Building on the Paris Agreement: making the case for embodied carbon intensity targets in construction

Progressive clients are targeting embodied carbon reduction through the introduction of carbon intensity targets (CITs). CITs challenge design teams to deliver buildings with supply chain carbon emissions below a set level per functional unit. Despite CITs acting as catalysts for innovation, there are few drivers for their use and substantial variations in their implementation. There is also no means for ensuring consistency between project CITs and national mitigation targets, nor a mechanism for ratcheting up ambitions as anticipated by the Paris Agreement on climate change. This paper discusses these concerns and suggests how CITs could in future be determined, implemented and enforced

Scenario analysis of embodied greenhouse gas emissions in UK construction

Motivated by national greenhouse gas (GHG) emissions budgets, the UK construction industry is pursuing reductions in emissions embodied in buildings and infrastructure. The current embodied GHG emissions benchmarks allow design teams to make a relative comparison between buildings and infrastructure but are not linked to sector or national GHG emissions reduction targets. This paper describes a novel model that links sector-level embodied GHG emissions estimates with project calculations. This provides a framework to consistently translate international, national and sector reduction targets into project targets. The required level of long-term GHG emissions reduction from improvements in building design and material manufacture is heavily dependent on external factors that the industry does not control, such as demand for new stock and the rate of electrical grid ‘decarbonisation’. A scenario analysis using the model suggests that, even if external factors progress along the better end of UK government projections, current practices will be insufficient to meet sector targets

Aligning carbon targets for construction with (inter)national climate change mitigation commitments

In the face of a changing climate, a growing number of construction firms are adopting carbon reduction targets on individual projects and across their portfolios. In the wake of the Paris Agreement, some firms are seeking a means of aligning their targets with sectoral, national and international mitigation commitments. There are numerous ways by which such an alignment can be achieved, each requiring different assumptions. Using data from the UK construction industry, this paper reviews current company commitments and progress in carbon mitigation; analyses the unique challenges in aligning construction targets, and presents a series of possible sectoral decarbonisation trajectories. The results highlight the disparity between current company targets and the range of possible trajectories. It is clear that a cross-industry dialogue is urgently required to establish an appropriate response that delivers both a widely-accepted target trajectory and a plan for its delivery. This paper is intended to stimulate and support this necessary debate by illustrating the impact of different methodological assumptions and highlighting the critical features of an appropriate response

Integrating embodied carbon into transport infrastructure scenarios

This report summarizes the aims, objectives and results of a DecarboN8 Seedcorn funded project completed in 2021. The project sought to develop resources that could support greater incorporation of capital (embodied) carbon emissions into transportation models and scenarios. Owing to a number of challenges related to data access, data quality and processing resource requirements, the project failed to deliver the primary intended outcome – an open and extendable prototype web resource on capital carbon emissions in transportation projects. However, the project did develop a large novel dataset and successfully delivered a number of the intended secondary outcomes. Subsequently, the links forged and insights gained throughout the project ultimately resulted in a successful funding bid to support further development in collaboration with key stakeholders. Datasets compiled under the project were incorporated into development of a new database and spatial tool under the Department for Transport’s Shared Digital Carbon Architecture (SDCA) programme, in turn informing strategic decision making within Government departments and Arm's-Length Bodies. The opportunity to deliver this subsequent high-impact project would not have arisen without stakeholder engagement supported by the DecarboN8 Seedcorn fund and the Centre for Research into Energy Demand Solutions (CREDS)

Thermodynamic insights and assessment of the ‘circular economy’

This study analyses the effect on energy use of applying a wide range of circular economy approaches. By collating evidence on specific quantifiable approaches and then calculating and analyzing their combined full supply chain impacts through input-output analysis, it provides a more complete assessment of the overall potential scope for energy savings that these approaches might deliver than provided elsewhere. Assessment is conducted globally, across the EU-27 and in the UK. Overall, the identified opportunities have the potential to save 6%–11% of energy used to support economic activity, worldwide and in the EU, and 5%–8% in the UK. Their potential is equivalent to the total scope for other industrial energy efficiency savings. The potential savings are further divided into those due to sets of approaches relating to food waste, steel production, other materials production, product refurbishment, vehicle provision, construction and other equipment manufacture. Each of these sets of approaches can make a key contribution to the total savings that are possible. Complementary use of energy and exergy metrics illustrates the way in which energy use might change and for the first time provides indication that in most cases other energy efficiency measures are unlikely to be adversely affected by the circular economy approaches. Potential for savings in the energy embodied in each key product input to each major sector is assessed, enabling prioritization of the areas in which the circular economy approaches have the greatest scope for impact and identification of supply chains for which they are underrepresented

Thermodynamic insights and assessment of the ‘circular economy’

