Structure minimizes resources used.

Buro Happold has taken many initiatives which combine traditional disciplines of construction with structural and environmental engineering.

The 1997 Kyoto Summit committed the world to a reduction in energy use in buildings, which in Britain accounts for between 40 and 50 per cent of [CO.sup.2] emissions. Buildings, to be sustainable, must embody minimum energy, be adaptable, and their services must be designed to consume minimum energy consistent with comfort. Buro Happold has investigated the use of structure, systems and materials to produce better environments for fewer resources.

One of the earliest buildings to address energy saving with minimum standardized structure and integrated service design was the Solid State Logic factory in Begbroke, Oxfordshire, England, an elegant, two-storey building designed in 1988 with architects Michael Hopkins & Partners. Set around a central top-lit atrium, the building is square in plan with a cast in-situ concrete first floor slab which overhangs the ground floor, shading it from summer sun. Ground and first floor are fully glazed with external blinds at first floor windows, timed to cope with the sun path. Sliding doors allow 50 per cent of the perimeter to open up for ventilation. The surrounding landscape of deciduous trees gives seasonal shading.

The underside of the floor slab was cast with domed coffers which have been fitted with circular glass light fittings. Supply and return air to and from the ground floor is ducted to diffusers incorporated in and above the light fittings. Raised floors 400mm above the concrete floor slab give space for services distribution. The roof is a highly insulated standard space-frame on a 14.4m grid with central rooflights.

The Royal Armouries Museum, completed in Leeds, England in 1996 with architects Derek Walker Associates, uses a massive envelope of exposed blockwork and concrete to maintain a stable temperature level. This was essential to protect the large number of valuable exhibits. Sunlight, which might degrade them, was reduced by using small slit-like windows. Services were integrated out of sight within the floor and column structure, In contrast, the Hall of Steel, where requirements were less critical, is a light and delicate structure clad with frameless glass panels.

Materials of dense mass which modify temperature differences can be combined with their innovative use as structural forms. The new underground railway station for Stuttgart, Germany with architects IOKP and Frei Otto is an example -- a series of elegant concrete vaults, a complex form designed using innovative methods of structural analysis and CAD modelling. Twenty-nine free-flowing vaulted shells transform the existing 1920s railway terminal into a multi-line new station and support the Schlossgarten park above. The 43 000[m.sup.2] underground station area is naturally lit by glazed skylights tilted towards the sun.

In temperate climates such as that of Britain, recent concern for the environment has changed designers' perception of building services -- the pendulum has swung from fully air-conditioned buildings to those ones totally naturally ventilated. Buro Happold believes that the starting point of the design of the environment should be the needs of the occupants -- the fabric of the building should respond to the need and functions of the space, designing systems in the most elegant, efficient and responsible way - rather than being driven by theory.

Temperature remains stable in the range of 15-18 degrees Celsius due to the thermal mass of the shells. The vaults rest on elliptical piers at 60 x 30m spacing. They are to be 350mm thick at the crown increasing to 650mm at the skylights and support 25 kN/[m.sup.2] of loading from the garden and adjacent piazza. The horizontal component of shell thrust is resisted by a three-way network of pos t-tensioned cables which run parallel to the top surface of the shells, rather like strings in a tennis racket, relieving the surrounding station walls of substantial horizontal and vertical loads.

In contrast, the west-facing glazed facade of Future Systems' Media Centre at Lord's Cricket Ground presented some serious challenges to the services engineer; the extensive glazing needed for a good view of the pitch led to problems of glare and overheating. The environment is comfort-cooled with ducted air passing through voids in the structural fabric. Daylight and sunlight effects were examined with a model in an artificial sun and sky; as a result the 40m glass frontage, of 12mm laminated and 6mm annealed glass, is angled downwards to prevent reflections dazzling players.

