Search Results (52)

The greenhouse effect, responsible for trapping heat in Earth’s atmosphere, has a parallel thermal phenomenon at the indoor scale known as the Room-Level Greenhouse Effect (RGHE), where solar radiation elevates room temperatures and increases energy consumption. The RGHE contributes to indoor temperature increases of 4–10 °C and elevates energy demands by 15–30% in high solar exposure zones, the effect being even worse in tropical zones. To address this problem, an innovative analog microarchitecture is proposed for real-time RGHE detection by sensing the sunlight intensity radiation factor (SIR). A compact analog system is introduced, comprising three stages: a Sensing Circuit Stage (SCS) that isolates the dynamic sunlight signal f (r) from static room condition factors (RCFs), an Amplification Stage (AS) that shifts and boosts the signal, and a Stabilized Peak Detection Stage (SPDS) that captures the peak solar intensity. The microsystem was tested across fixed f (m) levels of 0.75 V, 1.0 V, and 1.5 V, and varying f (r) values of 3 mV, 4 mV, and 5 mV. It successfully detects peak voltages ranging from 1.69 V to 1.92 V, with stabilization achieved within 60 µs, enabling accurate detection of the f (r) signal. The proposed microarchitecture offers a scalable approach to localized thermal monitoring in smart building environments using fully analog circuitry, designed and simulated in Cadence Virtuoso using the TSMC 180 nm technology library. 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

To address the limitations of conventional split air conditioners (SACs) that lack proper ventilation, resulting in indoor pollutant buildup and health risks, this study develops and evaluates the performance of a sustainable hybrid air conditioning system that integrates Indirect Evaporative Cooling (IEC) with SAC to enhance indoor air quality (IAQ), thermal comfort, and energy efficiency in tropical climates, compared with a standalone SAC system. The hybrid SAC + IEC system is designed to meet stringent comfort criteria while reducing indoor formaldehyde and carbon dioxide concentrations. Experiments were conducted in a controlled classroom environment using a cross-flow tubular heat exchanger with optimized nozzle configurations. Temperature, humidity, and pollutant levels were continuously monitored under varying tropical conditions. The IEC achieved an average cooling capacity of 1430 W, substantially exceeding the target of 566 W, and reduced the fresh air dry-bulb temperature by up to 8.79 °C, maintaining primary air near 25.2 °C, with energy efficiency ratios varying between 30% and 100%. The hybrid SAC + IEC system outperforms the standalone SAC system in maintaining acceptable formaldehyde and CO₂ levels while delivering comfortable thermal conditions within the indoor standards. These results demonstrate that the Hybrid SAC + IEC system optimizes energy efficiency and improves cooling performance and indoor air quality (IAQ) for tropical environments. Full article

The Urban Heat Island’s (UHI) effect intensifies thermal discomfort for urban communities, increasing energy requirements. This study assesses the incorporation of Phase Change Materials (PCMs) into building envelopes to reduce Urban Heat Island (UHI) impacts in the Trichy urban area, characterised by a dry-summer tropical savanna environment. To evaluate energy efficiency and indoor temperature regulation, simulations were conducted using Design Builder and Climate 6.0 software. The results show that overall room electricity consumption decreased from 480 kWh to 380 kWh, demonstrating the energy-saving benefits of the modifications. Overall energy consumption was reduced to 271.9 kWh/m²/year from 312.23 kWh/m²/year in the base case, a 13% decrease, equating to 40.33 kWh/m²/year in energy savings. The payback period for PCM installation was predicted to be around 30.64 years. These results show that PCM-enhanced building envelopes reduce UHI effects and improve thermal comfort and energy efficiency, making them a feasible, sustainable urban development strategy. 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

