which the twenty-first century paying public demands, and to focus public interest on major issues of conservation and sustainability.

Slimbridge is a far remove from the Charlesand-Camilla, London-oriented Cotswolds.

Instead of long views and big skies, estuarine Gloucestershire offers a flat, introspective, rather monotonous landscape in which sudden and dramatic prospects of the Severn come as a shock. The route to the WWT lies through an overgrown and mundane commuter village along a narrow road across drainage channels - access to the site was the first problem faced by the architects.

The Slimbridge Centre had grown in an ad hoc way from the 1940s onwards. In the 1960s, the cottages and other small structures which Peter Scott and his colleagues initially inhabited were supplemented by relatively modest new visitor facilities designed by Hughes & Bicknell.

Grouped around a hard surfaced courtyard, these buildings were divorced from the wetlands environment beyond and provided a poor introduction to the site. An element of inspiration and delight, as well as response to functional needs, fuelled the project which WWT developed with

ECD Architects from 1995 and for which it secured 50 per cent Millennium Lottery funding towards a total cost (excluding fees) of £3.75 million.

This a model Lottery project, one to set against so many disastrous misapplications of precious public money. At half of one per cent of the cost of the Millennium Dome, a voluntary organisation of international repute and proven achievements, which depends largely on visitor income and the support of a large (75,000) membership, has been re-equipped for the future. The architecture of the building and, of equal significance, its highly progressive environmental agenda, reflect the ideals and aspirations of the client and respond to a carefully considered brief. WWT wanted much-improved restaurant facilities, a bigger shop, a conservation centre and exhibition areas. Additional housing for staff was also included in the project.

David Turrent of ECD believes that the way in which the brief was developed with WWT, led by managing director Tony Richardson, was a model for projects of this kind. It was clear that a substantial part of the 1960s visitor and administration complex - the existing cellular offices, auditorium and exhibition space - should be retained, refurbished and incorporated into the new development. Part of the architects' brief was to seamlessly integrate the existing fabric with the new build and this integration has been successfully achieved.

Approached from the car park (still a bleak expanse, but to be 'softened' in due course) the Wetlands Conservation Centre reads as an entity. The focal point of the L-shaped complex, a counterpoint to its overall horizontality, is the 16m high observation tower, a well-used visitor amenity and emphatically not there for show.

(Accessible by staircase or lift, it is generally full of binocular- and camera-carrying enthusiasts and there is plenty of space for wheelchairs.) The cladding of the buildings, brick on the ground floor with timber above, reinforces the horizontal emphasis and reflects the structural hierarchy - a concrete framed base supporting a steel structure with timber cladding. Roofs are generally covered in cedar shingles. It would have been too easy to give the buildings a self-consciously folksy or decorative look but, as in the best work by Edward Cullinan Architects or Penoyre & Prasad (this is the tradition in which the project belongs), this temptation has been eschewed in favour of a straightforward and purposeful aesthetic. The centre is entered at first floor level, via a steel and timber bridge crossing a specially created stretch of water - the bridge is 'rather heavier in practice than first envisaged,' says David Turrent. 'As usual, it comes down to health and safety.' The visitor arrives in a very generous foyer area. At present, this space seems attractive but its use is unresolved - it would be an obvious location for a display on the history and purpose of Slimbridge. From here, visitors, having passed the ticket desk, descend via a gentle ramp, through the exhibition spaces and eventually out into the wetlands beyond across a network of specially-made boardwalks. From the foyer space, there is a view down into the doubleheight restaurant and cafe space, with its sweeping, boat-like timber roof. Unfortunately, pervasive cooking smells and the intrusive clatter which inevitably emanate from catering areas are already seen as a problem and there are ideas of a glazed partition as a relatively cheap solution. The restaurant is itself, however, an agreeable place, generously day-lit, with views of water and wildfowl - big sliding doors can be thrown open in fine weather.

ECD Architects had its origins in a concern for 'environmentally conscious design' and green issues continue to figure prominently in its work and that of its sister practice, ECD Energy and Environment. At Slimbridge, the environmental concerns of the architects tie in neatly with those of the client. The new centre is heavily insulated to reduce energy consumption and makes optimum use of natural light. The observation tower acts as a chimney, part of a natural ventilation strategy for the building. The timber which is widely used in the structure and cladding is a renewable resource. Demolition of existing buildings has been kept to a minimum. Rainwater is collected and recycled as 'grey water'. Rather than being channelled to a main sewer, waste is directed into a reedbed sited some distance from the building, where it is naturally broken down and neutralised. All these measures constitute a concrete response to the central issue which the WWT addresses - the fact that man's ever-growing demand for energy and the resultant destruction of the natural environment threatens the very existence of other species.

