Embodied Emissions: From End-of-Life to Re-Use and Recycling

To reduce embodied carbon, retrofitting and re-using buildings is preferable to demolition and building new.

At the “end-of-life” phase of buildings, any materials that are not recycled contribute substantially to rapidly growing waste production. To avoid this waste challenge – as well as the need to extract, process and transport new raw materials – retrofitting (to improve energy efficiency) and re-using buildings can be preferable to demolition and building new. The longer a building and its elements last, the less embodied carbon is expended (Historic England 2019). The average lifetime of buildings of all types currently ranges from around 30 years in China and India (Liu, Bangs and Müller 2013; Pauliuk et al. 2013; Hong et al. 2016) to 80 years in the United States of America (Müller et al. 2006; Kapur et al. 2008). Extending building lifetimes would create significant opportunities to reduce aggregate embodied carbon.

In the circular economy, the material waste from buildings is “designed out”.

Applied to the built environment sector, the so-called circular economy envisions a future where the material waste related to buildings is “designed out.” This is achieved by keeping construction materials in use and extending the life of a building for as long as possible (Haas et al. 2015). The re-use and recovery of materials is essential towards achieving circular production and use of building materials. The most carbon savings at a building’s end-of-life comes from re-use: the re-use of a building, then reusing components, then reusing materials. By comparison, recycling and reprocessing of materials have lower decarbonisation benefits. Another path towards circularity is improving the efficiency of materials to enable better operating performance of buildings (see chapter 3).