These buildings are rubbish

The pile of recycled radiators is the first clue that things are a little different on this site.

The radiators will be used to heat the new low-energy conference centre and entrance buildings currently under construction at the Earth Centre, where Jackson is project manager for contractor Taylor Woodrow.

Jackson stands outside his site hut, boots sunk in the mud, shoulders hunched against the bitter wind that whips off the Pennines, contemplating his hard-fought acquisitions. Then he's off. Marching across the site, keen to show the work his team are doing at the centre and to explain how the contractor has adapted to working on a millennium project billed to "inspire understanding of sustainable development".

Striding out of the hut compound, Jackson warms to his task. "You see this," he says, shouting to make himself heard against the wind, sweeping his arm in a broad circle to highlight an expanse of newly landscaped ground. "This was originally an old slag heap, from the days when this site was a colliery."

He explains how, earlier last year, the area was landscaped to sculpt an amphitheatre for outdoor performances in the summer. "To get the grass to grow on the colliery waste, we had to mix treated sewage into the top 700 mm to get some organic matter into the ground. By spring, this will all be covered in vegetation."

Then he's on the move again, pacing purposefully along a muddy, rutted path towards the new entrance building. "See that lake," he says, without breaking pace. "We built that to hold the rainwater run-off from the landscaping around the amphitheatre. It stops the rainwater from flowing straight into the river, to reduce the risk of flooding."

As project manager for Taywood, Jackson is responsible for the design-and-build contract of the second phase of works at the Earth Centre.

In its nine months on site, the contractor has completed the landscaping of the amphitheatre and construction of a new electricity substation. The firm is also responsible for the construction of the ill-fated entrance canopy, where a delivery of steel of a different grade to that specified has temporarily halted work. Their endeavours are now directed at completing the stunning new entrance building and conference centre, both designed by Bill Dunster Architects, ready for an Easter opening.

Now almost complete, the entrance building stands on a series of wooden legs, high on the riverbank overlooking the Don, its gently curving wooden roof echoing the surface of the river below. The building has been constructed from a host of recycled materials, most of which have been sourced locally. Jackson stops outside the door to introduce section manager Matt Armitage, the man whose task it was to source the materials. "Matt found the wooden pylons that support the building in a local lorry park," says Jackson.

Like Jackson, Armitage talks knowledgeably and enthusiastically about sustainability and sourcing materials with low embodied energy. He is clearly pleased with his contribution to the project and, in particular, his pylon discovery. "They were a bit of a bargain," he says. "The architect had specified turned Douglas fir for the columns – it would have set us back about £20 000 to buy them new. We paid just £15 a pole for these," he says, proudly. "And one of them had 'GPO 1909' written on it!"

However, having acquired the poles, the next task was to finish them to an acceptable standard for use in the building. Nobody was prepared to risk their lathes on recycled timber. "In the end, we had to build our own lathe," explains Armitage. "It was a real Bodgit & Scarper operation – but it worked."

The building is constructed mainly from timber. The wooden legs support a glulam frame that had to be sourced from France. "It was the only place we could find a manufacturer that could produce the glulam with the tight curves needed for the roof," explains Jackson. The manufacturer's concern over quality meant that only new wood was used to form the beams. However, most of the building's remaining timber was either recycled or came from Forestry Stewardship Council-certified sources.

To ensure a sufficient supply of timber, Jackson and his team have built up a local network of contacts and suppliers. "We know all the local scrap merchants and yards," says Armitage.

"And they know other suppliers, who have friends who know someone else." The contractor was fortunate, too, in that an ex-miner had set up a salvage yard nearby specialising in reclaimed timber. Other hard-to-find materials were obtained over the internet, through recycling organisations such as www.salvo.co.uk, where a finder's fee is charged for locating each item.

Even with this extensive network of local suppliers, it was still proving difficult to furnish the contractor's needs. "We got to the stage where Matt was finding out which local buildings were due to be knocked down, and then talking to the preferred demolition contractors while they were still looking at the site," says Jackson. "At one point, things got so bad that Matt had to set off with £100 of petty cash in his pocket to reserve some radiators that were desperately needed for the entrance building," he says, grinning.

