Arts: Working In The Woods

Buildings For The 21st Century: Procurement Executive Hq, Ministry Of Defence, Abbey Wood, Bristol: The sixth IoS Green Building Award has gone to a sylvan office complex. By David Nicholson-Lord reports there is to say here alright

From A Distance, the Abbey Wood complex of offices outside Bristol looks like a mix of Le Corbusier and Amazing Stories. This is partly because of its size - it covers 98 acres and can accommodate up to 6,500 people - and partly because of its glitter and brilliance: white facades of Portland stone contrast strikingly with neighbouring suburban red brick. Add the campus-style setting and modular layout - aerial views of the buildings hint at reproduction by binary fission - and it begins to sound oppressively hi-tech. But in fact, it's quite the opposite.

Abbey Wood, a collection of 17 office buildings which since 1995 has housed the new headquarters of the Ministry of Defence's Procurement Executive (PE), was named this month as Green Building of the Year in the award co-sponsored by the Independent on Sunday and the Heating and Ventilating Contractors' Association. The project, which cost pounds 254 million and brought together around 5,000 staff from 14 different locations, was the largest single government-office relocation and it has paid off handsomely - staff and buildings now cost pounds 105m a year less to run. Much of those savings result from green design principles. And many of these are remarkably simple.

Take trees, for example. The interplay between buildings and landscape is one of Abbey Wood's most impressive features. The PE took scrubland scarred by mining and tipping, reclaimed a slagheap for roads and car parks, rescued an ancient wood, rerouted a stream and transplanted 150 metres of native hedgerow alongside it. The hedgerow forms one of the "wildlife corridors" that weave between the offices. For much of the perimeter, a newly created lake provides security, and also holds the rainwater run-off from the site, taking it down past pebble beaches, weirs and fountains to form the biggest area of water between the Severn Estuary and the Wildfowl and Wetlands Trust at Slimbridge. It has already been colonised by dragonflies, stickleback, tench and nesting swans.

Altogether 7,000 trees and 28,000 shrubs have been planted, creating a diverse landscape in which woodland glades and wildflower meadows are interspersed with small "outdoor rooms" for sitting and sunbathing and avenues planted with daffodils and birches. One senior PE executive has likened the effect to "the outdoors becoming part of the workplace".

And the landscape also saves money - indirectly, by cooling buildings, protecting them from the sun and the wind, and directly, on maintenance. "Trees," says Alan Walker, direction of the relocation project, "made good business sense". More trees and less mowing of lawns means savings of pounds 17,000 a year - nearly pounds 1m over the buildings' 50-year lifespan. Careful costing of design proposals - the approach known as "value engineering" - produced other green solutions. There is no air-conditioning, for example - staff did not want it, fearing stuffiness and sick-building syndrome, and energy efficiency told against it. This saved pounds 5m in building costs alone. Tall atria indoors produce lots of natural light, and so naturally lit are the atria that evergreen trees planted there are actually growing unlike most indoor landscapes, where trees have to be replaced every 10 years.

Perhaps the key element, however, is "passive design", a concept which will be familiar to anyone who has seen a pueblo, an igloo or a crofters' cottage. Abbey Wood began, in concept, as a series of "doughnuts" - buildings grouped around a central courtyard. Studies showed that this, however, would sterilise the space in the middle, cutting staff off from the outside world. Hence the courtyards were opened up, developing their distinctive splayed shape - the doughnuts became "croissants". At the same time, a framework of "warm" and "cool" facades was evolved. Buildings facing south and west are of thick stone and concrete with smaller windows, cutting out glare and minimising temperature swings. North-facing facades have larger windows and lighter curtain walls.

At Abbey Wood, "passive design" has helped to reduce energy consumption by 80 per cent; energy efficiency is six times greater than the standard office building - a saving of over pounds 30m over its life-span. The value- engineering approach saved, in, total , an estimated pounds 27m on the project costs. Using the lake as a security measure, for example, saved pounds 300,000. Hence the aphorism that became a motto for the architects, the Percy Thomas Partnership: "good design need not cost more than bad".

