Engineer Jorg Schlaich was evidently bemused when asked, after delivering the seventh Lubetkin lecture at the riba: 'You've given us the big idea for engineering. Now can you tell us the big idea for architecture?' The question ignored the essential modesty of the man, but in other respects seemed reasonable. He had certainly presented a big idea: the generation of solar electricity, in hot climates, via huge expanses of glass with a tall chimney at the centre for the hot air to rush up and drive a turbine. Plastic water tubes would store heat during the day and release it at night, ensuring 24-hour operation.
Having ideas is one thing; executing them another. Schlaich has been working at this for the past 20 years, and a small-scale prototype has been built in Spain. The real thing, he proposes, would be staggeringly huge. A 200mW power station, five of which could replace one conventional nuclear plant, would have a chimney 1500m high. Schlaich has worked out how to build the chimney in concrete as an extended cooling tower, but with a bicycle-spokes type support system inside to prevent distortion and collapse under wind load. Schlaich envisages on-site manufacture of glass and cement (the main components), powered by electricity from the first of several stations.
Schlaich, who as well as being a professor at the University of Stuttgart is founding partner of Schlaich Bergermann and Partners, is better known for bridges and more conventional, although still innovative, buildings. As always, the lecture was sponsored by the British Cement Association and Schlaich lamented the virtual disappearance of the concrete shell building: 'The most innovative and lightest structural form - although not very good for sales of cement.' He regrets the way that Germany has standardised bridge spans at 45m, and the pre-eminence of the box girder. Their only advantage is their low price and use of labour, which makes them an odd solution to choose in times of high unemployment.
Schlaich showed some truly crass examples of bridges designed for German railways, and revealed his consummate political skills when he explained how he set the railways and the planners against each other to get a better, and pricier, bridge built in Berlin. He feels that much education is needed: 'Our bridges are so ugly that you can't convince people that bridge design is culture.' But neither was he asking for a bottomless purse. 'If I had to build a bridge with no financial restriction,' he said, 'I wouldn't know what to do - I'd probably build it in gold.'
Schlaich's mixture of a delight in materials and design coupled with concern about social issues fulfilled perfectly the brief for the Lubetkin lecture - and fulfilling briefs is exactly what the best engineers do.