In The Age Of Decarbonisation, Should You Still Build A New Skyscraper?
They define London’s post-millennium skyline. From the iconic 180m-tall Gherkin to the 310m-tall Shard, skyscrapers have formed part of the bedrock of the British capital’s modern urban economic model and sense of self.
However, with a post-pandemic upheaval in office culture, a greater awareness of environmental factors and a high-profile scheme kicked out by the government late last year, is London’s love affair with the skyscraper set to change?
What cut the Tulip down to size?
Eyebrows were raised in November when the high-profile Tulip scheme was quashed by the UK government.
The 305m-tall tower, which would have been built next to the Gherkin in the heart of the City, had received criticism for everything from its design to its height possibly interfering with aircraft radar.
Despite these criticisms the project had widely been expected to be approved, but was thrown out by government minister Michael Gove in November 2021.
The scheme was rejected in part due to what was deemed an unsustainable design and use of concrete, despite the planning inquiry noting that the design team had “gone to enormous lengths” to ensure the project met high environmental credentials.
The planning tussle over the Tulip tower has highlighted the new reality of how environmental arguments can scupper major new high-rise schemes.
New London Architecture is a research body dedicated to the built environment. “I was surprised at the vehemence" of the argument against the Tulip in terms of sustainability, which came in the run-up to the COP26 climate summit, said Peter Murray, the body’s curator-in-chief.
“He [Gove] said it was unacceptable to have this great concrete stem from a sustainability point of you. Now almost every tall building has a concrete stem in it as its service core."
At the heart of the controversy over the Tulip decision is how much embodied carbon (the carbon that is used during the construction phase of a building) is acceptable for a new tower.
If high-rise buildings come with a higher embodied carbon cost, then their operating carbon (the amount needed to run day-to-day operations such as lighting or heating) needs to be low to compensate. Data from the International Energy Agency has said that no matter how energy efficient the operation of a new building is, it can never compensate for the amount of carbon emitted during construction.
In its decision, the government said that a new building the size of the Tulip should need to be carbon neutral in terms of operational carbon to justify the carbon cost of building it.
"Although considerable efforts have been made to adopt all available sustainability techniques to make the construction and operation of the scheme as sustainable as possible, fulfilling the brief with a tall, reinforced concrete lift shaft, would result in a scheme with very high embodied energy and an unsustainable whole-life cycle," it stated.
“Green issues are going to be an important aspect of planning and how you deliver net-zero with a tall building is still being debated. A lot of that debate depends on how much lifetime costing you take into account when it comes to the carbon costs [of the project], Murray added.
“An argument in favour of developing tall buildings such as PLP’s 22 Bishopsgate is that they will still be there in 100 years time. If you think of New York, only one or two towers have come down in 100 years. People don’t take towers down.”
Despite the pandemic, London hasn’t lost its appetite for tall towers. According to the latest annual tall buildings survey produced by Knight Frank and New London Architecture, Greater London has 587 new towers in the pipeline, up 7.9% from 544 in 2019. Over 100 new towers are planned for central London.
New policy looks to be influenced by the latest London Plan, a document which outlines planning priorities and policies across the city.
According to Knight Frank’s Head Of Planning Stuart Baillie, government intervention has led to mixed messaging. Commenting in the Tall Building’s survey he said: “The under supply in grade-A office stock and the ongoing challenge of needing at least 52,000 new homes per annum will mean continued growth in London’s tall building pipeline in the medium to long-term.
“There are a few instances where the Government’s intervention in the London Plan would seem to have led to a degree of mixed messaging in relation to building height.
“The policy changes should result in a more open and transparent approach to building height but no obvious end to the complexities of promoting 20 storey-plus tall buildings in London.”
Burnishing those ESG credentials
Following the rejection of the Tulip, ESG has become key to justifying their new projects.
Whether it is including adequate social space or limiting carbon emissions, the modern office block has moved on from adding a few bike racks to the basement and the odd electric car charging point.
Dutch developer Edge is constructing a 26-storey tower near London Bridge that aims to be the most sustainable office tower in London. Edge Executive Managing Director Fons van Dorst said that the ESG issue has gone from an occasional aspiration to a core part of many companies' operations, which is changing their office requirements.
“Companies have become rapidly more conscious of their social responsibility and we are moving away from the idea that sustainable buildings are a premium anymore," he said. And ESG is a big part of their corporate agenda.
“If you want to make a statement, your offices are as big a part of your corporate image. And if a company picks the right building, it can really help as a catalyst to strengthen the story around your corporation.”
Architecture practice PLP has designed a number of the City of London’s towers including 22 Bishopsgate the 43-storey One Bishopsgate Plaza. PLP partner Mark Kelly, who designed One Bishopsgate, said that in future many developers will be ensuring new towers are designed with ESG in mind as a way to attract and retain top talent.
“The changes are tenant-led in a way," he said. "Occupiers are realising that in order to obtain the best talent that they need for their businesses, they're having to offer more than just a desk.
“There is a tenant drive to incorporate new technology into their buildings, which does increase construction costs. But if it gets you the tenant and means that your per square foot rent is higher then it is worth doing it."
There is also much more willingness now to realise the benefits of modular construction, not just the programme benefits but the sustainability aspects as well, Kelly said.
Reaching for the sky?
Despite the rush of new towers, London’s skyline is still relatively modest compared to American cities. London’s tallest tower, the 310m-tall Shard at London Bridge squeezes in as a designated 'supertall' tower, however it is 9m shorter than New York’s Chrysler Building, built in 1930.
Supertalls in the region of the 541m One World Trade Centre are unlikely to be considered in the near future. However, according to Kelly, London may import a different trend from the States, the high-rise resi scheme.
“Some of the other possibilities are not associated with the big footprint offices, but could be the taller, slimmer residential buildings that act as a sort of marker on the skyline," he said.
“As a London resident I find that quite exciting and it brings into the debate, what does high-rise really mean? To me it doesn’t seem unreasonable to live relatively close to the City, and is an appropriate response to local housing issues.”
Local housing issues may become an important factor in future development debates. A further issue that will need to be considered is the cost of demolishing what is already on-site.
When it comes to the Tulip, the carbon cost of demolishing the current building, which had only been completed in 2003, had to be included in the embodied carbon costs of the new tower, which ultimately led to its refusal.
J.P. Morgan Chase received criticism when it decided to demolish 270 Park Avenue for its new headquarters.
Last week U.K insurer Aviva announced that it is to vacate its current headquarters at 80 Fenchurch Street in 2023. If the site becomes the location of the City's next big tower scheme it could be a test as to whether the ESG considerations that doomed the Tulip are repeated.
In the Tulip decision the government noted that the educational value of the new tower's visitor centre could be enhanced, and if the provision was better it may have helped overcome the sustainability concerns.
Van Dorst said that to be successful developers of future towers may need to ensure that their new schemes aren’t closed off from the world outside, not only to gain planning consent but also as a way of encouraging high-profile tenants. “Building a sustainable building will not be enough anymore, you need to be inclusive and sensitive to your environment," he said.
“People are invited into the buildings, we are sharing our auditorium with the local school. Towers will no longer be screened off with speed gates when you walk in. People will be able to sit down, have a coffee, and do work. That’s where we think the next move will be.”