There are currently 170 finished and occupied apartments on the site next to the Millennium Dome in south-east London, and another 230 are under construction. They form the first stage of a long haul for joint developers Taylor Woodrow and Countryside Properties, who started work on the site in late 1999. By 2005, there will be 1079 flats and 298 houses mixed in with commercial development. But right now, it is crunch time for Hodkinson, because the first set of figures has just been published.
The developers set the benchmarks to reflect John Prescott's vision for the project. The deputy prime minster wanted to fly the flag for the UK as a world leader in sustainable urban development and trailblazing construction techniques. As the government effectively owned the Greenwich Peninsula site through its regeneration agency, English Partnerships, the developers produced benchmarks that reflected the political agenda at the time. They included construction methods that rested heavily on prefabrication, as called for by Sir John Egan, and greater energy efficiency to help meet the Kyoto summit's call for a reduction in the world's carbon dioxide emissions.
Seven construction benchmarks were used on the project. Three cover environmental issues, looking at reducing embodied energy, water and energy consumption. The other four cover time, cost, waste and defects. As the benchmarks were introduced before the government brought in key performance indicators, or KPIs, there are no figures for comparison with industry standards.
Early criticism stemmed from the fact that the village's developers had stepped back from a commitment to hitting the headline targets they had set themselves at the time of the bid. Instead, they have to gradually improve their performance to meet standards that become more stringent as the project progresses, with four milestones en route to completion.
The construction targets
Site operatives are busily at work on the new apartments that adjoin the finished and occupied buildings put up in the first development phase. Here, a partially prefabricated metal-framed cladding system is being installed over the insitu concrete structure, which is a nod in the direction of prefabrication when compared with the site-assembled stick system used on the finished block.
Prefabrication is being employed because it can improve construction performance – although it has proved to be expensive. Initially, the use of modular volumetric units was considered for the construction of whole buildings, which it was estimated would reduce construction time by up to a half, but were found to be too costly and unsuited to buildings where indiviudal apartments vary in layout.
However, prefabricated bathroom pods were found to be more cost effective, and have been used throughout phase one to improve the quality of the finished product.
Finding solutions that improve construction performance without adding to cost is a big challenge – particularly as one of the bars the team has to limbo under is construction cost. Establishing partnerships with suppliers is seen as one way to resolve this dilemma.
The bathroom pods are a case in point. Hodkinson says: "We are in discussion with pod manufacturers and it does seem costs can be reduced. We are now looking European-wide to expand our supplier base and it's beginning to pay off." It is proving cheaper to import the units from the Continent because some European suppliers specialise in making bathroom pods, whereas UK suppliers produce them as part of their general activities.
One reason why the move towards prefabricated cladding may pay off is that getting the building watertight early is vital to speeding up construction time. "We will get the bulk of the 25% improvement [in construction time] from building the exterior envelope quicker, and then getting the internal services resolved quickly," says Hodkinson. Currently, it takes 30 weeks to get the building watertight; Hodkinson reckons that this could be cut to 15 weeks using a metal stick system to build loadbearing internal and external walls, although it will cost 10% more. Getting the building finished and on the market quicker could offset this with a quicker revenue stream.
Hodkinson is particularly upbeat about the partnership formed with cladding supplier Telling, which will supply a panellised cladding solution to replace the current stick-built system. Hodkinson says that if this is combined with the metal stick system for the structure, build time can be further reduced from 15 weeks to 10. Invisible components, for example the cladding backing panels can be standardised across the whole project to save money.
Prefabrication is not the solution to all the construction issues. For example, quality can be improved using prefabrication, as is the case with the bathroom pods, but good site practice is necessary to prevent them being damaged, and to deliver zero defects and to reduce site waste. The team has introduced a system of staged inspections to improve quality and spot defects quickly. These start at the briefing stage and continue until after the unit is occupied. The inspections are carried out at critical stages regardless of whether a subcontractor has finished that phase of work, for example, after first fix to ensure the services are going in properly. "It's quite a challenge, bringing about phased inspections, as it's a new way of working for housing developers," Hodkinson says.
The environmental targets
A combined heat and power system chugs away providing hot water and electricity to the occupied flats. This is contributing a whopping two-thirds towards the target of reducing primary energy by 65%, as waste heat is used for heating hot water and there are minimal electricity distribution losses.
Power and heat will be provided from five or six energy centres. Each incorporates a CHP engine sized to produce the base load hot water requirement for the flats, and will also produce 50% of the electricity needs of the development. The energy centre also incorporates back-up gas boilers to provide winter heat centrally to the apartments and a huge insulated hot water tank to store heat generated by the CHP engine. Each energy centre varies in capacity from 100 to 450 apartments.
Making effective use of "free" solar energy is part of the strategy to meet the primary energy targets and covers several innovation topics. Taking advantage of passive solar gain is one example, glazing is maximised on the south-facing elevations with balconies above the windows providing solar shading in the summer. Renewables are being explored, although not very seriously. Photovoltaics are being installed on one building and a wind turbine will also be tried, which will provide a mere 3 kW of electricity. Clearly Hodkinson does not see this as cost effective, citing a payback period of 120 years for the photovoltaics and 45 for the wind turbine; he says they are being installed for demonstration purposes.
The energy target will be met by more prosaic strategies, such as better heating zone controls and educating the occupiers not to waste energy.
One headline innovation topic that has bitten the dust is the greywater recycling plant.
A site was identified for the plant and detailed negotiations took place with Thames Water. Hodkinson says the decision to pull the plug was made because of capital and life-cycle costs, and for technical and marketing reasons. He admits the target for water consumption may not be achieved: "Our view is that greywater recycling is not viable – we have taken it as far as we can within the constraints of viability." He points out things could change over the lifetime of the project, however, and greywater recycling might become viable further down the line.
Hodkinson says the project team will hit all the other targets; indeed, the figures show that good progress has been made on several fronts. The tall order, though, is incorporating all these improvements and, at the same time, reducing construction costs by 30%. The current savings stand at only 5%, which is within prescribed targets for the first phase, but leaves a big challenge to meet later on in the project.
Some accounting tweaks, called "adjustments", have been incorporated to make this easier. Exceptional innovations have been taken out of the benchmark so that the costs of, say, the renewable energy devices are excluded. Even so, it is not going to be easy. Hodkinson is placing his confidence in future progress, saying: "If we can build quicker with less waste and a right-first-time mentality then, all things being equal, we should be able to reduce costs." He pauses and adds: "All I can say is we are feeling the pain."