Search Results (7)

Computational fluid dynamics (CFD) may aid the design of barn ventilation systems by simulating indoor cattle thermal welfare. In the literature, CFD models of mechanically and naturally ventilated barns are proposed separately. Hybrid ventilation relies on cross effects between air change mechanisms that cannot be studied using existing models. The objective of this study was to develop a CFD methodology for modelling animal thermal comfort in hybrid ventilated barns. To check the capability of CFD as a design evaluation tool, a real case study (with exhaust blowers) and an alternative roof layout (with ridge gaps) were simulated in summer and winter weather. Typical phenomena of natural and mechanical ventilation were considered: buoyancy, solar radiation, and wind together with high-speed fans and exhaust blowers. Cattle thermal load was determined from a daily animal energy balance, and the assessment of thermal welfare was performed using thermohygrometric indexes. Results highlight that the current ventilation layout ensures adequate thermal welfare on average, despite large nonuniformity between stalls. The predicted intensity of heat stress was successfully compared with experimental measurements of heavy breathing duration. Results show strong interactions between natural and mechanical ventilation, underlining the need for an integrated simulation methodology. Full article

Global warming can cause deep and extensive changes in the Earth’s climate and changes in the time and place of climatic phenomena. The present trend analysis study assesses cold stress using the thermo-hygrometric index (THI) in the two seasons of autumn and winter in outdoor environments in Iran. The data related to the average of the two variables of daily air temperature and relative humidity from 60 synoptic meteorological stations for a statistical period of 30 years were obtained from the Iranian Meteorological Organization. The THI index was calculated for autumn and winter, and the level of thermal discomfort was determined for each station. The Mann–Kendall statistical test with the help of Minitab ver17.1.0 software was also used to investigate the changes in air temperature, relative humidity and THI index. The THI for autumn increased in 68% of the stations, and this increasing trend is statistically significant in 51% of these stations. The THI for winter increased in 83% of the stations, and this increasing trend is statistically significant in 51% of these stations. In autumn, 53% of the stations were in the range of thermal discomfort, and in winter only 5% were in the range of thermal comfort. The decreasing trend in THI in some climatic types, along with the increasing trend in air temperature, can indicate the decrease in relative humidity in the monitored stations during the studied years. It is recommended to know the temporal and spatial distribution and the probability of occurrence of cold stress through the use of THI in order to adopt preventive measures and policies in the outdoors in Iran. Full article

The thermo-hygrometric sensation of pedestrians in outdoor environments can be quantified by means of bioclimatic indices. In this work, the Mediterranean Outdoor Thermal Comfort Index (MOCI) is applied in the city of Rome (Italy) for the purpose of investigating the effect of local environmental conditions (urban, suburban, rural) on pedestrian thermal comfort. Hourly values of MOCI are calculated for the May–September period in the years 2015–2021 using weather quantities acquired by the four monitoring stations of the Regional Agency for Environmental Protection included in the metropolitan area of Rome. MOCI data are analyzed based on the comfort and (cold/hot) discomfort conditions during both daytime and nighttime. At the urban station, 26% of daily records exceed the comfort threshold revealing the effect of urban overheating, whereas only 0.1% of hot discomfort occurrences are recorded overnight. Here, greater nighttime thermal comfort is experienced than in non-urban locations suggesting that the nocturnal thermo-hygrometric conditions are satisfactory for inhabitants in downtown Rome, despite the urban heat island. It also suggests that other factors, such as orography and atmospheric circulation, influence outdoor thermal comfort. The development of this work will therefore include at least these two elements. Full article

