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Considering the heat capacity inside vertical spiral ground heat exchanger (VSGHEX) in the simulation is one of the most noteworthy challenge to design the ground source heat pump (GSHP) system with VSGHEXs. In this paper, a new simulation model for VSGHEXs is developed by combining the ICS model with the CaRM. The developed simulation model can consider the heat capacity inside VSGHEX and provide dynamic calculation with high speed and appropriate precision. In order to apply the CaRM, the equivalent length was introduced. Then, the equivalent length was approximated by comparing the results of the CaRM and the numerical calculation. In addition, the calculation model of the VSGHEX was integrated into the design and simulation tool for the GSHP system. The accuracy of the tool was verified by comparing with the measurements. The error between supply temperatures of the measurements and calculation is approximately 2 °C at the maximum. Finally, assuming GSHP systems with VSGHEXs, whose spiral diameter was 500 mm and depth was 4 m, were installed in residential houses in Japan, the required numbers of VSGHEXs were estimated. The results showed a strong correlation between the total heating or cooling load and the required number. Therefore, the required number can be estimated by using the simplified approximate equation.

Among the various approaches to agriculture, urban greenhouse farming has gained attention for its ability to address food security and disruptions to global food supply chains. However, the increasing impact of climate change and global warming necessitates sustainable methods for heating and cooling these greenhouses. In this study, we focused on the potential of slinky-coil horizontal ground heat exchangers (HGHEs) to meet the energy demands of urban greenhouses, assuming they are installed beneath the greenhouse to optimize space utilization. Climate data, an energy consumption profile for a greenhouse being designed in La Pocatière (Québec, Canada) and in-situ ground thermal properties assessments were used to build numerical models using FEFLOW and to evaluate the performance of the HGHEs simulated. Four scenarios were simulated and compared to a base case, considering the greenhouse’s maintenance of a constant temperature above an HGHE limited to the greenhouse’s dimensions. Our findings reveal that a minimum of 7.1% and 26.5% of the total heating and cooling loads of a small greenhouse (133 m2 area) can be covered by HGHEs installed at a 1.5 m depth when there is no greenhouse above. When installed under a greenhouse with a constant inside temperature of 21 °C, the coverage for heating loads increases to 22.8%, while cooling loads decrease to 24.2%. Sensitivity analysis demonstrates that the constant temperature in the greenhouse reduces the system’s reliance on surface temperature fluctuations for both heating and cooling, albeit with reduced efficiency for cooling.

•Dataset of energy demand for terrace houses including self-sufficiency indexes.•Archetypes are representative of 3 climatic zones and ground thermal conductivities.•Archetypes’ characterization supports energy policies on ground source heat pumps.•The methodology aims to be replicable supporting district scale retrofit strategies.•Integrated data collection will create the description of the whole building stock. According to the recent policies regarding energy use in buildings and the need of retrofit strategies, the aim of this work is to support policies concerning the installation of ground source heat exchangers in urban and historical areas, raising the awareness on the potential energy saving achievable with optimal sizing and limited impact on the urban environment. Archetypes have been developed distinguishing among existing and historic buildings, focusing on single-family terrace houses, which are the typical residential buildings in European historic centres. A methodology for the optimal sizing of ground source heat pumps, eventually considering dual-source system or air system has been developed combining simulations of a photovoltaic system to estimate the self-sufficiency and the self-consumption for five orientations of the building. Extreme results have been obtained for warm climates, with negligible heating energy demand and possibly free cooling systems rather than traditional cooling systems needed in wintertime. Penalty temperature was acceptable despite unbalanced energy demands. With proper inclination, photovoltaic systems could provide up to 40% of self-sufficiency share also in northern climates. An energy - economic analysis was carried out obtaining a variety of cases representing a general overview of the European building stock and the potential benefits achievable in terms of renewable energy share, energy savings and economic investments needed to be extended to simulations at urban scale. [Display omitted]

Recently, a growing demand for geothermal applications has led to the exploitation of energy efficiently by developing grouting materials in the borehole between pipes and the ground. Therefore, the current study developed newly formulated cementitious grouts by the integration of expanded graphite (EG)-based hybrid additives synthesized by building chemical bridges between silica particles and EG in the presence of amino functional silane coupling agents. These produced hybrid additives with controlled EG and silica ratios were utilized in grout mixtures used in borehole heat exchangers to enhance the thermal conductivity. According to the optimization study on the formulation development of grout mixtures with bentonite, silica sands, cement, and superplasticizer by adding neat EG and EG-based hybrids, the relationship between the carbon amount and water demand was found to have a significant impact on thermal conductivity. The highest thermal conductivity value of 2.656 W/mK was achieved by the incorporation of 5 wt% hybrid additive with the ratio silica/EG of 1:5 compared to the reference grout, which showed a thermal conductivity of 2.373 W/mK. Therefore, the enhancement in thermal conductivity was dependent on the increase in the EG content and also the additive loading ratio, resulting in a slight increase in the water demand.

