Automakers continue to seek energy-efficient solutions to improve passenger comfort while reducing power consumption in electric vehicles. One challenge is the energy-intensive process of heating the cabin, which affects vehicle range. To address this, a novel seat heating system was developed, integrating heating elements in key thermoreceptor regions to optimize thermal comfort. The system was tested in real vehicle conditions with human subjects, and results were compared to a conventional heated seat. Findings indicate that the novel heating system significantly reduces the time required to reach thermal neutrality. After 5 min, it effectively minimized cold sensations, whereas the conventional system still left passengers feeling cold. After 10 min, 26

The sleep quality is strongly impacted by the comfort and indoor air quality inside bedroom and thus the ventilation conditions. The simplified mechanical ventilation by adopting an air-conditioner and an outdoor air blower provides an affordable means to condition the bedroom. So far, no systematic studies have optimized such simplified mechanical ventilation design, which involves dual jet sources with different air temperatures. This study optimized the simplified mechanical ventilation in a typical residential bedroom located in two climate zones in China. The design variables included the installation position and supply air jet direction of the air-conditioner, as well as the installation position and opening size of the outdoor air blower. A multi-objective genetic algorithm (MIGA-II) was employed for the optimization, with a Kriging surrogate model to speed up the solution. The design was to ensure the sleeping adult thermally comfortable and the inhaling CO2 concentration as low as possible. Measurements were conducted in lab to obtain data to validate the results. This study found that the air-conditioner should be installed on the long side of the room to form small circulation zones along the short sections of the room, while the outdoor air blower should be installed adjacent to the air-conditioner to make use of the air-conditioning jets to deliver the outdoor air to the breathing zone. As compared with the regular design, the optimal design enhanced thermal comfort by more than 10 % and inhaling air quality by over 60 %.

Photovoltaic (PV) systems are important for sustainable energy infrastructure, but their rapid deployment introduces complex fire dynamics that current regulations fail to address adequately. While existing standards focus on the electrical safety of individual components, they often neglect the risks arising from the interaction between the PV array and the building envelope. This review synthesizes current research on ignition mechanisms, thermal behavior, and the aerodynamic propagation of smoke to evaluate these overlooked hazards. A primary finding is that the interstitial space between the panel and the roof functions as a “heat trap,” significantly altering airflow patterns and accelerating flame spread even across fire-rated materials. The analysis further highlights that standard testing protocols do not sufficiently account for the urban dispersion of toxic combustion byproducts, such as hydrogen fluoride and volatile organic compounds. By evaluating recent advancements in Computational Fluid Dynamics (CFD) and helium-based surrogate testing, this paper demonstrates that accurate prediction of pollutant transport requires coupled modeling of wind effects and thermal buoyancy. The study concludes that ensuring urban fire resilience demands an evolution from component certification to integrated system assessments that include installation geometry, ventilation strategies, and environmental impact.

Urban decarbonization can benefit from façades that both generate power and manage heat. This study examines a semi-transparent PV glazing coupled with a phase-change layer (PCM, ~25 °C melt) and an embedded water loop as a tri-functional façade element suitable for dense cities. A steady state CFD was built with radiation baseline (pressure-based RANS, k–ω SST viscous model, fully conjugate heat transfer) with Discrete Ordinates in participating media to resolve solar transport through PV–PCM–glass and quantify heat flux partitioning. At a summer design point, the sunlit face absorbs ~780 W/m² on average; ~200 W/m² are rejected immediately to ambient (~21% radiative, ~79% convective), while the remainder is routed into the laminate. Results show strong cooling footprints over the serpentine on the PV side and “cold stripes” on the room side (~12–31°C), evidencing effective heat draw toward the coil and reduced indoor loads. Water-side removal derived from outlet temperature yields ~190 W for the numerical simulated panel, and a closed local energy balance corroborates the optical–thermal setup. This study delivers design-relevant metrics (PV operating temperature, exterior/room-side fluxes, useful heat recovery) and highlights levers, like coil pitch, PCM thickness, flow rate, and film coefficients.

