Journal Articles

Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915

Browse

Author: search.filters.author.Dowdell DHas files: Yes

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Dynamic carbon budgets and carbon debts for Aotearoa New Zealand and its building sector
    (Elsevier Ltd, 2026-01-01) Weerasinghe SN; McLaren SJ; Boulic M; Dowdell D; Chandrakumar C
    The remaining carbon budget (RCB) is a crucial parameter when setting climate budgets for nations and economic sectors that want to measure their progress in climate change mitigation. The Paris Agreement is the most widely used and accepted climate change mitigation target, and the global RCB specified by the Intergovernmental Panel for Climate Change (IPCC) provides the carbon budget remaining from the beginning of 2020 that can be emitted as CO2 before the Paris Agreement’s target is exceeded. This research investigates the global RCB allocation to the national and building sector level in Aotearoa New Zealand, including consideration of different sharing approaches and modelling of potential future dynamic parameters for the RCB allocation, that are required to stay below 1.5 °C warming between the years 2024 and 2050. The average national RCB ranges from 159 to 339 MtCO₂ from year 2024; based on an average annual emissions rate of 38 MtCO₂, it will be depleted in 4–8 years. Therefore, this study proposed a dynamic carbon debt framework that provides a more realistic representation of dynamic RCBs and the carbon debt over future years. Key findings include the urgency of timely interventions, the need for additional mitigation strategies beyond the current policy approach which is largely focused on increased plantation forestry, and the usefulness of time-disaggregated carbon budgeting to address exhaustion of the RCB. Overall, this study demonstrates the relevance of dynamic budgeting to guide effective climate policy at both the national and building sector levels.
  • Thumbnail Image
    Item
    Policy implications of time-differentiated climate change analysis in life cycle assessment of building elements in Aotearoa New Zealand
    (Springer-Verlag GmbH, 2025-03-21) McLaren SJ; Elliot T; Dowdell D; Wakelin S; Kouchaki-Penchah H; Levasseur A; Hoxha E
    Purpose: Climate change policies are increasingly including time-dependent carbon targets for different economic activities. However, current standards and guidelines for climate change assessment of buildings ignore these dynamic aspects and require use of static life cycle assessment (LCA). This research investigates how to better account for the timing of greenhouse gas (GHG) emissions and removals in LCAs of buildings and construction products, using a static and dynamic LCA case study of roofs, walls and floors in Aotearoa New Zealand residential dwellings. Methods: Static and dynamic LCA methods were used to assess the climate change impact of two assemblies each for external walls, ground floors and roofs used in stand-alone residential dwellings in Aotearoa New Zealand. Each assembly was modelled for a life cycle extending from material production, through to element construction, operational use, and final end-of-life treatment. Results were calculated as total GWP100 results for each life cycle stage, GWP100 results disaggregated into time periods, and as instantaneous and cumulative radiative forcing up to year 190. Sensitivity analysis was undertaken for the building reference service life, exposure zone, location, and end-of-life treatment. Results and discussion: Four time-related aspects were found to be particularly significant as regards their contribution to the final static LCA (sLCA) climate change results: -Inclusion versus exclusion of biogenic carbon storage in landfill -Modelling of end-of-life recycling activities using current versus future low or net zero carbon technologies (in module D) -Building reference service life (50 versus 90 years) -Choice of modelling parameters for landfilled timber and engineered wood products. Use of dynamic LCA (dLCA) enabled priorities to be identified for climate change mitigation actions in the shorter and longer term, and showed that half of the assemblies achieved net zero carbon by year 190 (timber wall, steel wall, timber floor). Conclusions: Timing of GHG emissions and removals should be included in LCAs to support decision-making in the context of achieving targets set in climate change policies. In particular, LCA results should show ongoing biogenic carbon storage in landfilled timber and engineered wood products. Carbon footprint standards, guidelines and calculation tools should be prescriptive about building and construction product reference service lives, the EofL fate for different materials/products, and modelling of forestry and landfill activities, to provide a level playing field for stakeholders.