Hot Months Research Articles

Remote Sensing - Based Analysis of LST and NDVI Correlation for the Coolest and Hottest Month of 2023 in Khanaqen City

Urban land cover characteristics often lead to variations in surface temperature. Remote Sensing (RS) and Geographic Information Systems (GIS) are valuable tools for obtaining detailed information about surface indices. This study evaluates the temporal variation of Land Surface Temperature (LST) in Khanaqen city, located in South eastern Iraqi Kurdistan and Eastern Iraq. The research investigates the relationship between LST and the Normalized Difference Vegetation Index (NDVI) for the coolest and hottest month of 2023 using Landsat images from the USGS Earth Explorer. The objective is to explore how green spaces influence LST during the cool, humid winter and hot, dry summer. Two satellite images from Landsat 9 were used to retrieve LST and NDVI for the study periods. The results indicate that green spaces significantly reduce LST in July, so that the result of the correlation analysis of variables, significant inverse correlation between LST and NDVI (R = -0.53, R2 = 0.28 and P value = 0.00) highlights the effect of vegetation cooling. Conversely, January shows a modest correlation (R = -0.01, R2 = 0.00, and P value = 0.90), indicating a minimal effect of vegetation cover on LST.

Isolation of Shewanella algae from blue crabs (Callinectes sapidus) in Northwestern Adriatic Sea

Abstract Blue crab (Callinectes sapidus) is one of the last reported invasive species that have colonized the Italian coasts, in particular the lagoons of the northern Adriatic Sea. Their massive presence is compromising shellfish farming, causing a serious economic crisis among the valley populations. To limit the economic damage, blue crabs have been introduced as human food in the Italian markets. This study aimed to evaluate the microbiological contamination of blue crab as potential risk to human health. From July 2023 to April 2024, 72 blue crabs were collected in coastal lagoons and 5-6 nm from the coast of the Emilia Romagna Region. Microbiological analysis revealed Shewanella algae as one of the most commonly identified microorganisms (18/72, 25%). Shewanella was isolated on Chromagar Vibrio™ and TCBS after an enrichment step in Alkaline Saline Peptone Water. Colony morphology, Gram stain, and biochemical tests (oxidase, catalase) sustained Shewanella identification, later confirmed by MALDI-TOF MS (MALDI Biotyper® Sirius, Bruker Daltonics). S. algae is a Gram-negative, rod-shaped, aerobic microorganism widely distributed in seawater, freshwater, and soil. In humans, it is considered an opportunistic pathogen, especially in people with impaired immune systems. Shewanellosis has been strongly associated with seawater exposure and typically arises in hot months. Clinical manifestations include skin and soft tissue infections, otitis media, keratitis, biliary tract infections, vertebral discitis, and bloodstream infections. Notably, in the last years, S. algae infections have increased globally, even in healthy young people. The present study suggests blue crabs as a potential source of S. algae throughout the year. The increasing identification of S. algae in marine waters worldwide, as well as in marine-derived foods like blue crabs, underscores the growing importance of S. algae as an emerging pathogen and its impact on public health. Key messages • Shewanella algae is an opportunistic pathogen, increasingly isolated in marine water and seafood. • Blue crab is an invasive species that has recently conolonised the Italian coasts.

Hybridization of Concentrated Solar Thermal, Geothermal, and Biomass: Case Study on Kizildere-2 Geothermal Power Plant

The usage of fossil fuel in the energy sector is the primary factor for global GHG emissions, so it is crucial to better utilize RE sources. One way to do that is to hybridize RE technologies to make up for their deficiencies while enabling a more synergistic power production. This study utilizes such an approach to hybridize the KZD-2 Geothermal Power Plant (GPP) with CST and biomass in the southwest region of Turkiye. The main motivation is to address the two main issues of GPPs—excess turbine capacities happening over the operating years and decreasing performance during hot summer months—while also increasing the flexibility of KZD-2. A topping cycle of CST–biomass is added utilizing a PTC field as the CST technology and olive residual biomass combustion as the biomass technology. The hybrid plant is simulated on TRNSYS, and the energetic data show that it is possible to generate more than 20 MWe of additional power during sunny and clear sky conditions while also increasing the Capacity Factor (CF) from 69% to 74–76%. Moreover, the financial results show that the resulting LCOAE is 81.19 USD/MWh, and the payback period is five or nine years for using the YEKDEM incentive or the spot market prices, respectively.