This work presents an evaluation of the effectiveness of active ventilation methods compared to passive ventilation methods in a typical B + GF + 9 building, focusing on the impact of burner height location on smoke control performance. The numerical model was validated using a full-scale room fire experiment involving a 4350 kJ/s wood crib load, where the HRR was calibrated via the mass loss method, achieving an RMSE of 210 kW and MRE of 5.04%. FDS simulations were conducted across six scenarios involving burners on the ground, fifth, and ninth floors. The findings demonstrate that, while natural ventilation allows the stairwell to reach lethal conditions with temperatures exceeding 180 °C and CO concentrations above 0.24%, the implementation of top-level mechanical pressurization maintains temperatures below the 60 °C tenability threshold. The mechanical ventilation system extended the Available Safe Egress Time (ASET) by 75% to 110%, with effectiveness increasing as the burner elevation approached the fan location. Overall, the study provides a validated approach for transforming stairwells into protected refuge zones in existing mid-rise buildings. Overall, merging empirical with computational methods is a proven basis for simulating scaled-up, complicated layouts. This guarantees accurate initial conditions when analyzing urban fire emergencies.

In recent years, the accurate numerical simulation of airflow in vehicle cabins has become increasingly important for optimizing thermal comfort and energy efficiency. This study investigates the impact of realistic boundary conditions on Computational Fluid Dynamics (CFD) simulations for vehicle ventilation systems. The research integrates detailed HVAC duct data to provide a more accurate representation of airflow characteristics, diverging from conventional approaches that often assume uniform inlet conditions. Using a 3D CFD model, airflow patterns were simulated under two scenarios, comparing a case with simplified boundary conditions to one incorporating detailed duct geometries and realistic conditions. The numerical model was validated using experimental data, including Laser Doppler Velocimetry (LDV) and Particle Image Velocimetry (PIV) measurements. The findings reveal that using realistic boundary conditions significantly enhances the accuracy of airflow predictions, particularly regarding velocity distribution and thermal comfort. This work highlights the critical role of detailed boundary condition specification in improving the reliability of CFD simulations for vehicle ventilation and other personalized ventilation applications.

Accurate prediction of urban air quality during fire events is frequently limited by the lack of experimentally validated source terms. Current pollution dispersion models often rely on idealized input parameters that fail to capture the complex thermal and chemical dynamics of real-world indoor fires. Addressing this gap, this study presents an experiment which reproduces an office-type fire using a wooden crib with a calibrated thermal load, enabling accurate determination of the HRR through the mass loss rate method. Temperature evolution was monitored with 27 thermocouples positioned across five vertical planes, while toxic gas concentrations were measured near the upper boundary of the exterior opening. The experimental data were used to calibrate and validate the numerical model, with HRR representing the primary parameter and temperature and toxic gas concentrations serving secondary validation metrics. Quantitative comparison showed good agreement between the experimental and simulated trends, with acceptable prediction errors and consistent reproduction of the dominant physical mechanisms governing fire development, ventilation-driven flow, and pollutant accumulation. Overall, the combined experimental–numerical approach provides a validated framework for future simulations on larger and more complex geometries, ensuring reliable input parameters for urban-scale fire scenarios.

Computational fluid dynamics (CFD) is a powerful method for predicting and optimising indoor environmental conditions due to its ability to simulate complex airflow patterns, temperature distributions and contaminant dispersion with high spatial resolution. However, the accuracy and reliability of CFD simulations depend strongly on robust verification and validation methodologies. This review critically examines how numerical models are experimentally validated in the context of indoor environmental quality (IEQ) studies, with a focus on the parameters used and methods adopted by researchers. The central objective is to understand if and how validation is performed and which variables are typically considered. The findings reveal major inconsistencies in the current literature regarding the choice of validation parameters, sensor deployment strategies and the reporting of calibration procedures, which limit reproducibility and cross-study comparability. To address these gaps, the review proposes a novel validation framework that integrates both thermal comfort and indoor air quality (IAQ) metrics into a unified approach. The review also reflects upon the advantages of advanced thermal manikins as comprehensive validation instruments capable of capturing the dynamic interaction between the human body and indoor environments, thereby enhancing the realism and applicability of CFD simulations in IEQ research. This work is, to the authors′ knowledge, the first to systematically dissect existing validation methodologies for CFD simulations of pollutant transport in indoor environments while simultaneously proposing a structured pathway forward, paving the way for standardisation efforts and the integration of more accurate, cost-effective monitoring approaches in both research and practice.