The rapid urbanization of developing cities has intensified the challenge of maintaining thermal comfort in buildings, particularly in hot–humid climates. This study investigates the impact of floor level on airflow patterns and indoor temperatures in multi-purpose mid-rise buildings in Onitsha, Nigeria, where increasing urban density and frequent power outages necessitate effective passive cooling strategies. Through a mixed-method approach combining empirical measurements, computational fluid dynamics (CFD) simulations, and thermal performance analysis, the research examined variations in ventilation rates and temperature distributions across different floor levels of a six-story educational building over an annual cycle, focusing on the hottest (27 February), coldest (28 December), most windy (3 April), and least windy (17 September) days. Results revealed distinct floor-level ventilation patterns: upper floors (fourth–fifth) achieved 39–40 air changes per hour (ACH) during hot periods while maintaining temperatures of 30–35 degrees Celsius (°C); middle floors (second–third) showed moderate ventilation (15–22 ACH) but experienced heat accumulation (35–42 °C); and lower floors reached 20 ACH during windy conditions. Temperature stratification varied from 15 °C between floors across the entire building during peak conditions to 7 °C during windy periods. Stack-driven ventilation in upper floors contributed to temperature reductions of up to 3 °C, while wind-driven ventilation promoted uniform temperature distribution across all levels. These findings informed floor-specific design recommendations: hybrid ventilation systems with automated controls, strategic architectural features including a minimum floor level area of 15% for the central atrium, and comprehensive monitoring systems with six temperature sensors per floor. This study provides evidence-based strategies for optimizing thermal comfort in tropical urban environments, particularly valuable for designing energy-efficient buildings in rapidly developing cities with hot-humid climates. Full article

This systematic literature review (SLR) focuses on indoor environmental quality (IEQ) in passenger transport vehicles within tropical and subtropical regions. It specifically examines indoor air quality (IAQ), thermal comfort (TC), acoustic comfort (AC), and visual comfort (VC) of passenger vehicle cabins (PVCs) in auto rickshaws, sedans, trucks, bus rapid transits (BRTs), buses, trains, trams, metro systems, aircraft and ferries of tropical and subtropical regions. The SLR used the PRISMA approach to identify and review scientific studies between 2000 and 2024 on the IEQ of PVCs in the tropics. Studies reviewed were found in SCOPUS, Web of Science, Science Direct, and EBSCO databases including relevant citation references. Findings reveal a significant geographical imbalance in research, with most studies concentrated in tropical Asia (78.2%), while sub-Saharan Africa (8.2%), South America (11.8%), and Oceania (1.8%) are considerably underrepresented. In 113 studies, most addressed IAQ and TC but limited attention to AC and VC. Moreover, fewer studies have jointly addressed all the IEQ parameters, highlighting the need for a more comprehensive approach to IEQ for tropical PVCs. Several studies alluded to in-cabin commuter risk linked to PM_2.5, PM₁₀, carbon monoxide (CO), and volatile organic compounds (VOCs). These risks are exacerbated by traffic hotspots, poor ventilation, ambient pollution, overcrowding, and poor vehicle conditions. Additionally, thermal discomfort is compounded by extreme heat loads, inefficient HVAC systems, and high vehicle occupancy. Common gaps include a paucity of IEQ studies and inadequate IEQ regulations or adapted standards in developing tropics. Infrastructural and regulatory deficiencies have been identified, along with strategies for mitigation. Recommendations are for more holistic IEQ studies in the tropics, including exposure studies for emerging gaps in new indoor pollutants, integration of AI and IoT for sustainable ventilation strategies, and development of effective regulatory frameworks considering region-specific conditions. Finally, Policymakers are encouraged to establish localized IEQ standards, enforce regulations, and prioritize upgrades to transport infrastructure. The SLR findings emphasize the urgent need for targeted interventions in developing tropical regions to address disparities in IEQ, ensuring healthier and more sustainable transport environments that could be replicated across transport systems worldwide. Full article

