Hot Season Research Articles

Assessing the role of evapotranspiration in reducing surface temperatures in Harare using the SEBAL algorithm

Within urban areas, buildings, roads, and paved surfaces, absorb and re-emit the sun's heat more than natural landscapes. Urban areas, where these structures are highly concentrated and vegetation is limited, become ‘heat islands’ contributing to a range of environmental, economic, and human health problems. Despite this, limited research, has, to date, been carried out to assess the influence of evapotranspiration (ET) on urban surface temperatures for Harare, Zimbabwe. In this study, the uSEBAL algorithm was used to estimate evapotranspiration (ET) and land surface temperature (LST) using Landsat images in Hazare, Zimbabwe. The influence of ET on LST was also examined during the hot and post rain seasons. Results showed significant negative relationships (p < 0.05) between ET and LST. High ET rates were recorded over water bodies and green spaces as compared to built-up areas. High ET rates resulted in correspondingly low LST. This is the first time such results are reported for Harare. The conclusion drawn from these results is that as ET increases, temperature decreases, thus there was a negative relationship between ET and LST during the hot season. Additionally, low ET coincided with high LST in low vegetation and densely built-up areas. From these findings we can deduce ways of mitigating effects of thermal discomfort in urban areas i.e., inclusion of green spaces and water bodies within the cities. It is recommended that more green spaces be created within residential zones and encourage construction of green buildings and cooling technologies.

Development and Testing of Solar Powered Evaporative Air-Cooling System with an Improved Performance

This study proposes a new active direct evaporative cooling system that uses a bundle of cotton fibers as an evaporating surface and activated carbon as a moisture adsorbent. A two-stage evaporative cooling experimental setup consisting of an activated carbon adsorbent in between the cooling pad was designed, fabricated, and tested at Bahir Dar, Ethiopia. The fiber bundle (pad 1) was wetted with water and ambient air was forced through it using a fan then the air that exiting from pad 1 was forced through a bulk of activated carbon (moisture adsorbent), and then the air from the adsorbent passed through the second wetted fiber bundle (pad 2). The energy source for the fan and pump was the solar photovoltaic energy system. The average temperature drop of the cooler without the moisture adsorber was 9.33°C and with the inclusion of the moisture, the adsorber gave an additional temperature drop of 1.5°C to 4.95°C. During the hot dry season, the average relative humidity of the ambient air, pad 1 outlet, adsorbent outlet, and pad 2 outlets were 28.26%, 76.12%, 55%, and 88.2% respectively. The cooler with moisture adsorbent had a cooling capacity of 3653 W, an effectiveness of 94.25%, and a COP of 52.2. The developed solar evaporative cooling system can provide energy-efficient, sustainable, affordable cold air for different applications. The cooler could be used by small-scale farmers, wholesalers, and retailers for the cooling and storage of horticultural products to reduce the postharvest loss in fresh produces.

Implementing natural ventilation and daylighting strategies for thermal comfort and energy efficiency in office buildings in Burkina Faso

In recent years, efforts to lessen the environmental impact of the building sector have focused more on passive strategies to develop eco-friendly buildings that reduce energy use and improve thermal comfort. To reduce the construction sector’s resource use, particularly in fast-urbanizing sub-Saharan countries, a paradigm shift is needed. Although integrated daylighting and natural ventilation solutions in building design and construction are still under development in sub-Saharan Africa, their scientific contributions to the construction industry are growing. Therefore, the purpose of this research is to investigate natural ventilation and daylighting improvements in Burkina Faso office buildings to maximize thermal comfort and energy efficiency. The country’s meteorological data from 2004 to 2018 was examined for climatic analysis and utilized in Integrated Environmental Solutions Virtual Environment (IESVE) for natural ventilation and daylight simulations and in Design-Builder (DB) for thermal comfort and energy consumption simulations. 4 simulation rounds were conducted in order to determine respectively from round 1 to 4 the effects of building shape, glazing type, window shading type, and window-to-wall ratio on the daylighting and natural ventilation office building model performances. The findings indicated that on a south–north axis orientation, a ”H”-shaped structure with blue-tinted glass, horizontal louvers for shading, and 30% window-to-wall ratio, is the best option. The best overall option reduced annual energy demand, cooling energy demand, and solar gains by 14.9%, 25.3%, and 68.3% respectively. Hourly average airflow increased by 64.8% and 2% in hot and cold seasons respectively. Indoor air temperature decreased by 3.4 °C in the hot season and increased by 0.4 °C in the cold season. The daylighting analysis results demonstrated benefits with measurements that did not reflect too much light, implying reduced glare and discomfort with Useful Daylight Illuminance (500-2500lux): 56%, Spatial Daylight autonomy (50%): 44.7%, Annual Sunlight Exposure: 12%. This research laid the groundwork for a sustainable, bioclimatic office building model in a landlocked developing nation like Burkina Faso by integrating Climate Based Design Modeling (CBDM) and natural ventilation parameters into the design process.

