Search Results (181)

The UK’s net-zero by 2050 commitment necessitates urgent housing sector decarbonisation, as residential buildings contribute approximately 17% of national emissions. Post-1950 construction prioritised speed over efficiency, creating energy-deficient housing stock that challenges climate objectives. Current retrofit policies focus primarily on technological solutions—insulation and heating upgrades—while neglecting broader sustainability considerations. This research advocates systematically integrating Circular Economy (CE) principles into residential retrofit practices. CE approaches emphasise material circularity, waste minimisation, adaptive design, and a lifecycle assessment, delivering superior environmental and economic outcomes compared to conventional methods. The investigation employs mixed-methods research combining a systematic literature analysis, policy review, stakeholder engagement, and a retrofit implementation evaluation across diverse UK contexts. Key barriers identified include regulatory constraints, workforce capability gaps, and supply chain fragmentation, alongside critical transition enablers. An evidence-based decision-making framework emerges from this analysis, aligning retrofit interventions with CE principles. This framework guides policymakers, industry professionals, and researchers in the development of strategies that simultaneously improve energy-efficiency, maximise material reuse, reduce embodied emissions, and enhance environmental and economic sustainability. The findings advance a holistic, systems-oriented approach, positioning housing as a pivotal catalyst in the UK’s transition toward a circular, low-carbon built environment, moving beyond isolated technological fixes toward a comprehensive sustainability transformation. Full article

African catfish (Clarias gariepinus, AC) is one of the most widely farmed freshwater fish species in Central Europe. Processing operations generate up to 55% by-products (BPs), predominantly carcasses rich in proteins, lipids, and minerals. This study develops a comprehensive valorization process for ACBPs to recover gelatin, protein hydrolysate, fish oil, and pigments. The processing protocol consisted of sequential washing, oil extraction, demineralization, and biotechnological treatment to disrupt the collagen quaternary structure. A two-factor experimental design was employed to optimize the processing conditions. The factors included the extraction temperatures of the first (35–45 °C) and second fraction (50–60 °C). We hypothesized that enzymatic conditioning, combined with sequential hot-water extraction, would yield gelatin with properties comparable to those of mammalian- and fish-derived gelatins, while enabling a near-zero-waste process. The integrated process yielded 18.2 ± 1.2% fish oil, 9.8 ± 2.1% protein hydrolysate, 1.7 ± 0.7% pigment extract, and 25.3–37.8% gelatin. Optimal conditions (35 °C/60 °C) produced gelatin with gel strength of 168.8 ± 3.6 Bloom, dynamic viscosity of 2.48 ± 0.02 mPa·s, and yield of 34.76 ± 1.95%. Life cycle assessment (LCA) identified two primary environmental hotspots: water consumption and energy demand. This near-zero-waste biorefinery demonstrates the potential for comprehensive valorization of aquaculture BPs into multiple value-added bioproducts. Full article

Modern deep neural network (DNN) accelerators must sustain high throughput while avoiding performance degradation from supply voltage (VDD) droop, which occurs when large arrays of multiply–accumulate (MAC) units switch concurrently and induce high peak current ($IC{C}_{max}$) transients on the power delivery network (PDN). In this work, we focus on ASIC-class DNN accelerators with tightly synchronized MAC arrays rather than FPGA-based implementations, where such cycle-aligned switching is most pronounced. Conventional guardbanding and reactive countermeasures (e.g., throttling, clock stretching, or emergency DVFS) either waste energy or incur non-trivial throughput penalties. We propose SparseDroop, a unified hardware-conscious framework that proactively shapes instantaneous current demand to mitigate droop without reducing sustained computing rate. SparseDroop comprises two complementary techniques. (1) SparseStagger, a lightweight hardware-friendly droop scheduler that exploits the inherent unstructured sparsity already present in the weights and activations—it does not introduce any additional sparsification. SparseStagger dynamically inspects the zero patterns mapped to each processing element (PE) column and staggers MAC start times within a column so that high-activity bursts are temporally interleaved. This fine-grain reordering smooths $ICC$ trajectories, lowers the probability and depth of transient VDD dips, and preserves cycle-level alignment at tile/row boundaries—thereby maintaining no throughput loss and negligible control overhead. (2) SparseBlock, an architecture-aware, block-wise-structured sparsity induction method that intentionally introduces additional sparsity aligned with the accelerator’s dataflow. By co-designing block layout with the dataflow, SparseBlock reduces the likelihood that all PEs in a column become simultaneously active, directly constraining $IC{C}_{max}$ and peak dynamic power on the PDN. Together, SparseStagger’s opportunistic staggering (from existing unstructured weight zeros) and SparseBlock’s structured, layout-aware sparsity induction (added to prevent peak-power excursions) deliver a scalable, low-overhead solution that improves voltage stability, energy efficiency, and robustness, integrates cleanly with the accelerator dataflow, and preserves model accuracy with modest retraining or fine-tuning. Full article

