By continuing to use the site you agree to our Privacy & Cookies policy

Your browser seems to have cookies disabled. For the best experience of this website, please enable cookies in your browser.

Close

Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Close

Plane sailing

building study

A dramatic curved plane over the whole office area is the most dramatic feature of the SAS Institute by Brocklehurst Architects - a building that emphasises workplace quality

You can normally tell a custom office design from a spec one. It is not necessarily that the space is any more or less flexible or adaptable, the building any more readily sub-let or sold. Rather it is the constraints and details of the client organisation's character that stimulate the designers into giving the building a more distinct personality. The client's particular focus on workplace quality was an opportunity seized upon by Brocklehurst Architects in designing the SAS Institute, the UK headquarters for SAS at Medmenham, near Marlow in Buckinghamshire.

SAS is a global company, working in more than 60 countries, and the largest privately owned software company in the world. It is also an organisation with a reputation for caring for its staff, coming 11th in a recent Sunday Times poll of companies that are good to work for. It is not an organisation with a one-size-fits-all property pattern book. In the US, what suits staff are 'stealth buildings' - cellular offices in reflective, black, glass blocks. In much of Europe, staff are typically housed in historic buildings - châteaux in France, the Netherlands and Sweden, for example - and were similarly housed in the UK until they outgrew the space. Building new in the UK on this scale was a step into the unknown for SAS, but one that it approached with an open mind.

SAS purchased the Wittington Estate at Medmenham in 1983. It originally had 11 staff working in the country house (by Sir Reginald Blomfield, dating from 1898) which, alongside the stables and kitchen garden, was set in 25ha of parkland reaching down to the Thames. Having outgrown the house, SAS expanded into the kitchen garden 10 years ago, where a training centre was built within the existing encircling walls; and more recently converted a stable block into catering facilities. The architect for both of these moves was Brocklehurst Architects.

During the period both Brocklehurst and SAS developed a reputation locally for a sensitive approach to the historic site and a commitment to maintaining it.

Recently, SAS needed to expand beyond its 200 staff, but had reached the development limit allowed on the Wittington Estate.

This coincided with the potential availability of a directly adjoining site, formerly a Ministry of Defence military police training establishment. This site included a number of buildings of no recognisable architectural merit, and site contamination, though the established landscape was important. In 1996, three outline planning applications were made for the site, one by SAS with Brocklehurst Architects for office space, one by a consortium to develop executive housing, and the third by a consortium planning a speculative business park. Only the SAS application was approved and SAS bought the site in 1997.

Planners and conservation officers have remained supportive through to the detailed planning consent in 1999 for 10,000m2 of offices. The two sites are gradually becoming as one, with landscaped links between buildings, though the formal axial approach to Wittington Court has been conserved.

The other consortia bids for the site had included provision of a cricket pitch for use by local people and, not to be left out, Brocklehurst included one, too. It is one of several factors that has shaped the location of the new building on the site.A second is keeping footjourney times down, especially as the new building now contains all the main catering facilities (the converted stables will have other uses). Another is the lie of the land, with the building reduced in impact by being set in the low part of the site; not forgetting the existing landscape - setting the building in one corner of the site, near some of the mature trees, will leave most of the site open, even when the planned second phase is built. This is reminiscent of Barry Gasson's placing of the Burrell Gallery at Pollok Park near Glasgow, though SAS is not so deliberately a building-withinthe-trees. But it is being integrated with the landscape and this is happening more and more as the surroundings mature; for example, with the semi-mature cherry trees recently planted along the front approach to the building now in blossom. The way this building sits in the landscape, and the landscaping of paths, roads and car parking by Landscape Design Associates, contributes a lot to the enjoyment of it. This is a striking investment by the client.

The first phase of the development has been the three-storey drum, housing reception, meeting spaces, catering and loading bay (the building has no 'back'), plus one curved arm of offices on two storeys, housing about 250 staff. Phase 2 (which has no definite start date due to the downturn in the IT sector) will be a second arm starting at the drum at about 90infinity to Phase 1, this time longer and housing 350 staff. In the meantime, the top floor of the drum is used for offices but will eventually become further seating for the restaurant as staff numbers increase. This general layout was fixed very early on, though the client pushed the original design more towards symmetry and formality.

Siting the drum on the lowest part of the plot has been used to dramatic effect. The existing wing, and the second when built, rise away from the drum. Each floor is openplan (except for a few senior executives' cellular offices dotted along the western perimeter), with the floors stepping up twice by 600mm, providing some structure to the space. (There will be three or four steps in Phase 2. ) But on the upper floor, the roof, with its bowstring trusses, sweeps the full length of the wing uninterrupted. What might at first be expected to be unrelenting, works, due to the curvature on plan.

