The Ultimate Flexible Building

Think of a building: how’s it doing in the pandemic? Has it adapted well to a change in circumstances? Can you see it remaining useful and relevant for the foreseeable future?

Whether the property in question is your home, work, where you shop or meet friends, it is a cast-iron certainty that it was not designed to cope with the changes brought about by Covid-19. Significantly though, some are doing much better than others. Small flats in otherwise empty cities have not converted well into home-working environments. Lonely and cramped, their residents yearn for the conviviality of the office. In contrast, the occupants of out-of-town homes, previously slaves to their commute, have been freed to enjoy spaces they previously only slept in. Meanwhile, millions of square feet of office space has become instantly, perhaps permanently, redundant. Large retail establishments were already struggling to cope with the drift to online shopping, and the pandemic has only accelerated the trend.

If it was not clear pre-Covid, it is now painfully obvious that huge swaths of property are going to have to be converted to facilitate a change of use. In parallel has come the realization that the design of new buildings can no longer be predicated on the idea that they will retain their original function forever. And as the construction sector looks to a net-zero carbon future, there is growing discomfort with the relatively short design life of much modern development, and calls for adaptive reuse to be considered more often, or even to become the default. 

So what can we learn from the way our society and our buildings have adapted, or not? What makes them flexible, adaptable or transformable? Is it luck? Or is there some kind of magic formula — an essence of adaptability — that must now, like a vaccine, be injected into our designs?

Flexing for an uncertain future 

The quest for flexibility quickly goes beyond technical questions to more philosophical ones: what does flexibility even mean in the context of a building? We need to differentiate between short-term spatial adjustments and the future adaptability of structures to serve different functions. One challenge is that it works over different time scales, points out Jim Coleman, head of economics at WSP in the UK. “Building occupiers need flexibility now, to cope with redistributed work patterns and to enable them to continue to perform tasks that are now happening in a different way in different spaces. But also they need it longer term. The pandemic has made them wary of future shocks, which could be political, another virus, driven by climate change, or the shock we haven’t foreseen.” 

Among owners too, there is a heightened awareness that what we require of our buildings in the future will be unknowably different. “I think people realize there is very little certainty any more and that you’re not going to be able to let or sell a property and say ‘that’s it’,” says Alex Lifschutz, director of London-based architect Lifschutz Davidson Sandilands (LDS), proponent of a “loose-fit” approach. “If you’re going to rent it, you’re going to have to constantly adjust your offer to be sensitive to what people want.”

The practice’s Hoxton Southwark is a good example: a speculative City office scheme that metamorphosed into a hybrid hotel and coworking space during planning. LDS’s adaptable design, with largely column-free slabs and a number of “soft spots” that allow floors to be opened up and stairs inserted, proved amenable to both — very different — functions. “If you work on the basis that the inside can change in the future, then it can change tomorrow. You can react to changes in policy, and it gives the developer a big advantage, because in between getting consent for bigger schemes and building them, the cycle has already changed.”

Danish architect Schmidt Hammer Lassen (SHL) has also noticed clients requesting more longer-term flexibility — for example, office space that could become residential, or car parking that can be converted into retail. Partner Kristian Ahlmark says it is possible to design in future flexibility, to an extent: “For office to residential, it is particularly necessary to rethink the services, especially plumbing. An office usually has centralized provision for bathrooms, but residential needs multiple distribution points. For parking that could convert, you need increased ceiling height — otherwise services for shops, for example, will not fit. In one of our car park designs we use the extra height to offer market space, and we have left soft spots that can be cut out of the structure to create an atrium.”

SHL is working with one client to create “the multifunction building of the future”, Ahlmark adds. “So we ask: can we design something that can change from a single commercial tenant, to multi-tenant to retail to residential? Can you do this and satisfy demands such as movement around the building, fire safety, and so on? We are interested in the dead ends — the limits. How far can we go before, in trying to be all things to everybody, you end up with a vague and characterless design?”