"Good design" also meant traditional finishes - wool for carpets, stone, granite and slate for floors, timber for furnishings, plasterboard and white emulsion paint for walls. Life-cycle costings over 50 years showed that these were cheaper. They also helped to produce an "asthma-friendly" building. With the help of a hit-list of nearly 100 unwanted chemicals and gases, products were scrutinised for substances that might cause building-induced sickness. "Most brand-new buildings have an overpowering smell when you first move in," says Nigel Cooper, of the Bristol-based consulting engineers Hoare, Lee. "Here, there simply wasn't one."

Other low-tech design elements include fresh air and openable windows. Mr Cooper waxes lyrical about the displacement ventilation system used at Abbey Wood - talking, for example, of lakes of cool air lapping round feet, encasing staff in "thermal envelopes" - but it can cope with people who want to open their windows in summer, either because they (wrongly) think it's cooler outside or as a gesture of individual liberty, denied to staff in many modern offices. But in the cafes and eating areas housed by the glazed atria, it's accepted that temperatures will vary more.

In the offices, however, temperatures are maintained in the 20-24 degrees Celsius range after careful analysis of the links between heating and staff productivity. And unlike air-conditioning, which tends to push air into a room at ceiling level so that the people below are still breathing stale air, filtered air at ground level supplies a gentle flow from air to ceiling. The fact that the executive is managing the same number of products with 35 per cent fewer staff is one indication, the designers believe, that they have got the temperature and ventilation mix about right.

Abbey Wood also works hard at being an environmentally responsible neighbour. It was built low-rise - only four storeys high - to avoid dominating the landscape. It streams and recycles its waste. And although it's on the outskirts of Bristol and has parking for 3,500 cars, the PE has put a strong emphasis on walking, bicycling and public transport. Cycleways cut along the site, linking up with networks built by the environmental charity Sustrans. New bus and train services have been developed - the PE paid 39 per cent of the costs of a new railway station at Abbey Wood and was a founder member of the local traffic forum. As a result, fewer than half those working on the site use their car to get to work.

Sixteen of the 17 buildings received the top rating of "excellent" in BREEAM, the environmental assessment method developed by the Building Research Establishment. Another way of judging its success is the response of staff. Before they moved in, surveys indicated high levels of anxiety about the prospect of open-plan working and sick-building syndrome. Now, apparently, they're back to worrying about pay.

The Green Building of the Year Award is supported by the Royal Institute of British Architects, the Department of Environment, Transport and the Regions, the Building Services Research and Information Association, the Chartered Institution of Building Services Engineers and the Building Research Establishment. For information on next year's award, contact Caroline Horne, Heating and Ventilating Contractors' Association, Esca House, 34 Palace Court, London W2 4JG.

IoS GREEN BUILDING OF THE YEAR

HIGHLY COMMENDED

Centre for Understanding the Environment, Horniman Museum, London. As described in this slot a couple of months ago, CUE was designed as a living exhibit of sustainable architecture. Built of timber and with a turf-and-wildflower roof, it is naturally ventilated and has a clerestory which lets in abundant light. In warm weather it "sweats" to cool itself: a solar pump brings up water from the adjoining pond to irrigate the roof garden, after which the water drips back into the ponds. It "sits lightly" on the ground, and was designed so that it can be easily moved.

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Groundwork Eco Centre, Hebburn, Tyne & Wear. A modern two-storey office block, with a 60-metre borehole which provides natural ground-water heating, and cooling, green trelliswork or "biotecture" on facades, and water systems which recycle rainwater and "grey" water from sinks and basins. The roof is made of recycled drink cans, and this is probably the only office block in Britain with compost toilets.

Rank Xerox UK HQ, Bridge House, Uxbridge, Middlesex. An impressive attempt to bring an outdated office block up to current standards. With the addition of new facades and open-plan interiors, all staff have a window view - and the need for artificial light has been reduced by nearly two-thirds. Waste recycling policies have been introduced and running costs are down by an estimated 50 per cent.