TOWARD A SOLUTION OF ALLOCATION IN LIFE CYCLE INVENTORIES: THE USE OF LEAST SQUARES TECHNIQUES

Purpose: The matrix method for the solution of the so-called inventory problem in LCA generally determines the inventory vector related to a specific system of processes by solving a system of linear equations. The paper proposes a new approach to deal with systems characterized by a rectangular (and thus non-invertible) coefficients matrix. The approach, based on the application of regression techniques, allows solving the system without using computational expedients such as the allocation procedure. Methods: The regression techniques used in the paper are (besides the ordinary least squares, OLS) total least squares (TLS) and data least squares (DLS). In this paper, the authors present the application of TLS and DLS to a case study related to the production of bricks, showing the differences between the results accomplished by the traditional matrix approach and those obtained with these techniques. The system boundaries were chosen such that the resulting technology matrix was not too big and thus easy to display, but at the same time complex enough to provide a valid demonstrative example for analyzing the results of the application of the above-described techniques. Results and discussion: The results obtained for the case study taken into consideration showed an obvious but not overwhelming difference between the inventory vectors obtained by using the least-squares techniques and those obtained with the solutions based upon allocation. The inventory vectors obtained with the DLS and TLS techniques are closer to those obtained with the physical rather than with the economic allocation. However, this finding most probably cannot be generalized to every inventory problem. Conclusions: Since the solution of the inventory problem in life cycle inventory (LCI) is not a standard forecasting problem because the real solution (the real inventory vector related to the investigated functional unit) is unknown, we are not able to compute a proper performance indicator for the implemented algorithms. However, considering that the obtained least squares solutions are unique and their differences from the traditional solutions are not overwhelming, this methodology is worthy of further investigation. Recommendations: In order to make TLS and DLS techniques a valuable alternative to the traditional allocation procedures, there is a need to optimize them for the very particular systems that commonly occur in LCI, i.e., systems with sparse coefficients matrices and a vector of constants whose entries are almost always all null but one. This optimization is crucial for their applicability in the LCI contex

A spatio-temporal life cycle assessment framework for building renovation scenarios at the urban scale

Reducing the energy consumption of buildings is a priority for carbon emissions mitigation in urban areas. Building stock energy models have been developed to support decisions of public authorities in renovation strategies. However, the burdens of renovation interventions and their temporal distribution are mostly overlooked, leading to potential overestimation of environmental benefits. Life Cycle Assessment (LCA) provides a holistic estimation of environmental impacts, but further developments are needed to correctly consider spatio-temporal aspects. We propose a spatio-temporal LCA framework to assess renovation scenarios of urban housing stocks, integrating: 1) a geospatial building-by-building stock model, 2) energy demand modelling, 3) product-based LCA, and 4) a scenario generator. Temporal aspects are considered both in the lifecycle inventory and the lifecycle impact assessment phases, by accounting for the evolution of the existing housing stock and applying time-adjusted carbon footprint calculation. We apply the framework for the carbon footprint assessment of housing renovation in Esch-sur-Alzette (Luxembourg). Results show that the renovation stage represents 4%–16% of the carbon footprint in the residual service life of existing buildings, respectively after conventional or advanced renovations. Under current renovation rates, the carbon footprint reduction would be limited to 3–4% by 2030. Pushing renovation rates to 3%, enables carbon reductions up to 28% by 2030 when combined with advanced renovations. Carbon reductions in the operational stage of buildings are offset by 8–9% due to the impacts of renovation. Using time-adjusted emissions results in higher weight for the renovation stage and slightly lower benefits for renovation

Nature

In this chapter we explore the nexus of Nature, Human and the Built Environment and how combined they shape and define the mindset required for regenerative sustainability. Importantly it demonstrates how rethinking sustainability must lead to regenerative economics, the central aspect of RESTORE. This chapter is based upon a number of patterns, developed throughout the short life of the working group, as the critical areas deemed necessary to scale jump from sustainability as usual (BAU) to Restorative Sustainability and on to Regenerative Sustainability

Challenge clusters facing LCA in environmental decision-making—what we can learn from biofuels

Purpose Bioenergy is increasingly used to help meet greenhouse gas (GHG) and renewable energy targets. However, bioenergy’s sustainability has been questioned, resulting in increasing use of life cycle assessment (LCA). Bioenergy systems are global and complex, and market forces can result in significant changes, relevant to LCA and policy. The goal of this paper is to illustrate the complexities associated with LCA, with particular focus on bioenergy and associated policy development, so that its use can more effectively inform policymakers. Methods The review is based on the results from a series of workshops focused on bioenergy life cycle assessment. Expert submissions were compiled and categorized within the first two workshops. Over 100 issues emerged. Accounting for redundancies and close similarities in the list, this reduced to around 60 challenges, many of which are deeply interrelated. Some of these issues were then explored further at a policyfacing workshop in London, UK. The authors applied a rigorous approach to categorize the challenges identified to be at the intersection of biofuels/bioenergy LCA and policy. Results and discussion The credibility of LCA is core to its use in policy. Even LCAs that comply with ISO standards and policy and regulatory instruments leave a great deal of scope for interpretation and flexibility. Within the bioenergy sector, this has led to frustration and at times a lack of obvious direction. This paper identifies the main challenge clusters: overarching issues, application and practice and value and ethical judgments. Many of these are reflective of the transition from application of LCA to assess individual products or systems to the wider approach that is becoming more common. Uncertainty in impact assessment strongly influences planning and compliance due to challenges in assigning accountability, and communicating the inherent complexity and uncertainty within bioenergy is becoming of greater importance. Conclusions The emergence of LCA in bioenergy governance is particularly significant because other sectors are likely to transition to similar governance models. LCA is being stretched to accommodate complex and broad policy-relevant questions, seeking to incorporate externalities that have major implications for long-term sustainability. As policy increasingly relies on LCA, the strains placed on the methodology are becoming both clearer and impedimentary. The implications for energy policy, and in particular bioenergy, are large