Secrets of ageing well

A good place to start, when trying to understand what makes some structures more conducive to adaptation, is the heritage buildings that are still in use today, even while the world around them has altered beyond recognition. LDS need look no further than its own office to understand how characteristics such as generous structural loadings, long spans and high ceilings can prepare buildings for uses that their original designers would never have dreamed of. “It’s a perfect example,” says Lifschutz. “It was built in the early Victorian period, before a laundry was inserted in the late 19th century. Later it became film studios and then it was bought by Island Records and used as their main offices.” Likewise, SHL’s office is a former warehouse that has also served as a gym and housing: “We cut a hole in it to make an atrium and structurally this was not a problem,” says Ahlmark. 

SHL is working on a large adaptive reuse project: the redevelopment of Commonwealth Pier in Boston. This historic waterfront structure, 1km in perimeter, is being converted by developer Pembroke into a multi-use office, retail and event space with extensive public realm. “But again,” says Ahlmark, “it has this generosity. It was built to accommodate trains, so we are not constrained by load-bearing walls or a small structural grid. I’m not sure that the office buildings of today are going to be convertible like that. They are built using systems that you can load on the back of a truck. If you build with 8m x 4m components you tend not to get the large spaces or spans that can be flexible in their reuse.”

Older construction differs in another important way from modern methods, says Audrey McIver, a director at WSP in London: legibility. Housing is one of the most frequently adapted building types, and England’s Georgian and Victorian homes remain much cherished in a variety of guises. “They are simple, cellular masonry construction,” she says, “so what is it about them that makes them still so desirable and useable?” It’s partly because they are readable on a human scale: “These buildings are handmade. You can easily see how they were built and owners can understand how to change them. A robot-built house perhaps would not feel like that, and it’s comparatively hard to move the bathroom in modular accommodation. Do people love these homes because they are flexible? Or do they make the effort to adapt them because they love them? It’s definitely a bit of both.”

The people problem

When it comes to adaptability, the dynamic between building and user is difficult to navigate but cannot be ignored. Even where buildings themselves are not that flexible, the market may respond flexibly to find a way to occupy them. In the 1990s, for example, it was common to find that obsolete mid-rise office buildings in Singapore had been part-colonized by backpacker hostels known as crash-pads, with office partitioning used to create tiny bedroom cells.

As the climate warms, it is not only buildings that need to adapt, but people too. One solution to unsustainable cooling demand is to redefine thermal comfort so that we learn to cope with greater variation. Japan was an early pioneer of this approach with its Cool Biz campaign, hiking set points to 28°C in government buildings in the summer months and encouraging workers to eschew heavy suits in favour of lighter clothing.

Coleman highlights a tension between designing buildings for performance and designing them to encourage more adaptability among users. “You run into dichotomies,” he says. “For example, you get these very specialized, highly specified, super environmentally friendly office buildings. In many ways they are admirable, but the more specialized a building is, the less likely it will adapt well. And I sometimes see this type of building as an excuse for the occupants not to change their behaviour. They may feel less likely to behave in an environmentally responsible way because they think the building is doing it for them.”

A related point is made by Robert Schmidt III, reader in architecture at Loughborough University, UK, and co-author of the book, Adaptable Architecture. “I know of a developer who owned one modern, open-plan building, and one dated cellular block,” he says. “It turned out that the older building was much easier to manage. The people in it did the adapting while the occupants of the higher-spec building proved more high-maintenance. They expected it to do the adapting for them and were constantly demanding changes.”

"Adaptability requires a nuanced approach and an acceptance that your building might not be endlessly adaptable"

Robert Schmidt III, Loughborough University

Adaptability vs material efficiency 

A building’s structure is where many of these trade-offs happen. “The basis of most of our designs is to have discrete, heavily loaded columns, and as few as possible so as not to disturb the layout,” explains Ross Harvey, structural engineer and director at WSP in Sydney. “This achieves the kind of large spans that have made old industrial buildings so adaptable, and gives occupants the flexibility to rearrange the configuration of floors. But it does mean that structural flexibility is harder down the line. It’s extremely difficult to move a heavily loaded column in a tall building.”

