In general, our contribution to the Buildings As Material Banks (BAMB) conference gives an overview of buildings that efficiently reuse structural components as well as a review of current research efforts addressing structural reuse. The reuse of structural components therefore offers great potential to save materials, energy and resources. While historic and contemporary projects highlight the environmental, time or cost benefits of building with reclaimed elements, many technological challenges remain. Further research provides parametric estimates of embodied carbon reductions when structural components are reused in a typical steel-framed, low-rise office building. Various scenarios regarding the impact of selective deconstruction, transportation, and cross-section oversizing are modelled and parameterized. The study computes carbon savings over one life cycle of the building project. Results show that reuse remains beneficial for long transport and high oversizing. The discussion calls for more comprehensive studies and refined metrics for quantifying selective deconstruction.
This report summarises the practices and technologies that can be implemented to significantly reduce CO2 emissions from the cement and concrete sector in Europe by 2050. An important message communicated in this report is to show that reduction efforts must be supported along the complete value chain and not by a single stakeholder. In this way, the concrete construction sector can reduce up to 80% of these emissions (compared to 1990) without major changes in terms of standards and with moderate investments. Moreover, this approach would be a major step towards a more circular economy in the sector which is estimated to be a key element of a sustainable economy. This report was written for the Europe Climate Foundation by Aurélie Favier, Karen Scrivener, Guillaume Habert and Catherine De Wolf at ETH Zurich and EPFL.
Greenhouse gas emissions from extracting and manufacturing building materials, often termed “embodied carbon,” are produced before buildings are occupied and are more critical to meeting global climate targets than commonly assumed. In order to motivate reductions in embodied carbon, we need better data and established benchmarks. Although Life Cycle Assessment (LCA) methods have been used to analyze individual buildings, there has not been an agreed-upon understanding of the order magnitude and range of variation of the embodied carbon of buildings. In order to address this knowledge gap, the largest known database of building embodied carbon was compiled, normalized, and analyzed. In addition to establishing the range of embodied carbon values, this research identified sources of uncertainty and proposed strategies to advance embodied carbon benchmarking practice. Kate Simonen, Barbara X. Rodriguez, and Catherine De Wolf addressed this in their Technology, Architecture & Design article.
The contribution of this work is the development of an interactive online tool, called deQo (database of embodied Quantity outputs), to provide reliable data about the Global Warming Potential of buildings (GWP, measured in kgCO2e/m2). Given the need for a long-term initiative, a framework is offered to create an interactive, growing online database allowing architects, engineers and researchers to input and compare their projects.DeQo is used for the Structural Engineers 2050 Commitment Initiative.
Whole life cycle emissions of buildings include not only operational carbon due to their use phase, but also embodied carbon due to the rest of their life cycle: material extraction, transport to the site, construction, and demolition. With feedback from a wide range of stakeholders – architects, structural engineers, policy makers, rating-scheme developers, this research presents an integrated assessment approach to compare embodied life cycle impacts of building structures.
Existing literature indicates that there is an urgent need for benchmarking the embodied carbon of building structures. To remediate this, a rigorous and transparent methodology is presented on multiple scales. On the material scale, a comparative analysis defines reliable Embodied Carbon Coefficients (ECC, expressed in kgCO2e/kg) for the structural materials concrete, steel, and timber. On the structural scale, data analysis evaluates the Structural Material Quantities (SMQ, expressed in kg/m2) and the embodied carbon for existing building structures (expressed in kgCO2e/m2). An interactive database of building projects is created in close collaboration with leading structural design firms worldwide. Results show that typical buildings range between 200 and 550 kgCO2e/m2 on average, but these results can vary widely dependent on structural systems, height, size, etc. On the urban scale, an urban modeling method to simulate the embodied carbon of neighborhoods is proposed and applied to a Middle Eastern case study. This research recommends new pathways for low carbon structural design, crucial for lowering carbon emissions in the built environment.
Life cycle impacts in buildings includes operational carbon for heating, cooling, hot water, ventilation, lighting, on the one hand, and embodied carbon for material supply, production, transport, construction and disassembly, on the other. Improved operational carbon has increased the percentage of embodied carbon in the total life cycle of buildings. Kuwait is looking at enhancing the sustainability of its built environment, as there is an urgent need to expand and build new cities. This research analyses the sustainability of the Middle Eastern built environment in order to provide the most appropriate strategies to respond to this demand.
Therefore, this paper looks at different alternatives to the current construction methodologies, such as cement replacement in concrete or rammed earth structural systems. The impact of three envelope and energy upgrades on the whole life cycle environmental performance of a Middle Eastern residential neighborhood is evaluated. Simulations are performed through urban modeling, resulting in a distribution of the embodied and operational impacts of buildings for the different design options. Based on the results showing embodied carbon can be lowered by 200 kgCO2e/m2, this paper offers guidelines for building codes and governments.
