Assessing Influence Factors on Daily Ammonia and Greenhouse Gas Concentrations from an Open-Sided Cubicle Barn in Hot Mediterranean Climate.

Knowledge of how different management strategies affect gas production from livestock buildings can be helpful for emission predicting purposes and for defining mitigation strategies. The objective of this study was to statistically assess whether and how measured concentrations of ammonia (NH3), methane (CH4) and carbon dioxide (CO2) were influenced by milking frequency. Concentrations of gases were measured continuously by using infrared photoacoustic spectroscopy in the breeding environment of an open dairy barn located in Sicily in hot climate conditions. Data were acquired by specific in-field experiments carried out in 2016 and 2018, when milking sessions occurred twice a day (2MSs) and three times a day (3MSs), respectively. The number of the milking cows was 64 in both 2MSs and 3MSs. The results showed that concentrations of NH3, CH4 and CO2 were statistically influenced by the number of milking sessions. From 2MSs to 3MSs, NH3 concentrations were enhanced (p < 0.001) due to the higher cow’s activity. Conversely, gas concentrations of CH4 and CO2 were lower for 3MSs compared to those for 2MSs due to the effect of the different feeding frequency. Overall, the milking frequency influenced barn management and cow behaviour by modifying the level of gas concentrations in the barn environment.

PurposeThis paper investigates thermal mass performance (TMP) in hot climates. The impact of using precast concrete (PC) as a core envelope with different insulation materials has been studied. The aim is to find the effect of building mass with different weights on indoor energy consumption, specifically cooling load in hot climates.Design/methodology/approachThis research adopted a case study and simulation methods to find out the efficiency of different mass performances in hot and humid climate conditions. Different scenarios of light, moderate and heavyweight mass using PC have been developed and simulated. The impact of these scenarios on indoor cooling load has been investigated using the integrated environment solution-virtual environment (IES-VE) software.FindingsThe results showed that adopting a moderate weight mass of two PC sheets and a cavity layer in between can reduce indoor air temperature by 1.17 °C; however, this type of mass may increase the cooling demand. On the other hand, it has been proven that adopting a heavyweight mass for building envelopes and increasing the insulation material has a significant impact on reducing the cooling load. Using a PC Sandwich panel and increasing the insulation material layers for external walls and thickness by 50 mm will reduce the cooling load by 15.8%. Therefore, the heavyweight mass is more efficient compared to lightweight and moderate mass in hot, humid climate areas such as the UAE, in spite of the positive indoor TMP that can be provided by the lightweight mass in reducing the indoor air temperature in the summer season.Originality/valueThis research contributes to the thermal mass concept as one of these strategies that have recently been adopted to optimize the thermal performance of buildings and developments. Efficient TMP can have a massive impact on reducing energy consumption. However, less work has investigated TMP in hot and humid climate conditions. Furthermore, the impact of the PC on indoor thermal performance within hot climate areas has not been studied yet. The findings of this study on TMP in the summer season can be generated in all hot climate zones, and investigating the TMP in other seasons can be extended in future studies.

Modeling and simulation analysis of solar absorption chiller driven by nanofluid-based parabolic trough collectors (PTC) under hot climatic conditions

Solar photovoltaic (PV) technology is a popular choice among other renewable energy sources, but its electrical efficiency decreases with a rise in PV panel temperature. Previous studies on passive cooling with phase change material (PCM) based approach face limitations of temperature drop and leakage issues. To address this issue, an evaporative cooling method that can enhance panel efficiency is investigated. The present study demonstrated a simple, optimized, and cost-effective evaporative cooling for hot and dry climate conditions. The system consists of jute cloth attached directly to the PV panel backside and water flowing from the top header to the jute cloth under gravity has been experimentally investigated in outdoor conditions during summer. The electrical and thermal characteristics (with and without cooling) of the panel were measured. The finding shows that the jute cooling in PV panels leads to a substantial reduction in average temperature by 18°C and a corresponding increase in electrical efficiency by 10.31%. The jute-cooled panel shows an average and maximum output power improvement of 4.33 and 7.10 W, respectively, compared to the referent panel, while consuming only 0.55 l of water per hour. The study also investigated the effect of water failure on jute cooling and water ingress to the junction box. In the event of water cooling system failure, the panel’s temperature increases by an average of 6°C in comparison to the referent panel. Furthermore, the proposed evaporative cooling system shows a cost-incurred payback period of 7 years against the referent system of 5 years.

