With the urgency of addressing climate change, cross-laminated timber (CLT) has become a sustainable material to substitute reinforced concrete (RC) in building applications. There is a growing ...number of studies on the life cycle assessment of CLT buildings worldwide, mainly based on historical weather files. This study integrates climate change on life cycle greenhouse gas emissions (LCGHGE) in CLT and RC buildings in five climate zones, including the product and construction (P&C), operational and End-of-Life (EoL) stages. The CCWorldWeatherGen tool is used to generate future weather data (i.e., the 2020s, 2050s and 2080s) for the A2 emissions scenario. The simulation results show heating demands will decline significantly and cooling demands will rise in all cases. By the 2080s, global warming will result in an average LCGHGE of 33.09% and 38.90% higher than the baseline scenario for RC and CLT buildings, respectively. Strategies to reduce space cooling demand and decarbonize electricity will become increasingly important in the future. The average LCGHGE of CLT buildings is 27.53%, 26.22%, 24.67% and 22.19% lower than those of RC alternatives in the baseline, the 2020s, 2050s and 2080s, respectively. The study demonstrates that the lower greenhouse gas (GHG) emissions and the greater benefits from EoL from CLT buildings outweigh the operational GHG savings benefits from the thermal mass of RC buildings, even when climate impact is taken into account. Therefore, CLT buildings are a feasible way to reduce GHG emissions from buildings in China.
With the development of internet, online reviews are user-generated content posted in the web-media era and can extract meaning from the comments through data-mining technology. The study uses python ...crawler to collect reviews and conduct post-occupancy evaluation on Oze National Park (ONP), a natural conservation in Japan. Content and semantic network analysis were adopted to study the high-frequency words and their relationships. Latent Dirichlet Allocation was utilized to uncover the dimensions of the comments. The conclusions were as follows: 1) Japanese tourists focused on landscape plants and nature, while the Chinese focused on facilities and experience, English concentrated on hiking activity. 2) The Ozegahara Plateau route and the Lake Ozenuma route were the two main courses in ONP. 3) 48% of the concept of the landscape of ONP was conveyed to the users. 4) Male tourists focused on location information and landscape, while females were concerned about the process and experience. The single-visitors paid attention to the road and boardwalk. Family tourism concentrated on experience and time while friends and couple-visitors preferred to perceive action. 5) The Lysichiton Americanus had become a basic feature of ONP, and visitors were satisfied with the landscape and experience.
Life cycle assessment (LCA) has been widely used to determine the environmental impact of mass timber construction (MTC) as a substitute for conventional construction. This article presents a ...systematic review of MTC from a life cycle assessment perspective. The goal and scope definition, life cycle inventory analysis, impact assessment and interpretation are examined and analyzed in 62 peer-reviewed articles. The results show the variety in scope, lifespan, system boundary, data sources and indicators. Studies on MTC have been conducted at the building material, component, structure, and entire building levels, as well as at the urban level. The majority of studies compare the LCA of reinforced concrete (RC) and cross laminated timber (CLT) buildings. The global warming potential (GWP) and life cycle energy are the most frequently evaluated category indicators among the articles. It is found that the average embodied energy of mass timber buildings is 23.00% higher than that of RC alternatives, while the average embodied greenhouse gas (GHG) emissions of RC buildings are 42.68% higher than that of mass timber alternatives. There is a clear general trend that mass timber buildings generally have lower GWP and life cycle primary energy (LCPE) than RC and steel buildings. Eventually, sensitivity analysis, carbon storage and outlook of the mass timber are also reviewed and discussed in the literature.
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•Passive, active and renewable ECMs under climate change are reviewed.•Insulation and window design are common ECMs, yet trends in research suggest a growing emphasis on potential ...strategy shifts to cooling techniques, photovoltaics and heat pumps.•ECMs should be tailored to specific climates, building types and cost-effectiveness.•Challenges of short-term gains versus long-term effectiveness of ECMs are discussed.•Embracing life cycle thinking, resilient design under uncertainty, and frequent building code revisions is crucial for climate change mitigation.
