The message from the AJ's Tall Storeys? conference last week was clear. Although the collapse of the World Trade Center towers sent out shock waves, the commitment to building tall remains firm.
The next generation of skyscrapers will simply be stronger and safer than ever before.
Towers remain crucial to the Corporation of London's planning strategy as the economic arguments in favour of them hold fast. Clients will continue to demand office space in the city's economic centre, and developers will meet that need.
The design of future towers, however, will need to respond both to the actual and perceived threats arising from 11 September. Arup director Tony Fitzpatrick, speaking at the event last Thursday, compared the 'analysable, logical predictability' of design conditions before 11 September against the 'universe of unpredictability' that now prevails.
In the immediate aftermath of the catastrophe, Arup embarked on an ambitious programme to respond to these new threats. In the new year it will publish a report proposing solutions to the design questions that have been thrown up. It is also developing defences against bioterrorist attacks.
Fitzpatrick has been undertaking impact studies to develop structures capable of withstanding aircraft attack. He has been developing hardened escape routes, better fire protection and improvements to access. And, building on evacuation tests at Canary Wharf, he has been exploring crisis management systems to achieve efficient, total evacuation. Fitzpatrick is confident: 'The world is different now - and we can respond to it.'
But if 11 September has altered design assumptions behind tall buildings, it has not impacted on the political will driving their construction.Archie Galloway, deputy chair for policy and resources at the Corporation of London, said the city was committed to its unitary development plan (UDP). 'The policies of the Corporation of London before 11 September still applied on the 12th and 13th and to this day, ' Galloway said. 'This is not a planning issue but a building regulations issue.' Corporation planner Peter Rees made it clear that it would not be enough for 'satellite' office locations like Canary Wharf to offer tall buildings. It was essential for the future of London that the central area offered what office tenants wanted.
The Corporation will continue to support applications for tall buildings and - as senior partner at Davis Langdon & Everest Paul Morrell argued - developers will continue to lodge them.
An office building, Morrell suggested, is 'a financial equation built in three dimensions'. The financial risks have increased for tower developers since 11 September and tenant anxiety levels have been raised, but the economic justification for towers remains sound.Morrell predicted a shift in balance, with fewer ego-driven tower proposals making it off the drawing board.
How far that balance shifts will depend on costs.
Fitzpatrick estimates the additional work needed to improve the safety of future designs would add no more than six per cent to total construction cost.
And, as the AJ's Paul Finch pointed out, as fast as new technical problems crop up, the steel and concrete industries step in to solve them.
Lee Polisano of KPF, currently embroiled in the Heron Tower inquiry, noted the different code and other standards operating in different areas of the world. He believed the biggest changes might take place in the US, where tall buildings are significantly higher than in London, a situation that is likely to continue.
Director of Canary Wharf Robert John was optimistic. The City is 'steadfast' and insurance is still covered - at a price. If the population of London increases as predicted, in the next 25 years the City will require a 20-25 per cent increase in office space. 'Tall buildings are part of the answer.
[They] are going to continue to grace our skylines, and in increasing numbers.'
That is presumably to the benefit of the insurance industry, which has suffered a massive financial blow following the attacks. Bill Gloyn of insurance giant Aon advised professionals and building owners alike to check their terrorism insurance and reinsurance arrangements, which could vanish with the demise of a company you might never have heard of. The good news was that the sector is facing up to what are new opportunities, as well as problems.