Search Results (109)

The increase in data center facilities has led to higher energy consumption and a larger carbon footprint, prompting improvements in thermal environments for energy efficiency and server lifespan. Existing literature studies often overlook categorizing equipment for power usage effectiveness (PUE), addressing power efficiency measurement limitations and employee thermal comfort. These issues are addressed through an investigation of the PUE metric, a comparative analysis of various data center types and their respective cooling conditions, an evaluation of PUE in relation to established thermal standards and an assessment of employee thermal comfort based on defined criteria. Thirty-nine papers and ten websites were reviewed. The results indicated an average information technology (IT) power usage of 44.8% and a PUE of 2.23, which reflects average efficiency, while passive cooling was found to be more applicable to larger-scale data centers, such as Hyperscale or Colocation facilities. Additionally, indoor air temperatures averaged 16.5 °C with 19% relative humidity, remaining within the allowable range defined by ASHRAE standards, although employee thermal comfort remains an underexplored area in existing data center research. These findings highlight the necessity for clearer standards on power metrics, comprehensive thermal guidelines and the exploration of alternative methods for power metrics and cooling solutions. Full article

This study investigates the limitations of localized heating in a single-story dwelling, using a validated computational fluid dynamics (CFD) model to analyze thermal stratification and its impact on occupant comfort. A comparative evaluation of turbulence models (k-ε and k-ω SST) and equations of state (Soave–Redlich–Kwong and Peng–Robinson) identified the k-ω SST model with the Soave–Redlich–Kwong equation as the most accurate and computationally efficient combination for capturing temperature gradients and achieving rapid convergence. Experimental validation demonstrated strong agreement between simulated and measured temperature profiles, confirming the model’s reliability. The results highlight a fundamental trade-off between localized thermal comfort and overall indoor temperature uniformity in conventionally heated spaces. While localized heating enhances comfort near the heat source, it generates vertical temperature disparities exceeding acceptable comfort thresholds at greater distances. Specifically, at 3 m from the heat source, the temperature difference between ankle and head height reached 6 °C, surpassing the 4 °C limit recommended by ASHRAE-55 for standing occupants. These findings underscore the need for alternative heating solutions that prioritize uniform heat distribution, energy efficiency, and optimized ventilation to improve indoor thermal comfort in residential buildings. This study provides critical insights to help develop and implement sustainable heating strategies and the design of energy-efficient dwellings. Full article

International thermal comfort requirements, such as ASHRAE standards, are used for classroom design in many countries, such as Australia, despite these standards serving thermal preferences for adult office workers in the USA or Europe. Subjected to mismatched thermal guidelines, students can be thermally uncomfortable in classrooms that are not correctly designed for their needs, and education buildings may consume significant energy on heating and cooling that is not appropriate to the location. The objective of this study is to critically examine the appropriateness of ASHRAE thermal comfort standards for classrooms in climates equivalent to New South Wales, Australia. Through a systematised literature review, this paper presents findings in four key areas: the relationship between thermal comfort and (i) local climate areas, (ii) classroom building types, (iii) students’ thermal comfort preferences and (iv) air conditioning. The research finds that international thermal comfort standards do not always provide suitable guidance for classrooms in diverse climate zones. The research identifies that reliance on mechanical heating and cooling can fail to meet students’ thermal comfort needs and undermines global environmental sustainability goals. This paper recommends localised thermal comfort benchmarks tailored to NSW’s climatic and educational contexts, contributing to improved classroom design, student wellbeing and energy-efficient learning environments. Full article

Ecuador faces a significant housing deficit, prompting government policies aimed at improving access to social housing for vulnerable families. Despite its relatively small geographic size, the country exhibits substantial climatic diversity, encompassing ten distinct Köppen–Geiger climate zones. These range from tropical rainforests to high-altitude Andean regions, each requiring specific housing strategies. However, social housing units are typically designed using a standardized model that disregards regional climatic variations, leading to suboptimal thermal performance and energy inefficiencies. This study evaluates the thermal comfort performance of standardized free-running social housing across six distinct cantons, using the ASHRAE 55-2020 adaptive comfort model. Dynamic simulations were conducted for both current climatic conditions and future scenarios for 2050 and 2100, employing tools such as Meteonorm 8.1 (for weather data), EnergyPlus 9.4.0, and DesignBuilder 7.0 (for thermal modeling). The findings reveal significant differences in indoor comfort levels among identical housing units due to localized climate conditions. Notably, high-altitude regions showed improved thermal performance under future scenarios, whereas coastal lowland areas experienced increased discomfort. These results underscore the urgent need for climate-responsive, adaptive housing designs tailored to local climatic realities across all regions of Ecuador. Full article

