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A variety of climate mitigation strategies is available to mitigate climate impacts of buildings. Several studies evaluating the effectiveness of these strategies have been performed at the building stock level, but do not consider the technological change in building material manufacturing. The objective of this study is to evaluate the climate mitigation effects of increasing the use of biobased materials in the construction of new residential dwellings in Sweden under future scenarios related to technological change. A model to estimate the climate impact from Swedish new dwellings has been proposed combining official statistics and life cycle assessment data of seven different dwelling typologies. Eight future scenarios for increased use of harvested wood products are explored under different pathways for changes in the market share of typologies and in energy generation. The results show that an increased use of harvested wood products results in lower climate impacts in all scenarios evaluated, but reductions decrease if the use of low-impact concrete expands more rapidly or under optimistic energy scenarios. Results are highly sensitive to the choice of climate impact metric. The Swedish construction sector can only reach maximum climate change mitigation scenarios if the low-impact building typologies are implemented together and rapidly. [ABSTRACT FROM AUTHOR]

The demand for wood-based energy is foreseen to grow as energy and climate policies around the world promote the use of bioenergy for climate change mitigation. However, the carbon impacts of forest bioenergy range widely in the literature. The value-choices made on the response of forest management to bioenergy demand have a major influence on the results obtained from modeling exercises and may actually change the contribution of forest bioenergy from climate worsening to climate change mitigation. Despite their relevance, there is very little information, or transparency, as to the empirical basis by which these assumptions are chosen and evaluated against. This study aims to fill in this crucial knowledge gap through a mix of critical review, analysis of historical statistical data, and expert judgement. Several prominent studies reporting climate change mitigation from forest bioenergy in three countries are reviewed: Canada, Sweden, and Southeast USA. This analysis shows that the studies rely on assumptions that bioenergy demand will spur supply responses aimed at more efficient forest management and/or relative increases in forest area. Confronting literature assumptions with trends in historical data, we present the most extensive reality-check of bioenergy literature assumptions to date. We find that studies projecting a large role of forest bioenergy in climate change mitigation rely on assumptions that are too optimistic, at times outright unrealistic. We believe scientists could avoid the misinterpretation of their results and improve the policy relevance of their work by more transparent reporting of: i) value-laden assumptions, ii) their influence on the results, iii) the process and rationale behind such assumptions, especially distinguishing between assumptions that reflect incremental changes in management from assumptions requiring transformational change in several industrial sectors. • Accounted carbon benefits of forest bioenergy depend on underlying assumptions. • Forest bioenergy mitigates climate change only when additional biomass is produced. • Forest management responses assumed in the literature are overly optimistic. • Post Normal Science tools can help scientists avoid misinterpretation of results. • Scientists should better convey that model results are contingent on value-choices. [ABSTRACT FROM AUTHOR]

• The life cycle climate change impact of a solar microgrid in Sweden was estimated. • Average and marginal emission factors were estimated with explicit system boundaries. • Average and marginal emission factors of electricity use in Sweden differ. • Integration of a solar microgrid into the main grid may contribute to climate change. • The environmental performance of a solar microgrid depends strongly on the context. Microgrids are small-scale electricity networks that integrate distributed electricity generation with consumers and, potentially, with storage devices. There is growing interest in these systems, as they can offer solutions for electrification of remote areas, deployment of distributed renewable energy resources, and decarbonization of electricity supply. However, the potential benefits of microgrids in terms of climate change mitigation have not yet been thoroughly assessed. In this study, Life Cycle Assessment was performed to determine the climate change impact of integrating a solar microgrid system in western Sweden into the Swedish electricity grid. To determine whether replacement of grid electricity with electricity from the microgrid can lower greenhouse gas (GHG) emissions, average and marginal GHG emission factors (EFs) for electricity use were estimated with explicit spatial and temporal resolution, using historical data on electricity generation and trade, and life cycle EFs for electricity generation technologies. The assessment, with both marginal and average EFs, showed that integration of the microgrid into the Swedish electricity grid did not provide GHG emissions abatements, as the electricity from the microgrid displaced grid electricity with lower carbon intensity. It was found that a microgrid without batteries would have lower climate change impact, but would still fail to lower overall GHG emissions. Moreover, it was demonstrated that the methodological approach used for estimation of EFs and the definition of spatial boundaries could influence the obtained results. [ABSTRACT FROM AUTHOR]