Introduction There is a growing demand for single or two-person residential housing units in the Republic of Korea because of the country’s rapid aging trend coupled with low fertility rate. Government data in 2017 revealed that Korean women are projected to have only 1.05 children in their lifetime, far short of the 2.1 needed to maintain population stability. Fewer and fewer young people are getting married because of soaring unemployment. Experts also cited the high cost of raising a child, long hours of work, and limited daycare options as contributing factors. Likewise, in 2016, the number of elderly people in Korea exceeded the number of young people for the first time in history. This trend prompted the increasing demand for small to mid-size rental housing. With skyrocketing residential rent and lease fees, high school or college graduates, university and college students, newlyweds, household of three or less, and senior citizens are left with limited options. Korea Institute of Civil Engineering and Building Technology recognized the potential of modular housing as a fitting solution to this socioeconomic problem. Efficiency of Modular Housing Modular houses are built through modular construction system which is more eco-friendly and faster method than onsite construction. In this system, over 70% of the housing components like windows, outer walls, front and back doors, bathroom, electrical wiring and piping, bath, and kitchen are produced and prefabricated in factories. These parts are then delivered to the construction site and assembled like LEGO blocks. Modular system 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 as structure for new houses. Modular unit lifting process. Photo credit: KICT. Enhanced Modular Housing Model The institute studied public rental houses that were built using the modular construction method. The results of the study were the basis of the development of design technology, environmental performance, structural and construction technologies, manufacturing productivity improvement, and quality control technologies for customer-tailored modular housing construction. A new model that meets housing construction standards and one that is capable of solving the common technical challenges of modular housing namely structural safety, sound insulation, and fire resistance was developed. Structurally safe mid-rise building Prior construction technologies in the Republic of Korea could only guaranty the structural safety of up to three-story modular homes. The new model used lightweight synthetic floor panels with increased shipping and lifting efficiency and internal and inter-modular joints that can support optimal structure performance. These secured the structural safety of modular homes with more than five floors – a first in the Republic of Korea. Soundproof and fire resistant units Noise insulation flooring structure and dry-wall construction were used to block external and inter-household noise transmission. To prevent the heat bridge and airtightness phenomena, shapes were joined in a stepped structure while integrated external thermal insulation corner walls were installed to improve the heat insulation of the units. Cost-efficient construction The new model was designed using the Modular Coordination (MC) and Building Information Modeling (BIM)-Integrated Design System. BIM allows developers to create virtual versions of the building through 4D simulations. This is a safe means for engineers to test building design and materials thus lessening the cost of actual execution. This reduced the design and construction duration by 10%. Applying the Design In 2017, the six-story Gayang Complex in Gayang-dong, Gangseo District, Seoul was completed. It is the Republic of Korea’s first multi-family public rental housing built using the modular construction system and can accommodate 30 households. This was erected 50% faster than a typical reinforced concrete construction. The housing units are now used for Seoul Metropolitan City’s public rental housing programs for young people who just started their careers. The Dujeong Complex in Cheonan was built using the modular construction system. Photo credit: KICT. In 2018, the institute, in collaboration with Korea Land and Housing Corporation, built the second modular housing for public rental projects in Cheonan City, Chungnam Province. Resources Korea Institute of Civil Engineering and Building Technology. 2017. Modular Public Rental Housing to Lead the Change in the Residential Facilities Trend. KICT. 2017. Celebrating the Completion of Modular Houses in Gayang-dong. 2019. South Korea's Fertility Rate Falls to Another Record Low. The Strait Times. Park Si-soo. 2017. No. of Seniors Surpass the Youth for 1st Time: Census. The Korea Times. Steve Miller. 2019. South Korea Aims to Turn Around ‘Extreme’ Birth Rate Crisis. Vox. Ask the Experts Seok-Ho Lim Senior Research Fellow, Department of Living and Build Environment Research, KICT Dr. Lim is a Senior Research Fellow at the Korea Institute of Civil Engineering and Building Technology. His research interests include modular housing, long-life housing, new-hanok/remodeling, certification/design criteria, standardization, building information modeling, and smart city. He received a Ph.D. in Architectural Planning and Design from Yonsei University. Korea Institute of Civil Engineering and Building Technology (KICT) The Korea Institute of Civil Engineering and Building Technology contributes to the development of the Korean construction industry, improves quality of life standards, furthers national economic growth, and improves social welfare. It promotes original technology in the fields of land, infrastructure, and construction. Leave your question or comment in the section below: View the discussion thread.