Energy conservation measures (ECMs) are often chosen for their immediate benefits, such as suitability to past/current climate conditions and rapid economic returns. However, the longevity of these ECMs poses a risk of becoming outdated or ineffective as climate change alters the very climatic parameters they were designed for. This paper provides insight into the foresight required when selecting an ECM, focusing on its long-term viability under global warming. The ECMs discussed encompass passive strategies such as building envelope insulation and window design, active systems like efficient HVAC and heat pumps, and renewable systems. The need for context-specific ECM selection tailored to local climate, building type, and cost-effectiveness is highlighted. Major challenges and barriers influencing the widespread adoption of ECMs under global warming are addressed, including: 1) considering long-term effectiveness in ECM decision-making, as measures effective initially may become disadvantageous in the future, and vice versa; 2) adopting a life cycle perspective considering both embodied and operational impacts; 3) developing robust, resilient building designs under climate change uncertainty; and 4) potential strategy shifts, such as transitioning from passive cooling techniques to active cooling systems. Meanwhile, policy interventions through regular updates to building codes and standards are needed to keep pace with evolving climate conditions and engage diverse stakeholders to balance multiple objectives, including environmental, societal, and human factors. Incorporating climate change into decision-making for ECM implementation is paramount for building energy adaptation to a warming climate.
With the development of mass timber, cross laminated timber (CLT) has gradually become a sustainable alternative to conventional building materials to alleviate the increasing energy consumption and ...carbon emissions by the building sector. This study aims to explore the life cycle greenhouse gas emissions (LCGHGE) and life cycle primary energy (LCPE) of three high-rise residential buildings in the cold region of China through a life cycle assessment approach. The three buildings are conventional reinforced concrete (RC), CLT and hybrid CLT buildings. The results show that CLT and hybrid CLT buildings produce 15.00% and 10.77% lower LCGHGE, respectively, compared to the RC building within a 50-year service life. A clear difference in greenhouse gas (GHG) emissions and primary energy (PE) in the product and construction stages is visible, with 46.52% and 37.24% of embodied GHG emissions reduced in CLT and hybrid CLT buildings, respectively, compared to the RC building. In the operational stage, RC building has lower PE and GHG emissions to CLT alternatives. The thermal mass effect has led to a 2.25% and 2.12% PE increase for space heating and cooling in CLT and hybrid CLT buildings, respectively, compared to the RC building. For the End-of-Life (EoL) stage, CLT demonstrates great recycling potential and biomass residues. The sensitivity analysis shows that the design of the low U-value of the building envelope and high-efficiency energy systems has a significant relationship with energy reduction during the operational phase of the three buildings, magnifying the impacts of the initial and EoL stages.
•CLT and hybrid CLT buildings produce 15.00% and 10.77% less LCGHGE than RC buildings in Tianjin, China, respectively.•Mass timber construction shows great advantages over RC buildings in the P&C/EoL stage.•The operational GHG emissions and PE of CLT and hybrid CLT buildings were 12–13% higher than those of the RC building.•Energy-efficient methods can enhance the LCA performance of hybrid CLT building.
The recycling potential (RP) indicates the ability of building materials to form a closed-loop material flow, that is, the material efficiency during its whole life cycle. Mass timber constructions ...and concrete buildings vary widely in RP, but the differences are difficult to calculate. This paper proposed a level-based scheme to compare the RP of mass timber and concrete buildings, and a BIM-Eco2soft-MS Excel workflow coupling Material Cycle Database and digital design tools were established to obtain information on building materials, resource consumption, and environmental impact for the RP calculation. Taking a residential building as an example, the difference in RP between mass timber and concrete at the material-level is firstly discussed. Then at the component-level, the RP of the wood structure component and concrete component is compared, and the optimization methods are proposed. Finally, the difference in RP between the mass timber building and reinforced concrete building at the building-level are illustrated. The results show that the RP of mass timber building is higher, and the disassembly ability is better. Within a 100-year service life, the RP of mass timber buildings is 73% and that of the reinforced concrete building is 34%. The total amount of material consumption and waste of the Variant CLT is 837,030 kg and 267,237 kg respectively, which is less than one-third of that of concrete buildings (3,458,488 kg; 958,145 kg). The Global Warming potential (GWP) of these two variants is −174.0 kgCO2/m2 and 221.0 kgCO2/m2 separately, indicating that the Variant CLT can realize negative carbon emissions and gain ecological benefits. A sensitivity analysis is conducted to explore the potential impacts of certain parameters on GWP and RP of buildings. The research can provide the reference for material selection, component design, and RP optimization of mass timber buildings. In addition, new ideas for assessing the potential of circularity as a design tool are proposed to support the transition towards a circular construction industry and to realize carbon neutrality.