This experiment was conducted to study the effect of heat stress on some reproductive and productive performance in purebred and crossbred female goats under both of hot (summer season) and mild climatic (winter season) conditions. Forty mature female goats (20 Baladi and 20 crossbred (50% Zaraibi x 50% Baladi) used in this research. Results- cundity were higher in experimental does during mild climate conditionsthan hot climate conditions. Birth weight recorded higher values inmild climate conditions in comparison with hot climate conditions. Concerningto breed, reproductive traits were higher in crossbred goat doescompared with purebred goat does. Crossbred goat does showed higher(P<0.01 or P<0.0001) in all productive traits than Baladi goat does. Cortisolhormone concentration showed lower (P<0.0001) concentration undermild climate conditions than hot climate conditions during differentstages of estrous cycle, pregnancy and postpartum periods. On the otherin crossbred goat does compared with purebred does during differentstages of estrous cycle, except diestrous period. Similar trend was foundduring pregnancy and postpartum periods (P<0.01 or P<0.0001). It could-productive and productive traits of goats and in the same time, crossbredwas better than purebred goats.

Background: High amounts of nonstarch polysaccharides in the diet may increase the amounts of fermentative materials in the hindgut, leading to an increase in fermentative heat production. Dietary β-mannanase is reported to decrease antinutritional effects of β-mannans, such as the potential increase of body heat; however, its efficacy on broiler chickens raised under hot climatic conditions has not been investigated. Objective: To investigate the effects of dietary β-mannanase on growth performance, cloacal temperature, relative lymphoid organ weight, and blood characteristics of broiler chickens raised under hot climatic conditions. Methods: A total of 1,701 1-day-old Ross 308 broiler chickens were randomly allotted to one of three dietary treatments with nine replicates. A basal diet was prepared and added with β-mannanase at 0.05 or 0.10% inclusion levels. The experiment was conducted for 30 days. Average room temperature was 28.8 ± 1.74 C and average relative humidity (RH) was 76.1 ± 11.49% during the experiment. Results: Growth performance of broiler chickens raised under hot climatic conditions was not affected by β-mannanase inclusion. Cloacal temperature decreased at the end of experiment (linear, p<0.05) with increasing inclusion levels of dietary β-mannanase. Increasing inclusion levels of β-mannanase tended to increase (linear, p=0.076) the relative weight of thymus, but had no effects on the relative weight of spleen and bursa of Fabricius. Blood characteristics were not influenced by dietary β-mannanase. Conclusion: Increasing inclusion levels of β-mannanase decrease cloacal temperature; however, it does not directly influence growth performance nor alleviates the heat stress of broiler chickens raised under hot climatic conditions.

Background: There is a high prevalence of overweight and obesity among adults. Obesity and overweight might be a risk factor affecting heat generation and excretion. Objectives: This study examines the relationship between overweight and heart rate in hot and very hot weather under experimental conditions. Patients and Methods: This experimental study was conducted with a sample of 35 participants with normal weight and 35 participants who were overweight in a climatic chamber. Each participant was asked to rest in a lying position on a bed for 30 minutes and the participants’ basic heart rate was recorded. Each participant performed 60-min light exercise (2.8 kmph) on a treadmill) while exposed to very hot and moderate humid climatic conditions. In the other phase, participants were asked to rest for 30 min and then performed moderate exercise (4.8 kmph on a treadmill) for 60 minutes while exposed to hot and moderate humid climatic conditions. Heart rate was measured every 2 minutes. Results: The mean and standard deviation of the heart rate in the hot climatic condition and moderate exercise were 103.84 (3.34) for normal weight subjects and 108.67 (3.27) for overweight subjects. The mean and standard deviation of the heart rate in a very hot climatic condition and light exercise were 96.13 (2.34) for those with normal weight and 105.84 (3.71) for those who were overweight. Heart rate significantly differed between the two groups in both climatic conditions (P < 0.001). Conclusions: The mean heart rate was higher in participants who were overweight than those with normal weight.

