Search Results (52)

Egg production is amongst the most rapidly expanding livestock sectors worldwide. A large share of non-renewable energy use in egg production is due to the operation of heating, ventilation, and air conditioning (HVAC) systems. Reducing energy use, therefore, is essential to decreasing the environmental impacts of intensive egg production. This review identifies market-ready alternatives (such as heat pumps and earth–air heat exchangers) to traditional HVAC systems that could be applied in the industrial egg sector, specifically focusing on their use in temperate and continental climates. For this analysis, energy simulations were run to estimate the typical thermal loads of caged and free-run poultry housing systems in various Canadian locations, which were used as examples of temperate and continental climates. These estimations were then used to evaluate alternative HVAC systems for (1) their capability to meet the energy demands of egg production facilities, (2) their environmental impact mitigation potential, and (3) their relative affordability by considering the insights from a systematic review of 225 relevant papers. The results highlighted that future research should prioritize earth–air heat exchangers as a complementary system and ground source heat pumps as a stand-alone system to reduce the impacts associated with conventional HVAC system operation in egg production. Full article

Earth–air heat exchangers (EAHX) use the soil thermal capacity to dampen the amplitude of outdoor air temperature oscillations. This effect can be used in hot and dry climates for room cooling, and depending on the EAHX design, this cooling can be achieved with very few resources other than those used during EAHX construction. This is an obvious advantage compared to the significant energy consumption and operational costs of refrigeration machines traditionally used in room cooling. Despite the large number of papers on EAHXs available in the scientific literature, very few deal with large-diameter EAHXs (with pipe diameters larger than 0.30 m), and even fewer present monitoring data gathered from a built and functional large-diameter EAHX. The present paper uses monitoring data and provides a detailed quantitative analysis of the performance of a large-diameter EAHX built for standalone cooling of an existing office building. The field monitoring was carried out during a characteristic hot and dry summer period of the south of Portugal. Results show that outdoor air to EAHX exit air temperature gradients reach 9 K and cooling capacities exceed 27 kW. Moreover, the studied EAHX is capable of standalone cooling for outdoor air temperatures up to 33 °C and meets more than 50% of the room design cooling demand for outdoor air temperatures as high as 37 °C. This evidences that large-diameter EAHXs have the potential to achieve significant reductions in CO${}_2$ emissions and in energy consumption associated with building cooling in hot and dry climates. Full article

This case study focuses on twelve compacted clay soil samples to understand their fundamental physical and thermal properties. For each sample, the density, thermal conductivity, thermal diffusivity, specific heat, and drying shrinkage were assessed. The identification and characterisation of the materials were also carried out by positioning them into the ternary diagram based on the percentage of sand, silt, and clay. These properties are definitive for the performance characteristics of materials used in rammed earth wall construction. The aim is to provide information for better knowledge and prediction regarding the dynamic heat flow in rammed earth walls. Experimental results show a relatively wide range of values for each property, reflecting the diverse properties of the sampled clays. The thermophysical characteristics of the 12 types of earth analysed showed correlations with reports in the literature in terms of density (1490–2150 kg/m³), porosity (23.22–39.99%), specific heat capacity (701–999 J/kgK), and thermal conductivity (0.523–1.209 W/mK), which indicates them as materials suitable for use in the construction of rammed earth walls. Using test data, a dynamic assessment of heat flow through simulated rammed earth walls was performed. For a better understanding of the results obtained, they were compared with results obtained for simulations where the building element would be made of concrete, i.e., a mineral wool core composite. Thus, heat flux at the wall surface and mass flux, respectively, during the 16 years of operation showed similar evolution for all 12 types of clay material analysed, with small variations explained by differences in thermophysical characteristics specific to each type of S1–S12 earth. In the case of walls made from clay material, there is a stabilisation in the evolution of the water content phenomenon by the 5th year of simulation. This contrasts with walls made of concrete, where the characteristic water content appears to evolve continuously over the 16-year period. Therefore, it can be said that in the case of the construction elements of existing buildings, which have already gone through a sufficient period for the maturation of the materials in their construction elements, the rammed earth wall quickly develops a moisture buffer function. In the case of simulating a mineral wool core composite wall, it cannot perform as a temperature or humidity buffer, exhibiting an enthalpy exchange with indoor air that is only 4% of that of the rammed earth walls; consequently, it does not play a significant role in regulating indoor comfort conditions. Overall, there is confirmation of the temperature and moisture buffering capabilities of rammed earth walls during both warm and cold periods of the year, which is consistent with other reports in the literature. The findings of this research provide a better insight into clay as a material for rammed earth walls for more efficient design and construction, offering potential improvements regarding indoor comfort, energy efficiency, and sustainability. The data also provides useful information in the fields of architecture and civil engineering regarding the use of clay as an eco-friendly building material. The results emphasise the importance of thoroughly understanding the thermophysical properties of clay to ensure the efficiency of rammed earth construction. Full article

