As part of the Architect L7 apprenticeship programme at the University of Nottingham, Evans McDowall Architects have supported Raissa with her research project on Designing for Longevity. The study focuses on the residential typology and explores the potential of longevity in construction to reduce greenhouse gas (GHG) emissions. The research provides a useful guide for decision making during the design stage and proposes an amended approach to lifecycle embodied carbon assessments.

The research analyses a series of wall constructions including three popular historic walls and contemporary walls, assessing their environmental impact in terms of life-cycle embodied carbon emissions. Current lifecycle embodied carbon assessments (LCAs) use a standard 60-year lifespan, despite evidence that many structures outlive this. Therefore, the research addresses the limitations of current lifecycle embodied carbon assessments and proposes amendments to reflect the true material lifespans of each wall build-up.

To inform a practical analysis of the wall build-ups, the lifecycle embodied carbon assessments have been calculated with actual material lifespans. The total calculated embodied carbon figures for the amended lifespans have been divided by the predicted number of years the wall build-ups will last. The results are presented as annual embodied carbon emissions. When comparing the annual embodied carbon emissions, it is clear that historic wall types present a lower kgCO2e/yr when calculated for their maximum lifespans rather than a 60-year lifespan, as is standard for LCAs. As historic walls generally outlast 60 years, the new measurements take into account the embodied carbon emissions beyond the 60-year period, allowing for a more accurate representation.

Modern walls with shorter lifespans present a higher amount of embodied carbon per year. This is influenced by how the layers are put together, as materials are often used in a way that will become part of a complex building construction of different materials with different age rates. This affects the integrity of other layers when maintenance needs to be carried out, generating further GHG emissions during the In-Use stage.

The research has the potential to generate a positive impact on decision making processes when it comes to material choices and construction, considering possible future replacements / maintenance of elements and how the layers should be put together. The study also represents an alternative perspective on our current approach to calculating lifecycle embodied carbon, demonstrating that analysing each material individually and incorporating their actual lifespans into lifecycle embodied carbon assessment represents a more realistic approach. It highlights how embodied carbon figures can be represented as a measure of kgCO2e/yr, providing a more accurate and honest way to convey embodied carbon emissions.

Author: Raissa Machado