To assess the progress towards a circular economy, numerous circularity metrics have been developed in recent years. However, there is a lack of alignment between circularity metric results and greenhouse gas emissions, as circularity metrics are mainly geared towards capturing material efficiency of circularity strategies and mostly disregard energy use. We target this gap by developing a new mass-based circularity metric that considers both material and energy resources (i.e., fuel and electricity). The circularity metric results are compared to the midpoint impact category Global Warming Potential in two case studies, where circularity strategies are applied to energy consuming products in several different scenarios. The results show that by including energy resources, the new metric is more aligned with GWP than purely material-based metrics. We discuss how this alignment changes in different systems and in which situations the circularity metric is a suitable proxy for GWP. 

Previous research has shown a lack of studies with comparisons between primary (virgin) and secondary (re-used) building materials, and their embodied emissions. The creation of different scenarios comparing the environmental impact of virgin vs. re-used materials is also motivated by the scarcity of raw materials in the world and the emergency of mitigating greenhouse gas (GHG) emissions from buildings. The aim of this study was to investigate scenarios, including new vs. re-used building products, applying the LCA method for a wooden single-family building. The findings showed a 23% reduction potential for total released (positive) CO2e when comparing the Reference scenario with Scenario I, using re-used wooden-based materials. Further, Scenario II, using all re-used building materials except for installations, showed a 59% CO2e reduction potential compared to the Reference scenario. Finally, Scenario III, which assumes all re-used building products, showed a 92% decreased global warming potential (GWP) impact compared to the Reference scenario. However, when including biogenic carbon and benefits (A5 and D module), the Reference scenario, based on newly produced wooden building materials, has the largest negative GHG emissions. It can be concluded that the re-use of building products leads to significant carbon savings compared to using new building products.

Greenhouse Gas (GHG) emissions significantly impact the environment and human health, but many people are unaware of how their daily choices affect climate change. Carbon calculators estimate emissions in sectors like construction, digital health, transportation, and food production. However, they are still developing and face challenges that require attention from both industry and academia. Researchers highlight the absence of a unified framework for assessing these tools, leading to simplistic binary evaluations, which result in inaccuracies in household tool evaluations. In the current study, an assessment framework has been created by integrating existing binary frameworks and incorporating the MCDA method for weighted multi-criteria evaluation, offering a quantitative scoring system for qualitative criteria. This dual-criteria framework addresses both practical and academic aspects of the evaluated tools. The framework was used to evaluate 15 tools chosen for their prominence in search engine results and their impact on scientific publications. Findings revealed that tools such as Svalna, WWF calculator, and Carbon Savvy produce comparable results, while others, like the UN CF calculator, show deviations up to 136 tons. The study highlights challenges related to feasibility, availability of resources, and user engagement, noting that the criterion for accessibility for special groups received a score of zero across all CF tools. The work is expected to yield enhanced understanding that will aid in the selection of appropriate CF tools, foster sustainable practices, and offer developers direction to ensure their designs conform to established standards.

The aim of this study was to investigate how the carbon accounting of a wooden single-family house is affected by (1) decreasing the carbon footprint by changes in building design, (2) differentiating biogenic carbon from fossil carbon and (3) including external benefits beyond the state-of-the-art system boundaries. The motivation of exploring different system boundaries, improved building design and investigating benefits aside of system boundaries rely on the fact of having the “full” picture of GHG emissions of building products. Changes in building design were analyzed by life cycle assessment (LCA) focusing on greenhouse gas (GHG) emissions, while the costs were assessed by using lice cycle cost (LCC). The findings showed that by including positive and negative emissions from the production phase for an improved building design within scenario 4 ‘Cradle to Gate + Biogenic Carbon + D module’ has the lowest embodied GHG emissions when compared to other approaches with −3.5 kg CO2e/m2/y50. Considering the impacts of the whole building, the lowest GHG emissions are within the scenario 8 ‘Cradle to Grave + Biogenic Carbon + D module‘ for the improved building design with −0.7 kg CO2e/m2/y50. The results suggest that a change to sustainable alternatives for building components that makes the whole building to be constructed by wood, could lead to significant reduction of GHG emissions compared to conventional material choices. Economically, testing sustainable solutions, the highlighted results are the construction costs that are almost double higher for CLT elements for the foundation compared to concrete.

In this study, an environmental and economic assessment of hydrogen production from biowaste and biomass is performed from a life cycle perspective, with a high degree of primary life cycle inventory data on materials, energy, and investment flows. Using SimaPro LCA software and CML-IA, 2001 impact assessment method, ten environmental impact categories are analyzed for environmental analysis. Economic analysis includes capital and operational expenditures and monetization cost of life cycle environmental impacts. The hydrogen production from biowaste has a high climate impact, photochemical oxidant, and freshwater eutrophication than biomass while it performs far better in ozone depletion, terrestrial ecotoxicity, abiotic depletion-fossil, abiotic depletion, human toxicity, and freshwater ecotoxicity. The sensitivity analysis of LCA results indicates that feedstock to biogas/pyrolysis-oil yields ratio and the type of energy source for the reforming process can significantly influence the results, particularly climate change, abiotic depletion, and human toxicity. The life cycle cost (LCC) of 1 kg hydrogen production has been accounted as 0.45–2.76 € with biowaste and 0.54–3.31 € with biomass over the plant's lifetime of 20 years. From the environmental impacts of climate change, photochemical oxidant, and freshwater eutrophication hydrogen production from biomass is a better option than biowaste while from other included impact categories and LCC perspectives it’s biowaste. This research contributes to bioresources to hydrogen literature with some new findings that can be generalized in Europe and even globally as it is in line with and endorse existing theoretical and simulation software-based studies.

