Search Results (179)

Ground-source heat pump (GSHP) systems are widely regarded as an energy-efficient solution for building heating and cooling. However, their actual performance in large commercial buildings is often limited by rigid control strategies, insufficient equipment coordination, and suboptimal load matching. In the Liuzhou Fengqing Port commercial complex, the seasonal coefficient of performance (SCOP) of the GSHP system remains at a relatively low level of 3.0–3.5 under conventional operation. To address these challenges, this study proposes a gray-box-model-based cooperative optimization and group control strategy for GSHP systems. A hybrid gray-box modeling approach (YFU model), integrating physical-mechanism modeling with data-driven parameter identification, is developed to characterize the energy consumption behavior of GSHP units and variable-frequency pumps. On this basis, a multi-equipment cooperative optimization framework is established to coordinate GSHP unit on/off scheduling, load allocation, and pump staging. In addition, continuous operational variables (e.g., chilled-water supply temperature and circulation flow rate) are globally optimized within a hierarchical control structure. The proposed strategy is validated through both simulation analysis and on-site field implementation, demonstrating significant improvements in system energy efficiency, with annual electricity savings of no less than 3.6 × 10⁵ kWh and an increase in SCOP from approximately 3.2 to above 4.0. The results indicate that the proposed framework offers strong interpretability, robustness, and engineering applicability. It also provides a reusable technical paradigm for intelligent energy-saving retrofits of GSHP systems in large commercial buildings. Full article

Agro-industrial facilities host processes and products that are highly sensitive to thermal fluctuations. Given the projected increase in air temperatures in tropical regions due to climate change, improving indoor thermal conditions in these facilities has become critically important. Conventional cooling systems are widely used to maintain adequate indoor temperatures; however, they are associated with high energy consumption. In this context, Ground Source Heat Pump (GSHP) technology emerges as a promising alternative to reduce cooling loads by exchanging heat with the ground. This study evaluates the reductions in cooling energy consumption and the return on investment of a GSHP system integrated with conventional cooling system, considering a prototype agro-industrial room located in two ecotones of the Brazilian Midwest: the Amazon Forest (AF) and Brazilian Savanna (BS). Building energy simulations were performed using EnergyPlus software v. 9 under current climate conditions and climate change scenarios for 2050 and 2080. Initially, the prototype room was conditioned using a conventional HVAC system; subsequently, a GSHP system was integrated to enhance energy efficiency and reduce energy demand. Under current conditions, cooling energy demand in the BS and AF ecotones is projected to increase by 16.5% and 18.3% by 2050, and by 24.5% and 23.5% by 2080, respectively. The payback analysis indicates that the average return on investment improves under future climate scenarios, decreasing from 14.5 years under current conditions to 10.13 years in 2050 and 9.86 years in 2080. The findings contribute to understanding the thermal resilience and economic feasibility of ground-coupled heat exchangers as a sustainable strategy for mitigating climate change impacts in the agro-industrial sector. Full article

The building sector represents a major source of global carbon emissions, with heating and cooling systems being particularly critical contributors, making the evaluation of sustainable low-carbon alternatives an urgent priority. In this study, life cycle assessment (LCA) methodology is used to analyze ground source heat pump (GSHP) systems against traditional heating, ventilation, and air conditioning (HVAC) systems based on project data from the city of Jinan and electrical grid characteristics of Northern China. It is specified that the functional unit is providing heating and cooling that maintains the indoor temperature of the building between 18 °C and 26 °C for 20 years. Following ISO 14040 standards, carbon emissions and economic performance across four phases—production, transportation, construction, and operation—over a 20-year life cycle were quantified using actual material inventory data and region-specific carbon emissions factors. The results demonstrate obvious environmental advantages for GSHP systems, which achieve a 51% reduction in life cycle carbon emissions compared to traditional systems based on the current power generation structure. Furthermore, sensitivity analysis shows that as the proportion of renewable energy in the grid increases to meet carbon neutrality targets, the reduction potential can even reach 88%. Economic analysis reveals that despite higher initial investments, GSHP systems achieve favorable performance with a positive 20-year net present value and an acceptable dynamic payback period for the project. This study shows that GSHP systems represent a viable strategy for sustainable building design in northern China, and the substantial carbon reduction potential can be further enhanced through grid decarbonization and renewable energy integration. The implementation of the GSHP system in newly constructed buildings, which require both heating and cooling, in Northern China, can be an effective strategy for advancing carbon neutrality goals. Full article