With its adjacent staff housing and rickyard block, the centre forms an oasis of innovative but appropriate new design in a deeply conservative rural hinterland. This is a building which is made for easy maintenance - with roof gutters wide enough to be walked along, for example - and designed to age gracefully. It is also a didactic example of design for the disabled, taking the basic legal requirements of access as the starting point and opening up every facility to wheelchair users - on the day of my visit, a dozen or more of the latter were enjoying the building. In short, this is a highly serious and unashamedly progressive building in a fine British tradition. It could have been earnest but dull, yet is enjoyable as well as socially and environmentally beneficial. Would that as much could be said of every Lottery project.

STRUCTURE The low-lying wetlands between the River Stern and the Gloucester and Sharpness canal is an ideal home for migrating wildfowl. However, the soft estaurine alluvium and a water table at ground level for most of the year presents a challenge to the structural engineer. The foundations for the new centre comprise mass concrete pads on a formation improved by the vibro-replacement technique, obtaining a bearing pressure of 150KN/m 2 with a total settlement of 15mm. The stone columns locally lowered the water table which helped stabilise excavations. The ground slab spans between these stone columns on a 2.2m grid. This solution reflects the 'green' policies of the client - more so than the continuous flight auger piling technique also considered. Vibrations through the ground were negligible and went unnoticed by the wildfowl, although the piling rig was lit up overnight to stop the birds colliding with it!

The two storey sections of building consist of in-situ concrete slab frames to first floor level which give thermal mass, avoid downstands and offer stability. Steel cantilever columns support the roof. The in-situ concrete frames suit the irregular geometry; the cantilever columns allow an internal space free of bracing. The restaurant section has a pinned frame; the tower has vertical vierendeel trusses to resist the wind. In all areas of the roof, cold-formed purlins span into simple steel beams and horizontal trusses, mainly in linear roof areas, transfer lateral loads to the cantilever columns over the reinforced concrete frames.

Michelle Dixon Dawson, Whitby Bird & Partners

CLIENT Wildfowl and Wetlands Trust ARCHITECT ECD Architects: David Turrent, David Billingham, Kenan Klico, Selcuk Avci, Raff Bertram, Simon Gathercole, Nigel Craddock ENERGY CONSULTANT ECD Energy & Environment: Miles Attenborough LANDSCAPE ARCHITECT SGS Environment ENGINEER (BUILDING SERVICES & STRUCTURAL) Whitby Bird and Partners QUANTITY SURVEYOR James Nisbet and Partners PROJECTMANAGER Davis Langdon & Everest MAIN CONTRACTOR Leadbitter Construction REED BED DESIGNER Professor Chris Baines CATERING CONSULTANT Diana Crighton CLERK OF WORKS John D Tupper Associates SUBCONTRACTORS AND SUPPLIERS aluminium windows and CREDITS curtain walling Fleetwood UK; sliding glazed doors and fixed glazed screens Woodlock Joinery; structural steelwork Thomas Steelwork; flat roofing Erisco Bauder; lift and hoist Coastal Lifts; cedar shingles John Brash; insulated external render CCS Scotseal; beech flooring Junkers; resin bonded paths Addapgrip; mechanicalARV Services; electrical EIS (Cheltenham); balustrading Flowline; timber doubleglazed windows 'O' Windows; spiral steel stair Ferguson Southwest; ironmongery Higrade Hardware; lighting Marlin Lighting Costs Costs based on tendered contract sum SUBSTRUCTURE FOUNDATIONS/SLABS £55.91/m

Piled foundations, pile caps and ground beams, lift pit and insitu concrete slabs to ground floor, tanked with flexible sheet damp-proof membrane SUPERSTRUCTURE FRAME £59.25/m

In-situ concrete columns and slab to ground floor and steel frame to restaurant, tower, upper floors and roof UPPER FLOORS £17.83/m

In-situ concrete floors and ramp on concrete columns.