The Paul Hamlyn Learning Resources Centre at Thames Valley University, Slough, England, with the Richard Rogers Partnership is an example of how the building was developed around the needs of the occupants and the function of the space manipulated as a result of the occupants' needs for daylight, sunlight and comfort. The building is divided, a concept which Rogers developed from the Lloyd's building, into 'served' and 'servant' spaces; a lofty entrance and two-store y open-plan study area under a curved roof is flanked by a solid three-storey 'bookstack' of service and storage spaces. Daylighting studies, using a physical model at Bath University daylighting laboratory, persuaded the team to turn the building through 180 degrees to give better qualities of light to the study area and reduce solar gain. The building's shape enhances low-energy use; the heating and cooling system can respond to changing demands of use and individual seasons. It is not air-conditioned; the ground floor and mezzanine study level (areas producing heat gain from large numbers of people and computers) are provided with limited displacement comfort cooling. The heating and cooling system uses the absorptive effects of the building mass and volume, opening windows, and shading and overhangs for protection. Low energy roof fans assist in drawing air through the building to supplement natural ventilation in the warmer months. The system is specifically programmed, like a car, to vary with the seaso ns, maintaining minimum winter and maximum summer temperatures of 19 to 25 degrees respectively to target an energy consumption in the order of 100KWh [m.sup.2] over a normal year.

The new office for the Building Research Establishment (BRE) at Garston, England, with architects Feilden Clegg, is designed to a performance specification as part of the Energy Efficient Office of the Future project. Working with services engineer Max Fordham & Partners, the concrete upper floors are of sinusoidal wave form sections to maximize the surface area of the ceiling, allowing the thermal mass of the concrete to temper the environment. Ventilation ducts set within the floors allow fresh air to flow from perimeter to the heart of the building. Recycled aggregate, material from a demolished building on site, was used in casting the floors. Photovoltaic cells are installed on the south facade.

Design of building services requires different strategies where they are to be inserted in an existing or historic building. Minimum intervention is required, with a detailed understanding of the building to make the best use of what is available. The Great Court at the British Museum with architects Foster and Partners (see p30) integrates structural, services, geotechnical and fire engineering and safety requirements. The environment is controlled with a combination of ventilation systems, radiant cooling and convective cooling, to reduce energy without impacting on the original fabric. Four new primary plant rooms are set in basements of surrounding buildings, serving fresh air which is refined to gallery conditions in two secondary plant rooms in the Great Court basement These are carefully sited just below two original stone 2m diameter spiral staircases, used for access, through which exhaust air supply is now extracted -- an example of the way elements of building fabric can be used for more than one function (p9). Another example -- the need for smoke extract from the basement in a fire -- was provided by setting extract ducts behind the cladding which conceals the columns around the Reading Room.

Solar gain is minimized with the use of low emissivity glass and by fritting the surface with dot-matrix, varying in density across the roof to reduce summer sun yet give ample daylight in winter.

Designing public buildings for minimal environmental impact in the tropics needs different measures and approaches. Ken Yeang, the Malaysian architect, is currently designing an 11-storey building for the National Library in Singapore which required multidisciplinary engineering. In concept the building is a rectangular library headquarters supported on columns over a public piazza, and linked to an arts centre and auditorium, a curved block which acts as acoustic shield to the library. South-east and west walls of the library are screened with timber louvres. The 10th floor is an open landscaped area; together with the piazza it makes full use of wind and natural ventilation. The building is cooled with a combination of natural ventilation, mechanically assisted natural ventilation, and air-conditioning. The glazed atrium roof is shaded with integral holographic elements which block high energy radiation.

Buildings must respond to their users, and allow them reasonable control over their environment. For example, the brief for the new operations centre of Wessex Water Services in Bath, England, designed by Bennetts Associates, was that it be an exemplar of environmentally sustainable and sensitive architecture. Steel and concrete construction is exposed so that its thermal mass and surface area mitigate temperature variations. It is orientated on an east-west axis to reduce impact of solar gain and to capture prevailing south-westerly breezes in summer, while its position on a sloping site gives excellent views over the Limply-Stoke valley, near Bath. Rainwater and grey water collection, solar panels, night cooling, external shading systems and recycled concrete are incorporated in the design. Windows can be opened for natural ventilation, with a Building Management System used as a 'minder' to modify human intervention.

For excellence, future architecture will need to be designed and engineered to allow closer control of the environment. This requires an approach which blurs the edges between the historical disciplines of architecture and its related engineering and construction disciplines. Multidisciplinary firms such as Buro Happold and their people, need to be involved in this holistic process if the quality of life in the developed world is to continue while reducing its planetary impact.