Lessons learnt from a real-time attribution and contextualisation trial in a National Meteorological and Hydrological Service

Abstract When a record hot month occurs, timely and credible attribution and contextualisation information can enhance public understanding and future preparedness. This is particularly effective if provided in real time by a National Meteorological and Hydrological Service (NMHS). Many NMHSs are working to integrate research-based attribution methods into their operational services. In this study, researchers and climate service staff collaborated to assess the feasibility of delivering such information swiftly and aligned with standard NMHS data and procedures. The record warm July (winter) temperatures of Tasmania, Australia in 2023 were chosen to illustrate the trial. Rapid results were available three days after the event. Approximately half of the unusual warmth was attributed to climate change, with the likelihood of breaking the previous record at least 17 times higher in the current climate compared to a stationary pre-industrial climate (14% vs. 0.4%). The warming trend became evident in the 1980s, and by 2060, average July temperatures in Tasmania match the record temperature of July 2023 under a high emissions scenario. However, average July minimum temperatures were not well modelled, necessitating the addition of a higher-resolution forecast-based attribution method. In subsequent analysis, almost all the forecast temperature anomaly, and reduced storm activity, was attributable to climate change. Statistical analysis revealed that a weak El Niño partly offset the unusual warmth. To expedite these additional approaches, information drawn from real-time forecasts could be used. Lessons learnt from this trial include technical improvements to align better with NMHS protocols including using consistent datasets and baselines, and refining and automating the method suite. Logistical and communication enhancements included training staff to run the suite, improving communication materials, and developing delivery channels. These learnings provide key considerations for NMHSs as they move towards providing timely and credible climate attribution and contextualisation information as part of their operational services.

Compound Hot and Dry Events in Argentina and Their Connection to El Niño‐Southern Oscillation

ABSTRACTThis work studies the simultaneous and sequential occurrence of hot and dry months in the summer season in Argentina, north of 40°S, based on three different databases: meteorological stations, a gridded observational dataset and a reanalysis product. The influence of the El Niño‐Southern Oscillation (ENSO) over the occurrence of these compound events is specially analysed using a logistic regression model. Monthly maximum temperature and precipitation data are used for the period 1979–2022 in four sub‐regions of Argentina: Northwestern Argentina (NOA), Northeastern Argentina (NEA), Cuyo (central‐western Argentina) and the Pampas (central‐eastern Argentina). Simultaneous hot and dry months and hot months preceded by dry months are the most frequent compound events. The highest frequencies are found in the centre part of the study region and NEA for simultaneous compound events, and in NOA and the Pampas region for sequential ones. In general terms, all datasets show a good representation of the spatio‐temporal variability of hot and dry months. The insights of the influence of ENSO on compound events revealed that La Niña enhances the occurrences of hot and dry months throughout the study region, with the exception of NOA, where El Niño conditions promote the occurrence of these events. Based on logistic regression models, we successfully quantify the relationship between ENSO and hot and dry months and demonstrate that ENSO plays a significant role as a driver of compound hot and dry events in the central region, Cuyo, NEA and a portion of the Pampas. This research contributes to the understanding of compound events in Argentina and how they are influenced by major drivers of climate variability providing useful information for the development of a predictive system for such events.