A Novel Flexible Method for Optimal Operation Modeling of Multi-Carrier Energy Systems

This research suggests a new flexible method for the optimal operation of multi-carrier energy systems based on optimization techniques for different weather conditions and seasons. The results apply to different modes (a hot summer day, a cold winter day and a normal day). A new cost function from the operator’s point of view is suggested considering the constraints on consumable gas supply and electrical energy in the cold and hot seasons respectively. Furthermore, a novel algorithm is suggested that gives the economical values of energy carriers, final cost, and the percentage of the direct electrical energy supply and outside the hub. In this method, load data, related prices, constraints, and penalties are applied to the suggested model, and afterward hub optimization assists in finding the optimal operation and costs. MATLAB software is used to check the results and the simulation outputs confirming the effectiveness of the proposed method.

SURFACE URBAN HEAT ISLANDS AND RELATED HEALTH RISK IN THE PHILIPPINES: A GEOSPATIAL ASSESSMENT USING MODIS DATA

Abstract. The study assessed the heat-health risk of the Philippines during 2020 using the MODIS derived Urban Heat Island (UHI) and gridded population data. The study found out that the urban areas experienced more intense heat than the rural areas. It also revealed that the UHI is more intense during March, April and Month or hot dry season. People living in Metro Manila are more exposed and vulnerable to the heat risk. Poverty is one reason that puts people exposed and vulnerable to the heat risk. The output of this study can aid decision-makers especially the urban planners.

Effect of commercially blended synbiotic product as a replacement for antibiotic growth promoters on growth performance and villi morphology of broiler chicks in dry hot season

Effect of commercially blended synbiotic product as a replacement for antibiotic growth promoters on growth performance and villi morphology of broiler chicks in dry hot season

Seasonal exergoeconomic assessment and optimization of a dual-fuel trigeneration system of power, cooling, heating, and domestic hot water, proposed for Tabriz, Iran

Exergoeconomic assessment of a multigeneration system, which is fed with a mixture of natural gas and syngas produced from municipal solid waste gasification process, has been conducted under climatic restrictions of both hot and cold seasons. In the basic state of the 1st scenario, for the constant net power of 30 MW and 50% mixing ratio, exergy efficiency and total cost rate of the system are 27.92% and 1328 USD/h in summer, and 33.81% and 1246 USD/h, in winter, respectively. Moreover, the total relative cost difference in the summer is considerably higher than that in the winter. In the basic state of the 2nd scenario, for the constant fuel mass flow rate of 1.5 kg/s, the system's annual exergy efficiency, annual total cost rate, and payback period are 30.79%, 1166.4 USD/h, and 2 years, respectively. The optimization has been performed based on the genetic algorithm considering two objective functions. The optimization results revealed that, the system's annual exergy efficiency and annual total cost rate got improved from 30.79% to 32.37%, and from 1166.4 USD/h to 796.52 USD/h, respectively, while the payback period increases from 2 to 2.1 years. The complete results of parametric studies are also provided for both scenarios.