Lowering the embodied carbon dioxide equivalent (embodied carbon) of buildings is an essential response to national and global targets for carbon reduction. Globally, construction industry is developing tools, databases and practices for measuring embodied carbon in buildings and recommending routes to reduction. While the TC350 developed standardized methods for the assessment of sustainability aspects in construction works and Environmental Product Declarations, there is no consensus on how this should be carried out in practice. This paper evaluates the current construction industry practice through a review of both academic and professional literature, and through focus groups and interviews with industry experts in the field. Incentives in the available building codes, standards, and benchmarks are also analysed, as are the existing methodologies, tools and datasets. The multiple data sources are used to identify the barriers to the effective measurement and reduction of embodied CO2e in practice. This paper recommends that Governments mandate for improved data quality and support the development of a transparent and simplified methodology.
To reduce embodied carbon in buildings, two strategies are available. First, material efficiency is improved. Second, the materials are chosen for their low carbon content. The operational carbon of buildings has lowered recently, but for immediate emissions savings innovations in embodied carbon are needed. This research demonstrates that most material mass lies in roofs and floor slabs, rather than in walls and columns. Therefore, the first strategy to reduce impacts would be to lower their material quantities in floor and roof design. For the second strategy, alternative materials are studied. Vaulted masonry structures combine both strategies: vaults span spaces efficiently and masonry has a lower embodied impact than steel and concrete. Results demonstrate that a combination of both strategies effectively lowers the embodied carbon of buildings: typical floor and roof structures range around 440 kgCO2e/m2 whereas vaulted tile masonry can be as low as 60 kgCO2e/m2.
Paper analyses data from 200 buildings to
identify the embodied environmental impact of building structures.
In recent years, the percentage of embodied carbon dioxide in the
whole life cycle impact of buildings has been increasing while
innovations have lowered operational carbon dioxide. Operational
carbon dioxide emissions are due to heating, cooling, ventilation
and lighting, whereas embodied carbon dioxide is associated with
materials extraction, manufacturing, transportation, construction,
maintenance and demolition. Limited research on the latter prevents
an accurate evaluation of the whole life cycle impact of buildings.
Therefore, leading engineers have emphasised the urgent need for a global, standard assessment method for embodied carbon dioxide. To this end, this paper offers a uniform method by describing current work, quantifying material weights and finally calculating embodied carbon dioxide ranges. The approach is cradle-to-gate but can be expanded to cradle-to-grave. The survey contains data on 200 recently completed buildings obtained from industry. The results show that structural material quantities vary between 200 kg/m2 and 1800 kg/m2 and embodied carbon dioxide caries on the range 150–600 kgCO2e/m2. These numbers are analysed by programme type, structural system, size, number of floors and Leadership in Energy and Environmental Design (Leed) certification. In doing so, the paper emphasises the important role that structural engineers play in sustainability.
CUBES is an interdisciplinary research group led by Dr
Alice Moncaster aimed at facilitating a quicker transition to a
low-carbon, more sustainable built environment.
Of all industrial sectors, the built environment puts the most pressure on the natural environment. In the European Union, it accounts for 50% of all extracted materials, 42% of the final energy consumption, 35% of greenhouse gases (GHGs) emissions and 32% of waste flows. It is evident that irrespective of which problem sits at the top of the policy agenda—resource scarcity, energy security, or climate change and global warming—the built environment has a key role to play across all. Most of our past and present research focuses on embodied and whole life carbon of buildings and we are currently extending our work further to include embodied materials, resource depletion, circular economy, and – in general – a more holistic environmental impact assessment. We often use an industry-academia co-production of knowledge, as it has proved one of the most effective pathways to real-world impact.
Improved operational energy efficiency has increased the percentage of embodied energy in the total life cycle of building structures. Despite a growing interest in this field, practitioners lack a comprehensive survey of material quantities and embodied carbon in building structures. This thesis answers the key question: “What is the embodied carbon of different structures?” Three primary techniques are used: (1) a review of existing tools and literature; (2) a collaboration with a worldwide network of design firms through conversations with experts and (3) the creation of a growing interactive database containing the material efficiency and embodied carbon of thousands of buildings.
In four-dimensional (4D) design, the “time” parameter, i.e. the complete life cycle of a building, is taken into account. Life Cycle Design of the built environment is generally studied on three levels: materials, components and building. However, the interactions between the levels are not yet implemented in design strategies. This dissertation analysed how interactions between the building, component and material levels can support design for re-use through sustainable material management.