Global and regional climate in 2023

Abstract2023 was the warmest year on record with a global mean temperature of 1.45 ± 0.12 degC above pre‐industrial levels, surpassing the previous record (from 2016) by 0.17 degC. The onset of El Niño in early July was accompanied by record‐breaking land and sea‐surface temperatures, with June to September all exceeding previous monthly temperature records, and July and August being the hottest months on record. Sea‐surface temperatures have attained record highs for all months since March 2023 and Antarctic sea ice reached record lows throughout the year.

Improving indoor air quality and cooling efficiency: Indirect dew-point evaporative cooling in South China summers

The escalating impact of global warming and the increase in respiratory illnesses have heightened the demand for fresh air systems. However, the substantial power consumption and environmental harm associated with traditional air conditioning systems conflict with current international aspirations for carbon neutrality. To address these issues, a high-performance and compact counterflow indirect dew-point evaporative cooler have developed. This innovative design eliminates the U-turn of the working air seen in conventional M-cycle coolers, resulting in reduced pressure drop and enhanced energy efficiency. This study evaluates the performance of the newly developed dew-point cooler and explores its potential use in providing cool and fresh air for indoor spaces during the sub-tropical summer season in Zhenjiang city, Jiangsu province, China. The results indicate that despite the relatively low fan efficiency (ranging from 5% to 36%), a high cooling coefficient of performance (COP) between 5.2 and 9.3 was achieved. The cooler has demonstrated its effectiveness in improving both thermal comfort and air quality indoors. In Zhenjiang, the cooler can function as a standalone cooling device in June. However, during the hotter months of July and August, it is more suitable as an efficient pre-cooling device when used in conjunction with a conventional air conditioner. The developed cooler exhibited highly stable performance over a three-month test period, consistently maintaining effective cooling and fresh air supply. This study confirms the potential of the counterflow indirect dew-point evaporative cooler as a sustainable and efficient solution for improving indoor air ventilation and thermal comfort.

Marker assisted selection and genome recovery for heat tolerance in segregants of rice (Oryza sativa L.)

Abstract In the present global warming scenario, it is urgent to impart heat tolerance into the popular high yielding rice (Oryza sativa L.) varieties to reduce yield loss to a great extent. Uma (a prevalent red-grained rice variety in Kerala) was crossed with Nagina 22 (N22), the popular donor for heat tolerance. From the seven promising heat-tolerant F3 plants previously identified through marker assisted selection and field screening, F4 lines (58 nos.) were raised and characterised morphologically. Heat tolerance was scored under natural heat stress during hot summer months in field conditions. Among the evaluated F4 progenies, 26 promising plants registered >75% spikelet fertility. Double panicles were observed in some of the tillers of fourteen F4 plants. During the selection with reported polymorphic markers between parents, all the 26 F4 plants produced the corresponding amplicon for RM5749 (linked marker for heat tolerance in the parental cross Uma x N22) and also for RM9, RM201, RM208, RM225, RM242, RM495, RM3586, RM6100, RM6836, and RM26212, corresponding to the heat tolerant parent N22. Genomic analysis revealed 64% recovery of the Uma genome in seven F4 plants, with maximum genomic regions of Uma on the chromosomes 3 and 5. These promising F4 plants could be forwarded to generate stable and high yielding heat tolerant rice varieties. The identified markers could be used for linkage analysis and QTL mapping in future. Keywords: Heat stress; Rice; spikelet fertility; SSR; QTL

Energy efficient design of buildings in hot climates through cooling of the envelope

The building envelope can afford many enhancements for lowering the cooling load in hot regions. In this paper, an active upgraded model utilizing an evaporative system to cool the envelope will be tested in the relatively humid climate of the coastal area of the Arabian Gulf. A couple of buildings were erected for this purpose. One was fully enclosed by a secondary structure around it, and the gap between the two was cooled using an evaporative cooler. This was compared to the second, which was insulated according to Dubai Municipality standards. A third comparison was also performed, which concerned the standalone secondary envelope with no evaporative cooling. The interior of all three cases was cooled using DX window-type air conditioners, and the power consumption measured. Thermal simulations were performed on similarly designed models using Ecotect 5.5 to see how each system would perform in full-scale functioning buildings. The measured tests on the building models showed a reduction of electrical consumption in both upgrades compared to the regulation insulated reference. The secondary envelope provided savings of 40 % and 47.3 % in the hot months of June and July, while the evaporative solution saved 52.1 % and 53.7 %, respectively. The simulation of a full-size building over the entire year showed the secondary envelope saving 48.9 % and the evaporative assisted 57.15 %.

