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Research Achievements

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Titel Modular Public Rental Housing to Lead the Change in the Residential Facilities Trend
Manage Buillding and Urban Research Instiute Date 2017.01.11 Hit 1,754

 

 
Developing a modular public rental housing technology to cope with low fertility and aging


Project Leader: Lim, Seok-Ho (Senior Research Fellow, shlim@kict.re.kr)

 

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Amid the increase of single- or two-member households due to low fertility and aging, there is a growing need for the next-generation housing model. A modular construction technology is a very economical method as it allows houses to be built like Lego blocks and to be promptly supplied and dismantled. This research is significant in that it solved the problems related to “structural safety, noise between floors, and fireproof performance,” which had long been technical challenges in modular housing, and presented a new public housing model that could flexibly cope with the country’s demographic structure and social and environmental changes. Furthermore, it will not only generate jobs by improving the structure of the construction labor market but will also promote the people’s awareness of the advantages of modular housing.
 


Modular construction method to present a new paradigm in the construction market

The household structure in South Korea is changing. Since the last several years, the number of single- or two-member households by recent high school or college graduates, university and college students, newlyweds, or senior citizens has been soaring, resulting in the increased demand for small to mid-size rental housing. The residential environment, however, is worsening, and the rent and lease fees are skyrocketing. Accordingly, “modular construction,” which is useful for building small houses, is considered a fitting solution to this socioeconomic problem.
 

 


Modular construction is a construction method that modularizes over 70% of the construction components (e.g., the frame of a house, the front doors, the bathroom, and the electrical wiring) in the style of Lego blocks, and prefabricates them in the factory. As these modules can then be brought to the site and assembled thereat, this method can reduce the construction costs and can minimize the construction-related noise. Furthermore, as modular housing can be built in the small leftover sites in various corners of a city, its applicability is much greater in big cities that lack large-scale housing sites. Suffering from the excessive competition for low-price orders, the housing market in South Korea is witnessing its business value worsening, which makes it difficult to expect job creation even with its advancement into overseas markets. It is expected, however, that once the modular construction method, which proposes a new paradigm in the housing and construction market, is activated, it will set a turning point for job creation and will trigger increasing profits in overseas markets.
 


Proposal of new public rental housing model via the demonstration of its economic, commercial, and technical viability

 

As modular housing is manufactured in one-room modules 3 m wide and 5 m long, it is effective in buildings with repeated, identical spaces, such as dormitories, studios, or hotels, making it suitable for apartment complexes for single- or two-member households. If demolished, modular housing will not produce construction waste; instead, it can be reused for the structure of new houses, making it ideal for sustainable and eco-friendly construction. As a leading research institute for the project, KICT formed an industry-academe-research consortium to develop a new residential model for coping with low fertility and aging by utilizing the modular construction system. The research team in the consortium aimed to develop modular housing technologies with the three empirical bases of economic value, commercial viability, and technical feasibility, and to propose a new public rental housing model by establishing a demonstration complex for public rental housing.
 
Towards this end, they first developed and verified the design technology, environmental performance, structural and construction technologies, manufacturing productivity improvement, and quality control technologies for customer-tailored modular housing construction, after which they developed a commercialization model that guarantees economic values for the promotion of the supply and commercialization of modular housing. Later, the research team built the country’s first demonstration modular complex; formulated the resident recruiting and selection plan, which included a presentation for the residents of modular housing units for residential stability and the improvement of the quality of life of non-homeowners like newlyweds and college students; and established the “operation system” for the modular-housing-tailored management and operation planning.
 
According to the above procedures, the country’s first multi-family housing and public rental housing for 71 households (41 households in Suseo Complex, 30 households in Gayang Complex) implementing the modular construction system will be offered. Gayang Complex, whose construction has already been started, having received use permission from Seoul City in 2016, is expected to be completed in early 2017. The public rental houses are supplied to the three housing-vulnerable groups (city workers, newlyweds, and recent high school or college graduates) and to university or college students. This research is also significant in that it has established a “consumer-tailored housing supply system.”
 


Safety • fire resistance ↑ noise • construction costs ↓, the next residential model that offers both technical and economic advantages

The first core research outcome from the aspect of scientific technology is that it solved the three technical challenges of modular construction — “structural safety, sound insulation, and fire resistance” — in accordance with the housing construction standards. For the cost reduction through standardization, the project established the “MC Design and BIM-integrated Design System,” and by employting the MC design, not only did it extract a housing standardization plan; it also established and informatized the library by unit member, joint, and unit. Furthermore, it reduced the design and construction duration by 10% by reviewing the constructability with 4D simulation.

Another outcome of the project is that for the first time in South Korea, it secured the structural safety of five-story or higher modular homes. To overcome the limitations of the existing technology, which had guaranteed the safety only of up to three-story modular homes, the project developed lightweight synthetic floor panels with increased shipping and lifting efficiency, and acquired technologies for optimal joint structure performance. Additionally, to address the issue of the “noise between floors,” which has become a serious social problem, the project achieved a level 3 heavyweight impact noise rating and a level 1 lightweight impact noise rating by developing the noise insulation flooring structure and walling technology, and acquired a level 1 inter-household sound insulation rating by blocking the external and inter-household noise transmission via dry-wall construction.
To save energy, the heat bridge and airtightness phenomena were prevented by joining shapes in a stepped structure. Also, by installing an integrated external thermal insulation corner wall, the heat insulation and airtightness performances were improved. In the foregoing ways, the project achieved a level 2 energy performance rating for modular homes, the first time that a construction project in South Korea ever acquired such rating.
 
 
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 ▲ Building a mock-up modular multi-family housing and 12 demonstration technologies (Jincheon Factory, Chungbuk K Corp., Aug. 2014)

1. BIM design system
2. MC design
3. Basic leveling
4. Internal joints in the modules
5. Inter-modular joints
6. Lightweight floor structure
7. Carrying fixture
8. Vibration device for assembling
9. Finishing technology for noise insulation
10. Energy-saving building skin
11. Hybrid fireproof structure technology
12. Customized fireproof filling


The biggest economic achievement of the project is that it proposed a new model for public rental housing using a modular construction method that allows rapid supply and demolition. Reducing the construction costs, which was up to 130% of RC construction and the Achilles’ heel of modular housing, to 110%, and even presenting the possibility of lowering it further to 90%, was another significant outcome of the project. The research team divided the work breakdown structure into three stages (the modular manufacturing process, the general onsite construction, and the onsite modular construction) and established the “modular construction standard cost structure,” implementing the standardized codes, to improve the cost management efficiency and the accuracy in the bidding process. In addition, to ensure price competitiveness, the project performed multilateral cross-checking for cost-saving based on the participation of a major domestic modular manufacturer, and acquired economical viability by reducing the construction duration to 50% of the typical RC construction method.

 
 

 

 

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