Indoor environmental quality (IEQ), encompassing thermal comfort and indoor air quality (IAQ), plays a crucial role in occupant well-being and operational performance. Although widely studied individually, integrating thermal comfort and IAQ assessments remains limited, particularly in large-scale tropical commercial settings. Hypermarkets, characterised by spatial heterogeneity and fluctuating occupancy, present challenges that conventional HVAC systems often fail to manage effectively. This study investigates thermal comfort and IAQ variability in a hypermarket located in Gombak, Malaysia, under tropical rainforest conditions based on the Köppen–Geiger climate classification, a widely used system for classifying the world’s climates. Environmental parameters were monitored using a network of IoT-enabled sensors across five functional zones during actual operations. Thermal indices (PMV, PPD) and IAQ metrics (CO₂, TVOC, PM2.5, PM10) were analysed and benchmarked against ASHRAE 55 standards to assess spatial variations and occupant exposure. Results revealed substantial heterogeneity, with the cafeteria zone recording critical discomfort (PPD 93%, CO₂ 900 ppm, TVOC 1500 ppb) due to localised heat and insufficient ventilation. Meanwhile, the intermediate retail zone maintained near-optimal conditions (PPD 12%). Although findings are specific to this hypermarket, the integrated zone-based monitoring provides empirical insights that support the enhancement of IEQ assessment approaches in tropical commercial spaces. By characterising zone-specific thermal comfort and IAQ profiles, this study contributes valuable knowledge toward developing adaptive, occupant-centred HVAC strategies for complex retail environments in hot-humid climates. Full article

This study addresses the issue of excessive cooling in data center server rooms caused by the sparse deployment of server cabinets. A precise air-conditioning control strategy based on the working temperature response of target cabinets is proposed. CFD software is used to establish the server room model and set control objectives. The simulations reveal that, under the condition of ensuring normal operation and equipment safety in the data center, the supply air temperature of the CRAC (computer room air conditioner) system can be adjusted to provide more flexibility, thereby reducing energy consumption. Based on this strategy, the dynamic load of the server room is simulated to obtain the supply air temperature of the CRAC system, forming a simulation dataset. A graph structure is created based on the distribution characteristics of the servers, and a regression prediction model for the supply air temperature of the CRAC system is trained using graph neural networks. The results show that, in the test set, 95.8% of the predicted supply air temperature errors are less than 0.5 °C, meeting ASHRAE standards. The model can be used to optimize the parameter settings of CRAC systems under real load conditions, reducing local hotspots in the server room while achieving energy-saving effects. Full article

This work analyzes the potential impact of thirteen passive and active factors on a low-income housing (LIH) model in a tropical climate. For this purpose, a study of material properties and energy modeling using Building Information Modelling (BIM) is carried out, which helps to evaluate these factors’ energetic and economic implications. Two significant assessments are highlighted, namely active and passive factor analysis and dominant factor analysis. The research studied the architectural design of a one-story house measuring thirty-six square meters outlined by the Ecuadorian Construction Standard (NEC) chapter 15 part 4. A 3D architectural model was generated using Revit 2024 simulation software and subsequently employed to establish an energy model used in Autodesk Insight Software 2024 to assess the factors influencing energy consumption and annual energy expenses. The analysis included a comparison with a model of the house based on the ASHRAE 90.2 standard. The active and passive factors were ranked according to their impact on energy efficiency in the model. The results show that Energy Use Intensity (EUI) has a higher reduction for the ASHRAE model of 4.63%, with 21.60% for the Energy cost. The active factors exhibited a greater impact on the energy performance of the LIH than the passive factors, with the PV-Surface coverage being the factor that generated the highest EUI reduction, with 39.66% and 78.51% for both models. The study concluded by emphasizing the importance of adopting active strategies to achieve energy efficiency and economical house design. Full article

Solar air heating systems offer an effective alternative for reducing greenhouse gas emissions at a profitable cost. This work details the design, construction, and experimental evaluation of a novel double-pass V-trough solar air heater with semicircular receivers, which was built with low-cost materials readily available in the Mexican market. Thermal performance tests were conducted in accordance with the ANSI-ASHRAE 93-2010 standard. The results indicated a peak collector efficiency of 0.4461 and total heat losses of 8.8793 W/(m² °C), with an air mass flow rate of 0.0174 kg/s. The instantaneous thermal efficiency varied between 0.2603 and 0.5633 with different air flow rates and an inlet air temperature close to the ambient temperature. The outlet air temperature reached 70 °C, making it suitable for dehydrating fruits or vegetables at competitive operating costs. Additionally, a second-law analysis was carried out, and the exergy efficiency was between 0.0037 and 0.0407. Finally, a Levelized Cost of Energy analysis was performed, and the result was USD 0.079/kWh, which was 31% lower than that of a conventional electric air heater system. Full article