Having committed the team to the use of recycled materials, Jackson's next problem was finding a subcontractor prepared to work with them. "At first, we couldn't find any subbies willing to work with recycled timber," he says.

The carpenters were concerned about varying levels of moisture in the timber and expensive tools getting ruined on old nails. The problem was only overcome by Taywood taking on the risk of sourcing materials and underwriting any problems the subcontractors might have.

To its credit, Taywood has also pioneered the use of new forms of recycled materials. Powdered ground granulated blast furnace slag (GGBS) – usually a waste product dumped and buried as landfill – was used to replace up to 70% of the cement in the building's concrete ground beams. "Cement has a tremendous amount of embodied energy," explains Jackson, "so replacing it with a waste product is better for the environment."

Alistair Hunter, Taylor Woodrow's design co-ordinator and engineer-in-charge, is more specific: "Normal reinforced concrete has 325 kg/m3 of cement; concrete made using GGBS has only 100 kg/m3." The main drawback with this cement is its slow curing time, which could extend the construction programme. "It takes 56 days to reach its design strength, as opposed to 28 days for normal concrete, so it would be difficult to use for multistorey constructions," explains Hunter.

Initial attempts to use the new material were not without their problems. The team reduced the water content to increase the strength of the concrete, and then added plasticiser to make it more workable. Unfortunately, too much plasticiser was used, which made the mix difficult to work with.

"It was a bit embarrassing," says Jackson.

With rain clouds starting to loom on the horizon, Jackson is keen to finish his tour. Next stop is a small electricity substation that looks like a terrace of three domestic garages. "It's a bog-standard substation constructed from normal blockwork that can be demolished and crushed at the end of its life. We've used recycled joists to support the roof and topped the roof with sedum [a kind of succulent] to slow rainwater run-off," says Jackson, adding that the building was constructed at no extra cost. "The client thinks this is his most sustainable building."

The tour takes in the site's recycling compound. Here, waste wood, stone, hardcore, metal, plastics and insulation all have their own bins. "All the materials are separated on site before they're sent to a recycling centre down the road – which reduced costs slightly – with the exception of plastic for which there are no recycling facilities," explains Jackson. "It's taken a bit of cajoling to get some of the subbies to separate their waste materials, but they have eventually taken it on board."

Stopping on the hillside overlooking the conference centre, Jackson points to a team hard at work placing lumps of concrete by hand into gabion cages that line the building's circular walls. "The crushed concrete is from an old colliery four miles down the road. And the guys putting the concrete in the cages are all local lads – so we're contributing to both social and economic sustainability, too," says Jackson, sounding more like a local politician than a project manager. The finished effect gives the conference centre the appearance of being constructed from a series of interlocking dry-stone walls.

The conference centre will be the centrepiece of the site. It features a large, circular main auditorium surrounded by three smaller, satellite meeting rooms. Once again, Jackson is keen to demonstrate his knowledge of the building's environmental strategy: "The massive walls act as a heat store, helping the building stay cool in summer and warm in winter."

As with the the entrance building, recycled materials are a major feature of the conference centre's construction. The steelwork I-beams for the roof came from a demolition site, and the steps leading into the centre will be made from recycled railway sleepers. These will be easy to source – "They're big on railway yards around here," says Jackson. The roof covering was another area where Taywood's salvage scavengers were involved. "We've looked at using the sides of lorries, even at old motorway signs, but we found that a lot of these materials are already recycled," says Jackson. In the end, a sedum roof was selected.

Jackson's knowledge and enthusiasm for sustainable construction is impressive, but it is tempered with a note of realism. "We have had to balance the environmental benefits with costs and a tight construction timetable," he says, splashing through the mud on the way back to his site hut. "The client gave us a sustainability brief. We've used it in certain key tenders, but not others, because you have to bring people with you rather than dictate to them."

One of the biggest problems for anybody using recycled materials is guaranteeing the work. "It is an issue with recycled materials – particularly on a design-and-build scheme with a guaranteed maximum price," says Jackson.

Back in his site hut, the recycling theme is continued. "This project has illustrated to us that recycled materials are viable for some applications," says Jackson. Taywood Homes, for example, is now looking at the possibility of using it for some applications. "If there is one thing we've learned on this project, it is a sense that these things can be made to work," he says.