Because of security there is only one office entrance from the more public drum.

It is on the ground floor and the office circulation follows from this. A two-storey circulation route runs along the eastern side of the building; the curvature of the route cleverly emphasised by the layout of a strip timber ceiling. Inboard of this two-storey space are, for each of the three steps, WCs, coffee points and stairs to the upper floor.

The layout of desking and the rather obtrusive storage cupboards is the responsibility ofSAS. Most of its staff have moved from cellular offices, so adjustment to open-plan working may take a little time.

Brocklehurst's interest in energy-saving, and SAS's previous unhappy experience with air conditioning, led the architect to seek out the best services engineer at the very start of the project. The list was whittled down to two, and Max Fordham and Partners won out in competitive interview. The client and consultants visited John Cabot College and the BRE Environmental Building to look at naturally ventilated buildings.

The east-west facing office wing has large glazing areas, deeply shaded with opening windows and blinds operated by staff. On the ground floor, deep concrete beams provide temperature-stabilising thermal mass, with chilled water running through them in summer. On the upper floor through-ventilation is assisted by roof vents.With the first summer approaching, it is accepted that there will be some learning to do. For Phase 2, the external treatment will need modifying to cope with north-south orientation.

On a sunny day in April, the interior was bright and fresh. The energy costs should be relatively low (though as Professor Peter Burberry of UMIST has pointed out, the way to save large amounts of energy is to occupy spaces more intensively). In the offices and the drum, finishes are kept light, though there are areas of colour - mustard yellow, raspberry red and deep pinks. The drum is entered through a glazed foyer, then a single-storey space leads to the three-storey atrium in fairfaced concrete, with views to the landscape beyond. A helical stair takes you to dining spaces and servery. The upper office floor is tantalisingly close but out of reach for security reasons, though the views and the quality of facilities are worth making the journey for.

This is a high-quality working environment, something the client was very committed to achieving.Having developed a relationship with Brocklehurst over many years, SAS was prepared to trust the architect. As Phil Bond, SAS UK chief executive, says, Brocklehurst understands the SAS culture and has created 'buildings that are elegant, functional and distinctive'.

Landscape

The masterplanning of the site involved the fusing of two historic parkland landscapes - Wittington House sitting in its own formal landscape and parkland and the former RAF Medmenham development site, a parkland landscape associated with a Pugin house, characterised by large, mature trees and mature woody boundaries. In addition, embowered in the woods is the Danesfield hillfort, a scheduled ancient monument, which contributes to the richness of the site, characterised by its strong earthworks and mature beech trees.

The landscape proposals sought to lower substantially the main building hub and elevate views to the monument over parking areas, establishing the level change with a gently curved retaining wall. It marks the transition between the looser woodland edge of the site and the more organised immediate setting to the building. The building itself is benched into the site, with the floorplate drawn into the immediate building curtilage to form a series of garden rooms immediately adjoining the offices, forming a transition to the wider parkland. Car parking and the main entrance were kept to one side of the building and sheltered in close proximity to the woody edge, allowing the newly established parkland setting to remain 'pure'.

The site entrance is marked by a simple circular hedge and wall gateway, connected to an avenue of lime trees extending to the building and car parking areas, contained with beech hedging, trees and parkland shrub understorey planting.

The entrance to the building is marked by a generous stone pavement, defined by a wide, low wall suitable for sitting and large semi mature trees. A grass moat, crossed by a slender timber bridge, establishes a green foil to the area, drawing on the formal earthworks of the fort, and marks the connecting pedestrian route back to Wittington House The hard landscape materials selected are simple and restrained, comprising white rendered walls with grey sandstone copings, gravel car parks, and loose gravel and stone pedestrian areas, granite sett work and timber. Planting material is similarly restrained, with large trees, clipped yew and beech hedging, parkland shrub understorey and lawns, echoing the adjoining estate landscape but in a more contemporary pattern.

Richness is added in the detailed herbaceous garden rooms close to the building and in the detail of the incidental woodland floor planting.

Alister Kratt, Landscape Design Associates

Structure

The curved wing and central hub each have distinct structural solutions. The wing open plan is achieved with long-span precast concrete panels and bowstring steel roof trusses, offset by 2.8m across the section to create a balcony on one side and a vertical circulation space with an adjacent single-storey corridor on the other.

The three-storey hub housing auxiliary accommodation is largely of in situ concrete troughs with a steel-framed roof structure. Within the inner core, a 12m diameter atrium allows vertical circulation; this required a high standard of finish to the in situ concrete. The cantilevered walkways, winding stairs and link bridges are all exposed grey concrete. Recessed lights were cast in and the steel roof structure encased in concrete.