This study analyses the effect on energy use of applying a wide range of circular economy approaches. By collating evidence on specific quantifiable approaches and then calculating and analyzing their combined full supply chain impacts through input-output analysis, it provides a more complete assessment of the overall potential scope for energy savings that these approaches might deliver than provided elsewhere. Assessment is conducted globally, across the EU-27 and in the UK. Overall, the identified opportunities have the potential to save 6%–11% of energy used to support economic activity, worldwide and in the EU, and 5%–8% in the UK. Their potential is equivalent to the total scope for other industrial energy efficiency savings. The potential savings are further divided into those due to sets of approaches relating to food waste, steel production, other materials production, product refurbishment, vehicle provision, construction and other equipment manufacture. Each of these sets of approaches can make a key contribution to the total savings that are possible. Complementary use of energy and exergy metrics illustrates the way in which energy use might change and for the first time provides indication that in most cases other energy efficiency measures are unlikely to be adversely affected by the circular economy approaches. Potential for savings in the energy embodied in each key product input to each major sector is assessed, enabling prioritization of the areas in which the circular economy approaches have the greatest scope for impact and identification of supply chains for which they are underrepresented

Bridging the climate mitigation gap with economy-wide material productivity

Projections of UK greenhouse gas emissions estimate a shortfall in existing and planned climate policies meeting UK climate targets: the UK’s mitigation gap. Material and product demand is driving industrial greenhouse gas emissions at a rate greater than carbon intensity improvements in the economy. Evidence shows that products can be produced with less carbon intensive inputs and demand for new products can be reduced. The economy-wide contribution of material productivity and lifestyles changes to bridging the UK’s mitigation gap is under studied. We integrate an input-output framework with econometric analysis and case study evidence to analyse the potential of material productivity to help the UK bridge its anticipated emissions deficits, and the additional effort required to achieve transformative change aligned with 2 and 1.5°C temperature targets. We estimate that the emissions savings from material productivity measures are comparable to those from the Government’s planned climate policy package. These additional measures could reduce the UK’s anticipated emissions deficit up to 73%. The results demonstrate that material productivity deserves greater consideration in climate policy

Science-Based Targets: On Target?

Companies are increasingly seeking to align their actions with the goals of the Paris Agreement. Over 1000 such companies have committed to the science-based targets initiative which seeks to align corporate carbon reduction targets with global decarbonisation trajectories. These ‘science-based targets’ are developed using a common set of resources and target-setting methodologies, then independently assessed and approved by a technical advisory group. Despite the initiative’s rapid rise to public prominence, it has received little attention to date in the academic literature. This paper discusses development of the initiative based upon a quantitative assessment of progress against each component of the science-based targets set by 81 early adopters, using information gathered from company annual reports, corporate social responsibility websites and Carbon Disclosure Project (CDP) responses. The analysis reveals a mixed picture of progress. Though the majority of targets assessed were on track and, in some cases, had already been achieved, just under half of the companies assessed were falling behind on one or more of their targets. Progress varied significantly by target scope, with more limited progress against targets focused on Scope 3 emissions. Company reporting practices were highly variable and often of poor quality. This paper concludes with a range of recommendations to improve the transparency, consistency and comparability of targets within this key agenda-setting initiative

Uncovering Blind Spots in Urban Carbon Management: The Role of Consumption-Based Carbon Accounting in Bristol, UK

The rapid urbanisation of the twentieth century, along with the spread of high-consumption urban lifestyles, has led to cities becoming the dominant drivers of global anthropogenic greenhouse gas emissions. Reducing these impacts is crucial, but production-based frameworks of carbon measurement and mitigation—which encompass only a limited part of cities’ carbon footprints—are much more developed and widely applied than consumption-based approaches that consider the embedded carbon effectively imported into a city. Frequently, therefore, cities are left blind to the importance of their wider consumption-related climate impacts, while at the same time left lacking effective tools to reduce them. To explore the relevance of these issues, we implement methodologies for assessing production- and consumption-based emissions at the city-level and estimate the associated emissions trajectories for Bristol, a major UK city, from 2000 to 2035. We develop mitigation scenarios targeted at reducing the former, considering potential energy, carbon and financial savings in each case. We then compare these mitigation potentials with local government ambitions and Bristol’s consumption-based emissions trajectory. Our results suggest that the city’s consumption-based emissions are three times the production-based emissions, largely due to the impacts of imported food and drink. We find that low-carbon investments of circa £3 billion could reduce production-based emissions by 25% in 2035. However, we also find that this represents <10% of Bristol’s forecast consumption-based emissions for 2035 and is approximately equal to the mitigation achievable by eliminating the city’s current levels of food waste. Such observations suggest that incorporating consumption-based emission statistics into cities’ accounting and decision-making processes could uncover largely unrecognised opportunities for mitigation that are likely to be essential for achieving deep decarbonisation

Methodology for the assessment of PV capacity over a city region using low-resolution LiDAR data and application to the City of Leeds (UK)

An assessment of roof-mounted PV capacity over a local region can be accurately calculated by established roof segmentation algorithms using high-resolution light detection and ranging (LiDAR) datasets. However, over larger city regions often only low-resolution LiDAR data is available where such algorithms prove unreliable for small rooftops. A methodology optimised for low-resolution LiDAR datasets is presented, where small and large buildings are considered separately. The roof segmentation algorithm for small buildings, which are typically residential properties, assigns a roof profile to each building from a catalogue of common profiles after identifying LiDAR points within the building footprint. Large buildings, such as warehouses, offer a more diverse range of roof profiles but geometric features are generally large, so a direct approach is taken to segmentation where each LiDAR point within the building footprint contributes a separate roof segment. The methodology is demonstrated by application to the city region of Leeds, UK. Validation by comparison to aerial photography indicates that the assignment of an appropriate roof profile to a small building is correct in 81% of cases