Stacked Up: The Long-Held Dream of Modular Construction

In Melbourne they are lifting the last modules to the top of a 44-storey apartment tower which has been constructed in just 16 months. In London, a 23-storey residential block comprising 632 modules is under way in Greenwich. And in California, the world’s leading tech giant is reinventing the corporate HQ as a campus of lightweight, movable pods.

The builders and designers behind these schemes believe that modular is the future. They hold that technological improvements and market conditions are aligning in such a way that modular construction is now finally ready to deliver that sunlit world of speed, efficiency and flexibility its supporters have been telling us about for decades.

It is easy to be cynical. Modular means different things to different people, but if there can be said to be a modular sector, it has made an art of being hopeful. Since the 1990s, a string of influential, often government-backed reports has envisaged a future construction industry where buildings are factory-produced before a rapid, safe and de-risked assembly. But by and large, this has still not come to pass, and most buildings worldwide are still manufactured in the traditional way: on site.

Recent developments around the world, however, do seem indicative of boundaries being pushed. While the Google HQ designed by Bjarke Ingels and Thomas Heatherwick is currently one of the most talked-about projects in the world, the La Trobe tower in Melbourne is the highest modular structure in Australia, and Creekside Wharf in Greenwich one of the tallest in the UK. In Singapore, meanwhile, an executive condo project taking shape on Canberra Drive is believed to be the world’s largest modular building project, with eight.

10-12 storey blocks made from some 3,300 modules. It is the kind of progress which is urgently needed, according to Kamran Moazami, head of building structures at WSP — in the developing world as much as in the overcrowded cities of the West. “The future is about prefabrication,” he says. “Throughout the world, as populations rise, there is a pressing need to build cheaper, safer and quicker. For housing in particular it is an absolute must.”

Manufactured arguments

But if modular really can supply those benefits, why is it that for many it remains a fringe specialism, restricted to temporary classrooms or cheap homes in the desert? There are many reasons, from the economic to the technical: “With tall structures, for example, there is an issue with tolerances,” says Moazami. “Conventional construction gives you the luxury of being able to adjust as the building goes up and accumulated weight causes some movement. You can design modular systems to very tight tolerances — and the computer model might be perfect — but on site the reality is sometimes different.” There are also concerns over lack of expertise and the reluctance of potential adopters to invest in training. “You have to know how to put these things together, but not many people on site have experience of building with modular on any scale,”adds Moazami.

Designing and kitting out a factory to make modules is another huge upfront and long-term investment. “You need a consistently high volume throughput to make it work economically,” says WSP director Jane Richards. The company discovered this for itself when working in the UK with student accommodation provider Unite to design a system that could provide accommodation blocks up to 14 storeys high. Modules featured a cold-rolled, light-gauge steel frame and were completely finished inside with en-suite facilities. “They even had beds and lampshades,” says Richards. “The idea was that the first person to open the door was the student who would live in it.”

However, the project foundered during the recession as demand dwindled and all-important volumes dropped. Attempts were made to sell to other markets, such as budget hotels, but still there was insufficient volume to keep the facility viable. The modules were perhaps too specific, and the business plan too uncompromising for that market at that time: “You need the right balance,” says Richards. “High volume, highly finished modules can be brilliantly efficient. But sometimes a kit-of-parts approach gives you more flexibility.”

Could the advent of building information models (BIM) linked to highly automated production facilities provide the flexibility required? “All of that certainly helps,” says Richards. “But you still need a manufacturing style and business model that works. For example, there are two basic approaches for these types of module. You can run one along a production line, like a car, or you can have it constructed in one place with people coming to the module. The latter is slower, but you can play with the design more easily to suit different markets.”

And the market is the vital driver, as the housing sector in major cities across the globe illustrates. Ever since the widespread adoption of prefabricated solutions in postwar Europe, the speed and efficiency of modular construction has made it an attractive solution in high-density urban areas, where demand for homes is high but the skilled labour needed to build using traditional methods is often scarce. This is precisely the scenario in many countries today. Leading the pack, Singapore’s construction regulator has set a mandatory target that 65% of tower superstructures must use “PPMC” (prefabricated prefinished modular construction) — at the recently completed Crowne Plaza hotel extension at Changi Airport, a PPMC system cut the number of workers required onsite by 40% and the time to construct a floor from two to three weeks to just three or four days.

But it is not just speed and efficiency that makes modular an appealing urban solution. Architects have long been fascinated by the flexibility offered by modules or pods, and the idea that buildings can be moved or added to, as if adapting organically to the fast-changing urban environment. One of the most famous examples is the Habitat 67 housing development, originally designed by Moshe Safdie for the 1967 World Expo in Montreal. An experimental stacked arrangement of 354 concrete “boxes”, which together comprise 146 residences, its modular approach was intended to create an architecture that could multiply and mutate — Safdie was commissioned to replicate the design in various locations from New York to Puerto Rico.