Another conflict arises when considering a structure’s environmental credentials. Not everyone agrees with the few-columns-long-spans approach. Julian Allwood, professor of engineering and the environment at the University of Cambridge, has pointed out that long spans require heavier beams — an inefficient use of material in an age when embodied carbon is a concern. Structures also tend to be over-specified, he adds, leaving unnecessarily generous safety margins, which may allow future users to add capacity but again could be seen as wasting the concrete or steel involved. Even Audrey McIver, an admirer of generous design, concedes: “If you over-specify ten buildings and only use that spare capacity to adapt one of them, then you’re wasting materials in nine of them.”

That will also apply to cost, points out David Cooper, president of WSP’s global property and buildings consultancy. “Most of the strategies for designing and building in flexibility have an adverse financial impact relative to short-term ROI. That’s the biggest hurdle to overcome, so there needs to be a discussion about their potential longer-term returns and benefits over the whole life of the building.”

But material efficiency need not always be at odds with flexibility, says Harvey. “For example, by power-floating concrete floors to smooth them instead of covering them with heavy screed, the weight saved gives you the extra capacity you need.” If you design a structure with no spare capacity, he adds, you will always limit the ability of users to change how they use the space. “And this need for flexibility applies even before the building is complete: suppose the developer of a residential tower decides late on to specify a screed rather than a power-floated floor? You would have to go back and beef up the structure, derailing the whole design process. This will continue throughout the life of a building, so the more flexibility it has, the longer its useful life is likely to be.”

"The biggest waste of materials and embodied carbon comes when the building becomes unwanted and has to be taken down"

Gary Pomerantz, WSP

Tall buildings contain the greatest amount of embodied carbon — and their demolition would involve expending considerably more — so it’s particularly important that they are adaptable for the long term. It’s not just how you engineer the structure, says Pomerantz, we need to think about the shape too. “Many of our office buildings in the US have large, deep floor plates which are not good for conversion to residential units, each of which requires access to the natural light found only at the perimeter. Slimmer floor plates in the future would really help.”

In other words, an over-optimized structure runs the much bigger risk of squandering an entire building’s worth of materials. “The biggest waste of materials and embodied carbon comes when the building becomes unwanted and has to be taken down,” points out Gary Pomerantz, executive vice president at WSP in New York. “Unobstructed floors give users flexibility and are usually going to be the most adaptable — it’s worth using materials to create them.”

But what to do about existing, deep-floor-plate office buildings which might now be obsolete? Pomerantz, a specialist in building systems, has some interesting ideas: “Why not mix things up a bit, like they do with tall buildings in Asia. You could convert the perimeter of some floors to residential, keep other floors as offices, and then instead of having the office data centre located on cheap land in the country, you could place it in the unused space at the centre of the residential floor. That way you help the building adapt to market changes, and you could even use the waste heat from the data centre to help heat the residential section. Win-win.”

This is a refreshing way of considering the problem of how to help buildings retain their relevance in a fast-changing world. Instead of forcing buildings to adapt wholesale from one use to another, reconfiguring parts of large buildings, in particular, might be the way to go. “Just imagine,” says Pomerantz, “in many Western cities the financial districts are like ghost towns at the weekend. If some of those fintech towers became mixed-use and occupied 24//7, whole sections of the city could come alive in a way they’ve never been before.”

It’s a positive vision, and a reminder that the interplay between real estate and its market has always presented designers with opportunities as well as problems. As the world emerges from the trauma of Covid-19, it will be fascinating to watch the built environment adapt to the challenges of the new era.

But surely occupants have a right to expect a new building to meet their needs? “Obviously there is a balance to be struck between building adaptability and human adaptability,” says Schmidt. “But first you need to accept that there is no point striving for 100% adaptability.” While researching Adaptable Architecture, Schmidt and his co-author Simon Austin identified 60 characteristics of adaptability, ranging from shallow plan depths and good light to location or having unique or quirky characteristics that endear a building to its users. “We found most had between 20 and 40. None got near 60 — nor could they, realistically. Adaptability requires a nuanced approach and an acceptance that your building might not be endlessly adaptable.”

A flexible design will often be a mixture of specific and generic forms of accommodation, he adds: “Get the mix right and it will last longer — maybe much longer, but not forever. There are always trade-offs in design. That’s why it’s fascinating.”