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Circular Economy Research in the Built Environment: A Theoretical Contribution
Full text linkCircular economy is quickly gaining momentum across numerous research fields. The founding principles of circular economies lie in a different perspective on, and management of, resources under the idea that an ever-growing economic development and profitability can happen without an ever-growing pressure on the environment. As such, the built environment has a lot to contribute, being the sector with the greatest environmental impacts. However, the few existing cases of current research in the built environment from a circular economy perspective seem to have just replaced the 3R principle (reduce, reuse, recycle) with the new ‘buzz-word’. In this paper, we argue that a significantly different research approach is necessary if the circular economy is to keep up to its promise of being a new paradigm for sustainability. We therefore propose a framework to formulate building research from within a circular economy perspective. The framework is built around six pillars and acknowledges the key role of interdisciplinary research and that of both bottom-up and top-down initiatives to facilitate the transition to ‘circular’ buildings. Although theoretical in nature, the framework has been tested against current discourse about buildings and circular economies and it has proven a valuable tool to cluster existing initiatives and highlight missing interdisciplinary links. As such it can provide a valuable starting point to contribute to the theoretical foundations of building research from within the new paradigm of circular economies and also shape future research directions
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Embodied carbon and building retrofit: A heritage example
Full text linkThere is a critical need to reduce energy and associated carbon emissions from the existing built environment to help mitigate climate change. This requires significant upscaling of energy retrofitting. However, at present, retrofit assessments commonly consider only the operational impacts, neglecting the embodied carbon of measures. If retrofits are to make the greatest lifecycle savings, this embodied carbon should clearly be included.
This chapter assesses the embodied carbon of 40 retrofit measures, chosen as options to retrofit 13 residential heritage buildings in northern England. The assumptions and decisions made in the assessment process and the suitability of the international lifecycle assessment (LCA) standard EN 15978 – designed primarily for new construction – for heritage retrofit are discussed. The contribution of the different lifecycle stages is assessed, and the total embodied carbon of the different measures is identified.
Embodied carbon costs varied significantly across the different measures and material options, while in many cases offering similar operational carbon savings. In some cases, lifecycle stages which are often deemed insignificant were found to have a substantial impact on total embodied carbon. The study also identified a lack of available LCA data for some measures and noted a number of areas where EN 15978 was challenging to apply for retrofit projects.
These findings emphasise the importance of assessing embodied carbon for energy retrofitting, including as many lifecycle stages in the assessment as possible, and increasing the availability of LCA data for retrofit measures. Greater attention to this issue is needed to maximise lifecycle savings from the retrofit of existing buildings and thus help to mitigate climate change
Embodied Carbon in Buildings: Measurement, Management, and Mitigation
No full textEmbodied carbon is, to some extent, an odd beast. Its importance is evident and the beneficial consequences of its reduction undeniable. We know that the built envi- ronment is a major source of our carbon excesses, yet most policies focus only on part of the picture by capping operational energy consumption, for the use of buildings. We also know that the Intergovernmental Panel on Climate Change (IPCC) has warned that carbon reductions are needed now, not in 30 years’ time. Lowering the immediate emissions related to current building construction and demolition, the embodied carbon, is an obvious way to do so. In recent years, research on embodied carbon has therefore increased.Many fields of research develop steadily over the years, led by a small and coherent community of experts. Others quietly die, as the world moves on. Yet, for a very few topics, a moment comes when the world suddenly wakes up to their importance, and interest and attention start to snowball. This is such a moment for the subject of this book, the greenhouse gas emissions resulting from the construc- tion of buildings. Within this snowballing, of industry consultancies producing tools, of manufacturers benchmarking their products, of academics working together on major projects and even of the rumblings of political and regulatory change, there is, however, a real danger that the knowledge will become so dispersed that any real progress will be lost. Instead of forming a coherent body of work to inform policy and evoke real change in how we construct our built environment, we run the real risk of finding ourselves in a meaningless avalanche of disconnected ideas. This book, therefore, sets out to perform a vital task – to extract coherence, not chaos, from this outpouring of intellectual endeavour.Following the Paris Agreement, many nations have revamped their carbon plans, climate change drafts and carbon reduction targets. However, most governments remain stuck on the same single track of promoting operational energy efficiency in buildings, seemingly reluctant to acknowledge that this ignores an essential part of the picture. More energy-efficient buildings may reduce energy use and carbon emissions in the long term, but without a parallel focus on embodied energy and carbon, the real savings that could be made right now are lost, often instead resulting in an increase in short-term impact. Without a holistic understanding of the data, a sincere estimate of the uncertainties and an appreciation of the impact of human behaviour – both of occupiers and of constructors – this is a gamble