Decarbonizing building energy use requires efficient heat pumps and low-impact geothermal exchangers. A novel standalone TRNSYS Type was developed for a patented shallow horizontal ground heat exchanger (HGHE), called flat-panel (FP), designed at the University of Ferrara. Beyond simulating the FP in isolation, the Type enables coupling with other components within heat-pump configurations, allowing performance assessments that reflect realistic operating conditions. The Type was implemented in TRNSYS models of a ground-source heat pump (GSHP) and of a dual air and ground source heat pump (DSHP) to verify Type reliability and evaluate potential DSHP advantages over GSHP in terms of efficiency and ground-loop downsizing. The performance of the system was analyzed under varying HGHE lengths and DSHP control strategies, which were based on onset temperature differential $DT$. The results highlighted that shorter HGHE lines yielded higher specific HGHE performance, while higher $DT$ reduced HGHE operating time. Concurrently, the total energy extracted from the ground decreased with increasing $DT$ and reduced length, thus supporting long-term thermal preservation and allowing HGHE to operate under more favorable conditions. Exploiting air as an alternative or supplemental source to the ground allows significant reduction of the HGHE length and the related installation costs, without compromising the system performance. Full article

In the context of China’s rural revitalization strategy, improving the livability and sustainability of traditional dwellings in border regions has become a critical priority. This study examines Chinese–Korean houses in border villages, where field investigations and quantitative analysis reveal persistent challenges: poor indoor thermal comfort and high energy consumption due to outdated building envelopes and inefficient heating systems. To address these issues, we propose an integrated retrofitting solution that combines building-integrated photovoltaics (BIPV) and ground-source heat pump (GSHP) technologies. Unlike previous studies focusing on isolated applications, our approach emphasizes the synergistic integration of active energy generation and high-efficiency thermal regulation, while preserving the architectural and cultural identity of traditional dwellings. Pilot results demonstrate significant improvements in PMV (Predicted Mean Vote) and economic viability, and achieve a high level of esthetic and cultural compatibility. Modular BIPV integration provides on-site renewable electricity without altering roof forms, while GSHP ensures stable, efficient heating and cooling year-round. This solution offers a replicable, regionally adaptive model for low-carbon rural housing transformation. By aligning technological innovation with cultural preservation and socioeconomic feasibility, the study contributes to a new paradigm of rural development, supporting ecological sustainability, ethnic unity, and border stability. Full article

In cold regions, performance reduction in a Ground-Coupled Heat Pump (GSHP) system has been frequently reported. Many operational strategies have been adopted to mitigate such an undesirable phenomenon. However, these strategies have limited effects because the specific heat rate of Borehole Heat Exchangers (BHEs) is usually treated as constant. In this study, eight BHEs were installed in typical loess areas in Northwestern China to investigate how borehole depth affects its thermal performance. Thermal response tests (TRTs) showed that deeper boreholes led to a higher fluid outlet temperature. Compared to 150 m and 100 m boreholes, the energy coefficient factor (η) for a 200 m borehole increased by 18.02% and 45.0%, respectively. Numerical simulation also confirmed that deeper BHEs perform better. In addition, the initial ground temperature influences the thermal performance sensitively, but in the opposite way for heating and cooling modes. These findings offer valuable insights for installing GSHP systems to achieve sustainable and high thermal performance in cold regions. Full article

Compared to shallow geothermal systems, coaxial medium-deep and deep borehole heat exchangers (MDBHE and DBHE) offer higher temperatures and heat extraction rates while requiring less surface area, making them attractive options for sustainable heat supply in combination with ground-source heat pumps (GSHP). However, existing simulation tools for such systems are often limited in computational efficiency or open-source availability. To address this gap, we propose a rapid modeling approach using the open-source Python package “pygfunction” (v2.3.0). Its workflow was adjusted to accept the fluid inlet temperature as input. The effective undisturbed ground temperature and ground thermophysical properties were weight-averaged considering stratified ground layers. Validation of the approach was conducted by comparing simulation results with 12 references, including established models and experimental data. The proposed method enables fast estimation of fluid temperatures and heat extraction rates for single boreholes and small-scale bore fields in both homogeneous and heterogeneous geological conditions at depths of 700–3000 m, thus supporting rapid assessments of the coefficient of performance (COP) of GSHP. The approach systematically underestimates fluid outlet temperatures by up to 2–3 °C, resulting in a maximum underestimation of COP of 4%. Under significant groundwater flow or extreme geothermal gradients, these errors may increase to 4 °C and 6%, respectively. Based on the available data, these discrepancies may result in errors in GSHP electric power estimation of approximately ±10%. The method offers practical value for GSHP performance evaluation, geothermal potential mapping, and district heating network planning, supporting geologists, engineers, planners, and decision-makers. Full article

