Wessex Water, Bath

A client committed to reducing environmental impact, an architect known for low-energy design and a construction manager anxious to test green construction techniques form the team behind one of the most ambitious of the projects. The £22m operations centre for 550 Wessex Water staff, under way on a rare brownfield site on the outskirts of Bath, is designed by Bennetts Associates and construction managed by Mace.

Wessex Water’s long-standing commitment to environmental sustainability set the tone for the project. It had already collaborated with Jonathon Porritt’s Forum for the Future in drawing up a company-wide environmental policy, and used FFF’s expertise to write the briefs for the design and construction team.

Bennetts Associates rose to the challenge of a fully sustainable design, which it sees as a natural extension to its trademark of low-energy, naturally ventilated buildings. Here, the practice also had to consider the transportation and efficient use of materials. The transport issue favoured locally produced steel and concrete, and locally quarried stone. “Sustainability might oblige us to talk of a more regional architecture,” says partner Rab Bennetts.

Meanwhile, Mace set out to match the client’s brief for environmentally responsible construction techniques by setting targets in four principal areas: minimising waste, recycling where possible, considering the environmental sustainability of the materials used and maximising off-site manufacture. The resulting philosophy now permeates the site at every level. Site workers are introduced to the project’s green theme on their first-day inductions, and use grey-water toilets; trade contractors were encouraged to produce sample panels of roofing and cladding to help in the drive against waste.

The Construction Industry Research and Information Association helped Mace measure the waste and set targets, but these were hampered by the lack of accessible data on usual industry practice. “One of the spin-offs is that this project will produce some benchmark data,” says Mace commercial manager Andy Tims. Having little comparative data to draw on was also an issue when the team wanted to measure the environmental impact of various materials. This had been placed high on the agenda alongside capital and life-time costs, quality and buildability.

Major design decisions flowed from this process. For instance, tern-coated steel was chosen for the roof instead of aluminium or zinc, after it was judged better in terms of appearance and life-cycle costs. However, Wessex Water project manager Neil Fisher says environment-friendliness was always assessed along with value for money. Bore-hole cooling and photovoltaic panels were impeccably green ideas that could not be justified on cost grounds.

In other cases, the desire to go green proved paramount. The team chose to crush the rock found on site and use it as structural fill, rather than importing it. In this instance, Mace believes that the loss of space on site and working around heaps of fill meant “there was a fine line between the costs saved and the operational difficulties. It was done for environmental reasons”.

It is likely that the operations centre would have been a green “demonstration” project even before it became part of the Movement for Innovation programme. But Mace and Wessex Water agree that its demonstration status should help it generate benchmark standards for a new generation of buildings.