Impact of employing phase change material in building wall on energy consumption and thermal comfort level

Energy crises are becoming a problem for many, most of the energy being produced is utilized in buildings. Building design and materials that are used in buildings play a vital role in saving electricity. Sustainable cities are one of the eleventh goal of Sustainable Development Goals to be achieved and this study is in context of SDGs for developing tools to create this globe sustainable and efficient society for humans. Phase change material is a type of material that can absorb and release heat energy as it changes between solid and liquid states. This ability to store and release thermal energy makes PCM a promising material for use in building insulation, Heating Ventilation Air Conditioning Systems, and other energy efficient applications. The use of PCM in buildings has the potential to significantly reduce energy consumption and improve thermal comfort levels. By incorporating PCM into building envelopes, such as walls, roofs, and floors, the material can absorb excess heat during the day and release it at night, helping to regulate indoor temperatures and reduce the need for heating and cooling systems. This study investigates the impact of using PCM in building envelopes. In this regard office building rooms are modelled in CAD software and are simulated in energy plus software. The simulation results are validated by considering the experiment and numerical study as a reference from paper. Model room is simulated for Hyderabad, Pakistan. Building envelopes without PCM have conduction rate of around 106.6 W/m2, whereas building envelopes with PCM have conduction rate around 42 W/m2. This shows that utilization of PCM reduced heat conduction up to around 40%. PCM reduced energy consumption of around 33.25 kWh/year/m2. Results show that without PCM air temperature was above the thermal comfort value. it reached 300C in hot months, it reduced up to 270C with the incorporation of PCM.

Original Research Paper

Plants inhabiting adverse growth conditions compete against stresses by the endogenous regulatory elements viz., promoters and terminators at the ‘right time’ (time-of-stress-act), ‘right place’ (tissue-of-act), and ‘right expression’ (time-of-transcription). Heat stress at the reproductive stage impedes pollen viability and stigma receptiveness, affecting the seed set. Prosopis cineraria, the dominant desert-inhabiting legume tree, is heat- and drought-tolerant. The distribution of heat shock elements in a heat-inducible promoter determines the magnitudes of target gene expression in different tissues/organs. Relative expression of P. cineraria heat shock protein 18.2 (PcHsp18.2) in alternate months of 2021 displayed the highest expression in summer. The flowers collected in June, the hottest month (47oC) of 2021, exhibited a high expression of PcHsp18.2. The germination of the pollen collected was 80%, and the trees eventually set seeds. Comprehensive analysis of the promoter (pPcHSP18.2) and terminator (tPchsp18.2) of PcHsp18.2 by expressing the gusA in tobacco exhibited the highest expression under heat stress as similar to the expression of PcHsp18.2 in environmental samples. Ectopic expression of gusA under PcHsp18.2 promoter and terminator resulted in an increased seed set due to the viability of pollen and stigma under heat stress. The gusA expression under PcHsp18.2 promoter and terminator was high-fold in anther compared to the Lat52 and g10 (endogenous genes under its promoter and terminator) genes under heat stress. The expression of genes under strong and balanced endogenous inducible promoter and terminator combinations, as in the desert-growing P. cineraria in transgenic plants, enables the development of resilient crops.