This case study is an overview of architectural design solutions implemented in the construction of farming facilities and the technological processes necessary to support a sustainable farm that runs with nearly zero waste in a closed-loop system that functions with full energy independence. The research will thoroughly investigate the specific location and configuration of the farm units in the target area—providing an extensive description of all necessary building typologies and infrastructures. The text will provide a summary of the agricultural solutions implemented at the farm, which is located in the region of Vojvodina in the Republic of Serbia. This region consists mainly of fertile agricultural land and could be a template for further designs and innovations in sustainable farming. This case study concerns the design of a resilient and self-reliant farm complex that consists of multiple animal species (broilers, pigs, and cattle), including a biogas station. The study is meant to show that adjustments made in architectural design, variations in building typology, and smart urban planning can contribute significantly to the improvement of sustainability in agricultural practices. This case study demonstrates that investments in sustainable solutions not only benefit the environment but can also deliver significant economic returns for investors—thereby further stimulating growth and development in the field of sustainable agriculture. Full article

Poly(vinyl chloride) (PVC) is one of the most widely used polymers due to its strength, low cost, and light weight. Industrial production is mainly conducted by suspension polymerization, which facilitates the control of the emissions of vinyl chloride monomer (VCM), a known carcinogen. However, the process consumes large amounts of water and energy and generates residual compounds such as polyvinyl alcohol (PVA) and polymerization initiators, which must be properly managed to mitigate environmental impacts. To improve sustainability, this study applied mass- and energy-integration strategies together with a zero-liquid-discharge (ZLD) water-regeneration system that uses sequential aerobic and anaerobic reactors to recirculate process water with reduced PVA. Although these measures reduce resource consumption, they can displace or intensify other impacts; therefore, a comprehensive evaluation of the system is necessary. Accordingly, the objective of this study is to quantify and compare the potential environmental impacts (PEIs) of the improved PVC production process through a scenario-based assessment using a waste reduction algorithm (WAR). This is applied to four operating scenarios in order to identify the stages and flows that contribute most to the environmental burden. According to our literature review, there is limited published evidence that simultaneously combines mass/energy integration and a ZLD system in PVC processes; thus, this work provides an integrated assessment useful for industrial design. The environmental performance of the improved process was evaluated using WAR GUI software (v 1.0.17, which quantifies PEIs in categories such as toxicity, climate change, and acidification. Four scenarios were compared: Case 1 (excluding both product and energy), Case 2 (product only), Case 3 (energy only), and Case 4 (product and energy). The total PEI increased from 2.46 PEI/day in Case 1 to 6230 PEI/day in Case 4, with the largest contributions from acidification (5140 PEI/day) and global warming (496 PEI/day), mainly due to natural gas consumption (5184 GJ/day). In contrast, Cases 1 and 2 showed negative PEI values (−3160 and −2660 PEI/day), indicating that converting the toxic VCM (LD₅₀: 500 mg/kg; ATP: 26 mg/L) into PVC (LD₅₀: 2000 mg/kg; ATP: 100 mg/L) can reduce the environmental burden in certain respects. In addition, the ZLD system contributed to maintaining low aquatic toxicity in Case 4 (90.70 PEI/day). Full article

In the context of the zero-carbon transition, this article provides a comprehensive review of Organic Rankine Cycle (ORC) technologies for low-grade heat recovery and conversion to power. It surveys a wide range of renewable and waste heat sources—including geothermal, solar thermal, biomass, internal combustion engine exhaust, and industrial process heat—and discusses the integration of ORC systems to enhance energy recovery and thermal efficiency. The analysis examines various configurations, from basic and regenerative cycles to advanced transcritical and supercritical designs, cascaded systems, and multi-source integration, evaluating their thermodynamic performance for different heat source profiles. A critical focus is placed on working fluid selection, where the landscape is being reshaped by stringent regulatory frameworks such as the EU F-Gas regulation, driving a shift towards low-GWP hydrofluoroolefins, natural refrigerants, and tailored zeotropic mixtures. The review benchmarks ORC against competing technologies such as the Kalina cycle, Stirling engines, and thermoelectric generators, highlighting relative performance characteristics. Furthermore, it identifies key trends, including the move beyond single-source applications toward integrated hybrid systems and the use of multi-objective optimization to balance thermodynamic, economic, and environmental criteria, despite persistent challenges related to computational cost and real-time control. Key findings confirm that ORC systems significantly improve low-grade heat utilization and overall thermal efficiency, positioning them as vital components for integrated zero-carbon power plants. The study concludes that synergistically optimizing ORC design, refrigerant choice in line with regulations, and system integration strategies is crucial for maximizing energy recovery and supporting the broader zero-carbon energy transition. Full article

