Offices

WHEN Electronics giant JVC decided to knock down and rebuild its head office and distribution centre in north London, it got a nasty shock: for the past 30 years it had been sitting on two huge lime pits. As the firm had already decided that it didn’t want to move, so it asked architect Kajima Design Europe to undertake one of the largest lime containment operations in Europe. The architect also had to minimise the impact of a major road on the office building – the North Circular runs along the southern edge of the site.

Once the headquarters had been demolished, attention was turned to the problematic lime pits. These were up to 8 m deep, and occupied an area 100 m long and 60 m wide. The pits contained carbide lime, a by-product of an industrial process to make oxygen. The lime, which was in danger of leaking out of the pits, was an environmental hazard, and not an ideal foundation for buildings. “Some of it was quite hard but the rest of it was just sludge,” says engineer Craig Butterworth of Buro Happold, who devised the containment strategy.

JVC’s office has the same cladding as the warehouse to its south but has a glass facade on the north side to maximise the views over the reservoir

The Environment Agency wanted the pits sealed or the lime removed. “Taking it away was not an option,” says Butterworth, but luckily the pit base was sitting on a natural barrier of firm London clay. The solution was to seal the lime in at the sides by digging a trench around the pits and driving 9 m deep plastic sheets into the London clay. The trench was filled with Bentonite, another type of clay that acted as a secondary barrier. Piles were then sunk through the pits to the firm clay to provide a foundation and were capped by a suspended slab that would also act as a base for the buildings above.

Kajima now had to make the best of the location. “The design came totally out of the site constraints – the site is hemmed in between heaven and hell,” says project architect Jason Pomeroy. The solution was to create a buffer zone between the office and the noisy North Circular by putting the distribution centre next to the road.

The north face of the office is clad entirely in glass so staff can enjoy views from their open plan floors over the Welsh Harp reservoir. The south side is clad with the same Planja profiled metal sheet as the distribution centre. “We are under no illusion that the area is dominated by industrial buildings,” says Pomeroy. “We wanted to create a scheme that hangs together as a collective, and pay respect to the surrounding architectural environment.”

The architect organised the building so areas that were less likely to be affected by noise faced the North Circular. This included the lifts and stairs within the cores, and the toilets. A series of meeting rooms were inserted between the cores. Because this side of the building faces south it was important to minimise solar gain. The answer is to illuminate the meeting rooms using a series of slit like, staggered windows with coloured glazing. “It’s an eye catching sight from the road, plus it breaks up the facade,” says Pomeroy. Everybody should be happy with this solution – the office workers can enjoy the view of the reservoir and motorists stuck in traffic jams on the North Circular will have something intriguing to look at too.

Project team

client JVC
architect Kajima Design Europe
engineer Buro Happold
QS Gardiner and Theobald
contractor Kajima Construction Europe
lime pit containment barrier Cofra