Refugee tents are essential temporary shelters in disaster-prone regions like Aceh, Indonesia, which experiences a warm and humid tropical climate. Ensuring thermal comfort in these shelters is crucial for the well-being and recovery of displaced individuals. This study evaluates the thermal comfort of refugee tents deployed in Aceh through a combination of field measurements and computational simulations using Ansys Fluent 19.2 (CFD software). Field measurements captured real-time environmental data, including temperature, humidity, and airflow inside and around the tents. Thermal comfort was assessed using the Indonesian National Standard (SNI 03-6572-2001) through Effective Temperature (ET), and the ASHRAE 55 through Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD). This study also analyzed the thermal performance of alternative tent configurations designed to improve thermal comfort in tropical climates. Two new tent designs were proposed: one with rooftop openings to release trapped hot air and another with both upper ventilation and a double-layer outer skin with a 10 cm air gap. The results show that the tent with upper ventilation reduces the air temperature by approximately 0.5 K and increases air speed by around 0.18 m/s. The design combining upper ventilation and a double skin achieves a greater temperature reduction of 2.9 K compared to the outside environment, with a faster airflow than ventilation alone. These findings highlight the importance of advanced ventilation strategies and thermal insulation in improving indoor environments, offering valuable insights for future refugee tent designs aimed at enhancing thermal comfort. Full article

Climate change poses significant challenges to energy efficiency and occupant comfort in residential buildings. This study introduces a simulation-based multi-objective optimization approach for architectural design, aimed at addressing these challenges and enhancing environmental sustainability. Utilizing EnergyPlus for energy simulations and jEPlus to identify objective functions and design parameters, the research employed the NSGA-II algorithm through jEPlus + EA for multi-objective optimization. A Morris sensitivity analysis assessed the impact of 25 design variables—including heating and cooling setpoints, air infiltration rates, insulation types, window selections, airflow rates, and HVAC systems—on key objective functions. Applied to a residential building in Sari, Iran, the study analyzed various climate change scenarios to minimize five main objectives: primary energy consumption, greenhouse gas emissions, indoor air quality, predicted percentage of dissatisfied, and visual discomfort hours. The weighted sum method was used to select optimal solutions from the Pareto front. Results demonstrated that the recommended energy retrofit strategies could reduce primary energy consumption by up to 60%, greenhouse gas emissions by 60%, predicted thermal dissatisfaction by 65%, and visual discomfort hours by 83%, while also achieving indoor air quality levels that meet ASHRAE recommended standards. However, the implementation of these energy-efficient solutions may require careful consideration of trade-offs in design decisions when addressing climate change challenges. Full article

The growing need for effective and sustainable solutions in humanitarian construction has prompted scholars and practitioners to explore technical approaches that address the challenges of natural disasters, health emergencies, armed conflicts and migratory flows. These solutions often encompass temporary shelters, durable shelters and multifunctional buildings designed to balance rapid deployment, cultural sensitivity and environmental sustainability. However, the assessment of sustainability in humanitarian construction remains insufficiently defined due to the complexities of crises, the variability of local materials and the impact of local climatic conditions. This study aims to bridge this gap by integrating Building Information Modeling (BIM) and simulation tools such as COMSOL Multiphysics 6.0 to study sustainable strategies for humanitarian housing. Using case studies aligned with IFRC, UNHCR and CRL (Red Cross of Luxembourg) family shelter standards, the research assessed a Climate and Local Skill-Centered Design (CLCD) by examining the performance of key design elements, including wall material emissivity and reflectance, natural lighting, and energy efficiency within the context of indoor thermal comfort. Simulation results revealed that wall finishing material reflectance significantly influences average daylight factors (D), with variations of 2% to 5% linked to lower reflectance values and changes in the window-to-floor ratio (WFR). Conversely, thermal comfort metrics indicated minimal variations in heat discomfort hours, maintaining indoor temperatures between 19 °C and 25 °C, consistent with ASHRAE Standard 55 thermal comfort criteria. This paper underscores the importance of integrating advanced IT tools and green local techniques and materials to optimize humanitarian housing for health, comfort and environmental performance, offering actionable insights for future humanitarian sustainable designs. Full article