This study compares the thermal performance and energy consumption of three vehicle seat heating systems: (1) a factory-installed system, (2) a commercial seat heating cover, and (3) an innovative system developed by our team. The new system uses strategically placed heating elements and a pressure-sensitive switch to activate zones aligned with human thermoreceptors, improving efficiency and comfort.Tests were conducted at 15 °C using voltages of 10 V, 12 V, and 14 V over 30 minutes. Temperature and power consumption were continuously monitored. Results show the novel system reaches peak temperature in half the time of the factory model, offering faster comfort and lower energy use. The seat cover delivered the lowest output, prioritizing safety but limiting effectiveness. Overall, the new design demonstrates a promising, energy-efficient alternative that enhances passenger comfort, particularly valuable for electric vehicle.

Enhancing energy efficiency in buildings is necessary for reducing environmental impact and operational costs, with domestic hot water (DHW) systems accounting for a significant portion of residential energy consumption. This paper provides a comprehensive overview of in-building direct wastewater heat recovery (WHR) systems as a means to improve thermal efficiency in DHW systems. Various direct WHR technologies are explored, focusing on vertical and horizontal heat exchangers, detailing their design, operation, and efficiency. The study analyses factors influencing the performance of these systems, including heat exchanger design, temperature differentials, flow rates, and maintenance requirements. Case studies are presented to demonstrate the practical applications and energy savings potential of WHR systems in residential and commercial buildings. Despite the clear benefits, challenges such as installation complexity, maintenance needs, usage patterns, and initial costs hinder widespread adoption. Retrofitting existing buildings poses significant hurdles due to space constraints and plumbing modifications, while maintenance is essential to prevent efficiency losses from fouling. The effectiveness of WHR systems is also influenced by the synchronization of hot water usage and wastewater production, which can be intermittent in residential settings. Economic considerations, particularly the upfront investment, can deter stakeholders despite favourable long-term returns.

The transformation of urban areas into smart cities integrates advanced technologies to enhance efficiency, sustainability and liveability. In this study, we employed a systematic literature review methodology to assess the environmental impacts of smart city initiatives. We applied strict inclusion and exclusion criteria to ensure the relevance and quality of the selected studies and conducted a qualitative content analysis to extract and synthesize key findings related to Life Cycle Assessment (LCA) and sustainability in the context of smart cities. Key benefits of smart cities include improved energy efficiency through smart grids and energy-efficient buildings, reduced emissions from smart transportation and electric vehicles, optimized water and waste management and data-driven urban planning. While smart cities rely on ICT for enhanced efficiency, data collection and processing must be done responsibly to limit the environmental impact of data centers and network infrastructure. This can be achieved through edge computing, energy-efficient data centers, and policies that promote digital sobriety. However, challenges such as the high energy use of ICT infrastructure, electronic waste, construction impacts, data privacy, cybersecurity risks and the digital divide are significant. Strategies to mitigate these include integrating sobriety, promoting a circular economy, stakeholder engagement and robust policy frameworks.

Current commercial aircraft ventilation design focuses on space optimization and pressure-related safety parameters. It inadequately takes into account the impact of the mixing ventilation system on pathogen dispersion in an enclosed space with low humidity. Current international guidelines relating to pathogen transfer reduction, suggest a combined approach using both traditional mixing ventilation systems and personalized ventilation. The present paper studies the impact of seat-integrated personalized ventilation diffusers on the air quality in the passenger breathing zone. The study employs an experimental setup backed by numerical simulations to evaluate the system’s potential to disperse pollutants near the breathing zone. Human thermal manikins were used to simulate the passengers in a full-scale mock-up of the airplane cabin. The velocity fields of the personalized ventilation diffusers and the thermal plume have been measured using PIV techniques. The experimental results were used to validate the CFD scenarios. The numerical part of the study used exhaled CO2 accumulation in the breathing zone to assess the effectiveness of the PV diffusers. Results indicate that the presence of the PV diffusers directs the exhaled CO2 upwards and can act as a barrier preventing pathogens from entering the breathing zone.

