Determining the carbon footprint reduction of reusing lightweight exterior infill walls: A case study of a school building in the United Kingdom

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.