The Influence of Weather Temperature on Crime Occurrence in Babylon Province

Objectives: This study investigates the influence of temperature fluctuation on specific types of crimes in Babylon in Iraq. It also analyzes how varying temperatures leave an impact on crime patterns and trajectories. Methods: The study uses quantitative analysis, descriptive statistics, and Geographic Information Systems (GIS) to examine temperature and crime data. Statistical techniques, including correlation and regression analysis, are applied to assess the relationships between temperature variables and crime rates. Results: The study results showed that there is a strong affinity between temperatures and crime rates. Murder crimes reach their peak in hot summer months. The study also showed that theft crimes, including burglary, increase during cold winter months. Statistical analysis validates these findings, highlighting a direct correlation between temperature and murder rates and an inverse correlation with theft rates. Conclusions: This study confirms the huge impact of temperature fluctuation on criminal behavior in Babylon, Iraq. Recognizing these seasonal variations may help construct effective crime prevention strategies. Additionally, the study explores multiple theoretical perspectives, underlining the importance of adopting a multidisciplinary approach to comprehensively grasp the intricate relationship between climate and crime.

Enhancing Energy Efficiency in Moroccan Construction through Innovative Materials: A Case Study in a Semiarid Climate

Rising global energy demand has intensified the need for sustainable building practices and reduced energy consumption in the construction sector. This study investigates the energy-saving potential of integrating innovative materials into building wall structures in semiarid climates. Specifically, we examine the combination of thermal insulation made from recycled textile waste and phase change materials (PCMs) in exterior walls. Using the dynamic simulation tool TRNSYS, we analyzed heat transfer through the modified wall assembly under semiarid climate conditions typical of Marrakech, Morocco. Our results show that this “bioclimatic” design significantly impacts cooling loads more than heating demands. The modified building achieved a 52% reduction in summer energy usage compared to a conventional reference building. This energy saving translates to a 39% decrease in greenhouse gas emissions. Importantly, this study confirms that this configuration maintains thermal comfort for occupants, with particular effectiveness during the hot summer months when cooling demands are highest.

Developing a Chained Simulation Method for Quantifying Cooling Energy in Buildings Affected by the Microclimate of Avenue Trees

This paper introduces a methodology aimed at bridging the gap between building energy simulation and urban climate modeling. A coupling method was developed through the Building Control Virtual Test Bed (BCVTB) and applied to a case study in Taipei City, Taiwan, to address the microclimate factors of street trees crucial to cooling energy consumption. The use of the Urban Weather Generator for weather file modification revealed a 0.63 °C average air temperature disparity. The coupling method emphasized the importance of accurate wind speed and convective heat transfer coefficients (CHTCs) on building surfaces in determining cooling energy. The results indicated that elevated CHTC values amplify heat exchange, with higher wind velocities playing a crucial role in heat dissipation. The presence of street trees was found to significantly reduce heat flux penetration, leading to a reduction in building surface temperatures by as much as 9.5% during hot months. The cooling energy was lowered by 16.7% in the BCVTB simulations that included trees compared to those without trees. The EnergyPlus-only simulations underestimated the cooling energy needs by approximately 9.3% during summer months. This research offers valuable insights into the complex interactions between buildings and their environments. The results highlight the importance of trees and shading in mitigating the heat island effect and improving energy-efficient urban planning.

Characteristics of air temperature on the southern and southeastern slopes of the Greater Caucasus in the modern period