with the future of our environment.We hope, therefore, that we have succeeded in representing, within this one volume, a persuasive argument for the importance of including embodied emissions in all aspects of construction. The argument is constructed over the first three sections through the main areas of debate over the measurement of embodied carbon, the key concepts of its management and a comprehensive overview of the mitigation strategies being proposed and enacted. The final section acknowledges that there are geographical differences in both context and approach, providing an overview of the state of knowledge and practice across regions of the world.Correct understanding of estimates is an essential starting point in the embodied carbon debate. If we cannot agree on our numbers, the conversation is prevented from moving forward. The first section, therefore, includes three chapters dedicated to uncertainty analysis, each of which offers novel and diverse points of view on the topic. The section also features chapters on the embodied carbon of different structural materials as well as the inclusion of some uncommon variables in embodied carbon assessments, such as surface albedo.The management section is perhaps the most diverse in the book and the one with the greater interdisciplinary outlook. It features chapters looking at early design tools, others aimed at bridging the current gap between research and practice and some looking at the significance of life cycle stages often neglected in embodied carbon assessments as well as the identification of carbon hotspots.The third section on mitigation is the natural conclusion of the ‘embodied carbon journey’ offered in the book. In other words, now that we know how to quantify embodied carbon and that we have also learned how to manage it, how can we actually reduce it? The section features a diverse set of chapters, looking at novel opportunities offered by the principles of a circular economy, sustainable technologies and optimisation strategies at both material and building levels.Views from different regions of the world conclude the book, and we are very proud of the broad coverage we managed to achieve. This section includes contri- bution from Australia, a world leader in embodied carbon, Africa, North and South America, Europe and China. We strongly believe all chapters offer a stimulating learning opportunity for all those interested.We hope that this book will succeed in its aims: to educate and enthuse both practitioners and scholars, to provide a comprehensive starting point for the novel researcher in the field and to act as an essential reference source for everyone working on this topic. Most of all, we hope to have created a document that collates, connects and makes sense of the current state of knowledge and that identifies clearly the questions still to be answered.We believe that bringing together key researchers in this area has already started the process of creating a virtual global community highlighting and validating theirdifferent views while acknowledging the similarity of the challenges we are facing. We hope that both readers of and contributors to this book will return to their work with renewed spirit and positivity, in the recognition that together we form a strong, passionate community working together to create real change towards a low-carbon future
Embodied emissions – knowledge building for industry
Full text linkA climate emergency has been declared and government, policymakers, industries, researchers and architects have tremendous potential to shift the entire industry towards a (net) zero greenhouse gas (GHG) emissions-built environment. In particular, they all play a different but equally important role in the early design phase when there is the greatest opportunity to make design decisions that can directly lead to buildings that reduce their overall GHG emissions towards zero within their life cycle. This chapter is specifically aimed at the role of building designers. Buildings account for 40% of total GHG emissions and are one of the main contributors to the climate crisis. Recent results show that as net zero emission buildings become more highly efficient, the contribution from EEG (embodied energy and greenhouse gases) increases, thus underlying its growing importance. Life Cycle Assessment (LCA) is used to assess embodied carbon and to provide early phase feedback in order to compare the environmental impact of different material, design and construction choices in buildings. However, it is still a relatively new method, and many designers often find it difficult to interpret the results in order to understand how a particular material, component and/or design proposal contributes to the overall GHG emissions in the built environment. This lack of fundamental knowledge and understanding presents a significant barrier to industry uptake and decarbonisation of the built environment. This chapter reports results from the International Energy Agency (IEA) EBC Annex 57 (subtask 4) using data from 80 international case studies, which were collected and systematically analysed alongside supporting data from the literature. The research findings are communicated through simplified diagrams and concise text presented in tabular form where possible, in order to support designers and other non-expert decision makers in the early stage design process. The results presented in this chapter offer a simple and easy to understand visual communication to help develop industry knowledge of net zero and embodied carbon, to help improve participation from key decision makers and more easily integrate science-based knowledge on embodied carbon in industry and in the mainstream.</p
Embodied carbon in building regulation – development and implementation in Finland, Sweden and Denmark
