Performance Of Ground Source Heat Pump Research Articles

Utilizing a CNN-RNN machine learning approach for forecasting time-series outlet fluid temperature monitoring by long-term operation of BHEs system

The Borehole Heat Exchanger (BHE) plays a pivotal role in enhancing heat exchange efficiency within Ground Source Heat Pump (GSHP) systems. The accurate prediction of the BHE's outlet fluid temperature is crucial for optimizing GSHP performance, energy storage, and resource conservation. However, conventional machine learning methods encounter challenges in manual feature extraction, learning complex nonlinear relationships, and adapting to real-world scenarios. To address these limitations, this research proposes a crossbreed model integrating Convolutional Neural Network (CNN) and Recurrent Neural Network (RNN) architectures to forecast long-term outlet fluid temperature in BHE systems. The model framework encompasses data preprocessing, utilizing refined data in the CNN module for temporal feature extraction, subsequently passed to the RNN module to capture sequential and temporal patterns from each dataset. Specifically, the advanced CNN-RNN architecture is designed to establish a comprehensive input-output mapping, leveraging essential input features such as inlet fluid, ambient air, and subsurface temperatures at varying depths (0, 10, and 20 m). Performance evaluation metrics, including R2, RMSE, MAE, and AARE, are employed to compare and assess prediction accuracy across various models, including LSTM, CNN, and SimpleRNN. The obtained results demonstrate the superior performance of the proposed model, achieving an RSME of 0.818, MAE of 0.642, AARE of 0.0305, and an R2 value of 98.75 %. This surpasses the performance of traditional prediction models (LSTM, CNN, and SimpleRNN) by 3.01 %, 5.80 %, and 19.52 %, respectively. Notably, the remarkably low MAE of 0.642 exhibited by a CNN-RNN model underscores its capability to outperform traditional approaches, especially when handling large datasets. These findings emphasize the significance of the developed model in facilitating efficient operation, positioning it as a valuable tool for advancing the long-term sustainability of BHE systems.

Effectiveness of phase change materials and their properties on the performance of geothermal and foundation-based energy systems: A review

As buildings contribute notably to emissions of greenhouse gases, it is important to move towards building heating and cooling systems with good sustainability attributes and efficiencies, such as ground-source heat pumps (GSHPs). In this review, an integrated picture of the effect of utilizing phase change material (PCMs) having various physical properties on the performance of GSHPs and foundation-based geothermal systems is presented. Two major questions are addressed in this paper: how effective is a PCM for enhancing the performance of both conventional GSHP systems and foundation-based geothermal energy systems? The results show that PCMs can be effective at enhancing performance for conventional GSHP and foundation-based geothermal energy systems by, on average, 17% and 36%, respectively. However, the degree of PCM effectiveness depends on some parameters such as its physical characteristics (thermal conductivity, latent heat, phase change temperature) and design considerations (ground loop configuration, depth, etc.) among other factors. The results also show that, in general, the greater the PCM thermal conductivity, the higher the effectiveness of the PCM. Furthermore, by adding composites such as expanded graphite to the PCM, the thermal conductivity of a PCM increases more than 250% which can potentially improve the performance of geothermal systems. More research is warranted to maximize the system performance improvements by enhancing the PCM.

Study on effects of multi-climatic parameters on performance of ground source heat pump through coaxial borehole heat exchanger

ABSTRACT The accurate calculation for heat flux of borehole heat exchanger (BHE) is of great importance for design of ground source heat pump (GSHP); the climatic conditions influence GSHP performance through GHE. In this study, a 2-D heat transfer model for coaxial BHE was built to investigate the effects of multi-climatic parameters on BHE heat transfer and GSHP performance. The outlet temperature, ground temperature profiles and COP of GSHP system for the cooling period were concerned. The effects of climatic conditions under different borehole depths, ground thermal conductivities and flow rates were studied. The studies showed that the outlet temperature from BHE increased about 10% and system COP declined about 5% in cooling mode with considering the effect of climatic conditions. The comparison indicates that the effects of climatic conditions on coaxial BHE are stronger than that on U-tube BHE. Generally, the climatic conditions influence BHE heat transfer mainly through the shallow ground and the influences strengthen with time. The effects can be more significant with a larger ground thermal conductivity, but it weaken with increase of borehole depth. Also, the effects of climatic conditions on BHE and GSHP seem to be independent of flow rate.

Uncovering the Efficiency and Performance of Ground-Source Heat Pumps in Cold Regions: A Case Study of a Public Building in Northern China

In cold regions, due o the impact of climatic conditions, the heat load in winter and the cooling load in summer are unbalanced. In the long-term operation of the ground-source heat pump (GSHP), the soil heat imbalance phenomenon has still not been successfully solved. Therefore, this study took the GSHP of a public building in the cold area of northern China as the research object. Based on the unit performance data of the system over 8 years and the measured data of the soil temperature field, the long-term operation efficiency of the GSHP in the cold region and the variation law of the soil temperature field were explored. In order to further study the problem of soil heat imbalance, the effect of heat exchange hole groups at different intervals on the underground soil thermal environment after 30 years of operation in the system was simulated, and the optimization scheme of heat exchange hole spacing was proposed. The research results support the improvement and optimization of GSHP design and construction, and have important practical significance for the popularization of GSHPs in cold regions.