In the paper, the characteristics of air temperature in the south part of the Greater Caucasus region and the effects of regional climate changes on this area in the modern period were studied. In the research, the air temperature observation data of 8 hydrometeorological stations operating in the region for the years 1961-2022 were used, and the modern classification of the average monthly, seasonal, annual and altitude time-space distributions of temperature was given.Based on the data of hydrometeorological stations in the south and southeast piedmonts of the Greater Caucasus Mountains, an electronic map was prepared for the distribution of average annual air temperature indicators on the territory, and for determining the indicators of areas without data. DEM (Digital Elevation Model) files obtained fromthe decoding of satellite images (satellite data) were used in the prepared map. The research shows that July and August are the hottest months when the temperature is 22.80C, while January is the coldest by temperature about 0.50C in this region. In this part of the Greater Caucasus province, in the cold months of the year, the average monthly temperature is indicating below 00C in the area located above the moderately mountainous part of the region. The dynamics of the average indicators of temperature of the multi-year period (1961-2022) are expressed by a positive trend. The average annual temperature distribution map of the territory shows that the air temperature is 15.00C in the low mountainous part of the region, while it decreases upwards and, according to the adiabatic law, equals 00C at altitudes above 3500 m. According to the climate studies conducted in the region, compared to the years 1981-2010, it was found that there was a temperature increase of 1.20C in the mountainous region in 2011-2022. Also, a comparative analysis of 10-year averages of air temperature trends, using the Holt- Winters model, shows that temperatures in 2100 are expected to increase by 3.00C compared to 2030. In the region, climate changes that worsen every year lead to water scarcity, desertification, drought, etc. and can expand the area of recurrence of environmental crises and destructive natural events. This research can be used in future climate change mitigation , climate atlases, infrastructure, agricultural and industrial projects in the region.

СТРУКТУРЫ ИСПОЛЬЗОВАНИЯ ПАХОТНЫХ ЗЕМЕЛЬ В ЛЕСОСТЕПНОЙ ЗОНЕ БАШКИРСКОГО ЗАУРАЛЬЯ СО ВТОРОЙ ПОЛОВИНЫ 20 ВЕКА

We analyzed modern use of arable lands of 1985 in forest-steppe zone of Post-Ural of the Republic of Bashkortostan. Climate is temperate continental. An average annual temperature is 1.6℃ and an average annual precipitation of 427.9 mm. The hottest month is July with an average temperature of 17.5 and the coldest month is January with an average temperature of -14.8℃. Modern agricultural lands usually are used as a hay (43%). Use can be caused with local cattle breeding as traditional horse breeding. Overgrowth captures by 25% of Pinus silvestris. Scot’s pine is growing better on dry lands because it captures more area of overgrowth.

An Innovative Energy Storage System Based on Phase Change Material and Solar Energy Integrated With an Air Handling Unit to Produce Heating and Cooling

ABSTRACTThis study investigates the potential of using phase change material (PCM) in a building using an air handling unit (AHU) assisted by solar energy. To further enhance the system, an energy storage system (ESS) can be considered. Implementing ESS would allow the captured solar energy to be stored efficiently, ensuring a continuous and reliable power source for cooling or heating the air, even during non‐sunlight hours. The air‐conditioned zone is considered to be 220 m2 in which 30 people work for 12 h a day. An energy analysis is conducted to evaluate the performance of the proposed system in terms of energy and exergy loss. The genetic algorithm (GA) method is used to optimize the system. The results indicate that the system, including PCM and solar system, can reduce energy consumption by up to 8.9% compared to conventional AHUs in the hottest month of the year (July). The results indicated that employing PCM leads to a decrease of 124 kWh in heat loss during January and 229 kWh in heat gain during July. Taking into account the beneficial impacts of both PCM and the solar system, the yearly assessment demonstrates a 2.69% reduction in power demand, equating to an energy saving of 679 kWh. Furthermore, PCM in the proposed system can be used in integration with AHUs based on renewable energy systems to store renewable energy for buildings.