No full textInitiatives on operational carbon have been an integrated part of legislation in many countries for decades, but the issue of embodied carbon is just starting its breakthrough in a regulatory context. This chapter provides an account of how the introduction of LCA-based limit values for whole-life-carbon has been approached in Finland, Sweden and Denmark. The starting point for these whole-life-carbon declarations have been the policies outlined via national climate acts, and there has been extensive knowledge exchange between the three neighbouring countries. Still, the LCA-based assessment methods outlined for the regulation have taken significantly different paths. For instance, the Swedish approach focuses on the upfront carbon from production and construction processes, whereas the other two approaches include the use- and the end-of-life stages. The methodological variations reflect the different national weightings between the ease-of-application for users and the accuracy- to-scope of the building model and its real life-cycle impact. All three approaches have drawn up reference values for typical buildings, and have already, or are planning to, introduce politically defined limit values for new buildings. At the same time, distributions from a global carbon budget approach show large discrepancies between the emsissions ‘allowed’ for new constructions (<2 kg CO2e/m2/year) and the limit- and reference values in place for the countries (around 9-15 kg CO2e/m2/year). This makes it clear that additional giant leaps are needed for policies in the building industry to operate within the planetary boundaries.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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Real and apparent variations in embodied carbon impacts provided in EPD for construction products
No full textEnvironmental Product Declarations (EPD) provide information on the environmental impacts associated with products over their lifetime. In the construction industry, they have been developed to provide environmental data for use in building level life cycle assessments, and the European Standard EN 15804 has been developed to ensure consistency and enable their straightforward use at building level using EN 15798 and for infrastructure using EN 17472.
The reported embodied carbon impacts of a construction product can vary significantly and many examples of variation can be found in even a cursory search of the academic literature, including that focused on EPD. However there is rarely an explanation of the causes of variation, and the literature often includes suggestions that EPD are not robust or credible, because the large variation in impact seen must be indicative of methodological problems.
This leads to two problems. Firstly, our understanding of variation in EPDs remains incomplete and inadequate. We have little specific understanding of the types and causes of variation, and their significance for different product groups.
Secondly, continually focusing on EPD variation without studying cause or effect, leads to repetition of general statements about the reliability and data quality of EPD, and this has potentially had an impact on the take-up and use of EPDs in practice and policy. It also seems to assume some future state that, once a perfect methodology has been decided on, it will then provide perfect EPD without variation, and only then can we be allowed to start to make decisions around carbon reduction using consistent methods and data. This approach does not seem to respond with the urgency required to address the climate emergency, nor 12% of global CO2 emissions caused by construction materials and construction processes.
By reviewing the significant number of EPDs for cement, steel, brick, sawn timber and concrete now available, this chapter explores whether technological and geographical differences could be responsible for the variations found.
A number of different factors were found to influence impacts in EPD, including technology (production methods, inputs and product design), geography (electricity and energy mix), time (e.g. changes in grid mix), methodology (e.g. choice of allocation approach and system boundary) and granularity (i.e. the specificity of the EPD). Of these, variations in impacts within EPD caused by differences in technology and geography were considered to be real (reflective of actual differences in impact between products) and were often very significant (>100%) and not normally distributed. Variations due to methodological differences did exist but were considered unlikely to be the major cause of the variations seen in the GWP impact of construction products.
Variation still remains an issue, which must be considered and addressed in product comparisons and building level assessments. However, the hypothesis, that EPD data are robust or credible because of the range of variation seen in their impacts, has been rebutted and methodological differences should not therefore be considered a reason to delay assessments of building level embodied carbon at building or infrastructure level
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Approaches and system boundaries for urban carbon accounts
Full text linkMore than half of the global population now lives in cities, and the share of the urban population is projected to further increase to about two-thirds by 2050. The majority of human economic activities, 80% of global GDP, 60% to 80% of final energy consumption, and 75% of final-energy-use carbon emissions are related to urban activities. Therefore, cities are central to climate change mitigation. Given the fact that global supply chains play a significant role in urban activities, cities predominantly rely on their hinterlands to supply the resources they need. When accounting for emissions associated with the entire supply chain of products that enter the city for further processing or consumption, so-called consumption-based emissions (CBE), typically, more than half of emissions of cities are imported from outside their borders. Thus, it is important to distinguish between different scopes of urban emissions. Different accounting scopes, such as production-based emissions (PBE) and CBE, may lead to significant differences in emission patterns of cities and may greatly change the interpretation of the success of cities’ carbon mitigation efforts. This chapter provides a brief summary of the relevant literature on urban carbon footprints with a specific focus on different system boundaries and embodied carbon emissions. We show how the choice of a footprint metric will influence the outcome of carbon accounting, mitigation policies, and policy evaluation.</p
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