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Heathrow Terminal 5

BAA's biggest project, Heathrow Terminal 5, has been a test ground for an environmental approach that is finding its way into design and construction schemes across the board.

The scheme's decade-long gestation has given the design team time to think through the performance of the 230,000m 2main building and its two 90.000m 2satellites. The project has still to be approved.

Work by expert groups on water and energy use was jointly shortlisted for BAA's environment award. Judges were impressed by the extent to which they had pushed beyond BAA's already tight performance parameters.

'Pressure to produce detail design is off and a proper strategic view can be taken, ' comments BA/BAA design team member Colin Bisp.

The energy team, part of a 350strong corps of designers, is aiming to reduce carbon dioxide emissions by 25% measured against BAA's most energy efficient terminal, Stansted.

The T5 water team is targeting an astonishing 70% reduction in consumption of potable water.

Strategies are drawn up by expert groups consisting of engineers, architects, service managers, users, property experts and utilities companies. The groups also examine and vet design.

The energy team began by breaking down the performance of its existing terminals. 'Our first problem has been benchmarking individual components, ' says Bisp. 'Data from our terminals was too general, simply by square metre, and fairly limited.'

Bisp says that to analyse the different areas of the building, 'we went to Department for the Environment Transport & the Regions best practice guidelines for offices and public buildings and modified them'.

Methods for energy reduction start with 'simply turning things off', he says. Using daylight and reducing high levels of lighting in retail areas is being examined.

The energy team is also looking to reduce the cooling load imposed by lighting. Each information display screen is served by an independent light source.

Huge energy savings can be made by transmitting light from a central source using fibre optics.

Bisp says basic baggage handling systems may be preferred to high-tech alternatives as they require less power.

BAA is looking at energy supply, assessing the feasibility of its own renewable generating infrastructure. The energy group concludes that currently only wind energy makes economic sense, rejecting solar thermal generation, borehole water for cooling, power from waste in on-site incinerators and for the time being photovoltaics.

Combined heat and power has, however, been judged to make good commercial and environmental sense, and is to be adopted across BAA's sites.

Working with power supplier TXU, BAA has applied for permission to build a 60MW CHP plant serving the central Heathrow terminals. A second 60MW unit will be added if T5 goes ahead.

So far, an overall CO 2reduction of 22% is in sight; 11% achieved by efficient energy use, 7% from CHP and 4% by using renewable supply.

The water supply issue has seen imaginative thinking. The supply must be safe, reliable and flexible for at least 50 years. It will need to meet a multitude of demands, including fire-fighting.

A conventional design drawn up for the T5 inquiry proposed a large storage tank fed by a main on the terminal's northern side.

Supply would have been repumped to strategic systems and for local distribution.

However, this would have created foul water discharges 30% higher than agreed with Thames Water. The water team has set out to reduce consumption of potable water to only 30% of total water use, by recycling and drawing on alternative sources.

The storage tank has been replaced with a twin mains input after investigation located a second main south of the airport. A third connection is to be made from Terminal 3. Three interlinked supply systems give two fall-back options.

To cut demand for potable water, boreholes on site will provide a major input to the T5's 3,900m 3/day system.

'We are sitting on a rising aquifer and believe we'll be doing something useful if we abstract from it, ' says Bisp.

Borehole water will be used in T5's cooling system. Up to 50% evaporation is expected in the cooling towers. The remainder will have increased salt content, and will be used for toilet flushing. Rainwater will be collected for landscape irrigation.

Project team

Terminal 5 Water expert group: Binnie Black & Veatch Vector Management WSP TPS Consult BAA British Airways DSSR Terminal 5 Energy expert group: Vector Managment WSP DSSR BAA TXU Europe Richard Rogers Partnership British Airways

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