Newswise — There are two main types of disasters. Unlike natural disasters such as tornadoes and earthquakes, fires belong to the category of social accidents. Building fire accidents cause heavy losses. Five years ago, 72 people died in the 2017 Grenfell Tower fire. As the Guardian wrote in their article, every death is avoidable, these types of social accidents can be prevented by new technologies. The Korea Institute of Civil Engineering and Construction Technology (KICT, President Kim Byung-seok) announced that they have developed a world-class exterior wall construction method with good thermal insulation and fire resistance.
As building insulation performance standards are increasingly strengthened to reduce greenhouse gas emissions, the construction of external insulation methods such as EIFS (Exterior insulation finishing system) has increased significantly. Especially as the exterior wall cladding system of high-rise or super high-rise buildings, aluminum composite material (ACM) with thermal insulation function is commonly used, which is convenient for construction and beautiful in appearance.
However, in the traditional ACM cladding method, due to the space existing between the building exterior wall and the finishing material, the phenomenon of hot air or heat inside the building escaping through the building structure often occurs thermal bridge phenomenon. In addition, due to the chimney effect when the strong air generated in the high-rise building rises or falls vertically, the fire in the high-rise building will quickly spread vertically.
Examples of such cladding fire incidents include the Grenfell Tower fire in London in 2017 and the 33rd-floor apartment fire in Ulsan, South Korea in 2020. The Ulsan apartment fire incident was a massive fire that destroyed an entire high-rise building and spread to surrounding buildings even though glass wool was used as insulation.
A research team led by Ph.D. Taewon Lee and research specialist Do-Hyun Kim of KICT’s Fire Safety Research Division developed a technique to improve these problems.
It is constructed as a unit ACM cladding module with insulation attached, but the hollow layers of the vertical and horizontal sections at the junctions between these modules are reinforced with insulation and flame retardant materials. The developed technology is a new building exterior wall structure and construction method, which can effectively reduce heat loss and fundamentally block the spread of fire by filling the existing vacant space with thermal insulation and fire-retardant materials. Two effects can be expected at the same time: energy saving and improved fire safety performance.
As a result of performance verification of the developed technology, it was confirmed that the thermal conductivity was 0.147 W/m2·K. This result exceeds the building energy regulations for residential buildings in central Korea (0.15 W/m2·K for exterior walls (direct)). Germany is one of the countries that has made the most efforts with the Energy Saving Act for Facade Systems (EnEV). EnEV requires all new exterior walls of heated rooms to achieve a U-value of 0.45 W/m²K. Compared with other countries, KICT outer cladding ACM technology overcomes strict regulations.
In addition, a large-scale fire test was conducted at the Fire Safety Research Department to verify the performance of preventing the spread of fire. As a result, in the case of fire spread delay time, it ensures more than 4 times the time compared with the existing ACM cladding without filling the hollow layer, from 5 minutes to 23 minutes, ensuring the golden time for fire accidents.
At the same time, a cross-validation fire test was conducted in BRE (Building Research Establishment), the only BS 8414-1 testing and certification organization in the world, and a real-scale fire safety test was carried out on the outer cladding system.
It took 21 minutes to develop the technology, 15 minutes more than the international standard, and its performance has been affirmed by international certification agencies.
Researcher Do-Hyun Kim said, “The application of economical and fire-resistant building exterior cladding technology will greatly contribute to saving energy consumption, reducing greenhouse gas emissions, and protecting people’s lives and properties from fire.”
This achievement was selected as the Grand Prize in the 2021 Disaster Safety Paper Contest held by the Ministry of Internal Affairs and Security (Paper: Development of a building exterior wall system that satisfies both fire safety and thermal insulation performance).
The Korea Institute of Civil Engineering and Construction Technology (KICT) is a government-funded research institute that aims to contribute to the development of the Korean construction industry and national economic growth by developing resources and practical technologies in the field of construction and land management.
The research in this paper was carried out under the KICT research program funded by the Ministry of Science and ICT (Project Nos. 20210199-001, 20220237-001)