The wing consists of 16 radial grids at 6m notional spacing. The roof is supported by feature trusses designed with twin, tension bottom chords and independent columns located on the lines of the main arc grids. Purlins, rooflight framing, projecting eaves profiles and wind-bracing integrate with the features of the main trusses.

Lateral wind pressures acting on the steel frame are stabilised by mobilising the diaphragm capabilities of the precast floor via diagonal roof bracing and bracing built into the wall construction of the projecting bays at each step in floor level.

The precast floor spans 13.8m to feature columns at 3m centres. The floor is barrel-vaulted to aid natural ventilation, with a network of pipes cast into the concrete used to cool the thermal mass. in situ concrete topping to the floor construction ensures diaphragm loads are transferred back to concrete walls that frame the WC/service enclosures.

Both wing and hub structures are founded on a concrete raft designed to span potential 3m voids, which might open up in the underlying chalk.

Mark Harris, Young and Webb

Environment

Lighting throughout the building is controlled by time clocks, dimming switches and light meters to ensure lights are turned off whenever they are not required. Perimeter lights turn off when external light levels provide sufficient natural light. All settings can be locally overridden by users.

High-level automated windows and opening roof vents are used to provide secure natural ventilation, controlled by the Building Management System (BMS). Combined with the first floor's exposed concrete soffit of large thermal mass, there is a big potential for free cooling at night, and this is expected to negate the need for air conditioning most of the time. Additional peak cooling is provided by means of a bespoke system of chilled-water pipework cast into the concrete 10cm above the ceiling surface, designed and modelled in-house by us. When the BMS decides it is required, chilled water at 15-18degreesC flows through the slabs overnight, pumped using base-load electricity (surplus grid electricity generated during the night). The BMS calculates the dewpoint to ensure condensation can never form on the slabs. Once the slab has been cooled, it is ready to absorb the internal gains for the next day.

Calculations show that the internal temperature should never be more than 1infinityC higher than outside.

The second particularly innovative measure at SAS is the reuse of treated sewage effluent to flush toilets within the building and irrigate the surrounding grounds, using a new sewage treatment plant built on site. Processed effluent is of sufficient quality to be stored and used for flushing approximately 50 WCs and urinals and for irrigating the extensive grounds around the building. The system is expected to save 5,500m 3of mains water per year. The water quality is higher than in the nearby River Thames.

Steve White, Max Fordham

CREDITS

TENDER DATE November 2000

START ON SITE DATE 12 March 2001

CONTRACT DURATION 66 weeks

GROSS EXTERNAL FLOOR AREA 5744m2

PROCUREMENT JCT 98 Private with Quantities

TOTAL COST £14,642,555

CLIENT SAS Institute

ARCHITECT Brocklehurst Architects: John Hancock, Matthew Maier, Jane Anderson

QUANTITY SURVEYOR Woodeson Drury

CIVIL ENGINEER Buro Happold

STRUCTURAL ENGINEER Young & Webb

ENVIRONMENTAL CONSULTANT Max Fordham

LANDSCAPE CONSULTANT Landscape Design Associates

FOOD SERVICE CONSULTANT Sterling Foodservice Design Associates

PLANNING SUPERVISOR Woodeson Drury (CDM Services)

MAIN CONTRACTOR Costain

SUBCONTRACTORS AND SUPPLIERS Electrical services RT Harris; mechanical services FG Alden; precast concrete Histon Concrete; curtain walling supply Schuco; curtain walling installationMid City Facades; aluminium roofing supply Corus Kalzip; aluminium roofing installation Kelsey Roofing; stairs, balustrades Edmonds & Co; structural glazing Bridgetown Developments; security systems Nova; windows Velfac; timber cladding Pury Construction; stone paving, kerbsMarshalls; raised access floor Kingspan; soft landscaping English Landscapes; in situ concrete Steve Lee Formwork; floor tiling Pilkingtons; terrazzo flooring Quiligotti; sheet flooring Axiom Group; carpets Gaskell; ironmongery Allgood; catering equipment GS Group; joinery Humphrey and Stretton; chilled ceilings SAS International

WEBLINKS

SAS Institute www. sas. com

Brocklehurst Architects www. brocklehurst. com

Woodeson Drury www. woodesondrury. co. uk

Buro Happold www. burohappold. com

Young & Webb www. young-and-webb. co. uk

Max Fordham www. maxfordham. com

Landscape Design Associates www. lda. uk. net

Sterling Foodservice Design Associates www. sterlingfoodservice. com

Costain www. costain. com

Have your say

You must sign in to make a comment.

The searchable digital buildings archive with drawings from more than 1,500 projects

AJ newsletters