The present study aimed to design a process of brown onion skin transformation by sequential extraction to a cellulose-based immobilization carrier, along with detailed analysis of obtained extracts, pointing to approaching a “zero-waste” model of circular economy. The process of brown onion skin transformation started with semi-continuous sequential subcritical extraction via consecutive use of five solvents of increasing polarity (96, 75, 50, and 25% ethanol and water), followed by alkaline liquefaction of solid residue by 10% aqueous solution of sodium hydroxide. The designed BOS transformation process resulted in 16.62 g of cellulose-based immobilization carrier derived from 100 g of brown onion skin. Extracts obtained by semi-continuous sequential subcritical extraction contained 37 mg/g of proteins, 40 mg/g of sugars, 17.5 mg/g of uronic acids, 28 mg/g of polyphenols, and 36 mg/g of flavonoids, while those obtained by alkaline liquefaction 19 mg/g of proteins, 58 mg/g of sugars, 10 mg/g of uronic acids, 6.6 mg/g of polyphenols, and 0.5 mg/g of flavonoids. The suitability of the cellulose-based enzyme immobilization carrier was evaluated by B. cepacia lipase immobilization by adsorption, where a maximal 31 U of lipase activity per 1 g of wet carrier was achieved. Based on the results obtained, it seems that the proposed process of brown onion skin transformation shows the possibility of being used for the production of a cellulose-based immobilization carrier, approaching the “zero-waste” model of a circular economy. Full article

Policy misalignment is a key factor affecting the implementation of solid waste management policies and resolving such a misalignment is critical to advancing the solid waste disposal capacity (SWDC) and supporting the goal of a “zero-waste city”. This policy misalignment indicator provides a measurable tool to track progress toward Sustainable Cities and Communities. This study used panel data from 281 cities at the prefecture level and above from 2018 to 2022. The study involved constructing an original database of central and provincial policy documents on urban waste governance and transforming the policy documents into an indicator to capture the degree of policy misalignment, which serves as the key explanatory variable in a fixed-effects model. The study further examined how fiscal decentralization, the digital economy, and regional and administrative characteristics influence cities’ responses to policy misalignments. These factors serve a vital function in moderating the effects of misalignment and explaining heterogeneity across cities. The empirical results show that a vertical policy misalignment significantly reduced the solid waste disposal capacity, while fiscal decentralization and digital economy development mitigated its negative effects. The adverse impacts were particularly pronounced in non-key cities, eastern regions, and cities with low government attention, highlighting the role of local capacity and administrative focus in mediating cross-level policy impacts. The heterogeneous effects observed across city types further offer targeted insights for designing sustainability-oriented waste management policies, enabling regions to tailor interventions based on their administrative capacity and development context. Full article

As a key medium in industry, lubricating oil plays a significant role in reducing friction, cooling sealing and transmitting power, which directly affects equipment life and energy efficiency. Traditional mineral-based lubricating oils rely on non-renewable petroleum, and they have high energy consumption and poor biodegradability (<30%) during the production process. They can easily cause lasting pollution after leakage and have a high carbon footprint throughout their life cycle, making it difficult to meet the “double carbon” goal. Bio-based lubricating oil uses renewable resources such as cottonseed oil and waste grease as raw materials. This material offers three significant advantages: sustainable sourcing, environmental friendliness, and adjustable performance. Its biodegradation rate is over 80%, and it reduces carbon emissions by 50–90%. Moreover, we can control its properties through processes like hydrogenation, isomerization, and transesterification to ensure it complies with ISO 6743 and other relevant standards. However, natural oils and fats have regular molecular structure, high freezing point (usually > −10 °C), and easy precipitation of wax crystals at low temperature, which restricts their industrial application. In recent years, a series of modification studies have been carried out around “pour point depression-viscosity preservation”. Catalytic isomerization can reduce the freezing point to −42 °C while maintaining a high viscosity index. Epoxidation–ring-opening modification introduces branched chains or ether bonds, taking into account low-temperature fluidity and oxidation stability. The deep dewaxing-isomerization dewaxing process improves the base oil yield, and the freezing point drops by 30 °C. The synergistic addition of polymer pour point depressant and nanomaterials can further reduce the freezing point by 10–15 °C and improve the cryogenic pumping performance. The life cycle assessment shows that using the “zero crude oil” route of waste oil and green hydrogen, the carbon emission per ton of lubricating oil is only 0.32 t, and the cost gradually approaches the level of imported synthetic esters. In the future, with the help of biorefinery integration, enzyme catalytic modification and AI molecular design, it is expected to realize high-performance, low-cost, near-zero-carbon lubrication solutions and promote the green transformation of industry. Full article