Communities operating urban greenhouses need affordable solutions to reduce their heating consumption. The objective of this study was to compare the ability of different simple ground-based solutions to reduce the heating energy consumption of relatively small urban greenhouses operated all year round in a cold climate. An urban greenhouse located in Montreal (Canada) and its thermal interactions with the ground were modeled with the TRNSYS 18 software. The following greenhouse scenarios were simulated: partially insulating the walls, partially burying the greenhouse below the ground level, reducing the inside setpoint temperature, and using an air–soil heat exchanger (ASHE) or a ground-coupled heat pump (GCHP). The heat exchangers for the last two cases were assumed to be located underneath the greenhouse to minimize footprint. The results showed that reducing the setpoint temperature by 10 °C and burying the greenhouse 2 m below the surface has the most impact on fuel consumption (−33% to −53%), while geothermal systems with a limited footprint (ASHE and GCHP) can reduce the fuel consumption by 21–35% and 18–27%, respectively, depending on the soil thermal conductivity and ground heat injection during summer. The scenarios do not provide the same benefits and have different implications on solar radiation availability, growth temperature, electrical consumption, and operation that must be considered when selecting a proper solution. Full article

The refurbishment of a social interest building using Earth-to-Air Heat Exchanger (EAHE) was studied in representative dry climatic conditions of Mexico (dry, very dry, temperate, and sub-temperate). A simulation method that uses both computational fluid dynamics (CFD) and building energy simulation (BES) was used to analyze the influence of the EAHE on the indoor conditions of a room. First, CFD simulations of the EAHE were performed using climatic data and soil properties of the four representative cities, and then the results were loaded into the TRNSYS software to estimate the indoor air temperature and the building room’s thermal loads. When connected to a building room on a warm day, the EAHE reduced the indoor air temperature by a factor ranging between 1.7 and 3.2 °C, while on a cold day, the EAHE increased the indoor air temperature of the room by between 1.0 and 1.9 °C. On the other hand, the EAHE reduced the daily cooling load of the room by a factor between 2% and 6%. The EAHE also reduced the daily heating load by between 0.3% and 11%. Thus, EAHE as a refurbishment technology can benefit social interest buildings in Mexico. Full article