Precision Livestock Farming (PLF) relies on several technological approaches to acquire, in the most efficient way, precise and real-time data concerning production and welfare of individual animals. In this regard, in the dairy sector, PLF devices are being increasingly adopted, automatic milking systems (AMSs) are becoming increasingly widespread, and monitoring systems for animals and environmental conditions are becoming common tools in herd management. As a consequence, a great amount of daily recorded data concerning individual animals are available for the farmers and they could be used effectively for the calibration of numerical models to be used for the prediction of future animal production trends. On the other hand, the machine learning approaches in PLF are nowadays considered an extremely promising solution in the research field of livestock farms and the application of these techniques in the dairy cattle farming would increase sustainability and efficiency of the sector. The study aims to define, train, and test a model developed through machine learning techniques, adopting a Random Forest algorithm, having the main goal to assess the trend in daily milk yield of a single cow in relation to environmental conditions. The model has been calibrated and tested on the data collected on 91 lactating cows of a dairy farm, located in northern Italy, and equipped with an AMS and thermo-hygrometric sensors during the years 2016–2017. In the statistical model, having seven predictor features, the daily milk yield is evaluated as a function of the position of the day in the lactation curve and the indoor barn conditions expressed in terms of daily average of the temperature-humidity index (THI) in the same day and its value in each of the five previous days. In this way, extreme hot conditions inducing heat stress effects can be considered in the yield predictions by the model. The average relative prediction error of the milk yield of each cow is about 18% of daily production, and only 2% of the total milk production. Full article

This study was carried out in order to outline the human bioclimatic stress/comfort conditions within the area of Iași city, Romania. The meteorological data were obtained over a 7-year period (December 2012–November 2019) from an observation network relying on 8 fixed observation points located in selected spots, relevant for the urban climate conditions in the region. The results demonstrate firstly that throughout the entire analyzed period, using the thermo-hygrometric index (THI), “very cold” conditions characterize 4% of the entire year in the inner parts of the city and 6% in the rural area, while the “hot” THI conditions vary from 18% in the middle of the urban heat island to 15% in the rural area. Overall, the rural areas are generally more comfortable than the inner city, especially during summer, when the urban heat island (UHI) core is starting to develop from the evening and persists during the night. On the contrary, the UHI renders the inner city more comfortable than the rural surroundings from October to April. Similar bioclimatic conditions are also presented in detail for the summer by the relative strain index (RSI), which exceeds the stress threshold value mostly during heat waves, when a significant contrast between urban and rural areas is felt. In brief, it has been determined that the most suitable area for human comfort in Iași city is inside the urban area during the winter and in the rural areas during the summer. Full article

This paper aims to analyse and conclude about the behaviour of the most commonly used human thermal comfort indices under a variety of atmospheric conditions in order to provide further information about their appropriateness. Utilising Generalized Additive Models (GAMs), this article examines the indices’ sensitivity when exposed to diverse classified atmospheric conditions. Concentrated upon analysing commonly used human thermal indices, two Statistical/Algebraic indices (Thermohygrometric Index (THI) and HUMIDEX (HUM)), and four Energy Balance Model indices (Physiologically Equivalent Temperature (PET), modified PET (mPET), Universal Thermal Climate Index (UTCI), and Perceived Temperature (PT)) were selected. The results of the study are twofold, the identification of (1) index sensitivity to parameters’ variation, and change rates, resultant of different atmospheric conditions; and, (2) the overall pertinence of each of the indices for local thermal comfort evaluation. The results indicate that the thermohygrometric indices cannot follow and present the thermal conditions’ variations. On the other hand, UTCI is very sensitive under low radiation condition, and PET/mPET present higher sensitivity when the weather is dominated by high radiation and air temperature. PT index provides the lower sensitive among the human energy balance indices, but this is adequately sensitive to describe the thermal comfort environment. Full article

A correct artwork preservation requires strict values of several microclimate parameters, in particular temperature, humidity, and light. In existing museums, the evaluation of the effectiveness of current building plant systems and management is essential to avoid artwork deterioration. In this work, we propose the use of five simple performance indexes that use monitored data to estimate the suitability of the whole museum system in the maintenance of benchmark values of temperature, humidity, and light. The new indexes also take into account microclimate daily span and spatial homogeneity, which can represent a criticality in the preservative process. We apply these new indexes to the results of a monitoring campaign in Palazzo Blu, a museum in Pisa, which lasted for almost four months during a temporary exhibition on Toulouse-Lautrec works. The indexes show a mainly acceptable instantaneous microclimate, but HVAC (Heating, Ventilating and Air Conditioning) system improvement is necessary to avoid high thermo-hygrometric daily span. This methodology is useful for the identification of microclimate criticalities and can help the cooperation between conservation experts and professionals giving hints to improve museum internal microclimate. In case ofalready optimal microclimate, these indexes can be useful in more complex analyses, including simulations of possible retrofit actions, keeping microclimate suitability as a constraint. Full article