Lesson from Japan: prefabricated houses for green development



Southeast Asia has become one of the fastest emerging economy regions in the world. The blooming young population and growing middle-class have led to a construction frenzy, stimulated by a high demand of residential housing. With sustainability and green issues that follow, it is undeniable that meticulous steps must be taken.

However, with constructions in most part of the world still going through conventional methods, it is becoming extremely hard to bring the new green standards among them. Along with the towering production cost and a vast build-up in demand, developers are too occupied to think about the environmental impacts of the buildings.

Even so, there’s a gleam of hope coming in the form of mass-produced construction and it may be the solution to overcome the rocketing demand for residential housings. By replacing on-site construction processes with off-site manufacturing, the time consumed and workers workload can also be dramatically reduced.


The idea of prefabricating houses began in late 1960s in Japan. The country was recovering from the aftermath of World War II, which had destroyed lots of homes. With the abundance of young occupants, the demand for residential housing was urgent. Now the four leading companies, Taisei Corporation, Sekisui House, Daiwa House, and Misawa House stepped up to solve the issue by rapidly building modular houses.

A house is categorized prefabricated when 2/3 of its materials are using prefabricated goods. Since this method was widely adopted, Japan has seen approximately 1.400.000 new houses built per annum. Average 85% of which is using prefabricated materials while 14% are built entirely prefabricated.

Japan’s approach to prefabricated houses is similar to automotive industry. Matthew Aitchison, researcher from The University of Queensland Australia, describes the house factories as ‘populated with robots, house parts trundling along assembly lines, with technician assembling them like a car.’ This is in contrast to conventional construction processes where we put on-site construction workers in front line, dealing with day-to-day construction process.

However, as this method was developed and tested worldwide, it failed to set as the new standard due to many of disadvantages at the time. The modular and less-personal experience yet expensive condemned the concept of prefabrication in housing a non-sense. As a result, prefabricated houses only see 3% of new houses population globally.

The Green Aspects

Studies report that the construction period has now been reduced to less than half the time needed in conventional methods. Thanks to the sophisticated manufacturing process, the consistency of the assembly part is extremely high, decreasing construction errors by almost 97% as the effectiveness of HVAC system is increased by 37%.Because of the off-site assembly methods, requirements for on-site skilled labors can be significantly minimized. Workers’ safety is also put to a better state, leading to lower working risks and exposure to hazardous materials. These advantages result in a more efficient and effective construction process, which finally reduce overall energy consumption and construction cost.

In regards to building life cycle, Sekisui House gives 20 years of support warranty in their product lines, assuming that the building’s life cycle is meant to last a minimum of 20 years.This number is taken based on the fact that the current residential development system demands more flexibility upon restructuring the city. Houses no longer need to last forever, since people are becoming more mobile and the need of new housing is shifting in a faster pace. With this in mind, a knockdown system is introduced to be able to dismantle the whole building when it is ready to be refurbished.

A factor to point out is how this new approach has improved in terms of design flexibility. After many years of research and development, combined with appropriate promotion efforts, Japan is now culturally receptive to this innovation. Customers are enticed by the especially high level of involvement in house designing process and the capabilities to customize it to meet their specific needs.

The downside of this concept lays on its high initial cost and the customer’s confidence to utilize it. Being in the weaker position in the construction business, financial plans are still limited. Even in Japan, budget allocations for prefabricated house are still put under the upper-middle class category, way below the lower economy class. Because of its new building paradigm, customers prefer to work with high-profile companies, leaving the rest staggering in growth.

Challenges and Opportunities

While Japan is perfectly conditioned to push the adoption of the new construction system, the rest of the region is struggling. Major investment is required to build factories and ready the infrastructure. Although it carries the same label of construction business, prefabricated housing is an entirely new genre. As time and cost are shifted from on-site construction to off-site manufacturing, supply chains and logistics gain more importance. Materials manufacturing will no longer rest in the hands of the builder. The parts assembled on site will be handled as delivered goods instead of raw material, thus require a more thoughtful process.

Building residential housing is like setting up a foundation upon the future of urban development, something to be carefully planned. If prefabricating materials can be seen as one feasible solution to the problems generated by the booming of construction industry, then all hands will have to play their parts. Government will need to set the rule on how things will be rolled out. Developers will have to create trustworthy products with high consistency in quality and appropriate marketing approach, all to gain the confidence from customers. Otherwise, stagnant interest and towering demand for prefabricated house will continue, as cost will remain high.

While challenges keep on coming, the method can act as a solution to a greener environment. Successfully bringing these prefabricated houses with sustainability in mind can lead to a mass produced sustainable housing. By then, we can probably see the dream of living in green and sustainable environment coming true. (AGB.com – RO, KC)

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