Assessing the effectiveness of green roofs in enhancing the energy and indoor comfort resilience of urban buildings to climate change: Methodology proposal and application

The effects of climate change on the built environment represents an important research challenge. Today, green roofs (GRs) represent a viable solution for enhancing energy and urban resilience in the face of climate change, as they can have a positive impact on the building's indoor thermal comfort and energy demand, as well as inducing various environmental benefits (easing urban heat island effects, improving the management of runoff water, reducing air pollution, etc.). Thus, it is important to be able to assess their effectiveness, both today and under future climate conditions, in order to evaluate whether they can also provide a valid long-term solution. In this paper, a simulation approach is proposed to evaluate the energy and indoor-comfort efficacy of GRs installed on a cluster of buildings with respect to climate change and demographic growth. To illustrate the proposed methodology, it has been applied to two European urban environments characterized by very different climatic conditions (Esch-sur-Alzette in Luxembourg and Palermo in Italy) considering their behaviour over a period of 60 years (2020, 2050, 2080). Results showed that, with respect to standard existing roofs (i.e., without the presence of green coverage), and considering the rising temperatures due to climate change, during cooling seasons GRs enabled significant energy savings (ranging from 20% to 50% for Esch-sur-Alzette and from 3% to 15% for Palermo), improvement of the indoor comfort (reduction of the average predicted mean votes − PMVs) and attenuation of the ceiling temperatures (2–5 °C for both contexts) of the buildings' top floors

A generalization of the orthogonal regression technique for life cycle inventory

Life cycle assessment (LCA) is a method used to quantify the environmental impacts of a product, process, or service across its whole life cycle. One of the problems occurring when the system at hand involves processes delivering more than one valuable output is the apportionment of resource consumption and environmental burdens in the correct proportion amongst the products. The mathematical formulation of the problem is represented by the solution of an over-determined system of linear equations. The paper describes the application of an iterative algorithm for the implementation of least square regression to solve this over-determined system directly in its rectangular form. The applied algorithm dynamically passes from an Ordinary Least Squares (OLS) problem to the regression problems known as Total Least Squares (TLS) and Data Least Squares (DLS). The obtained results suggest further investigations. In particular, the so called constrained least squares method is identifed as an interesting development of the methodology

Predicting Sustainable Economic Welfare – Analysis and perspectives for Luxembourg based on energy policy scenarios

Ambitious energy policies have been established in Luxembourg, which has one of the highest Gross Domestic Products (GDP) per capita in the world but still much depends on imported fuels and electricity. Born as an alternative to GDP, the Index of Sustainable Economic Welfare (ISEW) is applied in this study as a framework to predict socio-economic and environmental performances of Luxembourg in relation to energy policy scenarios. The ISEW for the 1960–2010 timeframe is firstly calculated and compared with GDP in order to disclose the impact of factors differently considered by the two indices, e.g. consumption trends, equity, air pollution, carbon emissions, consumer durables expenditures, investments, etc. A forecasting model to predict the ISEW trend until 2030 is then proposed to assess the relevance of national energy policies. The analysis of historical time-series shows that the ISEW grows over time at much slower pace than GDP, mostly due to increases in defensive expenditures. This gap may decline in the future by implementing those energy policies, providing a slight but tangible recovery of the economic welfare over the next 10–15 years. Several insights are ultimately given on the benefits and drawbacks of using the ISEW framework to assess long-term sustainability issues

Rethinking Sustainability Towards a Regenerative Economy

This open access book is based on work from the COST Action “RESTORE - REthinking Sustainability TOwards a Regenerative Economy'', and highlights how sustainability in buildings, facilities and urban governance is crucial for a future that is socially just, ecologically restorative, and economically viable, for Europe and the whole planet. In light of the search for fair solutions to the climate crisis, the authors outline the urgency for the built environment sector to implement adaptation and mitigation strategies, as well as a just transition. As shown in the chapters, this can be done by applying a broader framework that enriches places, people, ecology, culture, and climate, at the core of the design task - with a particular emphasis on the benefits towards health and resilient business practices. This book is one step on the way to a paradigm shift towards restorative sustainability for new and existing buildings. The authors want to promote forward thinking and multidisciplinary knowledge, leading to solutions that celebrate the richness of design creativity. In this vision, cities of the future will enhance users’ experience, health and wellbeing inside and outside of buildings, while reconciling anthropic ecosystems and nature. A valuable resource for scientists and students in environmental sciences and architecture, as well as policy makers, practitioners and investors in urban and regional development