Abstract
Global concentrations for greenhouse gases (GHGs) have seen a stark increase since the industrial revolution. Drastic measures are being implemented across many industries to meet net-zero targets by 2050 and mitigate the worst impacts of climate change. The built environment is a critical sector for climate change mitigation as buildings, and their associated construction and use, account for 36% of global final energy use and approximately 40% of energy and process-related carbon dioxide emissions. Additionally, the developed floor area is projected to double globally by 2060. Therefore, the built environment needs to reduce impacts while enabling new development. The environmental impacts of buildings must be measured to ensure impacts are being reducing and not merely shifted from one aspect of a building’s life to another or to another sector. Life cycle assessment (LCA) has become the predominant means of assessing the environmental impacts that occur throughout all stages of a products, or in this case a building’s, life. Therefore, this work investigates how LCA should be used to support the decarbonisation of the built environment and in doing so assesses the environmental impacts of multiple impact reduction strategies for buildings.The presented work in this thesis includes: a systematic literature review; an attributional LCA (aLCA) of a design-for-disassembly (DfD) building; a comparison of aLCA and consequential LCA (cLCA) results for an off-site construction building; and a cLCA for the use of on-site energy generation (PV) and on-site energy storage (battery) in an office building. A systematic literature review of 108 peer-reviewed academic articles found that LCA is typically used late in the design process and multiple strands of work are attempting to better integrate LCA and life cycle thinking earlier into the design process. The aLCA of the DfD building was conducted to investigate how strategies that focus on end-of-life and reusability compare against current industry target values for embodied [A1-A5] carbon, energy use [B6] and material reuse. The DfD study highlighted the importance in conducting LCAs for buildings and illustrated that simple metrics for amounts of materials designed to enable reuse can be used to track increases in circularity in the built environment without facing uncertainty commonly hindering end-of-life assessments. The off-site construction study highlighted that aLCA and cLCA results cannot be directly compared because they are addressing different goals for the assessments. The cLCA of energy technologies serves, to the best of the author’s knowledge, as the first study to use 15-minute measured data for a full year to assess the environmental impacts from changing a building’s operational load profile through the use of PV and a battery following a consequential methodology. Therefore, the study demonstrates the most rigorous cLCA for the use of batteries in buildings to date.
Based on the work presented in this thesis, the following statements can be made regarding the application of LCA within the built environment. aLCAs of individual buildings are descriptive by nature and their results should not be used to state the environmental impacts of changing demand for materials or processes. cLCA should be used to evaluate the effects of different impact reduction strategies and inform policy-level decisions. In addition, cLCA can be used to assess the impacts from changing a building’s operational energy use as these impacts occur over an extended period. However, the suitability of cLCA for individual buildings cannot be ascertained at this time due to the nature of when materials and construction-related processes are required through a building’s life cycle. It is recommended that the displaced processes for initial material use and construction practices be investigated to improve the assumptions commonly used for cLCAs when applied at building-scale.
| Date of Award | 29 Mar 2023 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Stephen Allen (Supervisor) & David Coley (Supervisor) |