Municipal solid waste (MSW) is a rapidly escalating global challenge, with Thailand exemplifying the persistence of a policy–practice gap in zero-waste transitions. Despite national initiatives such as Zero Waste Thailand, household segregation and recycling rates remain modest, particularly in semi-rural municipalities. This study addresses this gap by introducing and validating the ARUN Model, a competency-based governance framework for community-level zero-waste management. Using a mixed-methods sequential explanatory design, quantitative data from 300 households were analyzed using exploratory factor analysis and regression modeling, complemented by focus group interviews with local leaders to interpret behavioral mechanisms. The findings revealed that Responsibility and Nurturing competencies exert the strongest positive effects on household zero-waste behavior, confirming the model’s reliability and construct validity. These results empirically demonstrate how community competencies shape sustainable waste practices and bridge the structural–behavioral divide in waste governance. This research provides the first empirical validation of a competency-based governance framework in a semi-rural Thai context, extending beyond participatory and capacity-based models. By integrating statistical rigor with community insight, the ARUN Model advances theoretical and practical understanding of competency-driven sustainability transitions. This study provides actionable insights for policymakers and supports the achievement of SDGs 11, 12, and 13, offering a locally rooted yet globally relevant pathway toward circular economy governance. Full article

This study addressed the persistent limitation of discontinuous and labor-intensive compost monitoring procedures by developing and field-validating a low-cost sensor system for monitoring oxygen (O₂), carbon dioxide (CO₂), and methane (CH₄) under tropical windrow conditions. In contrast to laboratory-restricted studies, this framework integrated rigorous calibration, multi-layer statistical validation, and process optimization into a unified, real-time adaptive design. Experimental validation was performed across three independent composting replicates to ensure reproducibility and account for environmental variability. Calibration using ISO-traceable gas standards generated linear correction models, confirming sensor accuracy within ±1.5% for O₂, ±304 ppm for CO₂, and ±1.3 ppm for CH₄. Expanded uncertainties (U₉₅) remained within acceptable limits for composting applications, reinforcing the precision and reproducibility of the calibration framework. Sensor reliability and agreement with reference instruments were statistically validated using analysis of variance (ANOVA), intraclass correlation coefficient (ICC), and Bland–Altman analysis. Validation against a reference multi-gas analyzer demonstrated laboratory-grade accuracy, with ICC values exceeding 0.97, ANOVA showing no significant phase-wise differences (p > 0.95), and Bland–Altman plots confirming near-zero bias and narrow agreement limits. Ecological interdependencies were also captured, with O₂ strongly anticorrelated to CO₂ (r = −0.967) and CH₄ moderately correlated with pH (r = 0.756), consistent with microbial respiration and methanogenic activities. Nutrient analyses indicated compost maturity, marked by increases in nitrogen (+31.7%), phosphorus (+87.7%), and potassium (+92.3%). Regression analysis revealed that ambient temperature explained 25.8% of CO₂ variability (slope = 520 ppm °C⁻¹, p = 0.021), whereas O₂ and CH₄ remained unaffected. Overall, these findings validate the developed sensors as accurate and resilient tools, enabling real-time adaptive intervention, advancing sustainable waste valorization, and aligning with the United Nations Sustainable Development Goals (SDGs) 12 and 13. Full article