Although none of these subsequent projects were ever realized, the idea of highly adaptable modular architecture lives on. In the Indian city of Vijayawada, residents will even be allowed to design their own high-rise apartment. The scheme, by Chinese architect Penda, will see buyers select prefabricated modules from a catalogue, which will then be inserted into the structural frame. The practice describes the approach as using “modern construction techniques to bring back a level of individualism and flexibility for the inhabitants of a high-rise”. Similarly, the designers of the Google HQ are keen to emphasize how modular architecture is about customization rather than uniformity. “We are trying to retain this feeling of having an environment that anyone can actually hack, if they want to,” Bjarke Ingels explained after the project’s launch.

If talk of hacking sounds very construction 2.0, then so too does the proposed site assembly method, with robot cranes — or crabots — to lift the prefabricated components into place. This is a reminder that the technological improvements underpinning the modular renaissance don’t just relate to the modules themselves. “Some of the biggest advancements recently have been in logistics — crane capacities, lifting and movement plant,” says Simon Underwood, chief executive of UK-based module manufacturer Elements Europe. This is helping companies such as his to broaden their market base into defence and healthcare, as well as different housing types: “It means we can now build bigger units to suit more open-plan arrangements, which are more aligned to the residential sector.”

Beyond the box

For now, however, only an estimated 11% of UK homes have significant modular input. One reason, and it has dogged modular for decades, is the concern that prefabricated buildings look boxy, samey and offer little scope for imaginative architecture. “I think this is changing though,” says Paul Monaghan, partner at London-based architect Allford Hall Monaghan Morris. “Look at the way housing designers are using modular in different colours and clever configurations.” He cites projects by developer Urban Splash such as the canal-side 43-home House project in Manchester, designed in collaboration with architect shedkm, where residents are able to specify the internal layout within a uniform shell of timber frame, cool black metal pitched roofs and black-framed bay windows.

Monaghan is an expert in the field: his modular approach to both housing and education projects culminated in his practice winning the 2015 Stirling Prize, UK architecture’s most prestigious award, for Burntwood School in London.

“There are a number of tactics we’ve developed for working with modular,” he says. “Our most successful projects are the ones where we have teamed up with the manufacturer at an early stage and designed for their way of working, rather than designing the building and then trying to make it fit a particular system.”

At Burntwood, the use of large, glazed precast concrete cladding panels was one of the project’s outstanding architectural features, and a superb illustration of the creative possibilities of factory production. So what was Monaghan’s secret? “It helps to have depth to the panels,” he says. “Otherwise the building can end up looking flat and banal. At Burntwood the facade is 450mm deep. We also employed some asymmetry so that the panels can be rotated to give variation in appearance without increasing the number of different-shaped moulds involved.”

Of course, it becomes much easier to design with modular if the modules themselves can be varied more easily. At the moment, to be cost-effective, factory production still relies heavily on the economies that come from mass production. The next step must be to broaden the Google idea of customization, combining more bespoke modules and structures with a factory process that remains cost-effective. Igor Kebel, director at Melbourne-based architect XO Projects, believes the rewards would be considerable. “One way forward”, he says, “might be for engineers to use parametric modelling to provide us with an interactive structural model — and then link that with the BIM for shop drawings and ‘file to factory’ manufacturing.” Combine this design approach with automated production, says Kebel, and it should be possible to introduce variations more quickly and efficiently. “Mass customization: if you can apply that, you could probably rule the world.”

And this is more than just an aspiration. Contractors and engineers are even now busy trying to find the right balance between bespoke design and volume production — and using the latest technology to boost their chances, such as 3D printing.

The irony is that, just as technology is creating the capability to design more flexibly, the “boxy” aesthetic is enjoying a resurgence in mainstream architecture. The influence of Habitat 67 is clear in projects such as Ole Scheeren’s Interlace development in Singapore, which was named World Building of the Year at the 2015 World Architecture Festival. Just as Safdie assembled concrete pods in different cuboid arrangements to make terraces, walkways and gardens (famously claiming to have used “all the Lego in Montreal” in the design process), so too has Scheeren stacked larger cantilevered volumes at varying angles to create a series of lively external spaces. Such “stacked” designs are becoming a staple of iconic architecture, from Herzog & de Meuron’s surrealist Vitra Haus in Weil-am-Rhein, Germany (2011) to OMA’s colossal Timmerhuis mixed-use development in Rotterdam (2015).

It all points towards a bold new dawn for the module. Robot technology is enabling faster, more accurate production of more flexible designs. BIM is allowing manufacturers, designers and contractors to play with modular configurations in a way that would have been difficult just a decade ago — and architects are becoming more adept at using new modular solutions in creative ways and more interested in the rigid geometries of the past.

Most important of all perhaps, a global shortage of traditional building skills is causing problems for developers — and a market that is hungry for new methods of procurement is a market where modular can flourish.