The food supply chain is responsible for a large share of the anthropogenic contribution to global warming, as well as being a major contributor to several other impact categories such as acidification and eutrophication. Therefore, it is necessary to find ways of limiting the impact from food production and the food supply chain. Many crops are not adapted to growing in regions with cold climate, which creates the need to either import them or to use production methods such as greenhouses to artificially create good conditions for the crops. Sweden is currently reliant on imports for many different crops, including tomatoes where most of the consumption is covered by import from the Netherlands. This study uses life cycle assessment to analyze the potential environmental impact of Swedish tomato consumption, by comparing several year-round domestic production scenarios with scenarios representing import from the Netherlands. This is done by using a greenhouse simulation software to simulate a theoretical greenhouse placed in both countries, and then using the simulation results in combination with data from the database EcoInvent to perform a life cycle assessment. The results showed that Swedish domestic production has the potential to decrease the environmental impact of tomatoes consumed in Sweden, when compared to import from the Netherlands. There were a couple of combinations of production scenarios and impact categories where the Dutch production performed better, but the Swedish production scenarios performed better in general. The results also clearly showed that scenarios using LED lighting systems consistently had a lower impact than similar production scenarios using high-pressure sodium lighting systems. The choice of energy sources was identified as a crucial factor when it comes to the environmental impact of the studied systems.

The concept of Circular Economy is a principle aiming to improve sustainable development by reducing resource use and impact on ecological systems. An increasing number of companies are applying this theory on design strategies and business models in order to close, slow and narrow material loops. To highlight the importance, guide practitioners, and evaluate the progress of circular economy, a high number of circularity metrics (C-metrics) have been developed. However, little attention has been given to creating a connection between quantification of circularity and environmental performance. Existing metrics also do not highlight the interplay between micro (product), meso (industrial symbiosis), and macro (regional) level circularity. Moreover, existing metrics do not capture all material loops and do not adopt a value chain perspective on material flows. To improve the connection between C-metrics and environmental performance, a framework connecting circular economy strategies and material flows was developed. Based on this framework, a material flow-based C-metric was designed aimed at converting mechanisms of closing, narrowing and slowing material loops into a single-point value. To evaluate its feasibility, the metric was tested on three circular business models that represent all three mechanisms in a value chain perspective. The results showed that the metric is feasible in more situations than existing metrics and that the circularity value is highly dependent on assumptions. In future studies, the metric should be tested and compared to Life Cycle Assessments on multiple system levels to ensure that it generates valid results. Furthermore, user input assumptions should be standardized to ensure metric reliability.

Biofuels policy instruments are important in the development and diffusion of biogas as a transport fuel in Sweden. Their effectiveness with links to geodemographic conditions has not been analysed systematically in studying biogas development in a less urbanised regions, with high potential and primitive gas infrastructure. One such region identified is Gävleborg in Sweden. By using value chain statistics, interviews with related actors, and studying biofuels policy instruments and implications for biogas development, it is found that the policy measures have not been as effective in the region as in the rest of Sweden due to different geodemographic characteristics of the region, which has resulted in impeded biogas development. In addition to factors found in previous studies, the less-developed biogas value chain in this region can be attributed particularly to undefined rules of the game, which is lack of consensus on trade-off of resources and services, unnecessary competition among several fuel alternatives, as well as the ambiguity of municipalities’ prioritization, and regional cultural differences. To strengthen the regional biogas sector, system actors need a strategy to eliminate blocking effects of identified local factors, and national policy instruments should provide mechanisms to process geographical conditions in regulatory, economic support, and market formation.

The objective of this paper was to explore long-term costs for a single-family house in Sweden during its entire lifetime. In order to estimate the total costs, considering construction, replacement, operation, and end-of-life costs over the long term, the life cycle cost (LCC) method was applied. Different cost solutions were analysed including various economic parameters in a sensitivity analysis. Economic parameters used in the analysis include various nominal discount rates (7%, 5%, and 3%), an inflation rate of 2%, and energy escalation rates (2-6%). The study includes two lifespans (100 and 50 years). The discounting scheme was used in the calculations. Additionally, carbon-dioxide equivalent (CO(2)e) emissions were considered and systematically analysed with costs. Findings show that when the discount rate is decreased from 7% to 3%, the total costs are increased significantly, by 44% for a 100-year lifespan, while for a 50 years lifespan the total costs show a minor increase by 18%. The construction costs represent a major part of total LCC, with labor costs making up half of them. Considering costs and emissions together, a full correlation was not found, while a partial relationship was investigated. Results can be useful for decision-makers in the building sector.

The aim of this study is to assess how the use of fossil and nuclear power in different renovation scenarios affects the environmental impacts of a multi-family dwelling in Sweden, and how changes in the electricity production with different energy carriers affect the environmental impact. In line with the Paris Agreement, the European Union has set an agenda to reduce greenhouse gas emissions by means of energy efficiency in buildings. It is estimated that by the year 2050, 80% of Europe's population will be living in buildings that already exist. This means it is important for the European Union to renovate buildings to improve energy efficiency. In this study, eight renovation scenarios, using six different Northern European electricity mixes, were analyzed using the standard of the European Committee for Standardization for life cycle assessment of buildings. This study covers all life cycle steps from cradle to grave. The renovation scenarios include combinations of photovoltaics, geothermal heat pumps, heat recovery ventilation, and improvement of the building envelope. The results show that while in some electricity mixes a reduction in the global warming potential can be achieved, it can be at the expense of an increase in radioactive waste production, and, in mixes with a high share of fossil fuels, the global warming potential of the scenarios increases with time, compared with that of the original building. It also shows that in most electricity mixes, scenarios that reduce the active heat demand of the building end up in reducing both the global warming potential and radioactive waste, making them less sensitive to changes in the energy system.