Buildings are responsible for a large part of energy demand worldwide. To collaborate to reduce this demand, this paper aims to present a computational model to analyze the performance of an earth–air heat exchanger (EAHE) based on computational fluid dynamics using the ANSYS/Fluent^® software in the simulations. This passive air conditioning system uses the soil as a heat exchanger, taking advantage of the fact that the temperature of the soil at a certain depth remains relatively constant, regardless of the weather conditions above the surface, promoting heating, cooling, or ventilation for buildings. The air temperature values obtained were compared with experimental data from sensors installed in an EAHE at the Federal University of Technology—Parana, Ponta Grossa/Brazil (25.1° South, 50.16° West) to validate the computational model. A high computational effort would be demanded to perform these simulations involving the whole soil domain and the climatic boundary conditions. In order to optimize the numerical analysis of EAHE, two reduced models for the soil and heat exchanger domains were verified. First, a constant temperature of 23.7 °C was imposed on the surface of the exchanger tube, corresponding to the average soil temperature at a depth of 1.5 m. Afterward, a reduced soil domain extending 0.5 m in all directions from the heat exchanger serpentine was considered. Likewise, constant temperatures were imposed on the upper and lower surfaces of the soil domain, also obtained experimentally. In both cases, the temperature values obtained through the fast simulations showed good agreement compared to the experimental values. Barely explored in the literature, the thermal behavior of the two identical indoor environments at the university was also compared, in which the climatized environment, with the EAHE working in a closed loop, obtained milder and smaller amplitude air temperatures. Full article

Energy efficiency in buildings is very important since it contributes significantly to fossil fuel consumption and consequently climate change. Several approaches have been taken by researchers and the industry to address the issue. These approaches are classified as either passive or active approaches. The purpose of this review article is to summarize a number of the technologies that have been investigated and/or developed. In this technical review paper, the more commonly used active and passive building energy conservation techniques are described and discussed. The pros and cons of both the active and passive energy techniques are described with appropriate reference citations provided. This review article provides a description to give an understanding of building conservation approaches. In the active classification, several methods have been reviewed that include earth-to-air heat exchangers, ground-source and hybrid heat pumps, and the use of new refrigerants, among other methods. In the passive classification, methods such as vegetated roofs, solar chimneys, natural ventilation, and more are discussed. Often, in a building, multiple passive and active methods can be employed simultaneously. Full article

The need for healthy indoor conditions, the energy crisis, and environmental concerns make building ventilation systems very important today. The elements of ventilation systems to reduce energy intensity are constantly the subject of much scientific research. The most recent articles published in the last three years are analyzed in this paper. Publications focused on the topic of reducing energy consumption in ventilation systems were selected and divided into five key research areas: (1) the aspect of the airtightness of buildings and its importance for the energy consumption, (2) the methods and effects of implementing the concept of demand-controlled ventilation in buildings with different functions, (3) the possibilities of the technical application of decentralized ventilation systems, (4) the use of earth-to-air heat exchangers, (5) the efficiency of exchangers in exhaust air heat-recovery systems. The multitude of innovative technologies and rapid technological advances are reflected in articles that appear constantly and prompt a constant updating of knowledge. This review constitutes a relevant contribution to recognizing current advancements in ventilation systems and may be helpful to many scientists in the field. Full article

Earth–air heat exchanger (EAHE) systems are used to pre-heat or pre-cool air before entering into a building using shallow geothermal energy. Assessment of EAHE systems is important to quantify the profitability of these systems. For this purpose, an EAHE system built at ICUBE at the University of Strasbourg in the northeast of France was studied using energy and exergy analyses for a typical heating period (between 25 February and 3 March). Energy analysis was used to determine the heat gained by the air in the system during the studied period and to determine the Coefficient Of Performance (COP) of the system. Additionally, exergy analysis, which considered temperature, pressure, humidity, and the variation in the control volume boundary temperature, was realized to determine inefficiencies in the system by determining the exergy destroyed in each component of the system and evaluating its exergetic efficiency. Results showed that the heat energy gained using the system was around 63 kWh and that the exergetic efficiency of the system was about 57% on average. The comparison of exergetic efficiency between the EAHE components showed that the fan has the lowest performance and should be improved to achieve better overall performance. Full article