In a Brazilian subtropical climate, Wood Frame construction, valued for sustainability and thermal inertia, is being tested for compatibility with Phase Change Materials (PCMs) to improve thermal performance. This study addresses the lack of research on these technologies in Brazil and evaluates the thermal performance of a single-story Wood Frame housing envelope with and without PCM in Curitiba-PR, located in southern Brazil with Cfb climate classification. Dynamic energy simulation followed ASHRAE Standard 55-2017 criteria for occupant thermal comfort. The results indicated that integrating PCM with thermal insulation (EPS) significantly improved thermal performance, reducing the daily indoor temperature range by up to 6.4 °C and increasing comfortable hours by 20%. However, Wood Frame construction without either BioPCM or EPS proved inadequate in achieving the minimum level of thermal performance required by Brazilian standards. This underscores the importance of evaluating potential users’ thermal comfort conditions alongside the building’s overall thermal performance. It also emphasizes the need to carefully consider the level of thermal insulation in conjunction with PCM for effective design decisions. Thus, this study promotes the integration of PCM and thermal insulation to enhance thermal comfort and sustainability in Wood Frame constructions in the subtropical climate of Brazil. Full article

Thermal coating paints offer a passive strategy to reduce heat gain in buildings, improve ventilation, and lower energy consumption. This study investigates the effectiveness of these technologies by comparing different housing structures and environmental conditions. Specifically, it examines thermal envelope solutions for cool roofs in homes along the Colombian Caribbean Coast. We quantify the thermal impacts using experimental data collected from 120 houses across eight municipalities in the Magdalena Department, Colombia. The research details the technology and analytical methods employed, focusing on thermal reductions achieved through thermal coatings to potentially reduce energy demand. A comprehensive measurement system, incorporating temperature and humidity sensors, is developed to assess the impact of the coatings. Thermal comfort is evaluated according to the ASHRAE 55 standard, with temperature reductions calculated for each house treated with thermal coatings. A methodology is applied to evaluate the thermal reduction between a house with a coating solution versus a house without it. The results show a temperature reduction on a house-by-house basis, from 1.5% to 16%. On average, the results yield a significant 7% reduction in thermal load. Additionally, a mobile application is developed to disseminate the results of this research, promoting the social appropriation of science among the involved communities. Full article

There are three main approaches to human thermal comfort; a psychological approach, a thermo-physiological approach, and an approach based on human energy balance. According to the ISO 7730 and ASHRAE Standard 55-2023 standards, the psychological approach defines thermal comfort as a mental state in which individuals feel satisfied with their surrounding environment. According to this definition, thermal comfort is very subjective and may vary between individuals, as well as according to the environment and climate. This study aimed to evaluate the thermal comfort levels of students in primary and high school classrooms situated within the semi-arid climatic conditions of Şanlıurfa. For this purpose, 15 Temmuz Şehitleri Secondary School, Kadir Evliyaoğlu College, and TOBB Science High School in Şanlıurfa were chosen as fieldwork locations. Within the scope of the study, the climatic conditions (classroom temperature, air velocity, humidity, radiant temperature, Tw, Tg carbon dioxide) were measured, and how the students felt under the thermal conditions of these classrooms was evaluated. The study encompasses both the heating season (winter) and the non-heating season (summer). Based on the findings obtained from the study, PMV (Predicted Mean Vote) and PPD (Predicted Percentage Dissatisfied) values and whether they are suitable thermal comfort for the people in these places tried to be determined by mathematical modeling and standards such as ASHRAE Standard 55-2023. While PMV values ranged between −0.58 (North) and 2.53 (East+South+West), PPD values were observed between 5% (South and some North facades) and 94% (East+South+West). While the South facade offers values close to the comfort range of 0.01–0.02 in terms of PMV, the East+South+West facade shows serious thermal discomfort with a PMV value of 2.53 and a PPD value of 94%. Full article

This study explores energy consumption, thermal performance, and indoor environmental quality (IEQ) in terminal buildings. Through detailed thermal analysis, this research identifies key sources of heat loss, such as thermal bridges in walls and windows, which significantly increase energy demands for heating. IEQ measurements show that the lack of mechanical ventilation, combined with high passenger densities, frequently leads to CO₂ levels exceeding recommended thresholds, highlighting the urgent need for improved ventilation systems. Energy requirements were calculated based on the TS 825 standard and compared to actual consumption data, showing that optimizing boiler settings could save 22% of heating energy without any additional investment. Simulations and economic analyses further showed that adding thermal insulation to the building envelope and installing double-glazed windows with improved U-values could achieve significant energy savings and reduce CO₂ emissions, all with favorable payback periods. A life cycle assessment (LCA) was conducted to evaluate the environmental impact of these interventions, demonstrating significant reductions in the airport’s carbon footprint. The findings underscore the importance of aligning operational standards with international guidelines, such as ASHRAE and CIBSE, to ensure thermal comfort and optimize energy use. Full article