Environmental simulation and refrigeration demand analysis for shield tunnel construction in hot summer and cold winter regions

The thermal hazards generated during the tunnel boring machine construction process significantly impact the physical and mental health of personnel. A field test was conducted on the tunnel of Metro Line 1 in Changsha, China, where the average temperature in the work zone reached up to 33.16 °C, and the air velocity was generally below 0.2 m/s. These conditions were unfavorable for ventilation and heat dissipation. In this paper, a full-scale CFD simulation model was established to simulate the construction environment and analyze the cooling demand. The results indicated that increasing the fresh air velocity could lower the temperature in the work zone; however, this effect was limited. When the fresh air temperature exceeded a certain threshold, it actually raised the average temperature of the work zone. Consequently, there is a need for supplementary cooling of the fresh air during the hot summer months. At a fresh air velocity of 15 m/s, the maximum temperature in the work zone was recorded at 27.8 °C when the fresh air was cooled down to 22.5 °C through auxiliary cooling measures. This approach effectively controlled the temperature in the work zone, reduced flow dead zones, and significantly improved air distribution and heat dissipation. Additionally, it ensured the physical and mental well-being of the construction workers and the safe operation of the equipment. This study provides valuable guidance for managing thermal environments in underground tunnel construction.

Climate factors dominate the elevational variation in grassland plant resource utilization strategies.

Specific leaf area (SLA) and leaf dry matter content (LDMC) are key leaf functional traits often used to reflect plant resource utilization strategies and predict plant responses to environmental changes. In general, grassland plants at different elevations exhibit varying survival strategies. However, it remains unclear how grassland plants adapt to changes in elevation and their driving factors. To address this issue, we utilized SLA and LDMC data of grassland plants from 223 study sites at different elevations in China, along with climate and soil data, to investigate variations in resource utilization strategies of grassland plants along different elevational gradients and their dominant influencing factors employing linear mixed-effects models, variance partitioning method, piecewise Structural Equation Modeling, etc. The results show that with increasing elevation, SLA significantly decreases, and LDMC significantly increases (P < 0.001). This indicates different resource utilization strategies of grassland plants across elevation gradients, transitioning from a "faster investment-return" at lower elevations to a "slower investment-return" at higher elevations. Across different elevation gradients, climatic factors are the main factors affecting grassland plant resource utilization strategies, with soil nutrient factors also playing a non-negligible coordinating role. Among these, mean annual precipitation and hottest month mean temperature are key climatic factors influencing SLA of grassland plants, explaining 28.94% and 23.88% of SLA variation, respectively. The key factors affecting LDMC of grassland plants are mainly hottest month mean temperature and soil phosphorus content, with relative importance of 24.24% and 20.27%, respectively. Additionally, the direct effect of elevation on grassland plant resource utilization strategies is greater than its indirect effect (through influencing climatic and soil nutrient factors). These findings emphasize the substantive impact of elevation on grassland plant resource utilization strategies and have important ecological value for grassland management and protection under global change.

Field investigation on thermal comfort of metro passengers in hot summer and warm winter zone of China: A case study in Guangzhou

In the hot summer and warm winter zone of China, the metro thermal environments and passengers’ thermal comfort were rarely examined, influencing factors such as commuter hours and individual factors were less discussed, and understanding them was beneficial for improving human thermal comfort and saving energy. In this study, a field study was undertaken in Guangzhou located in the region during the summer of 2023. Four metro stations and three metro lines were selected, a total of 1481 valid questionnaires were gathered. The results revealed that the metro thermal environment was highly commendable during the hot summer months, with a thermal acceptability vote (TAV) ranging from 81 % to 89 % across the entrance (ET), concourse (CC), platform (PF), and carriage (CR). Furthermore, the upper limit of the 80 % acceptance range for operative temperature (Top) was 29.11 °C in the ET, 27.82 °C in the CC, 29.13 °C in the PF, and 28.44 °C in the CR. These temperatures exceed the actual mean Top values in these locations, indicating there is a significant potential for energy savings in metro environments. The upper limits of Top values for passengers with low, medium and high metabolic rates are 30.34 °C, 28.92 °C, and 28.25 °C, respectively. Thermal sensation votes (TSVs) fell well within the comfort zone specified in ISO 7730 (−0.7 < PMV < 0.7) during both peak and off-peak hours. No difference was found in TSVs between the two genders and among the different ages.