Thermochromic Halide Perovskite Windows with Ideal Transition Temperatures

AbstractUrban centers across the globe are responsible for a significant fraction of energy consumption and CO2 emission. As urban centers continue to grow, the popularity of glass as cladding material in urban buildings is an alarming trend. Dynamic windows reduce heating and cooling loads in buildings by passive heating in cold seasons and mitigating solar heat gain in hot seasons. Here, reduced energy consumption in highly glazed buildings in a mesoscopic building energy model is demonstrated when thermochromic windows are employed. Savings are realized across eight disparate climate zones of the United States. The model is used to determine ideal critical transition temperatures of 20–27.5 °C for thermochromic windows based on metal halide perovskite materials. Ideal transition temperatures are realized experimentally in composite metal halide perovskite films composed of perovskite crystals and an adjacent reservoir phase. The transition temperature is controlled by cointercalating methanol, instead of water, with methylammonium iodide and tailoring the hydrogen‐bonding chemistry of the reservoir phase. Thermochromic windows based on metal halide perovskites represent a clear opportunity to mitigate the effects of energy‐hungry buildings.

Selection criteria of cooling technologies for sustainable greenhouses: A comprehensive review

The demand for food items is increasing to match population growth rates. Meanwhile, many countries struggle to guarantee a full year-round production of crops because of the harsh weather conditions in cold and hot seasons. Greenhouses are used to mitigate the harsh weather conditions and allow for a full year-round production of crops by controlling the microclimate and ensuring that the crops acquire the required level of temperature, humidity, water, and light. Several design factors play a crucial role in the successful deployment of the greenhouse. These parameters include shape, orientation, structure, cover material, and climate control technologies. Climate control strategies include cooling and heating technologies. This paper presents a comprehensive review of cooling technologies for greenhouses, especially ones deployed in hot climates. Technologies such as natural ventilation, shading and reflection, evaporative cooling, desiccant cooling, and combined cooling technologies are presented and discussed. Moreover, this paper explores recent advancements in the field of cooling technologies and systems. The paper also explains existing strategies to save energy and improve the efficiency of greenhouses. The results of this review are expected to guide researchers in the process of selecting the most suitable cooling technology for their specific regions.

Trend of malaria incidences and its association with rainfall in Kalahandi District of Odisha, India.

In Odisha, Kalahandi is one of the most exposed and vulnerable districts to malaria incidences due to its poor socioeconomic condition and extreme climate. The study aimed to explore the temporal characteristics of malaria incidences in Kalahandi and to identify its relationship with rainfall for the period from 2011 to 2018. Out of the total blood films examined, 8.84% were found positive in Kalahandi between 2011 and 2018. Plasmodium falciparum is the most dominant species accounted 88.3% of the total cases. Very high mean annual parasitic index (API) >15 is recorded throughout the study years. The highest incidences are recorded in the monsoon season followed by postmonsoon. The correlation value of the annual blood examination rate with P. falciparum, Plasmodium vivax, and API has shown a very high positive correlation. Rainfall shows a (+) correlation with malaria incidences in the cold (0.47) and hot seasons (0.01) and (-) correlation in the monsoon (-0.54) and postmonsoon season (-0.54).

УСОВЕРШЕНСТВОВАНИЕ СИСТЕМЫ ВОДОИСПАРИТЕЛЬНОГО ОХЛАЖДЕНИЯ КОРОВНИКОВ

The research was carried out in order to solve the problem of elevated air temperatures in livestock buildings during the hot season. The maximum intensity of moisture evaporation from the surface of the sample, blown by air flows of different speeds and directions, is achieved with the alternating action of the flow from opposite directions. As a means of creating a comfortable microclimate that can provide a change in the direction of air flows in barns, it is most advisable to consider the joint use of accelerating axial fans installed along the entire room and fine spraying of water, which gives a significant (up to 11°C) cooling effect. The developed devices for inducing air exchange and air conditioning for livestock farms have design features that allow you to change the direction of the air flow injected by the fans by 180 °, which provides a non-stationary ventilation mode that prevents the formation of stagnant zones in the air volume of the room, increases the assimilation capacity of the air and improves its quality indicators. The direction of the air flow is set using a reversible electromagnetic starter, or a system of cables and counterweights. At the same time, the cooling of the air flow using fine water spray is carried out taking into account the direction of its movement and is regulated by the control unit. Changing the direction of the air flow to the opposite also provides an increase in the surface area of the bodies of animals in contact with the flow, and, as a consequence, an increase in the cooling effect. The use of the proposed developments will make the microclimate in the summer more comfortable for animals, which will positively affect their productivity.

