There’s a certain stereotype in real estate and if you want to be seen as the best of the best, you have to build the tallest, shiniest tower of all. For years, decades, perhaps even centuries, there has been a battle for who can build the tallest tower and dominate the skyline.
But those tall towers are ordinarily crafted out of tonnes of steel, concrete and glass. They are shining trophies of ego. And now, often, of unsustainability.
Developers, architects, occupiers and even tourists will never fall completely out of love with tall buildings, but in an era of environmentalism and a clear and immovable goal to reach net-zero carbon by 2050, is there a way for tall buildings and sustainability not to be mutually exclusive?
For Simon Bird, director at LOM Architecture and Design, the answer is a resounding yes. Although there will have to be a bit of a change in mindset along the way and a whole lot of collaboration. And, just a touch of blue-sky thinking.
Bird says that tall buildings actually lend themselves to a lot of the Passivhaus design principles in that they minimise energy use, maximise the use of fabrics and have a pretty efficient overall envelope design. But tall buildings also provide very little opportunity for on-site renewables – a smaller footprint means a smaller roof space so less scope for photovoltaics or other renewable energy production methods.
The biggest challenge with tall buildings and the environment is the embodied carbon within the building materials. Those tonnes of concrete, steel and glass also mean tonnes and tonnes of carbon.
But there is an answer, says Bird. Several in fact, such as thinking increasingly about the use of timber in construction and in taking a leaf out of Lego’s book and designing tall buildings as completely demountable and reusable.
“Both of those things, however,” says Bird, “require a fundamentally different way of thinking about how we deliver the scale of a building.”
Timber frames
The green benefits of using timber for buildings have been talked about in the architectural community for a number of years. Its use, however, has been reasonably limited. Fire safety has put one overwhelming brake on its use in construction, as has its structural inferiority to the favoured steel and glass. Wood warps and softens and gets damp.
All these things have meant that timber-framed buildings have been relatively low-rise. But could that be changing? In 2017, a 53m-high wooden-frame student housing block was completed in Vancouver and, more recently, Lendlease has completed construction of a 45m-tall timber-framed tower. Neither measure up to the 310m Shard in London obviously, but with advances in technology and such a determined focus on ESG, could the new trophy tower of the future be a stumpier, wooden building?
Bird says that at the moment timber structures are confined to eight to 10 storeys because of the nature of the wood. Going higher requires hybrid structures, bringing in amounts of steel and concrete to help deal with the compressive strength and tensioning that is needed in tall buildings.
But he says that the corporate ideal of a shiny, tall building is changing. He believes that corporates today also have a different idea of what makes them look attractive to talent. And he says it is that which could bring about a boom in timber buildings.
“Timber expresses a different kind of statement,” says Bird. “It fundamentally expresses a care in the environment. There is a different focus now from building big corporate glass boxes where it’s a single entity expressing itself to something that’s going to be more broken down. It’s more of a community. We are starting to think about expressing different things in those buildings. I don’t think we are going to replicate what we’ve done before in steel and glass. I think it’s an opportunity to reimagine.”
Be more Lego
A reimagined future for tall buildings could come from a trip back to our childhood days. We need to start thinking about buildings like Meccano or Lego, says Bird, and be able to take them apart and reuse them.
“It may be that a better approach is – if we accept the fact that we have to build with steel and concrete – can we make those buildings completely demountable?” says Bird. “So any carbon that we put in there is stored for later use. It has to be genuinely reusable. And that requires a different way of thinking. We need to think differently about how buildings are put together so they can be easily taken apart and then reused and repurposed in that same form.
“We can either build something very solid that we know can be built flexibly for however many years in the future,” he adds. “Or we allow the space to be demolished and rebuilt and reused without loss of quality as part of that process.”
The ultimate solution, however, to developing truly sustainable tall buildings is to turn entirely to nature, says Bird.
“I think the ideal environmentally friendly building would be something that you grew absolutely every element of,” he says. “In an ideal world, I think we’d be growing buildings. If we’re really taking it to that extreme, we need to be growing the resources that go into buildings because we can’t just continue to take things out of the ground.”
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