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Study on the impact of illuminance on comfort and productivity in Japanese office buildings
No full textThe lighting environment in office workspaces plays a vital role in influencing both comfort and productivity. Maintaining optimal illuminance level is crucial for enhancing work performance. Previous studies have explored elements such as brightness perception, users’ lighting preference, productivity, and perceived comfort in response to changes in illuminance. However, research on comfortable illuminance levels remains limited. This study measures illuminance conditions in selected office environments while simultaneously examines the relationship between brightness perception, lighting preference, and productivity. It also aims to identify a comfortable illuminance range for office workers, aiming for both well-being and energy efficiency. The monthly field survey was conducted in 23 office buildings in the Kanto region of Japan. The number of responses collected was 4,660 for survey 1 and 2,637 for survey 2, totaling 7,297 responses. Results showed that regardless of the average indoor illuminance, workers were satisfied with the current lighting conditions in their offices. Moreover, both brightness perception and lighting preference exhibited a positive correlation with productivity which was highest when workers perceived the lighting as moderately bright indicating preference to the current lighting level. During this time, the indoor illuminance was found to be between 500 to 700 lx. Although the overall impact of illuminance was not high, they did influence individual comfort and productivity of occupants
Energy-Saving Performance of VRF Systems with Different Fresh Air Units in Different Climate Regions
No full textTo address the issue of poor indoor air quality caused by the lack of fresh air in traditional variable refrigerant flow (VRF) systems, a combination of VRF and fresh air systems is increasingly adopted in practical engineering applications. However, these two systems are often operated independently, which may result in increased energy consumption. To enable coordinated operation, this study proposes a novel integrated VRF–fresh air system that aims to reduce total energy consumption while ensuring adequate indoor air quality. Based on a full operating condition model, this study evaluates the energy performance of the integrated system with different fresh air unit configurations. Results show that during the heating season, heat recovery effectively reduces the heating load on the VRF system, achieving seasonal energy savings ranging from 28.47% to 45.46%, with greater benefits observed in colder regions. In the cooling season, the combination of heat recovery and bypass control can deliver up to 19.98% seasonal energy savings, especially when outdoor air enthalpy lies between the minimum and maximum indoor setpoints. These findings underscore the importance of optimizing the design and control of fresh air units to enhance the overall energy efficiency of integrated systems
Thermal comfort in outdoor urban parks of Kathmandu
No full textUrban parks are an important part of public green spaces and are frequently used by visitors for outdoor recreation and activities. Although Nepal has many urban parks that attract many visitors, the availability of data regarding outdoor thermal comfort remains lacking. This study aims to assess thermal sensation votes, determine the acceptable temperature, and predict the comfortable temperature in an urban park. A thermal comfort survey was conducted in Balaju Baisdhara Park, Kathmandu during summer in May 2025. Microclimatic measurements were taken using digital instruments positioned at a height of 1.1 m above ground level. A total of 307 questionnaire responses were collected during the field survey. The results show that 51.1% of visitors perceived their thermal environment as “slightly hot,” while 41.4% reported feeling “neutral.” Despite the relatively high air temperature (i.e., mean temperature at 29 °C), 41% of respondents indicated their thermal environment as “acceptable”. The maximum acceptable temperature was found to be 28.3°C and comfortable temperature of 26.4°C. These findings can be the benchmark for urban park design
Stochastic optimal control of chiller systems: Data-driven vs. hybrid AI
No full textAccurate control of chiller systems is critical for energy efficiency, yet conventional data-driven models often fail under