In order to explore the increase in the environmental benefits of solar ground source heat pump (SGSHP) systems, this study assesses the environmental benefits of SGSHPs through a comprehensive sustainability evaluation, integrating life cycle assessment, carbon emission analysis, and emergy analysis based on a real project in Tianjin (39.13° N, 117.2° E). By comparing an SGSHP with the conventional GSHP system, improvements in sustainability performance are quantified. The analysis reveals that the SGSHP system has a full-cycle EI16 of 1.88 × 10³, which is 15% higher than the GSHP value of 1.63 × 10³. The SGSHP demonstrates a significant advantage in terms of carbon emissions at all stages, with an overall carbon emission of 31,671 kgCO₂-eq, which is a reduction of about 9.4% compared to the 34,955 kgCO₂-eq of the conventional GSHP system. The emergy conversion rate of SGSHP is 3.58 × 10³, which is 16.23% higher than that of GSHP. This shows that the system with the addition of solar energy is able to convert raw energy into useful heat or cooling energy more efficiently, reducing emergy wastage and making it operate more efficiently, with emergy saving and environmental advantages. The SGSHP system has an ESI value of 1.12, indicating that it is in a developmental or intermediate stage, with significant potential for sustainable economic contributions. In contrast, the GSHP system, with an ESI value of 0.98, demonstrates that it is not sustainable over the long term. By using a comprehensive environmental assessment framework and comparative data analysis, this study aims to better understand the SGSHP system’s performance in energy use, carbon emissions, and ecological impact, providing a scientific foundation for its wider adoption. Full article

Resource maps for open-loop ground source heat pump (GSHP) systems were developed based on heating and cooling experiments to identify areas with potential for reduced operational costs. Experiments conducted at a public hall, where groundwater temperatures fluctuate seasonally, clarified the relationships between the coefficient of performance (COP) of a heat pump and three key parameters: groundwater temperature, flow rate, and energy consumption. Multiple regression analysis produced equations for estimating the energy consumption of both the heat pump and the water pump. Results indicate that groundwater temperature influences the COP, increasing it by 0.07969 per °C during heating and decreasing it by 0.1721 per °C during cooling. These equations enable the estimation of energy consumption in open-loop systems from groundwater temperature, groundwater depth, and building type. Resource maps developed for the Nobi Plain in central Japan reveal that annual energy consumption is lower in the northwestern region, where groundwater temperatures are generally lower, except in marginal zones for hospitals and offices. Full article

The bore field in ground source heat pump (GSHP) systems usually encounters thermal accumulation in long-term operation, but there is no quantitative index evaluating this process and its magnitude. A heat accumulation evaluation metric has been proposed, based on the linear trend Slope (°C/a) of the curve of soil temperature variation. Using this metric, the influence of various factors on soil temperature has been quantitatively analyzed. The results indicate that, under constant heating durations, each 10-day extension of cooling periods leads to an increase of 0.038 °C/a in soil temperature. Extending the recovery period within an annual cycle facilitates soil self-recovery and mitigates subsurface thermal accumulation. Increasing the spacing between boreholes effectively reduces thermal interference, whereas a greater number of boreholes exacerbates thermal accumulation. Deepening vertical boreholes from 100 m to 200 m reduces the average annual soil temperature increase by 0.1076 °C. Appropriately increasing backfill thermal conductivity enhances heat exchange efficiency and suppresses thermal accumulation. Higher water flow rates result in logarithmic increases in the evaluation metric, thereby intensifying soil thermal accumulation. Intermittent operation extends recovery periods, thereby alleviating soil thermal imbalance. Under balanced cooling and heating loads, increasing the system lifespan from 10 a to 30 a reduces the evaluation metric by 47.2%. Full article

Both ground source heat pumps (GSHPs) and energy underground structures are engineered systems that utilize shallow geothermal energy. However, due to the construction complexity and associated costs of energy tunnels, their heat exchange efficiency relative to GSHPs remains a topic worthy of in-depth investigation. In this study, a thermal–hydraulic (TH) coupled finite element model was developed based on a section of the Torino Metro Line in Italy to analyze the differences in and influencing factors of heat transfer performance between energy tunnels and GSHPs. The model was validated by comparing the outlet temperature curves under both winter and summer loading conditions. Based on this validated model, a parametric analysis was conducted to examine the effects of the tunnel air velocity, heat carrier fluid velocity, and fluid type. The results indicate that, under identical environmental conditions, energy tunnels exhibit higher heat exchange efficiency than conventional GSHP systems and are less sensitive to external factors such as fluid velocity. Furthermore, a comparison of different heat carrier fluids, including alcohol-based fluids, refrigerants, and water, revealed that the fluid type significantly affects thermal performance, with the refrigerant R-134a outperforming ethylene glycol and water in both heating and cooling efficiency. Full article