A reinforcement learning-enabled iterative learning control strategy of air-conditioning systems for building energy saving by shortening the morning start period

Air-conditioning systems in commercial buildings are usually switched on in advance to precool the indoor spaces to create an acceptable working environment upon the office hour. However, the central cooling systems often fail to provide enough cooling supply capacity due to the high cooling demand at the morning start period especially in hot seasons. In this situation, the imbalanced cooling distribution in the air-conditioning systems often results in large difference of cooling-down speed among different building zones, so that the precooling time has to be extended, leading to significant energy waste. This study proposes a new iterative learning control strategy to properly manage the cooling distribution (i.e., water valve openings of air-handling units) for achieving uniform cooling (i.e., synchronously reaching the indoor dry-blub temperature setpoint) among building zones during the morning start period. A reinforcement learning method (Q-learning) is adopted for the control parameter setting of the developed iterative learning controller. Validation tests are conducted and results show that the proposed control strategy could reduce the daily precooling time up to 12.1% during typical days in Hong Kong by achieving uniform cooling. The daily energy consumption could be reduced between 5.1% and 17.8% by shortening morning start period, corresponding a weekly electrical energy saving between 1,376 kWh and 2,916 kWh in the test building.

The Impact of the Urban Heat Island on the Sensation of Thermal Comfort and Electricity Consumption in Sfax in Central-Eastern Tunisia during the Hot Season

This study follows on from the work on the urban climate of Sfax and its energy repercussions. The spatial configuration of the urban heat island (UHI) and the spatial distribution of the thermal comfort indices, the heat index (HI), the universal thermal climate index (UTCI) and the temperature humidity wind index (THW), resulting from the car survey method, essentially show the impact of land use and the distance from the coastline on the spatial distribution of air temperatures. A maximum difference of 7 °C between the city centre and the countryside is measured in very hot summer weather. During the night phase, the apparent temperatures are oppressive, particularly in the city centre, where HI and THW comfort indices exceeding 40 °C were calculated. Compared to the HI and UTCI, the THW demonstrates a much stronger variation due to the influence of wind between open areas and the downtown area. The intensity of thermal discomfort decreases as one moves towards the rural area (−15 °C compared to the centre), hence the impact on the consumption of electrical energy dedicated to air conditioning. The central part is the most energy-intensive area compared to the peripheral areas, especially during hot days when the use of air conditioners becomes constant, day and night.

Association between air pollution exposure and coronary heart disease hospitalization in a humid sub-tropical region of China: A time-series study.

Emerging evidence has highlighted the possible links of environmental pollution with several cardiovascular diseases (CVDs). The current study aimed to explore the impact of short-term air pollution exposure on CHD hospitalization in Hefei. Data about the daily number of CHD admissions (from 2014 to 2021) were retrieved from the First Affiliated Hospital of Anhui Medical University. Air pollutants and meteorological data were obtained from the China Environmental Monitoring Station and the China Meteorological Data Service Center, respectively. The correlation between air pollution and CHD hospitalization was assessed using distributed lag non-linear model (DLNM) and Poisson generalized linear regression. In the single-pollutant model, NO2, O3, and CO strongly correlated with CHD hospitalization rate. Specifically, exposure to NO2 (lag0, relative risk [RR]: 1.013, 95%CI: 1.002-1.024, per 10 μg/m3 increase) and CO (lag13, RR: 1.035, 95%CI: 1.001-1.071, per 1 μg/m3 increase) revealed a positive correlation with an increased rate of CHD hospitalization. Interestingly, O3 had a protective association with hospitalization of CHD (lag0, RR: 0.993, 95%CI: 0.988-0.999, per 10 μg/m3 increase). Similar results, to those of the single-pollutant model, were revealed following verification using two-pollutant models. Subgroup analyses indicated that young people, women, and people in hot seasons were more susceptible to NO2 exposure, while the elderly, women, and people in cold seasons were more susceptible to O3. Furthermore, the elderly were more susceptible to CO exposure. Overall, exposure to NO2 and CO increases the rate of CHD hospitalization, but exposure to O3 shows a protective association with the rate of CHD hospitalization. Therefore, early preventive measures against air pollutants should be applied to protect vulnerable patients with CHD.