Structural steel work to tower floor ROOF £74.12/m

Terne-coated stainless-steel roof on plywood decking to curved roof areas and projecting eaves. Western red cedar shingles on battens and counter battens to pitched roof areas. Built-up warm deck felt roofing to all flat roofs and refurbished existing roofs. Concrete paving slabs on felt to roof gardens and lightwells STAIRCASES £27.71/m

Galvanised steel staircases with balustrade and handrails.

In-situ concrete external stair with asphalt weathering and timber anti-slip decking over EXTERNALWALLS £54.32/m

Cavity construction with facing brick, insulation and block inner skin to the ground floor. Tongue and grooved Western red cedar cladding with concealed head fixing on battens, on breather membrane, plywood sheathing and insulation to upper floors. Insulated render system to existing exposed brickwork EXTERNALWINDOWS AND DOORS £59.99/m

Thermally broken double-glazed pre-finished top-hung timber windows. Curtain walling to main entrance and projecting windows. Double-glazed Honduran pine framed sliding and fixed screens to restaurant. Aluminium single glazed top hung windows to observation tower. External doors insulated with cedar clad external leafs and plywood faced inner leafs INTERNALWALLS AND PARTITIONS £15.33/m

Generally blockwork partitions to ground floor and timber stud plasterboard faced partitions elsewhere INTERNALDOORS £15.30/m

Painted timber flush doors to private areas and birch faced timber flush doors to public areas INTERNAL FINISHES WALL FINISHES £6.17/m

Plasterboard and plaster, birch-faced plywood to temporary exhibition area. Glazed tiling to wet areas FLOOR FINISHES £37.59/m

Junckers timber flooring to temporary exhibition space and ramp. Ceramic tiling to restaurant seating and shop.

Generally linoleum and carpet tiles to private areas. Non-slip vinyl to wet areas CEILING FINISHES £17.25/m

Birch-faced plywood to curved and pitched areas.

Plasterboard to cellular rooms

FITTINGS AND FURNISHINGS FURNITURE £13.47/m

Shelving, blinds, kitchen units, loosed fitting fire fighting appliances. Reception desks and graphics designed by others SERVICES SANITARYAPPLIANCES £6.94/m

Standard quality low-flush glazed ceramic WCs, urinals and wash hand basins. Disabled WCs and cleaner's sink MECHANICAL INSTALLATIONS £76.23/m

Passive ventilation system throughout ELECTRICAL SERVICES £46.04/m

Electrical power and lighting installations throughout with back up generator. Fire and security alarm system, CCTV system, data system and lightning protection. Public address system LIFTAND CONVEYOR INSTALLATIONS £13.82/m

Eight-person hydraulic lift to tower. Mechanical dumb waiter to restaurant mezzanine BUILDERS'WORK IN CONNECTION £14.47/m 2 PRELIMINARIES AND INSURANCES PRELIMINARIES, OVERHEADS AND PROFIT £95.55/m 2 EXTERNAL WORKS LANDSCAPING, ANCILLARY BUILDINGS £903,400 Approach ramp fabricated from structural steel on timber antislip decking. Timber anti-slip boardwalks and balustrading on timber frame structure. Resin-bonded aggregate to entrance paths. New lakes formed from puddle clay. New vehicular access bridge and culverts. External lighting and bollards.

Reed bed water recycling system. Ancillary buildings two semi-detached three-bedroom houses and single-storey grounds administration offices cost summary Cost per m 2 Per cent

(£) of total SUBSTRUCTURE 55.91 7.91 SUPERSTRUCTURE Frame 59.25 8.38 Upper floors 17.83 2.52 Roof 74.12 10.48 Staircases 27.71 3.92 External walls 54.32 7.68 Windows and external doors 59.79 8.46 Internal walls and partitions 15.33 2.17 Internal doors 15.30 2.16 GROUP ELEMENT TOTAL 323.65 45.77 INTERNAL FINISHES Wall finishes 6.17 0.87 Floor finishes 37.59 5.32 Ceiling finishes 17.25 2.44 GROUP ELEMENT TOTAL 61.01 8.63 FITTINGS AND FURNISHINGS 13.47 1.90 SERVICES Sanitary appliances 6.94 0.98 Services equipment, disposal installations, water installations, space heating, air treatment 76.23 10.78 Electrical services, protective and communication installations 46.04 6.51 Lift and conveyor installations 13.82 1.95 Builders' work in connection 14.47 2.05 GROUP ELEMENT TOTAL 157.50 22.27 PRELIMINARIES 95.55 13.52 TOTAL 947.36 100.00

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