Search

The concept of net-zero, climate-neutral buildings is attracting global attention, and it is widely recognised as a key solution for achieving climate neutrality targets in the construction sector. However, an increasing and confusing abundance of differing labels, definitions, and approaches is increasing worldwide. This article aims to chart the current progress of national net-zero building pathways and identify gaps and challenges that present a significant barrier to industry uptake and decarbonisation of the built environment worldwide. The national net-zero pathways include an analysis of building legislation, policy and voluntary frameworks in four selected countries, Norway, the United Kingdom, the United States and Singapore, which are all leading regional actors in the race to zero and achieving a climate-neutral construction sector. Firstly, the study provides an overview of each country-specific context and motivation related to climate change adaptation and mitigation in the construction sector. Secondly, a review of the essential features from market-leading net-zero definitions, methodologies, schemes, and tools describing specific building approaches is conducted in each investigated country. Finally, based on the selected net-zero building case studies, the article presents the most promising design strategies for both embodied and operational environmental impact reductions, considering each specific climatic and country context. The research results indicated that the system boundaries for embodied and operational indicators (energy or GHG emissions) presented in investigated net-zero frameworks vary significantly. Consequently, there is an urgent need for a harmonised and transparent standardisation to provide coherence through performed life cycle assessments of buildings. In terms of the design strategies for achieving net-zero ambition according to the investigated frameworks, the common approach is the integration of the passive and active design strategies for operational energy or GHG emission reduction. However, it is evident that in some net-zero building examples, the consideration of the embodied environmental impacts and potential reduction strategies is missing because of not being included and mandatory in the national net-zero framework. This work is built upon the current body of knowledge on existing net-zero building frameworks and already constructed buildings and provides practical indications for building policy development and environmental impact reduction strategies in future climate-neutral, net-zero building projects. • A review of the net-zero building frameworks in Norway, the United Kingdom, the United States and Singapore is presented. • Examines design strategies for embodied and operational environmental impact reductions based on net-zero building cases. • System boundaries and compensation options vary significantly among analysed net-zero frameworks. • Integrating climate mitigation measures with resilience design strategies is missing in the current net-zero frameworks. [ABSTRACT FROM AUTHOR]

The shipping sector is seeking options to reduce its emissions of greenhouse gases (GHGs) and achieve ambitious climate change mitigation goals. Unlike short-sea shipping that can rely on electrification of coastal vessels, drop-in biofuels are among the most promising options for deep-sea shipping decarbonization. However, environmental sustainability analyses of marine biofuels are limited, and usually do not include the influence of future changes in the background energy system nor the climatic effects of near-term climate forcers (NTCFs). In our study, we assess the climate change mitigation potential of various marine biofuels produced from forest residues in Norway (a country with ambitious plans for emission reduction from shipping) using a prospective life-cycle assessment (LCA) where the projected trends in the energy and transport sectors are integrated with improvements in the biofuel value chain for the next decades (2030–2050). Relative to fossil-based alternatives, climate mitigation potentials of biofuels range from 65% to 85% with short-term (GWP20) and to 78%–87% with long-term (GTP100) climate impacts. The inclusion of NTCFs reduces the mitigation benefits of biofuels in the short term, while it slightly increases them in the long term. The explicit modeling of technology and socio-economic changes under future policy scenarios indicates a reduction in the climate impacts of biofuels by up to 54% in 2050 when compared to the current situation. The amount of residues potentially available in Norway is sufficient to meet the present demand for liquid fuels in deep-sea shipping, thus providing yearly climate mitigation of 0.9–1.1 million tons of CO 2-eq (equal to 6–7% of today's climate impacts from the entire transport sector in the country). Our analysis shows the large climate change mitigation potential of drop-in biofuels, and it provides new quantitative estimates that can help guiding a sustainability shift in the deep-sea shipping sector. [Display omitted] • Climate mitigation from biofuels can range from 65% to 87% relative to fossil fuels. • Future inventory databases can cut up to 54% of marine biofuel's climate impacts. • NO x and SO x lower the climate impacts of biofuels in the short and medium terms. • Marine biofuels can mitigate 6–7% of the Norwegian transport sector's emissions. [ABSTRACT FROM AUTHOR]