The European Union's ambitious goals to reduce carbon emissions and improve energy efficiency has highlighted the importance of renewable energy technologies like solar collectors. Buildings, responsible for a significant share of the EU's energy consumption and greenhouse gas emissions, can benefit from solar collectors integrated with thermal energy storage systems to optimize both heating and cooling. This study investigates how the integration of nano-enhanced phase change materials (nePCM) into a transpired solar collector (TSC) can improve thermal energy storage and efficiency. To explore this, an experimental setup was constructed and tested under real conditions. This study evaluates a transpired solar collector (TSC) integrated with nanoenhanced phase change materials (nePCMs) for thermal energy storage. Experimental results revealed plate temperatures exceeding ambient by up to 20 degrees C and nighttime outlet air temperatures raised by 2-3 degrees C. The system achieved an average efficiency of 50 %, validated by a mathematical model (MBE: 3.13 %, RMSE: 3.86 %). This demonstrates the potential of nePCMs to enhance solar energy storage and efficiency under real-world conditions.

Next-generation district heating relies on large hot-water storage tanks, which in turn require accurate, computationally efficient full-scale modelling for resolving stratification and thermocline dynamics and supporting design, control, and long-horizon planning. This work cross-validates three numerical modelling approaches on the same 1900 m3 vertical tank during a 10 h charge: a high-fidelity CFD, a custom finite-difference (FDM) model, and a system-level nodal (lumped-parameter) simulation. The CFD setup (2-D axisymmetric, buoyancy-dominated laminar interior) underwent five-level space-time refinement; the adopted mesh/time step delivered stable advancement and mesh-independent thermocline thickness. Against experiment, CFD reproduces profiles with MD <= 1.25 degrees C, MBE <= 2.91 %, and RMSE = 1.4-3.9 % over 0-10 h. FDM accuracy improves markedly with resolution; at 500 control volumes it matches CFD in the hot/cold layers and captures thermocline evolution within the experimental uncertainty band, while requiring hours rather than days of runtime. The system-level nodal simulation executes in seconds and suits long-horizon studies, but with <= 40 nodes in the present implementation it cannot resolve short-term thermocline sharpening. A clear tradeoff between accuracy and computational cost was observed: CFD suits short, detail-focused analyses; finite-difference models handle day-scale studies efficiently; nodal models serve seasonal planning. Most prior work on hot-water storage tanks focuses on small or medium volumes and a single modelling approach, rarely reporting uncertainty. To address this, three approaches-CFD, finite difference, and nodal models-were compared under identical conditions on the same dataset, with guidance on method selection and expected errors.

The increasing concerns about CO2 emissions and climate change have pointed out the urgency of promoting sustainability in the building sector. One promising solution to enhance the energy efficiency of buildings and diminish environmental impact is the integration of phase-change materials (PCMs) into ventilated façade systems. This review article critically examines the current state of research on this innovative approach, with a particular focus on fire safety considerations. The paper explores the integration of PCM into ventilated façades, highlighting the potential for significant improvements in energy consumption, thermal comfort, and reductions in CO2 emissions. However, the flammability of PCMs introduces substantial fire safety challenges that must be addressed to ensure the safe application of this solution. The fire safety of both ventilated façades and PCMs is approached, followed by specific fire safety concerns when PCMs are integrated into ventilated façade systems. The conclusion states that while the integration of PCMs into ventilated façades offers substantial environmental benefits, attention to fire safety is essential. This necessitates the implementation of rigorous fire protection measures during the design and construction phases. By addressing both the environmental advantages and fire safety challenges, this review aims to provide a comprehensive understanding of the potential and limitations of PCM-integrated ventilated façades, offering valuable insights for researchers, engineers, and policymakers in the field of sustainable buildings.