Ground-source heat pumps are an efficient technology for heating and cooling in buildings. However, the main limitation of their widespread application is the borehole heat exchanger’s (BHE) high investment cost. Hybridizing GSHP systems may overcome this limitation. This research work analyzes the long-term energy performance of a dual-source heat pump (DSHP) system, which uses the air or the ground as external heat/sink sources, in three representative European climates. First, a BHE cost-effective design solution is proposed for each climatology; then, a complete energy analysis is carried out, and the optimal source control parameters that best enhance the system performance in each climate are determined with the use of a complete dynamic model of the DSHP system developed in TRNSYS. Simulations were carried out for a 25-year operation period. Results show that the DSHP maintains the efficiency during the simulated period, with deviations lower than 1.7% in all cases. Finally, the source control optimization method results in only slight efficiency gains (<0.35%) but with a stronger effect on the ground/air use ratio (up to 25% use of air in cold climates), reducing the thermal imbalance of the ground and leading to a consequent BHE size length and cost reduction.

Generally, Central Asia is typical for regions with strong solar radiation and various natural cooling sources. The heat gain from the building envelope accounts for a large part of the cooling load there. Thus, the pipe-embedded envelope is receiving attention as a semi-active system of utilizing natural energy for cooling. In this study, the performance of the pipe-embedded envelope used in Urumqi is numerically investigated. The energy saving potential regarding evaporative cooling and a ground-source heat exchanger (GSHE) is evaluated over a complete summer. The results show that the built-in pipes can reduce 80% of the solar heat gain through windows, with an effectiveness of around 60%. External windows rather than internal windows should be insulated because the air cavity is cool. With respect to the pipe-embedded wall, it becomes a radiant cooling panel absorbing the heat from the room, with an effectiveness around 83%. The seasonal cooling energy is decreased by 25%–50% in a typical office with a pipe-embedded envelope. Offices with a large window-to-wall ratio are acceptable because natural cooling is employed. GSHE performs the best among the selected sources. The effectiveness of evaporative cooling is also satisfactory, with an energy saving rate of 27%. Overall, the pipe-embedded system is suitable for climatic regions like Urumqi.

A desiccant-based hybrid cooling is among the most cost-effective air conditioning systems. The main purpose of this paper is the assessment of the potential of ground-assisted direct evaporative cooler together with a desiccant evaporative cooling cycle integrated with a ground source renewable energy for the pre-cooler process. Simulation results obtained using the TRNSYS software are compared with experimental data. The simulation of the mentioned systems are conducted in Bari (south of Italy), Palermo (south of Italy) and Ramsar (north of Iran) for the humid-mild climate of July. Assuming the low regeneration temperature (Treg) for the desiccant wheel is one of the highlights of this paper. Utilizing ground source heat exchanger (GSHE) will result in increase of the system potential in providing thermal comfort. The average thermal comfort achieves in Bari, Palermo and Ramsar in 95.72%, 93.94% and 93.15% of the time from 6 AM to 6 PM in July with utilizing the combination of GSHE and desiccant cooling system. The COP of this cycle is highly dependent on the Treg, and varies in the range of 0.35-0.53, 0.34-0.6 and 0.34-0.52 for the maximum Treg of 50 °C in Bari, Palermo and Ramsar, respectively.

From a literature review, various concepts and methodologies useful for the development of the preliminary stages of planning and design of a ground source heat pump were documented. A prototype of a cooling system for a room in the Universidad EIA was proposed. The heat pump selected to supply the demand has a power of 1-9 kW, and the proposed heat exchanger system corresponds to a closed-loop horizontal slinky-type with an approximate pipe length of 1,301 m, which was calculated through Excel spreadsheets and configured in three or six trenches with a total area required for the installation of 911 and 952 m2, respectively. These results provide the initial conditions for the implementation of an air conditioning project at the site, using shallow geothermal energy. Other alternatives for the heat exchanger systems and considerations for future projects are also presented.

Ground heat pump systems (GHPSs) are esteemed for their high efficiency within renewable energy technologies, providing effective solutions for heating and cooling requirements. These GHPSs operate by utilizing the relatively constant temperature of the Earth’s subsurface as a thermal source or sink. This feature allows them to perform greater energy transfer than traditional heating and cooling systems (i.e., heating, ventilation, and air conditioning (HVAC)). The GHPSs represent a sustainable and cost-effective temperature-regulating solution in diverse applications. The ground heat exchanger (GHE) technology is well known, with extensive research and development conducted in recent decades significantly advancing its applications. Improving GHE performance factors is vital for enhancing heat transfer efficiency and overall GHPS performance. Therefore, this paper provides a comprehensive review of research on various factors affecting GHE performance, such as soil thermal properties, backfill material properties, borehole depth, spacing, U-tube pipe properties, and heat carrier fluid type and velocity. It also discusses their impact on heat transfer efficiency and proposes optimal solutions for improving GHE performance.