Rational management of scarce water resources is necessary. These resources are not utilised effectively. Therefore, the efficacy of irrigation management at the field level can be enhanced, and the irrigated areas can be expanded through rigorous irrigation management. By estimating water requirements in a straightforward, realistic, precise and feasible manner, achieving optimal water consumption for quality production and profitability is possible. In the context of the development of water resources in tropical and hot climates such as Ghana, estimating water demand assists farmers in planning and adjusting their requirements over time. This study assessed the water requirements of a greenhouse banana during the dry season to assure year-round cultivation, as Ghana has two primary seasons: wet and dry. The estimate was predicated using WSN and the JDL–Mivar data fusion model, which was dependent on the determination of perspiration. The results were contrasted with the existing literature, considering both climatic and biological data and other parameters during the cultivation period due to the model’s ability to fuse datasets. The study determined that the optimal indoor temperature for banana cultivation was 38.1 °C, while the minimum threshold was set at 21 °C. Significant differences and fluctuations in the maximal daily transpiration rates were observed in the water requirements for ‘WN’ values, which ranged from 25 to 50 m³/(ha·J). Banana plants require an intake of 10–20 litres of water per day during their growth season, according to the data collected from the WSN moisture sensor. The banana plants transpired between 100 and 600 kilogrammes of water for every kilogramme of dry matter produced during the humid climate, as indicated by the transpiration ratio, which ranged from 100 to 600. The Leaf Area Index (LAI) fluctuated from 3.3 in June to 4.89 in December. Our proposed method for monitoring bananas in a greenhouse will provide the cultivator with precise information about the bananas that are cultivated within the greenhouse environment. The optimal Leaf Area Index is between 3.6 and 4.5 for bananas to achieve their maximum yield potential. The relative humidity for bananas is typically around 80%, ranging from 65% to 75% during the night and approximately 80% during the day. Full article

Thermal insulation is a reliable strategy for achieving optimal thermal comfort in built environments and is among the most effective energy-saving measures. Currently, environmentally friendly insulation materials produced from plant and animal fibers constitute a significant component of the building industry, largely due to their minimal embodied energy and concerns about certain synthetic insulation materials’ potential adverse health effects. The main objective of the present study is to encourage and facilitate the utilization of environmentally friendly thermal insulation materials derived from biological sources, including vegetal and animal fibers, to improve thermal comfort and consequently reduce energy consumption in buildings. The study attempts to simulate the indoor air temperature profiles of a single building constructed using locally sourced materials and insulated in a series of stages with the aforementioned insulation materials. Firstly, insulation is applied exclusively to the roof. Secondly, the insulation is applied to the remaining wall surfaces. Alternatively, the insulation is applied to both the roof and the wall surfaces simultaneously. The objective is to ascertain the optimal combination of bio- and geo-insulating materials to achieve thermal comfort in buildings constructed with local materials in tropical climates. The Gauss-Seidel iterative method was employed to solve the energy equations that had been written on the walls and roof of the building. The equations were then discretized using the nodal method. To ascertain the thermal comfort of the simulated buildings, a comparison was made of the indoor air temperatures. The results of the simulations demonstrated that the utilization of wood fiber, reed panels, and straw bales as insulation materials led to a notable enhancement in comfort levels across all five building types, with an average increase of 17.5%. Among these materials, wood fiber emerged as the most effective insulation option, reducing temperatures by up to 19%. Its integration into the sheet metal-clad Banco building would be particularly advantageous. The findings demonstrate that the simultaneous insulation of walls and roofs with natural fiber thermal insulation materials markedly reduces indoor air and wall temperatures in buildings by up to 19% in comparison to uninsulated walls and roofs. Full article

