Close
This focus area aims to develop new connections for infill walls to enable deconstruction without damaging other parts, assisting with reuse of non-structural component materials.
Description
PDR1B Dr Shoma Kitayama, worked with Dr Ornella Iuorio at the University of Leeds. The project aimed to enable the circularity of external infill walls used for buildings in the UK and to facilitate the national effort toward achieving net zero by 2050.
The infill walls are removed during the refurbishment of the buildings to adapt spaces to new functions and/or to comply with new energy efficiency or humidity control targets. While a building is used typically for 60 years before it is demolished, the infill walls are used only for about 30 years. The infill walls are typically made of lightweight steel frames and gypsum boards.
A recent study showed that the lightweight steel frames for infill walls in multistorey buildings can be used for 100 years. The gypsum boards may also be used for a longer period than the current actual period (30 years from manufactured time to the recycled time).
The recycling of lightweight steel and gypsum boards incurs environmental burdens, as materials must be collected, sorted, transported, cleaned/pre-processed, and then re-manufactured. Thus, the project is currently investigating the possibility of reusing the whole infill walls and parts of infill walls (only gypsum board or only steel frames) that will reduce the amount of materials sent for the energy-intensive recycling processes.
The researchers planned the experimental study at the university laboratory, which was conducted in 2022 at the structural laboratory of the University of Leeds. Dr Shoma Kitayama was awarded the Alan Turing Institute Post-Doctoral Enrichment Awards in autumn 2022.
The design and test data were shared through publications and presentations at conferences as well as the ICEC-MCM centre meeting in May-23 in Birmingham. HLM Architects provided the Leeds researchers data of building construction for use in life cycle assessment. The life cycle assessment study evaluated how the deconstruction and reuse of infill walls affects the environmental performance of the building and results will be shared in a journal publication, currently under review.
Publications
Kitayama, Shoma & Iuorio, Ornella. (2023). Disassembly and Reuse of Structural Members in Steel-Framed Buildings: State-of-the-Art Review of Connection Systems and Future Research Trends. Journal of Architectural Engineering. 29. 03123006. 10.1061/JAEIED.AEENG-1615.
Reducing carbon emissions in the construction sector is essential in a period of climate emergency. Disassembly and reuse of structural members are considered to reduce the carbon emissions from the construction and deconstruction of buildings. In this context, it is important to review the current state of the art to provide a framework for the development of future structural systems that can enable the easy disassembly and reuse of steel-framed buildings. This paper (1) presents a review of more than 100 documents to discuss the feasibility of disassembly and reuse of structural members; (2) develops detailed schematic illustrations to explain the design concepts and the underlying mechanics governing the behavior of demountable connections; (3) sheds lights on the technical and design challenges to implement disassembly and reuse of the structural members; and (4) defines future research needs to facilitate the disassembly and reuse of the structural members.
Kitayama, S., Iuorio, O. Using bolted connections for the construction, de-construction and reuse of lightweight exterior infill walls: Experimental study. Archit. Struct. Constr. 4, 123–133 (2024). https://doi.org/10.1007/s44150-024-00108-0
Bolted connections offer advantages in terms of disassembly and reusability, potentially replacing conventional connections like screws, welds, or chemical bonds. This research investigates the behaviour of bolted connections between lightweight exterior infill walls and beams of primary structural members that are conventionally connected using screws. Although previous studies have investigated bolted connections in different structural members, understanding of the behaviours of these specific connections remains limited. The connections between infill walls and steel beams primarily experience shear loads under serviceability conditions. Therefore, an experimental study was conducted to gain insight into their shear behaviour. The obtained experimental results were analysed using existing predictive equations from design standards that are used across European, North American and Oceanian countries, to identify the most suitable equations for designing such connections.