Multi-objective energy and exergy optimization of hybrid building-integrated heat pipe photovoltaic/thermal and earth air heat exchanger system using soft computing technique

This research is dedicated to the numerical assessment of the performance of a novel system that uses solar and geothermal energy at the same time, which is capable of heating/cooling the outside air before it enters the air conditioning system of a building and supplying the required electricity for the building. The desired system consists of a photovoltaic/thermal-heat pipe (PVT-heat pipe) unit and an earth-air heat exchanger (EAHE). To cool the outside air in hot seasons of the year, the air is passed through the EAHE system and the exhaust air from building is used to cool the photovoltaic panels. Outside air heating in cold seasons is also possible by passing air through the PVT-heat pipe and EAHE systems. The genetic algorithm-based two-objective optimization is used to determine the necessary conditions to simultaneously maximize the annual useful energy and exergy yields of the hybrid system. The performance metrics of the optimal system are compared with the corresponding values of the PVT-EAHE unit. Outcomes revealed that the annual useful energy output of the PVT-heat pipe-EAHE system (93925.6kWh) is less than the PVT-EAHE system (96448.6kWh), while the PVT-heat pipe-EAHE system is able to produce more exergy (10904.5kWh) than the PVT-EAHE system (10015.5kWh).

Unfolding unique features of precipitation-temperature scaling across India

Warming of the climate is now unequivocal. However, probable dynamics of changes in the precipitation regimes remains disputable under potential future warming. Theoretically, increasing atmospheric heat translates to increase the atmospheric moisture holding capacity at the Clausius-Clapeyron (C-C) scaling rate in the absence of moisture limitation, which in turn raises the possibilities of more intense precipitation events. Here we investigated the scaling relationship between observed and reanalysis precipitation with surface air temperature and dew point temperature at daily and sub-daily time scales on annual and season-wise basis. To reach a robust conclusion, entire Indian mainland is considered as the study area that spans across a vast climatic characteristics. More influential temperature dependence is found for heavier precipitation events than the lighter ones on annual basis as well as for different seasons. Negative and peak type scaling patterns between the daily surface air temperature (SAT) and precipitation is noticed across the different climatic regimes of the study region. In contrast, positive dependence between dew point temperature (DPT) and precipitation is obtained to be dominant across the study region. Negative sensitivity noticed for the daily surface temperature is mainly the consequence of the local cooling effect due to the occurrence of precipitation and the moisture limitation at higher end of the local temperature. In general, the scaling relation varies from season to season, which tend towards a negative scaling in hotter seasons, but a positive scaling in colder seasons. Extreme precipitation can be better portrayed by sub-daily temperature conditions prior to the start of the storm events. Scaling relationship obtained between the sub-daily precipitation and surface air and dew point temperature exhibits greater consistency in the relationship across the regions. The Western Ghats region is consistently noticed to exhibit a positive scaling relation, whereas rest of the country exhibits mostly a peak type relation. The SAT considered up to 6-h prior to the precipitation might not reflect the actual response of precipitation towards the temperature increase, possibly due to the prevailing cloudy conditions preceding the precipitation event. Findings of this study provides a better understanding related to the anticipated changes in precipitation regimes under future climate with a warming condition across different climatic regimes.

Seasonal variation in molecular and physiological stress markers in Asian elephants.

