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]

• Different urban factors were identified to affect UHI during different seasons and times of day. • Spatial extents of the effect of various urban variables on UHI are presented. • Relationships between urban variables and UHI were strongly influenced by humidity. This study utilizes year-round temperature data observed in 15 cities around the United States (U.S.) to investigate the relationships between UHI and urban design attributes, and answer the following questions: (1) Whether and to what extent these relationships vary with the diurnal cycle and across seasons?, (2) What is the spatial extent within which UHI is affected by different urban variables?, and (3) Which climatic factors determine the correlations between UHI and urban variables? Our analysis revealed that while surface reflectance, vegetation and building height are more influential on winter UHI, the effect of anthropogenic heat and building density is independent of the season. Also, tree canopy cover, impervious area and built-up area were more dominant on nighttime UHI, and albedo, surface reflectance, vegetation and building height had stronger influence on daytime UHI. With regards to the spatial extent, while the effect of 3D urban variables and imperviousness was prominent in the immediate vicinity (250 m–1 km), the effect of vegetation, surface reflectance and anthropogenic factors extend to a larger surrounding area (4 km–8 km). Lastly, the relationships between UHI and urban variables were noted to be strongly driven by humidity in each location. [ABSTRACT FROM AUTHOR]