This research pioneers the incorporation of grape pomace (GP) as a sustainable additive in unfired adobe construction materials, establishing a novel circular pathway that valorises agro-waste in zero-emission, low-energy building components. Five mix designs were developed with GP contents of 0%, 2.5%, 5%, 7.5%, and 10% by weight, using a soil matrix composed of 15% clay, 25% silt, and 60% sand with a 20% water content. Comprehensive characterization included physical properties, mechanical performance, thermal behavior, acoustic properties, and durability assessment. The incorporation of GP demonstrated dose-dependent effects on all measured properties. Bulk density decreased linearly from 1951 kg/m³ (0%GP) to 1595 kg/m³ (10%GP), representing an 18.3% reduction. Optimal mechanical performance was achieved at a 2.5–5% GP content, with compressive strength ranging from 1.51–1.64 MPa and flexural strength of 0.56–0.80 MPa, while higher GP contents resulted in significant strength reductions. Thermal conductivity improved substantially, decreasing from 0.99 to 0.25 W/Mk (66% RH) with increasing GP content, indicating enhanced insulation properties. The sound insulation performance showed a single-value sound reduction index (Rw) of 41–43 dB for all compositions, making them suitable for facade applications. Statistical analysis revealed significant correlations between GP content and material properties. The results indicate an optimal GP content of around 5%, which balances mechanical integrity, thermal performance, and durability while providing environmental benefits through the valorization of agro-waste. This research offers a sustainable approach for producing low-energy, eco-friendly building materials by incorporating grape pomace into unfired adobe, promoting waste valorization and improved thermal and acoustical insulation for green construction. Further research is needed to assess durability performance, standardize production methods, and evaluate large-scale implementation. Full article

An integrated statistical–graphical framework is introduced for designing sustainable cement grout mixes that incorporate polyethylene terephthalate (PET) waste and supplementary cementitious materials (SCMs) for semi-flexible pavement applications. A correlated multivariate linear mixed-effects model employs additive log-ratio transformations of PET and SCM proportions (fly ash or silica fume relative to cement) to predict 1-day, 7-day, and 28-day compressive strengths and 28-day flexural strength within a single unified framework. This approach quantifies both the systematic strength penalty of PET substitution and the benefits of SCM additions. The model results demonstrate high random-intercept correlations, substantial reductions in the Akaike information criterion (AIC) and root mean squared error (RMSE) compared to a null model, and marginal and conditional coefficient of determination (R²) values of 0.96 and 0.99, respectively, confirming major capture of the variance in the mechanical response. Complementary ternary plots visualize predicted 28-day performance across the cement–PET–SCM compositional space. These plots reveal that zero-PET formulations along the cement–binder edge achieve maximum strengths, with both fly ash and silica fume maximizing compressive and flexural strengths and any PET addition uniformly degrading performance. By combining rigorous compositional modeling with intuitive visualization, the proposed framework offers quantitative rigor, practical mix design guidelines, and a scalable protocol for optimizing sustainable grout formulations and informing future exploration of alternative fillers, flow regimes, and durability assessments. Full article

The main goal of this study is to address the problem of environmental water pollution caused by organic dyes through waste valorization by synthesizing geopolymer-based adsorbents. In this work, geopolymers were synthesized using fly ash modified with chitosan and polyvinyl alcohol as a starting material. The obtained materials were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and determination of the point of zero charge. We examined the adsorption potential for organic dye (methylene blue, brilliant green, crystal violet) removal through the influence of contact time, initial pH and concentration of adsorbate solution, and temperature on adsorption. The obtained results were analyzed using theoretical kinetics and isotherm models. Interpretation of the obtained results was performed using the Box–Behnken design and chemometric methods of multivariate analysis. The findings showed that modification with chitosan significantly enhanced the adsorption efficiency of the synthesized materials up to 95.9% for methylene blue adsorption. The parameters identified as having the greatest influence on the adsorption process were contact time, pH-value, initial dye concentration, and the type of dye being adsorbed. Full article

In recent years, European cities have implemented numerous initiatives to reduce the use of resources and improve the resilience of climate change by promoting shifts toward the circular economy (CE). This comparative case study investigated the results of the applications of the CE model in the built environment from two different national approaches and perspectives of strategic planning in capitals that represent the “old” (Copenhagen) and “new” (Ljubljana) European Union (EU) member states. This paper introduces the original methodology to assess the implementation of the strategic approaches in the adaptation of the CE in architecture and urban design using a set of 10 selecting indicators. Although both cities have ambitious strategic goals and are undertaking actions aimed at shifting to the CE, they are driven by different motivations (climate crisis vs. urban revitalization and zero waste policy) and exhibit different implementation patterns (top-down systemic/institutional vs. gradual/sectoral). The results highlight the key role of a comprehensive approach to CE implementation, particularly the development of institutional frameworks and dedicated infrastructure and digital tools for transition management, the involvement of external stakeholders in the circular vision, wide-range educational activities, and the promotion of CE initiatives. However, limitations resulting from the lack of a comprehensive and standardized measurement framework pose a challenge to effectively accelerate progress in the shift toward a CE in the built environment. The main contributions of this study are: (1) to identify and verify the methods and strategies undertaken by European cities for the adaptation of a CE in the built environment and (2) demonstrate the different dimensions, levels, and the most relevant factors in the strategic management of the processes of transformation toward the CE. In addition, recommendations for future implementations based on CE systems are indicated. Full article