Purpose: The purpose of this study was to examine the impact of five key build parameters – layer thickness, deposition angle, infill, extrusion speed and extrusion temperature, and their interactions – on the maximum flexural force in specimens which are made of polylactic acid (PLA). Design/methodology/approach: Through a previous study on the flexural properties of PLA specimens, a statistically significant effect of layer thickness was indicated, requiring further experimentation to establish the values of quadratic term in the model, as well as to perform optimization. Instead of performing a conventional Central Composite Design, a novel, definitive screening design (DSD) was used as statistical method. DSD allowed the reduction of the number of runs required for optimization while minimizing aliasing. Findings: Significance of deposition angle and infill as main effects was established. Moreover, significant two-way interactions between infill/layer thickness and infill/extrusion speed were detected and discussed. The optimization procedure showed that minimum level of deposition angle, maximum levels of extrusion speed and infill and near mid-level of layer thickness yield maximum flexural force. Research limitations/implications: In this study, the three levels of infill were 0.1, 0.2 and 0.3, which corresponds to 10, 20 and 30 per cent of infill, respectively. In everyday practice, infill is usually kept within this range since it allows time-efficiency, i.e. significant reduction of build time. Though, unsurprisingly, higher infill is positively correlated with flexural strength, this study provides practical directions for optimal selection of other key parameters when working with low infill values. Social implications: Optimal 3D printing with low infill can contribute to lower material waste and pollution, while PLA plastic’s biodegradability remains high on the environment protection agenda. Originality/value: According to available literature, no previous studies have investigated the FDM extrusion of PLA material using a combination of low infill, deposition angle, layer thickness, extrusion speed and extrusion temperature.

This Vertical-axis wind turbines (VAWTs) are emerging as promising alternatives to conventional horizontal-axis wind turbines (HAWTs) for renewable energy generation, particularly in urban and offshore environments. Despite increasing interest, a comprehensive evaluation of their technical, economic, and environmental performance remains limited. This review, based on a targeted literature search, critically evaluates and compares the performance, economic viability, environmental impact, technological advancements, and adoption barriers of VAWTs and HAWTs. VAWTs demonstrate lower aerodynamic efficiency (20–35%) and capacity factors (20–35%) compared to HAWTs (efficiency 40–50%, capacity factors 30–45%), yet offer advantages such as omnidirectional wind capture, simpler ground-level maintenance, lower noise emissions, reduced avian impact, and greater feasibility for space-constrained urban settings. Economic analyses indicate that VAWTs typically have higher levelized costs of energy (60–80 EUR/MWh) than HAWTs (40–60 EUR/MWh), although these are partially offset by reduced operational costs. Environmental assessments favor VAWTs in terms of land use, biodiversity impact, and water consumption. Technological progress, including AI-based aerodynamic optimization, hybrid rotor designs, advanced composite materials, and Maglev bearings, has enhanced the competitiveness of VAWTs. The main adoption challenges are lower power output, scalability constraints, and lack of support from policymakers. While HAWTs remain dominant in large-scale wind energy production due to superior aerodynamic performance and economies of scale, VAWTs offer significant benefits for decentralized, urban, and offshore applications where installation flexibility, noise, and environmental considerations are critical. Continued innovation and more policy support could increase VAWT market penetration and contribute to more diversified, sustainable energy portfolios.

Sustainable use of biomass energy sources can reduce dependency on fossil fuels. Wood biomass is the primary source for heating in Slovenia, with firewood and wood pellets having the highest share. Slovenia’s largest consumers of wood fuels are households primarily using wood from their forests or imported wood pellets. This research used a life cycle assessment to analyze and evaluate the environmental impacts of using firewood and wood pellets for household heating in Slovenia for the first time. The results showed that wood logs have a considerably greater effect on stratospheric ozone depletion, ozone formation, and fine particulate matter (PM) formation. The impact on global warming was lower due to short transportation distances and using log boilers with high combustion efficiency (0.016 and 0.041 kg CO₂ eq for wood log and wood pellet combustion, respectively). An increase in transportation distance from 100 km to 1000 km resulted in an 84.9% increase in the values for the categories ozone formation and human health, a 120.4% increase for fossil resource scarcity, and a 102.4% increase in global warming, supporting the premise that short distribution routes are necessary for more sustainable use of the energy source.

Based on the available literature, the status and prospects for further development of the building integrated photovoltaics (BIPV) market were analyzed. The results of the analysis show that the high investment costs and the lack of information about installed BIPV systems and BIPV technology are a problem for the stakeholders. BIPV technology is an interdisciplinary problem, so the cooperation of a large number of different experts is important. However, it is not yet at a satisfactory level. Another problem is the overlapping of responsibilities of HVAC installers, interior designers and facade manufacturers. On the other hand, the incentives of the EU regulatory framework and beyond to use renewable energy sources in both new buildings and renovation of old buildings, as well as the desire for energy independence, encourage the application of BIPV technology. An analysis of the electricity production potential of BIPV integrated into the walls and roof of the building was made for four geographical locations. A comparison of the production of electricity on the walls and on the roof of the building was carried out. The analysis shows that on the 4 walls of the building, where each wall has the same area as the roof of the building, approximately 2.5 times more electricity than on the roof can be generated. In the absence of available surface for installing a PV power plant on the roof, the walls represent a great potential for BIPV technology.