Thermal comfort is a fundamental goal of architecture aiming at protecting individuals from harsh weather conditions. In Nigeria’s savanna climate zone, such as Kaduna, poor indoor thermal comfort leads to over-reliance on air-conditioning systems. There is limited research on the application of passive design strategies in the Nigerian savanna climate, which creates a barrier to their widespread implementation in residential buildings. In response to the increased awareness of climate change and the need for sustainable design, this study explores the potential of passive design strategies, focusing on the combination of rooftop insulation and reflective materials with mechanical ventilation as a means of improving indoor thermal comfort solutions. This study conducted a 3-day field experiment of typical dwellings in Kaduna, a major city in the Nigerian savanna climate zone. The data collected from this experiment served as the basis for a simulation study using EnergyPlus software, which tested and evaluated 3 different strategies: passive design (roof insulation + reflective materials), mechanical ventilation, and a combination of passive design and mechanical ventilation. This study highlights the potential for passive design strategies to provide a more sustainable, cost-effective solution, reducing dependence on air conditioning while supporting indoor comfort. Additionally, the research methodology and insights gained offer a basis for developing future building codes in Nigeria that emphasize sustainable practices. Such codes would guide architects, builders, and policymakers in designing homes that respond to local climate needs and align with broader sustainability goals. Further research could explore additional passive measures, including advanced window technologies, shading, and natural ventilation, to maximize sustainable residential design potential in tropical savanna climates. Full article

The growing global concern over heat-related health risks, exacerbated by climate change, disproportionately affects low-income populations, particularly in tropical regions like Indonesia. This study investigates indoor thermal conditions in home-based enterprises (HBEs) within the informal urban settlements of Surakarta City, Indonesia, focusing on the struggle for thermal comfort under constrained conditions. By addressing the thermal comfort challenges in low-income urban housing, this research contributes to sustainable development goals, aiming to enhance living conditions in tropical climates. Our methodology included detailed field measurements of thermal comfort using standard indices in these dwellings, complemented by surveys and interviews to understand building designs, occupant behaviors, and adaptation strategies. Findings indicate that temperatures inside the dwellings frequently exceeded 30 °C during 50–60% of working hours, prompting residents to adopt coping strategies such as opening windows, adjusting work schedules, and utilizing shading devices. Space limitations necessitated multifunctional use of dwellings, exacerbating heat and humidity from activities like cooking and ironing. Despite reliance on natural ventilation, ineffective architectural layouts impeded airflow. This study highlights the urgent need for sustainable architectural solutions that accommodate the dual residential and commercial functions of these spaces, aiming to improve living conditions in such challenging environments. Full article

The development of bio-insultation materials has attracted increasing attention in building energy-saving fields. In tropical and hot–humid climates, building envelope insulation is important for an energy efficient and comfortable indoor environment. In this study, several experiments were carried out on a bio-insulation material, which was prepared by using rice husk as a raw material. Square rice husk-based insultation panels were developed, considering the ASTM C-177 dimensions, to perform thermal conductivity coefficient tests. The thermal conductivity coefficient obtained was 0.073 W/(m K), which is in the range of conventional thermal insulators. In a second phase of this study, two experimental enclosures (chambers) were constructed, one with rice husk-based insulation panels and the second one without this insulation. The measures of the temperatures and thermal flows through the chambers were obtained with an electronic module based on the ARDUINO platform. This module consisted of three DS18B20 temperature sensors and four Peltier plates. Daily temperature and heat flux data were collected for the two chambers during the dry season in Panama, specifically between April and May. In the experimental chamber that did not have rice husk panel insulation on the roof, a flow of up to 28.18 W/m² was observed, while in the chamber that did have rice husk panels, the presence of a flow toward the interior was rarely observed. The rice husk-based insulation panels showed comparable performance with conventional insulators, as a sustainable solution that takes advantage of a local resource to improve thermal comfort and the reduction of the environmental impact. Full article

