Development of Smart Modular Multi-story Hanoks
▲ Senior Research Fellow Lim Seok-ho, Department of Building Research
The Concept of Smart Modular Hanoks
A smart, modular, multi-story hanok is a multi-story hanok (Korean traditional house) comprised of cube-shaped modules that are pre-assembled, transported to a building site, and then assembled together like Legos, allowing for the excellent and quick completion of the building process. In other words, this type of hanok combines the off-site, modern modular construction method with the features of a traditional Korean house. This type of construction method improves the living environment of traditional Korean hanoks and improves their overall economic efficiency. In 2021, the Korea Institute of Civil Engineering and Building Technology (KICT) utilized integrated steel and wood technologies as well as structural glue-laminated timber (GLT) to advance its design and construction technologies and to create a smart, modular, multi-story hanok with a prefab percentage of 80% or more.
Traditional Korean hanoks are very expensive, due to the use of onsite construction technologies, and typically have poor thermal and sound insulation. The KICT's module technology—used in 2017 to complete a demonstration project for a 6-story, multi-unit dwelling—solves these problems, improving housing performance, economic efficiency, and constructability. While researching this new construction process, developers created a bonding technology designed especially for lifting and stacking—enabling single-story hanok modules to be constructed into multi-story buildings—and developed a smart technology that improves the structural safety of the hanok balconies. The balcony is one of the major design elements of the multi-story hanok and features an upper handrail (gaeja-nangan) that projects outward.
Using these technologies, developers were able to lay the groundwork for further technological and economic improvements, while also reducing costs by more than 30% (an effect of reducing the construction period by more than half). Traditional hanoks built onsite typically cost KRW 12 million per 3.3 m2. In order to verify the reusability, recyclability, and portability of their modular hanoks, developers dismantled and immediately reassembled the modular components. They then performed a series of assessments to demonstrate the constructability and technical feasibility of the smart, multi-story hanoks. The modular hanok construction technology was developed as part of the Hanok R&D Group and the Modular Multi-unit Dwelling Demonstration R&D Group, funded through the KICT's SME support project, implemented for two years, beginning from 2019.
Key Technologies of Smart, Modular, Multi-Story Hanoks
a. Development of Wooden, Modular Houses Using GLT
GLT, with its verified structural integrity, is a critical element of building multi-story, modular hanoks. GLT is used in the modular hanok construction process for the development of converged and integrated joints, which are also equipped with horizontal and vertical connections and rings for lifting. In order to improve the overall performance of smart modular homes, it is necessary to create passive structures and dramatically reduce energy consumption, which can be achieved by using new materials for the external wall body (façade).
Since South Korea has a relative lack of natural wood resources, GLT must be utilized by overlapping smaller pieces of wood, as opposed to large planks, the latter of which would create an overwhelming demand for wood. As seen in Figure 2, interconnected wooden modules for multi-story hanoks are constructed using steel hardware and applied with an exterior finishing material that preserves the traditional hanok appearance after the building has been completed. During the R&D process, the structural safety of these fabricated wooden modules was verified using a lift test (Figure 3).
b. Standardization of Modular Hanok Technologies
In order to secure the economic feasibility of multi-story, modular hanoks, it was imperative for developers to standardize and normalize all associated modular construction processes. As seen in Figure 4, developers sought to realize economy of scale and normalize modular development through the mass production of the MC design and by maintaining the preferred dimensions of key housing materials and parts.
c. Technologies for the Assembly and Construction of Modular Hanoks
The assembly and construction processes for modular hanoks, as shown in Table 1, were applied to the demonstration project completed in Yangpyeong, Gyeonggi-do, Korea. The completed demonstration project consists of three standard modules, each measuring 3 m×6 m, and an additional half-module (3.5 modules total) that spans two stories (92.56 m2 in total floor area). It took about three days to assemble the modules, and following construction, developers conducted a series of habitability performance tests, such as tests for airtightness and sound insulation. A BIPV system was attached to the surface of the outer wall of the “smart hanok,” and the solar energy produced as a result was used to light the interior of the eco-friendly hanok. In order to fully realize the developers’ vision of a “smart hanok,” a high-insulation, large-exterior, finish-integrated panel was applied to the structure and the joints were minimized to improve airtightness, sound insulation, and heat insulation performance. After the structure was completed, the developers conducted a series of verification and performance assessments, the results of which showed that the developers had achieved their goal of dramatically improving the habitability performance of traditional hanoks.
The scenic views of Korean houses—most commonly seen when traveling by train or looking down from a nearby mountain—are mostly comprised of hanoks that were erected during the Saemaeul Movement and have become one of the unique and representative features of South Korea. Now that Korea has risen to become one of the world’s top 10 economic powers, it is time to restore the dignity and identity of Korean houses to a level befitting national prestige. When people travel to other global regions, such as Switzerland in Europe, they often find themselves admiring and envying how the houses perfectly harmonize with the natural environment. It is clear that the governments of these countries had excellent insight and invested a considerable amount of money, over a long period of time, in systematic landscape management and housing maintenance at the national level. Even though Korea is known for its hanoks, which perfectly harmonize with Korea's natural environment and topography, the nation is now filled with apartments, which do not reflect Korea’s national identity, as well as low-end row houses and poor-quality single dwellings. It is high time for Korea to undergo a national housing transition and reorganization that revives and preserves the country’s original land and beauty.
This study on modular hanoks was originally begun with these goals in mind. Hanoks, a type of traditional housing in Korea, have been overlooked and neglected in modern times due to their high costs, prolonged construction periods, and overall poor living environments. However, attempts should now be made to improve and popularize the traditional hanok by incorporating modern architectural technologies. As researchers and developers, we dream of creating a traditional hanok that anybody can enjoy. Although similar attempts have been made sporadically in the past, these attempts have undeniably failed due to excessive stubbornness on the part of those unwilling to modernize traditions and a lack of the general economic feasibility of hanoks. The development of modular “K-hanoks”—which combine bold modern construction methods and technologies with hanok apartment buildings, public buildings, and cultural and tourism auxiliary facilities—is leading the way for the reimagination of traditional hanok buildings.