ENVIRONMENT FRIENDLY

The Department of the Environment is going green - and quickly. John Gummer's energy efficient new residence is now just weeks away from being complete.

Developed by Land Securities, the new Eland House in the heart of Victoria in London, which will take over from the DoE's fading headquarters at Marsham Street, has just 16 weeks left of its fast track 88 week programme.

The building is notable for its use of environmentally friendly technology but perhaps more remarkable is the way contractor Mowlem is meeting the demanding programme through a co-ordinated use of off-site prefabrication.

Land Securities had been looking for opportunities to develop the site of the 1960s monolith which was the previous Eland House for some time. It already had an outline scheme in place by autumn 1993 for a speculative office building when it managed to secure the DoE as tenants.

At this stage Land Securities had already started negotiations with Mowlem for the contract but suddenly the project took on greater urgency. The programme which had been envisaged was accelerated to meet the DoE's requirements and the energy efficient aspects of the building which Land Securities had already considered took on greater significance.

As a result Dave Rogers, Mowlem's project manager, and his team found themselves on site, the morning after liquid celebrations for receiving planning approval, contemplating a very rapid programme for the œ35 million shell and core building. But while the demolition contractor got going so did the Mowlem team.

To meet the demanding schedule, Rogers realised that construction had to be kept simple, which was dependent on the design, and had to work simultaneously on as many fronts as possible. 'One of the key factors in achieving the fast programme has been going for a very systemised method of construction,' said Rogers. 'But also as the engineers were evolving the design we were working with them to make sure it stayed within the parameters of fast building.' This has very much been the crux of the project - a buildable design geared towards the way Mowlem wanted to achieve the programme through as much prefabrication as possible.

'Everything that we could think of that could be panelised, systemised and built and tested in advance has been done on this job,' said Rogers. This sort of co-ordinated approach depends on good relations though and the open way in which client, professional team and contractor have worked together has obviously been essential.

'We had open lines of communication on the design of everything - the frame, the cladding, the roofing - and it has really worked,' remarked Rogers. 'If you're going to build this building in this timescale everybody's got to have the right approach to doing it. You have to adapt the design to fit in with prefabrication, but clearly quality is the most important. We have to start with that premise and then work out how we are going to make the concept fit that.'

Mowlem generally and Rogers in particular has definitely taken a liking to this way of building. This isn't the first time that the company has done it this way but the technique has been very much refined on this project. It isn't simply about prefabrication alone though but also about the detailed planning which has been done well in advance to make it work.

'There are a hell of a lot of meetings - often about things happening off site - but all with the objective of making it simple when it gets here,' said Rogers. 'Here it's just as important what happens off site as what happens on site. There are days when I'm the only one in the office because they [the Mowlem team] are all abroad project managing their own little bit.'

The fact that they are abroad sourcing and checking materials for what is going to be a government building is perhaps a little ironic and unfortunate.

But while Mowlem was putting piles in the ground the team were thinking about services, temporary works for the roof construction ironmongery for the toilets etc. In fact, currently being installed into the structure are the many prefabricated toilet modules which Mowlem has had manufactured in Scotland. Complete and self contained, the modules are lifted into place requiring just a link up to the soil stack and services.

Equally significant in terms of prefabrication, and quite innovative in terms of energy efficiency, are the prefabricated cladding panels manufactured in Germany. They consist of glazing and insulated panels with one window which has a sliding, motor operated solar shade (a section of opaque glass) built-in which is automatically activated when built-in sensors detect higher internal temperatures. The sensors are linked into an overall building management system which monitors temperature throughout the building, the wind speed and the external temperature and controls the shades as appropriate.

These cladding panels are being installed on the south, west and east elevations in order to reduce the amount of solar gain in summer and to maximise it in winter to maintain the correct internal temperature. Although the technology isn't particularly new it is believed to be the first time that it has been used in this way.

These panels are just one element of the energy efficient and environmentally friendly aspects of the building, which reduce energy demand and which are giving the building a good score under BRE's environmental audit scheme 'BREEAM'. Others include chilled ceilings, a solar wall on the front elevation of the building which absorbs heat and an independent generation plant. This is effectively a gas fired engine which drives an alternator to provide power at times of peak demand and which passes waste heat into the system when it operates. This reduces peak demand supply from LEB and sets the electricity loads within an accurately predictable band.

In terms of engineering though, the most complex part of the construction has been the foundations. With a Victorian sewer and a London Underground tunnel running through the site this stage was far from straightforward and involved piling around the obstructions in such a way as to enable the structure to be built to a regular grid above. 'Bearing in mind the difficulties in the ground and the complexities of the foundations to get out of there on programme was no mean feat,' remarked Peter Frackiewicz of Land Securities.

Although the project started with this demanding engineering, the key to its continued good progress has been the way prefabrication has been embraced. 'It is certainly the fastest job of its size that I have done,' said Rogers.