London landmark building will generate 8% of its energy needs

Rooftop turbines on the 'Razor' are first in world to be built into fabric of apartment block
Adam Vaughan
guardian.co.uk, Sunday 14 March 2010 08.00 GMT
Peering down 148 metres from the top of the latest addition to London's skyline, the traffic-clogged Elephant and Castle roundabout and its notorious neighbour, the Heygate estate, below feel an unlikely location for a world first. But next week, this new skyscraper, nicknamed "the Razor", will take a crucial step towards becoming the world's first building with wind turbines built into its fabric.
While wind speeds in the concrete jungle at the tower's base would render a wind turbine pointless, at 42 storeys up they are capable of 35mph gusts – a serious challenge for the workers who created the complex steel structure – and are projected to generate 8% of the building's electricity needs.
The building – officially called the Strata tower – is a £113m milestone in the £1.5bn project to regenerate the Elephant and Castle area. The Strata development, which comprises the tower and a smaller "Pavillion" building, is a statement of the new demographic Southwark council hopes the area will attract – its 408 apartments range from £230,000 to £2.5m.
But the tower also marks an innovation for the building sector, which under government regulations will have to make all new buildings zero-carbon by 2019.
Justin Black, director for Brookfield, the developer, said the decision to choose wind was a "conscious decision to experiment". He pointed out that the entire southern facade of the building would have had to be covered in solar photovoltaics to generate the same amount of energy. "The brief we gave to Hamilton's Architects was we wanted a statement, we wanted to create benchmarks for sustainability and urban living. We wanted something bold, we wanted remarkable. It's what I term Marmite architecture – you either love it or you hate it, there's no in between," Black said.
Next week the blades for the 9m-diameter turbines arrive on site and will be winched on to the roof for installation in early April, before the building is opened by London major Boris Johnson – circumstances permitting – on 1 July. The 19kW turbines, which were made bespoke for the project, will have five blades rather than the usual three to reduce noise. Vibrations to the rest of the building should be eliminated by a five-tonne base fitted with four anti-vibration dampeners.
Unlike a conventional turbine standing in a field, the three in the Strata tower are expected to use the Venturi effect — think of wind being forced between two large buildings — to suck wind in from many angles and accelerate it through the tubes. As well as generating a predicted 50MWh annually, the turbines will also generate money – an estimated £16,000-£17,000 annually – through the government's new and controversial feed-in-tariff, which starts on 1 April.
Other attempts have been made to minimise the tower's environmental footprint, which is 6% above the energy efficiency required under building regulations. For example it uses a natural ventilation system and there is no air-conditioning. A wholly glazed building was ruled out to increase insulation and reduce noise.
Paul King, chief executive of UK Green Building Council, hailed the building as pioneering but warned that wind power was unlikely to become widespread in skyscrapers: "You've got to take your hat off to the design team for delivering a building that clearly captures the imagination. I doubt whether wind power will become a common feature in high-rise inner-city projects – but without this type of bold innovation, how would we ever know? Let's see how it works and learn from the real performance data that is gathered."
Strata is not alone among efforts to build wind-powered "cities in the sky". The Bahrain World Trade Centre already has wind turbines slung between its two towers, China has plans for high-rise buildings with turbines built into their fabric, and the Lighthouse tower in Paris' La Defense district should be topped by turbines when it's completed in 2015. Not all such wind towers have met with success though: Dubai's Anara Tower was cancelled, while New York's Freedom Tower, which was to replace the World Trade Centre, lost its proposed turbines in a redesign.