The proper design and installation of systems that enable the efficient control and removal of smoke and hot gases in underground parking facilities are necessary for protecting the public and property in the event of a fire. This paper discusses how studies using Computational Fluid Dynamics (CFD) related to smoke venting have contributed to improving fire safety in underground parking facilities. As vehicle fire incidents continue to rise globally, particularly in regions with a high density of underground parking, the need for comprehensive measures to mitigate these incidents has become increasingly urgent. This paper examines the applicability of CFD as a tool to address the challenges of smoke control in underground car parks, including those caused by fires involving electric vehicles. CFD application under various fire scenarios and ventilation strategies allows for identifying more effective smoke removal solutions, improving the protection of occupants and property. However, despite the potential of CFD simulations to enhance fire safety and smoke exhaust efficiency in underground parking, it is important to recognize the limitations of these simulations, particularly in dealing with the complex challenges posed by electric vehicle fires.

In the actual context of growing concerns over sustainability and energy efficiency, Phase Change Materials (PCMs) have gained attention as promising solutions for enhancing energy storage and release efficiency. On another hand, materials based on graphene oxide (GO) have proven antibacterial activity, biocompatibility, efficiency in microbial growth inhibition, and pollutant removal. Integrating nanoparticles into PCMs and creating Nano-Enhanced Phase Change Materials (NEPCMs) have opened new horizons for optimizing the performance of these systems and sustainable development. The key objective of this work is to gain insight into NECPMs, which are used in solar wall systems to enhance solar energy storage. Paraffin RT31 was mixed with Cu nanoparticles, graphene oxide (GO), and Cu-decorated GO (Cu@GO) at loading ratios ranging from 1% to 4% (w/w nanoparticles with respect to RT31). The compositions were characterized through Differential Scanning Calorimetry (DSC) and rheology tests. The decoration of the carbon-based nanoparticles was performed using the ultrasonication procedure, and the decoration efficiency was confirmed through X-ray Photoelectron Spectroscopy (XPS). The rheologic measurements were performed to correlate the flow behavior of the NEPCM with their composition at various temperatures. The study methodically investigated these composites’ latent heat values, phase change peak temperatures, and solidification phase change temperatures. Compared to pure paraffin, the solidification of the formulations obtained using Cu@GO exhibits the largest increase in latent heat, with a 12.07% growth at a concentration of 2%. Additionally, at a 4% concentration of NEPCM, the largest increase in thermal conductivity was attained, namely 12.5%.

With the increasing focus on indoor environmental quality, driven by the growing amount of time people spend in enclosed spaces, this study presents an approach to enhancing air distribution in office environments and confined spaces. A novel low-induction air diffuser is designed to deliver fresh, clean air in close proximity to occupants while maintaining their thermal comfort. Clean, unpolluted air is pivotal to healthy and productive workplaces. Yet, this paper underscores the importance of not sacrificing thermal comfort in the pursuit of improved indoor air quality. Inadequate thermal comfort may lead occupants to deactivate ventilation systems, negating the benefits of improved air quality. Inefficient temperature control can also result in discomfort, distractions, and reduced productivity. The innovative low-induction air diffuser resolves this issue, enhancing air quality near occupants without causing thermal discomfort. By directing air gently and efficiently, this solution is prepared to transform personalized ventilation systems, mitigating the discomfort associated with traditional jet flows while delivering high-quality breathable air. This research serves as a bridge between improved indoor air quality and thermal comfort, for office environments. It introduces a practical, energy-efficient solution that satisfies the core requirements of a healthy workspace—clean air and comfortable conditions.

The building sector plays an important role in the global climate change mitigation objectives. The reduction of CO2 emissions and energy consumption in the building sector has been intensively investigated in the last decades, with solar thermal energy considered to be one of the most promising solutions due to its abundance and accessibility. However, the discontinuity of solar energy has led to the study of thermal energy storage to improve the thermal performance of solar thermal systems. In this review paper, the integration of various types of phase-change materials (PCMs) in transpired solar collectors (TSC) is reviewed and discussed, with an emphasis on heat transfer enhancements, including nanomaterials. Thermal energy storage applied to TSC is studied in terms of design criteria, materials technologies, and its impact on thermal conductivity. This review highlights the potential of nanomaterial technology integration in terms of thermal performance improvements. The utilization of nanomaterials in solar walls holds the potential to significantly enhance their performance. The integration of diverse materials such as graphene, graphite, metal oxides, and carbon nanoparticles can pave the way for improving thermal conductivity.