Free-living species exhibit seasonal variation in various life history traits, including vital rates such as birth and death patterns. Different physiological mechanisms are thought to underlie the expression of life history traits that contribute to lifetime fitness. However, although the broad impacts of seasonality on life history traits and trade-offs is well established in many systems, the exact physiological mechanisms responsible for driving differences within and between individuals are poorly understood. Among them, molecular and physiological stress pathways, such as stress hypothalamic-pituitary-adrenal axis and oxidative stress, have potential to mediate relationships between individual survival, reproduction and environmental seasonality. Here, we determine how different physiological markers of stress including faecal cortisol metabolites (FCMs), heterophils/lymphocytes (H/L) ratio, two markers indicating oxidative balance including a marker of oxidative damage (reactive oxygen metabolites, ROM) and a marker of antioxidant defences (superoxide dismutase, SOD) and body weight vary in a large semi-captive population of Asian elephants (Elephas maximus) exposed to extreme seasonality (e.g. elevated temperatures). Individuals showed higher FCM levels and H/L ratios during cold season, indicating increased stress, and the lowest FCM levels during monsoon season and H/L ratios during hot and dry season, but we found no pattern in oxidative stress (ROM and SOD) levels. Hot season also associated with a decline in body weight. The present study shows how different physiological parameters (FCM levels and H/L ratio), molecular (oxidative stress) and body condition vary with seasonal changes, and how these parameters might allow individuals to adapt to such variations. Our results on an endangered long-lived species are crucial in indicating the most productive timing for conservation efforts, predicting how individuals cope with environmental changes, and allow for a more accurate representation of how animal physiology operates in nature.

Influence of temperature-humidity index, calf sex, and parity on gestation length in Holstein cows

The present study aimed to analyse the gestation length (GL) variability in locally born purebred Holstein dams (n = 1047), in a private farm, under Saharan climate. The overall GL mean was 278.73 ± 6.67 days. A general linear model revealed that the GL was significantly affected by calf sex (p = 0.035) with a minor increase of 0.19% in males, dam parity (p = 0.016) and calving season (p < 0.0001) including the shortest lengths recorded in heifers and during heat stress period. Moreover, a negative regression (-1.96%) in recent years was recorded in GL by the influence (p = 0.01) of years of birth, breeding, and calving of cows. Our findings show that cows that were inseminated and gave birth during the cold season (temperature-humidity index, THI < 74) had 11.54 days longer (p = 0.048) gestation period compared to animals that were inseminated and gave birth during the hot season (THI > 84). Similarly, the association (p = 0.003) between dam parity and calf sex revealed that the GL of multiparous cows that gave birth to male calves was higher (3.07 days) than that of male calves from heifers. The findings can contribute to a better understanding of the environmental and animal factors association's effects on GL in Holstein cows under hyperarid zone and assisting in the adequate management of pregnant females.

Influence of Heat Stress on Milk Production in Fraternal Twins

The aim of this study was the evaluation of heat stress in milk production in dairy cows (daily milk yield; milk production in 1st lactation). The comparison was performed between fraternal twins (full sisters), produced on the same farm and same parity. One of the twins produced in a hot period whereas her sister produced in a cooler period. Also, there can be differences in milk production between fraternal twins. Therefore, a second group of fraternal twins was also created that produced without heat stress. Databases of fraternal twins were analysed using PROC GLM analysis of Statistica&#174; with selected effects. In conclusion, a negative effect of heat stress on milk production was found. There was an obvious tendency (in some cases insignificant) for worse milk production during heat stress in both the daily milk yield during hot days and in 1st lactation started in the hot season. Fat content (in %) was also lower in the hot period but differences were insignificant. On the other hand, there was found very low differences in milk production (and milk components) between fraternal twins produced in season without heat stress.

Portfolio of distribution maps for Octopus vulgaris off Mauritania

This study introduces the concept of portfolios of distribution maps, which consist of the reduced set of empirical orthogonal maps that best explain spatial biomass distributions of a given species over time. The approach is demonstrated for the distributions of common octopus (Octupus vulgaris) off Mauritania over the last thirty years. The maps in the portfolio are the subset of empirical orthogonal maps that allowed to recover 60% of the spatiotemporal biomass distribution variance and whose temporal weights were significantly correlated with abundance. For octopus during the hot season, one single map explained half of the overall variance of the distribution data, while during the cold season, the portfolio of octopus distribution maps consisted of four maps, with the temporal weights of the second map being negatively correlated with upwelling intensity six months before. The size of each portfolio represents the number of distinct spatial patterns describing octopus spatial distributions. Assuming that specific but hidden processes explain each biomass spatial distribution of the portfolio, the size of a map portfolio might be interpreted as a proxy for system resilience. A small portfolio could reflect systems that are more fragile.