Iuorio, O., Kitayama, S. (2024). Experimental Study on the Feasibility of Disassembling and Reusing Lightweight Façade Wall Systems. In: Ungureanu, V., Bragança, L., Baniotopoulos, C., Abdalla, K.M. (eds) 4th International Conference "Coordinating Engineering for Sustainability and Resilience" & Midterm Conference of CircularB “Implementation of Circular Economy in the Built Environment”. CESARE 2024. Lecture Notes in Civil Engineering, vol 489. Springer, Cham. https://doi.org/10.1007/978-3-031-57800-7_23
This paper presents experimental investigations into the feasibility of disassembling and reusing exterior lightweight infill walls. The work stems as necessary steps towards the advancement of circular economy principles in future constructions. The experiment employed the single-shear test method commonly used to assess the shear strength of steel connections. The test samples consisted of cold-formed steel plates attached to hot-rolled steel plates, connected by screws. The cold-formed steel plate represents the track, a component of exterior lightweight infill walls, while the hot-rolled steel plate represents the beams of the primary structural frame. In total, twenty-one specimens were made: nine were tested after screwing, nine were tested after unscrewing and re-screwing, and three were tested after unscrewing, re-screwing, unscrewing, and re-screwing. The unscrewing step demonstrates the disassembly of the infill walls, while the re-screwing demonstrates their reuse. The experimental results revealed that the average peak strengths of the samples with different connections exhibited negligible differences. This can be attributed to the interaction between the screws and the connected cold-formed steel and hot-rolled steel plates, a mechanism further discussed in this paper. The test outcomes imply that exterior lightweight infill walls can be disassembled from the primary structural frame’s beams after the infill walls’ service life, and subsequently reused in the construction of other exterior lightweight infill walls. The study also demonstrated that more specimens should be tested to confirm the observation.
Shoma Kitayama, Reusable Exterior Walls: Outside In. Read more.
Kitayama, Shoma & Iuorio, Ornella. (2022). Design for de-construction of lightweight infill wall systems. 10.1201/9781003348450-172.
This paper discusses the design for de-construction of lightweight infill wall systems. The paper reports the deconstruction and reassembly processes of a sample light steel frame skeleton. Each of the steel members in the frame skeleton was connected by screws, which were removed by a screwdriver. The observations and findings during the deconstruction and re-assembly processes are presented. The authors observed that the screws in the sample steel frame were safely removed, and the members were re-assembled without causing any damage. The authors compared the stiffness of the frames before and after the deconstruction and observed that there was no change in the stiffness in the frame.
Shoma Kitayama, Ornella Iuorio, Irene Josa, Aiduan Borrion, Leon Black, Determining the carbon footprint reduction of reusing lightweight exterior infill walls: A case study of a school building in the United Kingdom, Journal of Cleaner Production, Volume 469, 2024, 143061, ISSN 0959-6526, https://doi.org/10.1016/j.jclepro.2024.143061.
The global construction sector consumes 40 billion tonnes of raw materials and is responsible for considerable CO2 emissions. With growing awareness of its environmental impact, the construction sector is looking to transition from a linear economy “take-make-waste” scenario towards more circular economy principles. Lightweight exterior infill walls are built between floors of primary structural frames to provide building façades. The design of these components is usually based on the current linear economic model. While lightweight exterior infill walls are becoming increasingly common in building construction in the UK, no studies have investigated the potential environmental benefits of designing them with circularity in mind. This means there's a lack of research on both the carbon footprint of these walls and the potential environmental benefits of reusing them. Thus, this article assesses the significance of the carbon emissions from lightweight exterior infill walls and examines whether there is any carbon reduction when lightweight exterior infill walls are demounted from the building frames and reused. This paper first examines the construction process of lightweight exterior infill walls and explores the opportunity to demount and reuse them. Then, the environmental impacts of the lightweight exterior infill walls are analysed using a lifecycle assessment framework. Sensitivity and uncertainty analyses are also conducted. The results demonstrate that (i) the embodied carbon of the lightweight exterior infill walls over their lifecycle represents approximately 22% of the embodied carbon of the entire building, and (ii) the disassembly and reuse of infill walls can reduce a building's embodied carbon over its typical lifetime by about 6% compared to the linear scenario where the walls were not reused.
Kitayama, Shoma & Iuorio, Ornella. (2023). Can we reuse plasterboards?. 10.1201/9781003323020-12.
Gypsum turns plaster when it is dehydrated, and it returns to gypsum when it is hydrated. Because of this, gypsum is 100 % recyclable in theory. However, in reality, only 4% (in mass) of the plasterboard is from recycled plasterboard. This is because of the substances, other than fresh gypsum from quarries, to make plasterboard, and the current demolition methods that cause material contamination. The current practice of manufacturing, construction, and deconstruction of plasterboard necessitates significant resource extraction and carbon emissions, and the situation is unlikely to change in the foreseeable future. Reusing, instead of recycling, construction material is effective in reducing resource extraction and carbon emissions, however, it has not been investigated at all for plasterboard. Thus, this paper explores the potential and feasibility of reusing plasterboard used for exterior infill walls, which is made of plasterboards and an increasingly used façade construction method in the UK.