Ground temperature (GT) variation significantly affects the energy performance of ground source heat pump (GSHP) systems. Both long-term thermal accumulation and short-term dynamic responses contribute to the degradation of the coefficient of performance (COP), especially under cooling-dominated conditions. This study develops a mechanism-based TRNSYS simulation that integrates building loads, subsurface heat transfer, and dynamic heat pump operation. A 20-year case study in Shanghai reveals long-term performance degradation driven by thermal boundary shifts. Results show that GT increases by over 12 °C during the simulation period, accompanied by a progressive increase in ΔT by approximately 0.20 K and a consistent decline in COP. A near-linear inverse relationship is observed, with COP decreasing by approximately 0.038 for every 1 °C increase in GT. In addition, ΔT is identified as a key intermediary linking subsurface thermal disturbance to efficiency loss. A multi-scale response framework is established to capture both annual degradation and daily operational shifts along the Load–GT–ΔT–COP pathway. This study provides a quantitative explanation of the thermal degradation process and offers theoretical guidance for performance forecasting, operational threshold design, and thermal regulation in GSHP systems. Full article

The transition to low-carbon heating systems is fundamental to achieving climate neutrality, particularly within the building sector, which accounts for a significant share of global greenhouse gas emissions. Among various technologies, heat pumps have emerged as a leading solution due to their high energy efficiency and potential to significantly reduce CO₂ emissions, especially when powered by renewable electricity. This systematic review synthesizes findings from the recent literature, including peer-reviewed studies and industry reports, to evaluate the technical performance, environmental impact, and deployment potential of air source, ground source, and water source heat pumps. This review also investigates life cycle greenhouse gas emissions, the influence of geographical energy mix diversity, and the integration of heat pumps within hybrid and district heating systems. Results indicate that hybrid HP systems achieve the lowest specific GHG emissions (0.108 kgCO₂eq/kWh of heat delivered on average), followed by WSHPs (0.018 to 0.216 kgCO₂eq/kWh), GSHPs (0.050–0.211 kgCO₂eq/kWh), and ASHPs (0.083–0.216 kgCO₂eq/kWh). HP systems show a potential GHG emission reduction of up to 90%, depending on the kind of technology and energy mix. Despite higher investment costs, the lower environmental footprint of GSHPs and WSHPs makes them attractive options for decarbonizing the building sector due to better performance resulting from more stable thermal input and higher SCOP. The integration of heat pumps with thermal storage, renewable energy, and smart control technologies further enhances their efficiency and climate benefits, regardless of the challenges facing their market potential. This review concludes that heat pumps, particularly in hybrid configurations, are a cornerstone technology for sustainable building heat supply and energy transition. Full article

The short-term performance of ground heat exchangers (GHEs) is crucial for the optimal design of ground-source heat pumps (GSHPs), enhancing their contribution to sustainable energy solutions. Local short-time thermal response functions, or short-time g-functions (STGFs) derived from thermal response tests (TRTs), are of great interest for predicting the heat exchange due to their fast and simple applicability. The aim of this work is to perform a sensitivity analysis to assess the impact of thermal parameter variability and TRT operating conditions on the accuracy of the average fluid temperature (T_f) predictions obtained through a local STGF. First, the uncertainties associated with the borehole thermal resistance (R_b), transmitted from the soil volumetric heat capacity (C_S) or some models dependent on GHE characteristics, such as the Zeng model, were found to have a low impact in T_f resulting in long-term deviations of ±0.2 K. Second, several TRTs were carried out on the same borehole, changing input parameters such as the volumetric flow rate and heat injection rate, in order to obtain their corresponding STGF. Validation results showed that each T_f profile consistently aligned well with experimental data when applying intermittent heat rate pulses (being the most unfavorable scenario), implying deviations of ±0.2 K, despite the variabilities in soil conductivity (λ_S), soil volumetric heat capacity (C_S), and borehole thermal resistance (R_b). Full article

As the demand for sustainable heating, ventilation, and air conditioning (HVAC) solutions rises, ground source heat pumps (GSHPs) offer high efficiency but are sensitive to subsurface thermal dynamics. The overall objective of this study is to evaluate the impact of ground temperature variations on GSHP performance by proposing a semi-analytical dynamic model capable of simulating medium- to long-term heat pump operations. The proposed model accounts for the interactions between the ground heat exchanger (GHE) and the heat pump. A case study using the proposed model demonstrates how ground temperature variations from external factors affect the coefficient of performance (COP) and the heating and cooling capacity of GSHP systems. For ±5 °C ground shifts, the heating capacity falls below peak demand if the subsurface temperature drops by more than 2 °C, requiring supplemental heating. Peak cooling and capacity vary by less than 1% and 3% for every unit of ground temperature change (°C), respectively. These results quantify both the resilience and limits of GSHP sustainability under realistic thermal disturbances. Full article