The COVID-19 pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has substantially damaged the global economy and human health. The spike (S) protein of ...coronaviruses plays a pivotal role in viral entry by binding to host cell receptors. Additionally, it acts as the primary target for neutralizing antibodies in those infected and is the central focus for currently utilized or researched vaccines. During the virus's adaptation to the human host, the S protein of SARS-CoV-2 has undergone significant evolution. As the COVID-19 pandemic has unfolded, new mutations have arisen and vanished, giving rise to distinctive amino acid profiles within variant of concern strains of SARS-CoV-2. Notably, many of these changes in the S protein have been positively selected, leading to substantial alterations in viral characteristics, such as heightened transmissibility and immune evasion capabilities. This review aims to provide an overview of our current understanding of the structural implications associated with key amino acid changes in the S protein of SARS-CoV-2. These research findings shed light on the intricate and dynamic nature of viral evolution, underscoring the importance of continuous monitoring and analysis of viral genomes. Through these molecular-level investigations, we can attain deeper insights into the virus's adaptive evolution, offering valuable guidance for designing vaccines and developing antiviral drugs to combat the ever-evolving viral threats.
•The spike (S) protein of SARS-CoV-2 is crucial for cell entry and subsequent antibody neutralization.•The S protein is subject to adaptive evolution, exhibiting multiple sites of positive selection.•Mutations in the S protein, whether isolated or in combination, influence transmissibility, immune escape, and pathogenicity.•This review discusses the structural implications of critical S protein mutations and examines the molecular mechanisms of epistatic interactions.
A nesting ubiquitiform (NU) approach was developed to characterize the mesostructural features of polymer-bonded explosives (PBXs), and then used to predicate some equivalent physical properties of ...PBXs, which can also be expected to be extended to other composites with complicated internal mesostructures. To verify the availability, two NU models for two kinds of PBX with different compositions are presented, which are PBX 9501 and LX-17, based on which, the equivalent thermal conductivities were calculated. Particularly, it is so encouraging that an analytical expression of the equivalent thermal conductivity was obtained only under a simply assumption of homogeneity. Moreover, it was found that the numerical results calculated by both the recursive algorithm and the analytical expression were in good agreement with the experimental data. In addition, it is also shown that such a physical property as the equivalent thermal conductivity is indeed independent of the meso-configuration of the location distribution of the explosive particles and the voids inside the PBX, which seems consistent with the common expectations and lays the foundations for the application of ubiquitiform to investigating some equivalent properties of composites.
Per- and polyfluoroalkyl substances (PFASs) in high-latitude polar regions and the Tibetan Plateau have received widespread international attention. Here, we measured 18 PFASs and 11 major isomers in ...the lake water, sediment, and surrounding runoff of Lake Nam Co in 2020. The concentrations of ultrashort-chain trifluoroacetic acid (TFA) and perfluoropropanoic acid (PFPrA) and major isomers of perfluoooctanoic acid (PFOA) and perfluoooctane sulfonate acid (PFOS) in water bodies in high-latitude polar regions and the Tibetan Plateau are reported for the first time. The results showed that the concentration of ∑PFASs in glacial runoff was approximately 139 % greater than that in nonglacial runoff. The concentrations of ∑PFASs in the lake water and sediment in the southern lake with multiple glacial runoff events were approximately 113 % and 108 % higher, respectively, than those in the northern lake. The concentrations of short-chain perfluorobutanoic acid (PFBA) and ultrashort-chain TFA and PFPrA, which may be indicators of ice and snow melt, exhibited significant spatial heterogeneity. Overall, the spatial heterogeneity of PFAS concentrations in the water, sediment and surrounding runoff of Lake Nam Co may be caused mainly by glacial melting.
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•Eighteen PFASs and major isomers of PFOA and PFOS were simultaneously analyzed.•Ultrashort-chain TFA and PFPrA in water on the Tibetan Plateau were first reported.•The concentrations of PFASs in the Nam Co Basin exhibited spatial heterogeneity.•TFA, PFPrA and PFBA had the most significant spatial heterogeneity.•PFAS spatial heterogeneity in the Nam Co Basin may be caused by glacial melting.
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