Modular building - the answer to a changing marketplace?

In a world where buildings must be cheaper, quicker, cleaner and more environmentally friendly than ever, developers are looking to other industries to build our future housing.

Two years ago Chinese construction company Broad Construction stunned the architectural community by assembling a 15-storey hotel in Changsha, China, in a mere 16 days.

At the cusp of its manufacturing revolution, rapidly emerging China has become notorious for its ability to raise entire cities from rolling wasteland at an eye-watering rate, leaving Western counterparts in its looming shadow.

The speed of construction is partly due to quality-control freedoms relating to the average life expectancy of a Chinese residential building, which has an industry standard of just 25 years. Building standards vary from province to province and are not tightly governed, meaning that their national Green Star environmental ratings are often sparsely and questionably observed. Regardless, Broad Construction's New Ark Hotel - the first in the world to be built almost entirely in a factory - was no minor achievement.

The New Ark Hotel's rapid assembly was accomplished via a method known as modular construction, which involves individually manufacturing and assembling each floor of the hotel in a series of parts before shipping them in modular units to site. Modular construction is hardly the new kid on the block, having been used in the US and the UK for over 50 years.

But the practice has garnered recent international attention, maturing from a gimmicky, flat-pack housing concept to a genuine player in the temporary property market, thanks in part to mavericks Broad Construction. The factory floor inspired Broad Construction's methods (93 per cent of the New Ark Hotel was prefabricated in a factory) and this is the general concept from which modular construction has evolved.

For decades, cars, pharmaceuticals, and more recently consumer electronics such as tablets and smartphones, have been manufactured in carefully controlled factory environments, enjoying the microscopic precision of autonomous machinery to assemble every component.

Production line

Each component making its way through the conveyor-belt of the supply chain can be tracked, quality-checked and cross-checked directly back to the manufacturing cell from which it was created. These sterile manufacturing conditions have allowed industries to hone products down to nanoscale, leaving little room for error and eradicating the need to compromise on quality.

Until now, the construction industry has represented the polar opposite. Complex, dirty and at the mercy of the elements, radical architectural design has often been compromised simply by the working environment of its construction site. Visionary projects with the potential to be completed in weeks can amble on for years or be abandoned completely due to weather, noise pollution and material shortages.

Buildings currently consume 40 per cent of the world's energy, and thanks to the enforcement of fines for overabundant carbon emissions and material, energy and heat wastage, sustainability has become a priority in the commercial building sector. Modular construction provides concise control over these concerns: each floor of their future property can be moderated in sterile, controlled conditions.

Flatpack housing

Broad Construction is one of the most notable companies to realise the potential of modular construction on a commercial scale. The New Ark Hotel was manufactured in an assembly-line not dissimilar to that found in an average industrial manufacturing plant

The 15.6m long x 3.9m wide x 0.45m high modules are very low waste; 96 per cent of materials purchased are used during manufacture, achieving a material saving of 600kg/m2 and a CO2 emission reduction of 300kg/m2. The first layer of each main board represents the floor, with the upper level constructed above as the ceiling. Sandwiched between the ready-constructed walls are the tubes for HVAC, water discharge and electric wiring, all assembled in-house before they leave the factory floor.

Much like an Ikea flatpack, all internal accessories such as columns, diagonal bracings, walls, doors and windows are shipped with the main board and installed on-site - contractors only have to bolt on the remaining accessories and connect electrics and plumbing, eradicating the need for engineering specialists on-site.

Cutting carbon emissions

Concrete is currently one of the manufacturing industry's biggest contributors to carbon emissions, with the construction industry representing their biggest market share. Reducing the amount of concrete used in modular housing not only makes them lightweight and quicker to build, but also cuts out the environmentally damaging, material-intensive manufacturing process.

With this in mind, Broad Construction's finished buildings are cement-free except for the foundations. The floors consist of a 3cm-thick polished steel sheet floor, a mere 300-400kg/m2 in weight, and an earthquake-resistant, 96 per cent recycled steel structure is at the heart of each building as opposed to poured concrete.

Earthquake-resistance is desirable in modular buildings, particularly when they are located in earthquake-prone regions such as Asia or built as temporary housing in a disaster zone. Each one of Broad Construction's houses features a lightweight diagonal bracing structure, which makes them resilient enough to survive earthquakes up to level 9 on the Richter scale.

Love thy neighbour

Modular housing is changing the way the construction industry is perceived. Anyone who has ever lived next to a building site can empathise with the extensive noise pollution, brick dust, chemicals and hazardous machinery that accompanies the construction of a new building.

The New Ark Hotel was installed much more quickly than traditional construction methods, at a rate of four to six floors per day. As the units are manufactured away from the site, residents aren't exposed to flying dust or polluted water, meaning much lower emissions are produced on-site. As all cut-offs can be reused in the factory environment, construction waste can be lower than 1 per cent.