unseen conditions due to poor generalization and unquantified uncertainty. This study proposes a hybrid AI chiller model using transfer learning (TL), combining physics-based knowledge with measured data, and applies it to a stochastic optimal control (SOC) framework. Uncertainty is estimated using a Monte Carlo simulation, allowing risk-aware control decisions. The SOC algorithm minimizes total power consumption by optimizing control variables while making uncertainty-aware decisions that reduce the risk of overcontrol. The hybrid AI model could achieve energy saving by 30.5% and decrease the degree of lower uncertainty compared to a baseline ANN model. These results highlight the value of incorporating both physical consistency and uncertainty quantification in AI-based control, enabling more robust and reliable HVAC operation under real-world variability
Comparison of EnergyPlus simulations with measured building performance Data
No full textThe reduction of greenhouse gas emissions is a global challenge, and in the building sector, energy conservation and the use of renewable energy are essential. Achieving these goals requires not only the improvement of building and equipment performance but also efficient operation and management. To this end, the use of digital twins, which replicate physical building spaces and elements in cyberspace, is expected. This study primarily aims to pre-assess the prediction accuracy of EnergyPlus as part of the development of a building digital twin, using a two-story office building in Sapporo, Japan, as a case study. The building is equipped with energy-saving systems such as a groundwater heat pump and a ceiling radiant heating and cooling system. A simplified EnergyPlus model simulation is performed first, and its power- consumption output is compared with measurements for validation. Next, a high-fidelity Modelica–Spawn coupled model is executed to reproduce full system dynamics, and its results are likewise compared with the measured data. The study concludes that to enhance the digital twin, a more detailed model of the building’s HVAC system and additional measurement data for further verification are necessary. This will contribute to more accurate simulations and the improvement of energy management strategies
Synergistic Antimicrobial Effects of Indigenous Herbs via Electric Fumigation: An
No full textEnvironmental disinfectant significantly reduces the incidence of nosocomial or hospital-associated infections (HAIs), which are major healthcare issues worldwide. To overcome the adverse effects with chemical disinfection, it is worthwhile to explore the alternative techniques with least or no side effects. The Fumigation (Dhoopana) is an age-old method described in ancient literature of Ayurveda which can be used in preventive as well as therapeutic applications. A comparative study was carried out to evaluate the efficacy of traditional and modern fumigation by using a mixture of herbal ingredients. A newly developed electric fumigation device was used to generate the required fumes to perform the In-Vitro investigation on gram-negative and positive bacteria. There were 63% and 67.5% microbial load reduction in case of traditional fumigation for surface and air flora respectively while 88.6 and 90.3% reduction noticed in case of modern fumigation for the same. Monochrome staining and haemolytic activities were also assessed before and after the fumigation which states that herbal fumigation having potential to deal with various pathogens. These findings give scientific evidence in support of Ayurvedic sanitization strategy that can be fine-tuned to have implications in the clinical, healthcare, and food industries, where sanitization is crucial
Essential and Fixed Oils from Plants: A Natural Approach to Mosquito Management
No full textVector-borne diseases account for more than 17% of global infectious diseases and are responsible for approximately 700,000 deaths annually, as reported by the World Health Organization. Mosquitoes serve as major vectors for diseases such as dengue, chikungunya, and malaria. Continuous exposure to synthetic mosquito repellents has raised serious concerns regarding their toxic effects on human health and the environment. This has encouraged the exploration of herbal alternatives with effective repellent and Larvicidal properties. The present review focuses on medicinal plants containing essential and fixed oils with proven mosquito control activity. A systematic literature survey was conducted using databases such as PubMed, Google Scholar, Research Gate, and Science Direct. Essential oils from catmint, sandalwood, thyme, marigold, rosemary, basil, cinnamon, clove, lemongrass, and peppermint showed strong mosquito repellent and Larvicidal effects. Additionally, fixed oils such as neem oil and karanj oil also demonstrated significant repellency. Most studies were performed against Aedes aegypti, Anopheles Stephens, and Culex quinquefasciatus. Phytochemical investigations revealed the presence of bioactive compounds including camphor, pinene, 1,8-cineole, camphene, and borneol, which are responsible for mosquito control activity. The review highlights the potential of developing synergistic formulations using essential oils incorporated into fixed oils as safe, effective, and eco-friendly alternatives to synthetic mosquito repellents