Detailed analysis of reverse osmosis systems in hot climate conditions

Field test of machine-learning based mean radiant temperature estimation methods for thermal comfort-integrated air-conditioning control improvement and energy savings

Aims: The aim of this study is to discuss the performance of SCC with natural pozzolana under hot climate conditions. Background: The performance of vibrated concrete under hot climate is well investigated. However, the effect of hot climate on SCC is tittle investigated. North African and Middle Eastern countries are subjected to hot and dry environments especially during summer periods. Hence there is a need to investigate the performance of SCC under hot climate. Objective: The objective of this paper is to study the effect of water curing duration followed by natural hot climate exposure on the performance of SCC with Natural Pozzolan (NP). Methods: It is an experimental investigation where Concrete specimens were exposed to a standard curing environment (relative humidity RH = 100% and Temperature T°= 20°C ± 2°C) for 0, 1, 3, 7, 14 and 28 days, followed by a second cure in a hot environment in open air on a laboratory terrace in North Africa area during summer time with a temperature of 35°C to 45°C and a relative humidity of 65% to 75%. The cement was substituted by NP in weigh at three substitution levels (0%, 15% and 25%). Results: The experimental results show the importance of the wet curing in hot climate, especially when NP is used. Substituting cement by NP improves the self-compacting concrete durability for the long term. Conclusion: The substitution of cement by natural pozzolan reduced water permeability and capillary absorption. The hot climate has no negative effect on the evolution of the mechanical strength and durability of the SCC with natural pozzolan when undergoing a long initial wet cure.

Livestock farming represents one of the primary sources of ammonia (NH3) and greenhouse gas (GHG) emissions, including methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2), having a significant environmental impact. Reducing emissions and recovering gas systems from these livestock buildings necessitate measuring gas concentrations to mitigate environmental impacts using an accurate, high-cost portable device. This study aims to evaluate the concentration of NH3 and GHGs in a semi-open dairy farm located in southern Sicily, a region with a hot climate. The measurement campaign was carried out during the spring of 2025. The concentrations of NH3, CH4, CO2, and N2O were measured in different barn areas (i.e., manger, feeding alley, and service alley) using a portable gas detector (GASMET GT5000) based on Fourier Transform Infrared (FTIR) technology. Statistical analysis revealed that NH3 concentrations were highest in the feeding alley, while CH4 concentrations peaked at the manger. N2O levels stayed low because there was no straw. Future research should investigate gas concentrations across different seasons (e.g., winter, summer) to analyze gas patterns under different climatic conditions. Additionally, the use of an accurate portable device enables further investigations into other barn typologies within the Mediterranean area to assess how farm construction and management practices influence gas production.