Escalating global climate change and the intensification of urban heatwaves have led to an increase in summer air conditioning cooling energy consumption. This phenomenon is particularly critical in tropical regions, as it may trigger an energy crisis. The rational setting of indoor thermal design parameters can help conserve energy to the maximum extent while ensuring thermal comfort for occupants. This study selected Haikou City, a unique tropical city in China, as the research location. Indoor environment measurements and a questionnaire survey were conducted with participants, and the outdoor thermal environment sensitivity, population attributes and differences in thermal sensation, thermal neutral temperature, and comfort range were calculated and analyzed. The following results were obtained. Based on the overall population, long-term residence, and temporary residence classification, the indoor thermal comfort needs of residents in tropical cities in Haikou were effectively identified. The actual thermal neutral temperature of the overall population is 25.7 °C, and 90% of the acceptable thermal comfort temperature range is 23.2 °C–28.0 °C. The actual thermal neutral temperature of the regular residents is 27.3 °C, and 90% of the acceptable thermal comfort temperature range is 23.3 °C–31.4 °C. The actual thermal neutral temperature of the temporary population is 25.5 °C, and 90% of the acceptable thermal comfort temperature range is 23.0 °C–28.0 °C. These research results have an important reference value for improving the setting of the temperature of air conditioning in tropical areas in summer and further reducing energy consumption, which is conducive to sustainable development. Full article

A numerical simulation model of a natural ventilation greenhouse is helpful for improving the production and quality of greenhouse crops in tropical areas. Field experiments show that the mean coefficient of variation of indoor light intensity in four seasons was lower than 10.0%. The highest indoor temperature reached 39.3 °C during summer, while the average indoor temperature ranged from 24 °C to 26 °C in the other three seasons. The average relative humidity in the greenhouse ranged from 76% to 87% annually, which was higher and more stable than that in the external environment. A three-dimensional steady-state numerical model of the greenhouse was established based on computational fluid dynamics. Under natural ventilation conditions, the maximum error between the simulated value and the measured value of the temperature in each measuring point was 5.90%. And the average relative error between the simulated and measured values was 3.0% in the range of 0.7−1.5 m of crop cultivation height. Finally, a numerical simulation of adding side windows and expanding the vents was carried out. The results show that these methods can homogenize the airflow distribution in the greenhouse and improve the utilization efficiency of natural ventilation without more mechanical system operations. Full article

The use of artificial lighting in a total or supplementary way is a current trend, with growing interest due to the increase in the global population and climate change, which require high-yield, quality, and fast-growing crops with less water and a smaller carbon footprint. This experiment aimed to evaluate the effect of light-emitting diode (LED) lighting on the production of basil, mustard, and red cabbage seedlings under controlled artificial conditions and in a greenhouse as a supplementary lighting regime. Under controlled conditions, the experiment was conducted with basil seedlings, comparing LED light with two wavelengths (purple and white light). In a greenhouse, mustard and red cabbage seedlings were evaluated under natural light (regular photoperiod) and with supplementary purple lighting of 3 h added to the photoperiod. The variables assessed were aerial fresh mass (AFM), aerial dry mass (ADM), root dry mass (RDM), plant length (PL), and leaf area (LA). Basil seedlings grown under purple light showed greater length and AFM than those grown under white light, with no effect on the production of secondary metabolites. In the greenhouse experiment, red cabbage seedlings showed an increase in AFM, ADM, and DRM with light supplementation, with no effect on LA. AFM showed no statistical difference in mustard seedlings, but the productive parameters LA, ADM, and DRM were higher with supplementation. None of the evaluated treatments influenced the production of phenolic compounds and flavonoids in the three species evaluated. Light supplementation affected red cabbage and mustard seedlings differently, promoting better development in some production parameters without affecting the production of phenolic compounds and flavonoids in either plant. Thus, light supplementation or artificial lighting can be considered a tool to enhance and accelerate the growth of seedlings, increasing productivity and maintaining the quality of the secondary metabolites evaluated. Thus, this technology can reduce operational costs, enable cultivation in periods of low natural light and photoperiod, and cultivate tropical species in temperate environments in completely artificial (indoor) conditions. Full article