3-D Modelling and design of spoof surface plasmon transmission line-based microwave sensors
No full textAt optical frequencies, highly localized surface waves kn own as surface plasmon polaritons (SPPs) Surface Plasmon polaritons, generally arise at the boundary between two materials having contrasting permittivity. To replicate these effects specifically at lower frequencies, researchers here have introduced plasmonic metamaterials. This method emplys subwavelength structural patterns on the metal surfaces in order to create spoof SPPs at microwave or terahertz fre quencies.Due to their inheritance of natural SPPs' dispersion charac teristics, field confinement, and subwavelength resolution, spoof SP Ps are anticipated to providenovel approaches to highly integrated, small, and highly performing advanced circuits and systems.The ev olution of spoof SPPs in recent years is covered in this paper, with particular attention paid to the fundamental idea, theory, design pro cess, and microwave engineering applications.The theory and conc ept of SPPs and spoof SPPs are first presented, An overview of this transition from conventional bulky waveguides to the compact ultrathin transmission lines (TLs) emphasizing the unique benefits offered by this new class of TLs this class of TLs has been reviewed. This research discusses the corresponding design methodology, innovative approaches for achieving reconfigurable spoof SPP structures and appropriate feeding mechanisms for spoof SPP transmission lines. In addition, practical implementations of plasmonic circuits are presented, that enables the researcher to developed SPP-based antennas, passive components and active devices for Applications. Finally, this research will contribute for the potential RF applications and prospective research directions for microwave spoof SPP technologies
In silico Analysis of Phytocompounds from
No full textNew Delhi metallo-β-lactamase-1 (NDM-1) is a major determinant of antibiotic resistance responsible for hydrolyzing β-lactam antibiotics, including carbapenems, in Klebsiella pneumoniae. This study aimed to find potential phytocompound inhibitors of NDM-1 from three medicinal plants, Andrographis paniculata, Gymnema sylvestre, and Plumbago auriculata, by using an in silico computational approach. The NDM-1 three-dimensional structure was obtained from the Protein Data Bank, and phytocompound structures were collected from the IMPPAT database. AutoDock Vina has been used for performing molecular docking, followed by visualization and interaction analysis using AutoDock Tools 1.5.7. Pharmacokinetic and toxicity screening (ADMET and ProTox-III) was performed to assess drug likeness and safety. Docking results revealed different inhibitory potentials among screened phytocompounds. Alpha-Amyrin from Plumbago auriculata shows the highest binding affinity (-8.9 kcal/mol), followed by Beta-Amyrin from Gymnema sylvestre and Plumbago auriculata (-8.8 kcal/mol). All selected phytocompounds showed favourable ADMET profiles and low predicted toxicity, with Beta-Amyrin, Alpha-Amyrin, Daucosterol, and Resiniferonol showing the safest toxicity scores. These findings suggest that selected phytocompounds, particularly Alpha-Amyrin and Beta-Amyrin, may provide promising lead compounds for developing NDM-1 enzyme inhibitors. Despite this, further in vitro and in vivo validation is required to confirm their therapeutic potential
Experimental Study on the Use of Blended Waste Oils as TOYA Stove Fuel: Emission and Efficiency Analysis
No full textThis study evaluated waste cooking oil (WCO), waste engine oil (WEO), and their 50:50 blend as alternative fuels using a TOYA commercial burner, analyzing thermal efficiency, emissions profile, and combustion characteristics. Results showed that the 50:50 blend demonstrated superior performance, achieving both the fastest water boiling time (5.31 minutes) and the highest thermal efficiency (19.8%). Flame temperature profiles revealed significant differences: WCO showed the lowest (420-453°C) and most variable temperatures, while WEO burned more stably at higher temperatures. Notably, the blend achieved the most consistent peak temperatures around 500°C, directly supporting its enhanced combustion efficiency. Emission measurements showed the blend's environmental advantages, producing significantly lower carbon monoxide (8.4 ppm vs 15-16 ppm for pure oils) and particulate matter (PM2.5: 412.6 μg/m³ vs WCO's 469.3 μg/m³) while maintaining moderate CO₂ output. The combination of stable high-temperature combustion, reduced emissions, and minimal residue formation confirms that blending WCO and WEO creates an efficient, cleaner-burning fuel. These findings demonstrate how waste oil blending can improve both performance and environmental impact in thermal applications