Global climate change leads to the exposure of olive orchards to higher temperatures than in the past. We followed yield and quality parameters of olive oils from Barnea, Coratina, and Picual, under hot climatic conditions through different levels of ripeness. Oil yield per tree increased throughout the monitoring period due to continuous oil accumulation. Toward the last harvest date, significant fruit drop occurred, which resulted in substantial loss in oil yield. Maximal oil yield was obtained in Barnea at a maturity index of 2.1–2.5, in Coratina at 2.3 and in Picual at 3.2. A reduction in quality parameters was found with delay of harvest date: free fatty acid content increased and the ratio of monounsaturated to polyunsaturated fatty acid declined, but only in one season. Nevertheless, all parameters remained within the trade standard for extra virgin olive oil (EVOO). In contrast to most previous studies, no consistent reduction was observed in total polar phenol content in the oils. Hence, maximizing oil yield should be the main criterion for the determination of harvest date under these conditions. It is therefore suggested that olives exposed to hot climate be harvested earlier than those in typical Mediterranean climate areas.Practical applications: Harvest timing has a strong effect on both oil yield and quality. However, in most of the studies published on the topic until now only a sample of fruit was taken to determine oil accumulation and quality, but little or no information is available on oil yield at tree level, which is an important parameter from the grower's perspective. Moreover, this study describes changes in oil yield and quality along the ripening period, under hot climatic conditions prevailing in Jordan Valley. The Mediterranean basin region, where more than 90% of the world's olive oil is produced is expected to be exposed to higher temperatures in the future due to global climate changes. The current work provides information on the effect of those unfavorable growing conditions on oil production and quality. One of the major findings is the necessity to harvest early (in a relatively low ripening index) under those conditions.

Seawater desalination using a cost-effective reverse osmosis system is crucial for hot climate countries suffering from water scarcity. The most favorable seawater membrane characteristics were identified under typical Egyptian operating conditions. Twelve different commercially available membrane elements were investigated. A reverse osmosis system was designed and simulated using available software (e.g., ROSA and IMSDesign). The characteristics of the most promising membranes were identified for operation at Matruh (Mediterranean Sea) and Sharm El-Sheikh (Red Sea). The present work shows that the lowest cost of seawater desalination is obtained with membranes having high salt rejection, high permeate flow, high membrane active area, and permeate flux greater than 0.914 m3 /(d·m2 ). Moreover, the cost of seawater desalination in summer is lower than in winter by 5% for Matruh and 2.7% for Sharm El-Sheikh. However, the impact of water salinity on the cost and specific energy consumption is higher than that of the seawater temperature. The cost of Mediterranean seawater desalination is lower than that of the Red Sea by 10.6%. Cost analysis at five different locations in Egypt shows that the highest cost takes place at Suez (Gulf of Suez), and the lowest cost occurs at Matruh (Mediterranean Sea). PRACTITIONER POINTS: Twelve different membranes were investigated for use under typical hot climate conditions. The cost of seawater reverse osmosis (RO) desalination is lower in summer by 2.7%-5% compared with winter. RO desalination costs up to 10.6% less for the Mediterranean Sea compared with the Red Sea. The optimum membrane element performance characteristics were identified for use under hot climate conditions.

This work is motivated by the difficulty of cultivating crops in horticulture greenhouses under hot and arid climate conditions. The main challenge is to provide a suitable greenhouse indoor environment, with sufficiently low costs and low environmental impacts. The climate control inside the greenhouse constitutes an efficient methodology for maintaining a satisfactory environment that fulfills the requirements of high-yield crops and reduced energy and water resource consumption. In hot climates, the cooling systems, which are assisted by an effective control technique, constitute a suitable path for maintaining an appropriate climate inside the greenhouse, where the required temperature and humidity distribution is maintained. Nevertheless, most of the commonly used systems are either highly energy or water consuming. Hence, the main objective of this work is to provide a detailed review of the research studies that have been carried out during the last few years, with a specific focus on the technologies that allow for the enhancement of the system effectiveness under hot and arid conditions, and that decrease the energy and water consumption. Climate control processes in the greenhouse by means of manual and smart control systems are investigated first. Subsequently, the different cooling technologies that provide the required ranges of temperature and humidity inside the greenhouse are detailed, namely, the systems using heat exchangers, ventilation, evaporation, and desiccants. Finally, the recommended energy-efficient approaches of the desiccant dehumidification systems for greenhouse farming are pointed out, and the future trends in cooling systems, which include water recovery using the method of combined evaporation–condensation, as well as the opportunities for further research and development, are identified as a contribution to future research work.

Empirical study of a wind-induced natural ventilation tower under hot and humid climatic conditions