Journal: Buildings & Cities

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Publisher

Ubiquity Press

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ISSN

2632-6655

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2020 - 20255
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Publications 1 - 5 of 5
  • Barriers and opportunities of fast-growing biobased material use in buildings
    Item type: Journal Article
    Göswein, Verena; Arehart, Jay; Phan-huy, Catherine; et al. (2022)
    Buildings & Cities
    Limiting global warming to 1.5°C requires immediate and drastic reductions in greenhouse gas (GHG) emissions. A significant contributor to anthropogenic global GHG emissions is the production of building materials. Biobased materials offer the potential to reduce such emissions and could be deployed in the short term. Timber construction has received the main attention from policy and industry. However, the implementation of timber construction at the global scale is constrained by the availability of sustainably managed forest supplies. A viable alternative is fast-growing plants and the use of agricultural waste products. These can be deployed faster and are better aligned to local supplies of biomass and demands from the building sector. Fast-growing materials are generally able to achieve net-cooling impacts much faster due to their short rotation periods. The GHG emissions due to the production of biogenic building material can be compensated by regrowth of the new (replacement) plant and, overall, this will absorb CO2 from the atmosphere. A range of biogenic materials can be promoted and used as insulation materials and structural materials. Policy relevance Materials play an important part of the transition to a low carbon society, especially as many existing construction materials have large amounts of ‘embodied carbon’ in their manufacture. Given the need to rapidly reduce GHG emissions, public policies can promote a rapid transition to low carbon biogenic materials. The use of fast-growing biogenic materials for use in construction products can create carbon-neutral or even carbon-negative products. The use of biogenic materials in construction materials delivers larger GHG savings than their use in other sectors (e.g. biofuels). The use of these materials can be scaled up quickly due to their short rotation period. An integrated policy approach is needed that provides synergy between the energy, industry, housing and agriculture sectors to encourage the use of biobased materials.
  • Biogenic carbon in buildings: a critical overview of LCA methods
    Item type: Journal Article
    Hoxha, Endrit; Passer, Alexander; Ruschi Mendes Saade, Marcella; et al. (2020)
    Buildings & Cities
    The increasing pressure to reduce greenhouse gas emissions from buildings has motivated specialists to develop low-carbon products incorporating bio-based materials. The impact of these materials is often evaluated through life-cycle assessment (LCA), but there is no clear consensus on how to model the biogenic carbon released or absorbed during their life-cycle. This study investigates and compares existing methods used for biogenic carbon assessment. The most common approaches were identified through an extensive literature review. The possible discrepancies between the results obtained when adopting different methods are made evident through an LCA study of a timber building. Results identified that land-use and land-use-change (LULUC) impacts and carbon-storage credits are not included in most existing methods. In addition, when limiting the system boundary to certain life-cycle stages, methods using the –1/+1 criterion can lead to net negative results for the global warming (GW) score, failing to provide accurate data to inform decision-making. Deviation between the results obtained from different methods was 16% at the building scale and between 35% and 200% at the component scale. Of all the methods studied, the dynamic approach of evaluating biogenic carbon uptake is the most robust and transparent. Practice relevance This critical review identified key methodological differences between the most commonly used methods and recommended standards for biogenic carbon accounting in buildings. This indicates a lack of consensus and guidance for conducting LCAs of bio-based construction products and buildings using bio-based materials. A case study applying four different LCA approaches on a timber building identified the inability to compare results and create proper benchmarks. Moreover, different methods lead designers to pursue different strategies to reduce a building’s carbon footprint. Regulators, the construction industry and the construction products industry are directly affected by this lack of comparability. This research highlights the flaws and benefits of commonly used methods. A clear and grounded recommendation is for practitioners to adopt dynamic biogenic carbon accounting for future assessments of bio-based materials and buildings.
  • Carbon budgets for buildings: harmonising temporal, spatial and sectoral dimensions
    Item type: Journal Article
    Habert, Guillaume; Röck, Martin; Steininger, Karl; et al. (2020)
    Buildings & Cities
    Target values for creating carbon budgets for buildings are important for developing climate-neutral building stocks. A lack of clarity currently exists for defining carbon budgets for buildings and what constitutes a unit of assessment—particularly the distinction between production- and consumption-based accounting. These different perspectives on the system and the function that is assessed hinder a clear and commonly agreed definition of ‘carbon budgets’ for building construction and operation. This paper explores the processes for establishing a carbon budget for residential and non-residential buildings. A detailed review of current approaches to budget allocation is presented. The temporal and spatial scales of evaluation are considered as well as the distribution rules for sharing the budget between parties or activities. This analysis highlights the crucial need to define the temporal scale, the roles of buildings as physical artefacts and their economic activities. A framework is proposed to accommodate these different perspectives and spatio-temporal scales towards harmonised and comparable cross-sectoral budget definitions.
  • Fast-growing bio-based material can heal the World
    Item type: Other Journal Item
    Habert, Guillaume (2021)
    Buildings & Cities
    The construction industry faces many pressures including: to deliver both rapid urbanization and a steep decarbonization of the materials that it uses. Radical reductions in GHG emissions are needed by 2030, so the construction industry must drastically reduce its operational and embodied emissions within a short time frame. It is imperative to start implementing realistic solutions straightaway. Fast growing bio-based agricultural materials can store carbon in less than a decade and provide a realistic solution for building materials. Positive change can be created quickly by creating both supply push (agriculture) and demand pull (public procurement and regulatory demand).
  • Lifetimes of demolished buildings in US and European cities
    Item type: Journal Article
    Berglund-brown, Juliana; Dobie, Isaac; Hewitt, Jordaina; et al. (2025)
    Buildings & Cities
    Building lifetime is a useful metric that serves as an input for many analyses, including property valuation, life-cycle assessment, material flow analysis and building stock analysis. Additionally, building lifetime is essential for the adoption of circular economy principles and retrofitting in construction, which ultimately will help reduce greenhouse gas emissions in the built environment. Yet, limited end-of-life building data and a focus on the design lifetimes of buildings means estimates for actual building lifetimes are outdated, not empirically based or else not compared across regions. By first sourcing and cleaning an extensive dataset of approximately 15,000 demolished buildings, this paper conducts a statistical analysis to: empirically estimate average building lifetimes in nine US and four European cities; analyse trends in building lifetimes across a number of design variables; and understand building obsolescence by applying techniques from survival analysis to buildings. An average lifetime of 71 years was found across all buildings, with a standard deviation (SD) of 28. Significant differences in lifetimes of use types were identified, with residential buildings lasting the longest. Age of the city did not appear to influence the survivorship of demolished buildings, but current and past demolition trends could.
Publications 1 - 5 of 5