Speakers addressed key issues in tower construction, from fire to urban context, in a panel discussion hosted by Architecture Today, MPA The Concrete Centre and Sapphire Balconies
In association with
In association with
Partner, Allies and Morrison
Partner, Allies and Morrison
Principal structural engineer, MPA The Concrete Centre
Design director, AKT II, London
Managing director, Sapphire Balconies
Head of marketing, Sapphire Balconies
Associate director, Skidmore, Owings & Merrill (Europe)
Founder director, ZZA Responsive User Environments
There was a salutary moment at the end of AT’s seminar on tall buildings, held in November. Delegates had heard inspirational and fascinating presentations on the architecture and engineering of tall buildings. They had seen new buildings that addressed their contexts and the needs of their occupants, and heard about the engineering of vertical extensions to existing buildings. They had galloped through the history of tall buildings, and heard about fire, balcony design and sustainability. Everybody was feeling good. And then they had a reality check. This came from Ziona Strelitz, a workplace researcher and design strategist. Things, she said, were not working as well as they should – tall buildings were proving less successful than anticipated.
Allies & Morrison’s 100 Bishopsgate, City of London
In 2004 she edited the BCO/RIBA design guide on tall buildings and was, she said, optimistic about the planned buildings of the time. But three years ago she revisited some of them on behalf of the Urban Design Group. Buildings that had been at the planning stage were, she said, now complete and occupied. And, she said, “many disappointed as realised.”
There were several factors. Buildings that looked transparent as design proposals were far more opaque when built. A lot at design stage “looked like mixed use. I imagined cross-pollination, public participation. It has been more limited. Access that the public has is very privileged.” Sustainability features were watered down, and the microclimate was frequently unacceptable. And in urban terms, she said, there was an unresolved conflict between planning’s desire for buildings that fit in, and marketing’s wish for a ‘stand-out’ building. The result was “a visual expressive smorgasbord that is unresolved.”
Doubtless there are buildings today at the planning stage or under construction that will be equally disappointing, but they are unlikely to be those discussed at the seminar, all of which were the result of a great deal of intelligent thought.
Canada Water Plot A1 tower, London, by Allies & Morrison
Two speakers from Allies and Morrison presented four of their projects. In all of these, partner Paul Eaton said, the practice is interested in: “how tall buildings meet the ground and make spaces; how tall buildings can broadcast character; and, organisation of form.” Joanna Bacon, also a partner with the practice, explained the genesis of the building at 100 Bishopsgate, which is just completing. It was, she said, a building that “did not try to stand out in the crowd”. Instead, the aim was to deliver some of the largest trading floors in the city, while also creating good public realm (in fact it occupies 38 per cent of the total site area). Contextually it had to cope with neighbours that fell away to one side, and also an adjacent church. The result is not one building but a pair, with the taller tower transforming in plan from a parallelogram to a square as it rises up.
Allies & Morrison’s Keybridge House viewed from South Lambeth Road
Ricardo Baptista, design director of engineer AKTII, talked about ways to make cities both taller and more sustainable. One way is to refurbish and even add to existing tall buildings. He gave the example of London’s South Bank Tower. The engineer worked out a way to add 11 storeys to the 31-storey original, without the need for any additional foundations. This was partly thanks to the fact that detailed original drawings were available, and also because sophisticated computational fluid dynamics allow engineers to make more precise allowances for wind loads.
Seifert’s South Bank Tower, London, remodelled and heightened by KPF with structural engineer AKT II
Because the original design included a certain redundancy, the engineer was able to use fin blades to transfer compression loads to the existing columns, obviating the need for any more fundamental structural changes.
Tony Jones, principal structural engineer with The Concrete Centre, showed how rapidly fire regulations are changing in the wake of the Grenfell Tower tragedy. He talked through the changes that have already been made and those that are proposed, and concluded by advising architects that they must make sure when designing that they are absolutely up-to-date with requirements.
Some of these changes affect balconies and this is one of the concerns of specialist balcony company Sapphire. Managing director Tristram Parsons explained that, while this is still open to interpretation, it seems that laminated glass is no longer allowed as a material for balustrades. This is because balconies are not supposed to contain flammable materials and the glue used in lamination is classed as flammable, although Parsons showed an example of a severe fire in which the adhesive was untouched.
At Manhattan Loft Gardens in east London, SOM’s approach is characterised by large sky terraces and exposed sturcture within the apartments
The company has developed an alternative solution, using vertical strips of non-laminated glass. It has also come up with connection details that retain the fire integrity of the external walls and recommends Class A soffits to prevent the spread of fire upwards.
Phil Obayda, associate director of SOM, showed that this level of innovative thinking has existed throughout the evolution of tall buildings. He then showed the practice’s Manhattan Loft Gardens in east London. This building aims to foster a sense of community with a mix of unit sizes and volumes, and large external shared spaces. This different approach is characterised by the large sky terraces and the deliberately exposed structure within apartments.
Manhattan Loft Gardens, London, by SOM
Obayda argued that high-rise buildings are a sustainable solution because they cut down on energy-hungry commuting, and looked at a range of approaches if we are to move towards zero-carbon buildings. This included the development of a composite timber and concrete structural system.
There is evidently a lot of new thinking going on in the field of tall buildings. If this is realised as intended, we may well avoid the disappointment that Ziona Strelitz felt when revisiting the previous crop of structures.