The performance of a hybrid solar desalination system is predicted in this work using an enhanced prediction method based on a supervised machine-learning algorithm. A humidification–dehumidification (HDH) unit and a single-stage flashing evaporation (SSF) unit make up the hybrid solar desalination system. The Al-Biruni Earth Radius (BER) and Particle Swarm Optimization (PSO) algorithms serve as the foundation for the suggested algorithm. Using experimental data, the BER–PSO algorithm is trained and evaluated. The cold fluid and injected air volume flow rates were the algorithms’ inputs, and their outputs were the hot and cold fluids’ outlet temperatures as well as the pressure drop across the heat exchanger. Both the volume mass flow rate of hot fluid and the input temperatures of hot and cold fluids are regarded as constants. The results obtained show the great ability of the proposed BER–PSO method to identify the nonlinear link between operating circumstances and process responses. In addition, compared to the other analyzed models, it offers better statistical performance measures for the prediction of the outlet temperature of hot and cold fluids and pressure drop values. Full article

The thermal performance and environmental impact of agricultural greenhouses (GH) connected to earth-to-air heat exchanger (EAHE) systems depend on the ambient temperature, soil temperature, EAHE system, and greenhouse specifications. The impact of an EAHE system on the temperature and humidity of a GH microclimate, as well as its effects on CO₂ emissions and heating energy consumption, are determined experimentally. Two scaled-down models of agricultural GHs (2 × 1.4 × 1.4 m³) were developed. Each GH was equipped with a heater. A spiral EAHE system was integrated into only one of the GHs. The temperature differences in the microclimate range from 3.5 °C to 7.5 °C, with the microclimates of GH + EAHE and GH being quite similar. In summary, the EAHE system helped to reduce the hourly energy consumption of the heating system by more than 40%. It also reduced emissions to the environment by more than 100 g (CO₂)/hour. The EAHE coefficient of performance (COP) for the cooling mode has a higher average value than that for the heating mode. The closed-loop performed better in cooling mode, while the open-loop performed better in heating mode. When the difference between the set temperature in the heater and the air outlet temperature of the EAHE system is smaller, the heater performs better in reducing energy consumption and CO₂ emissions of the heater. The COP_heating range is between 0 and 3.4 and the COP_cooling range is between 0.5 and 7.3. The energy consumption ranges between 0 and 1.41 kWh and the CO₂ emissions are between 0 and 359.55 g. Thus, using EAHE in agricultural greenhouses improves thermal performance and reduces environmental impact, providing an overall benefit in terms of energy consumption and environmental sustainability. Full article

The climate change assessment of the Intergovernmental Panel on Climate change is based on a radiative forcing methodology, and thermodynamic analysis of the climate does not appear to be utilized. Although equivalent to the radiative model, the thermodynamic model captures details of thermodynamic interactions among the earth’s subsystems. Carbon dioxide emission returns the net chemical energy exchanged with the climate system to the surface of the earth as heat. The heat is equal to the sum of the heat produced by fossil fuels and deforestation minus the heat of surface greening. Accordingly, trends of climate parameters are calculated. Nearly 51.40% of carbon dioxide production has been sequestered by green matter, and surface greening is approximately 3.0% per decade. Through 2020, the heat removed by surface greening has approached 12.84% of the total heat. Deforestation on the other hand has contributed nearly 22.85% of the total heat of carbon conversion to carbon dioxide. The increase in sea and average land surface air temperatures are 0.80 °C and 1.39 °C, respectively. Present annual sea level rise is nearly 3.35 mm, and the calculated reductions in the temperature and geopotential height of the lower stratosphere are about −0.66 °C and −67.24 m per decade, respectively. Unlike natural sequestration of carbon dioxide, artificial sequestration is not a photosynthetic heat sink process and does not appear to be a viable methodology for mitigating climate change. Full article