"Modular construction helps move the disruptive side of construction away from the hustle and bustle of residential or commercial areas," says Tom O'Hara, director of Business Development for US-based modular construction company, Capsys. "This kind of development can take 18-24 months, but with modular construction, preparation is less than half that. This kind of project would only take days or weeks of work on-site."

As well as being cheaper, quicker and cleaner, modular building is the industry's poster boy for sustainability. Modular manufacturing allows total control over energy conservation, as every aspect of heat retention can be fine-tuned in the factory and constructed with higher levels of accuracy.

"We can do a unique airflow test on each of our modules that is not possible in traditional building," says O'Hara. "We essentially suck the air out of an apartment and measure the difference between the exterior and interior. As a result our buildings are 100 per cent more airtight than required - simply because the corners are actually square and flush."

Window insulation in modular housing can also be up to two to four times higher than local government standards. When this is accompanied by a heat recovery fresh air unit and a CHP system, modular houses can become up to 50 per cent more energy efficient. Fresh air filtering systems also allow cleaner and purer air to circulate the building, with ventilation cycles running five to ten times per hour. All fixtures, fittings and controls can also be customised to increase energy efficiency, including low-energy LED lamps controlled by smart building management.

Flying the flag for sustainability even at ground level, Capsys's entire workforce can travel to work on public transport because their tools are kept in the factory.

"Our factory is the height of sustainability, and the industry as a whole has huge potential," says O'Hara. "We fully meet LEED's [US Green Building Council] legislation as we are very low-waste. All orders are structured and manufactured to a specific size which means few cut offs and little wasted materials. This also allows us to recycle materials such as gypsum that disintegrate in rain - traditionally if these were left exposed on a building site they would just be thrown away."

A country of opportunity

As well as being suitable for use in earthquake-prone regions and the rapidly increasing population of Asia, modular construction is a unique solution to a very American problem. The US is a sprawling country populated by cities often located hundreds of miles apart; modular construction allows buildings to be prefabricated in factories then delivered around the country on the backs of lorries and trains.

"Modular construction is about taking the building out of the building site and putting it in a controlled factory environment," says O'Hara. "Most modular construction firms try to deliver within 300-400 miles of a factory, they are purely regional businesses.

"Unfortunately, low-emission projects like modular construction aren't often backed by the US government; they don't want to encourage one technology over another, just sustainability on the whole across the entire industry."

Despite initial resistance, modular construction has slowly gained popularity in New York in recent years. Former Mayor Michael Bloomberg is publicly supportive of the technology, launching his adAPT NYC micro-housing competition last year in an effort to improve modular housing construction in the city. Capsys are manufacturing the units for My Micro NY, a complex of entirely self-supporting 325ft2 units previously a prohibited size for the city.

O'Hara says the problem with modular construction in New York is that it has become a catch-22 situation - the technology is growing in popularity but there are too few specialist companies to fill demand, and as a result developers are wary of the cost of building modular.

"Traditional construction is design-bid-build, whereas modular is simply design-build. If you put out a plan to build modularly, there aren't a lot of people who can respond," O'Hara says. "And so developers worry about whether they're getting a competitive price.

"But the My Micro NYC project is around 60 modules so it really only takes a few weeks to build them all. We'll probably be able to build the modules faster than they can build the foundation."

Capsys manufacture their modules in a repurposed zeppelin hanger in downtown Manhattan. Their urban location and the suitability of modular construction in built-up New York means they barely deliver outside of a 100-mile radius of city. But building modular properties in one of the busiest melting-pots on the planet also has its shortfalls. Fire safety zone regulations in New York City stipulate it's impossible to build timber-framed structures more than two-storeys high, so Capsys have to compromise by supporting their buildings with steel frames.

Modules are manufactured in an assembly line, with sub-cells handling each section of the module before it moves to the next cell. While their assembly line is still fairly human-led with few robotics, O'Hara believes the industry has the potential to become automated in the same fashion as automotive factories.

Offering a flexible solution

American cities like New York enjoy wide boulevards rather than typical European streets, and as result can fit larger modules with larger living spaces, giving modular construction firms more flexibility in design.

However, O'Hara says the projects that represent the most promising avenues for modular construction are the ones built on a much smaller scale. Social housing projects for disabled people, young offenders, and the elderly, are the most interesting projects to work on, he says, due to the challenge of fitting adaptable technology into a much smaller space and on a tighter budget.

"These are single residency, small apartments measuring 255-350ft2," says O'Hara. "Typically, the homeless, incarcerated and institutionalised are housed in these spaces."

The challenge of these types of units is that they must be personalised, adaptable, fully functional apartments for people who may be handicapped in any number of ways. This level of flexibility is modular construction's potential niche in the market.

"They are LEED-certified, accessible and disability-friendly, so rather than making cheap boxes they must be cutting-edge and built to last," says O'Hara.

"This is the way modular construction must go in the future if it wants to survive. These are the kinds of applications where modular construction really shines."

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