The emission of ammonia (NH₃) is predominantly caused by agriculture, especially by livestock keeping. The health effects of NH₃ and the related formation of particulate matter are the reasons for solid efforts to reduce their ambient concentrations. In addition, the impact of global warming on livestock is increasing due to heat stress, likely also increasing NH₃ emissions. Therefore, adaptation measures are under discussion to reduce the heat stress of animals inside livestock units. Because of the relationship between temperature increase and NH₃ release, the impact of the adaptation measures to cool the indoor air of livestock units (three different energy-saving air preparation systems, an inversion of the feeding and resting times by half a day, a reduction of the stocking density and doubling the maximum volume flow rate) was investigated. The NH₃ release was calculated by the following predictors: indoor air temperature; ventilation rate describing the turbulence inside the livestock building; and the diurnal variation caused by the animal activity. These parameters were calculated by a simulation model for the indoor climate of livestock buildings. The monthly mean of the NH₃ emission for several adaptation measures, which were applied to reduce heat stress, were compared with the emission of a reference building for 1800 fattening pigs, divided into nine sections with 200 animals each for an all-in-all-out production cycle to calculate the mitigation potential. The higher the cooling power of such adaptation measures, the higher the mitigation potential for NH₃. In particular, those adaptation measures which cool the inlet air (e.g., cooling pads reduce the emission by −2%, earth-air heat exchangers by −3.1%) show the best performance to mitigate the NH₃ emission of livestock buildings. Full article

Instead of fossil fuels, clean renewable energy resources are being used to meet space heating and cooling needs, to reduce global warming and air pollution worldwide. In the desert of the Arabian Peninsula, extensive solar irradiance and drastic variations in air temperatures (daily and/or seasonally) are common; thus, geothermal energy resources are a promising solution that is nearly independent of weather fluctuations. Due to a lack of information about in-ground temperature profiles in these regions, the use of geothermal energy resources for domestic applications is very limited. Therefore, this study aimed to measure the in-ground temperature (T_g) up to 3.5 m in depth for one year. Due to the difficulty of digging in the ground (i.e., gravelly sand; rocky, dry soil), numerical equations were adopted and used to simulate the in-ground temperature (T_g) for a depth > 3 m. These equations were validated by comparing the measured and simulated values of T_g for depths ≤ 3 m under extreme weather conditions. The validation yielded a mean absolute error (E_MA) of ≤ 1.2 °C and a root mean square error (E_RMS) of ≤ 1.42 °C. The measurements showed that at 3 m depth, the in-ground temperature was 32 °C in summer and 29 °C in winter. The simulation showed that values of T_g increased with depth in winter and decreased in summer and became constant as 30 °C at 13 m depth throughout the year (i.e., the undisturbed ground temperature (UGT)). This temperature would provide considerable heating and cooling capacity if an earth-to-air heat exchanger were implemented in arid regions where ambient temperatures exceed 47 °C on summer days and drop below 10 °C on winter nights. The theoretical prediction of T_g using the proposed equations is a useful tool for designers who use geothermal effects for indoor space cooling and heating in the desert of arid regions. Full article

Earth-to-air heat exchangers (EAHEs) are widely used to reduce the indoor temperature and associated cooling energy demand of buildings. This study investigated the potential reduction in indoor temperatures via energy-efficient ventilation through EAHEs in an existing architectural campus building (ACB) with an energy-efficient renovated building envelope in the hot and humid climate of Karachi, Pakistan. The building information modeling (BIM) program Autodesk Revit was used to develop a virtual ACB BIM model. An EnergyPlus parametric analysis of the ACB BIM model in DesignBuilder facilitated quantification of the influences of operating parameters such as pipe installation depth and pipe diameter for EAHEs with similar total pipe lengths and air-exchange rates on the performance of the EAHEs during the cooling season. A 3 m deep and 0.1 m diameter pipe layout in open space significantly reduces indoor temperature via a specific duct layout in an exemplary ACB. The results show that a pipe diameter above 0.1 m is unsuitable because of the reduction in convective heat transfer due to the increase in the pipe’s surface area and the decrease in pressure in the pipe. The findings of this study can be used to improve the indoor thermal comfort of buildings in climates with comparable properties. Full article