Numerical investigation on free cooling performance of ground-source heat pump in a solar greenhouse

This paper presents the numerical study of a ground source heat pump with borehole free cooling in a solar greenhouse. The system is mainly composed of a solar greenhouse with a water-water heat pump, a ground heat exchanger, and several pipes for free cooling. Thermal performances of ground source heat pump with and without borehole free cooling are investigated. The cooling time of the solar greenhouse is divided into transitional seasons (May and September) and summer seasons (from June to August). The mixed mode, including the free cooling mode and the ground source heat pump cooling mode, runs in summer seasons. During the entire transition seasons, the free cooling mode consumes 33.6% of the electricity in the ground source heat pump cooling mode and the soil thermal storage in free cooling mode is 76.3% of that in ground source heat pump cooling mode. Throughout the summer seasons, the power consumption of the mixed mode is 4.3% lower than that of the ground source heat pump cooling mode, and mixed mode soil thermal storage is 19.5% lower than that of ground source heat pump cooling mode. The results indicate that borehole free cooling system has better energy-saving performance during whole cooling period. In addition, a borehole free cooling system can also reduce the thermal imbalance in the soil.

Dynamic numerical investigation of the long-term performance of a GSHP system considering groundwater seepage and layered subsurface coupling conditions

This study presents a novel analytical model for ground source heat pump (GSHP) which comprehensively considers the dynamic interaction between building load, borehole heat exchanger (BHE) and heat pump unit, and the BHE under groundwater seepage and layered subsurface coupling conditions, as well as the impact of seasonal ground temperature fluctuation. The model achieved comprehensively reflect the influence of complex geological condition, interaction of unit system and seasonal fluctuation on GHSP performance. The model is utilized to simulate and analyze the long-term dynamic performance and the evaluation index (SCOP) is introduced to evaluate it, the results indicate that, after the 20 years of operation, the SCOP decreases by 9.1% from 4.81 to 4.37. Moreover, by analyzing the influence of load variation on outlet liquid temperature, it can find that the maximum value of the outlet temperature of the circulating fluid and the building cooling load appear at different times, with a difference of 44 days. Finally, the effect of seepage and seasonal ground temperature fluctuates on GSHP performance is investigated, the results reveal that the seepage effect is beneficial to it, and the seasonal ground temperature fluctuate will have an adverse effect on it.

Experimental evaluation of IDA ICE and COMSOL models for an asymmetric borehole thermal energy storage field in Nordic climate

• A large-scale asymmetric borehole field was modelled in IDA ICE and COMSOL. • Simplification of asymmetric borehole field layout was investigated in 3-D model. • Borehole field models were validated by DTS-measured brine temperatures. • Validation of borehole field models showed good agreement. • Simplified-geometry borehole field model can reduce computational work. Appropriate modeling of borehole thermal energy storage (BTES) system is crucial for accurate prediction of BTES-coupled ground source heat pump performance with accessible computational load. This study aims to validate 3-D numerical models developed in IDA ICE 4.8 and COMSOL for a large-scale asymmetric borehole field consisting of 74 groundwater-filled boreholes with average depth of 310 m in Otaniemi, Finland. Comparisons were conducted between the detailed-geometry IDA ICE and COMSOL borehole field models and between the detailed-geometry and simplified-geometry IDA ICE borehole field models. All these models were validated by 1.5-years brine temperatures measured by temperature sensors and a distributed temperature sensing monitoring system. The results show the detailed-geometry IDA ICE model can estimate the BTES inlet and outlet brine temperatures as well as the COMSOL model. The average inlet and outlet brine temperature differences against the measurement data in the detailed-geometry IDA ICE and COMSOL models were both within 1 ℃. The simplified-geometry IDA ICE models can predict the borehole field inlet and outlet brine temperatures with a similar high accuracy (within 1 ℃ against the measurement) and can reduce the computational time by 72 % less than the detailed-geometry IDA ICE model.

Integrated operation of PV assisted ground source heat pump and air source heat pump system: Performance analysis and economic optimization

The ground source heat pump (GSHP) system is widely recognized as an efficient, clean and economical renewable energy technology for buildings, and can be utilized for building cooling, heating and hot water supply. In the hot summer and cold winter zones of China, however, the total thermal load (heating load and hot water load) of GSHP systems is greater than the cooling load, which may cause a significant soil temperature drop and GSHP performance deterioration. To solve the above problems, a photovoltaic (PV) assisted GSHP and air source heat pump system (PVGSHP-ASHP) was proposed. This paper investigated the performance and feasibility of the PVGSHP-ASHP system, using a case campus building in Changsha city, China. The PVGSHP-ASHP system was firstly established by TRNSYS, and then, its operational performance was evaluated and compared with the PV assisted GSHP (PVGSHP) system and the PV assisted GSHP and electric heater (PVGSHP-EH) system. Finally, the economic optimization of the integrated operation of the PVGSHP-ASHP system was carried out with the combined simulation of TRNSYS and GenOpt. The results showed that for the PVGSHP system, the soil temperature reduced from 18.1 °C to 11.8 °C after 15 years of operation, which caused a decrease in the annual coefficient of performance of the GSHP (COPGSHP) and an increase in the annual electricity consumption. Although the PVGSHP-EH system can solve the load imbalance problem, its annual lifecycle cost (ALCC) increased by 39.3 % due to the low efficiency of the EH. The PVGSHP-ASHP system can solve the appeal problem with high annual COPGSHP and COPsys values of 3.49 kW/kW and 4.69 kW/kW, respectively, and only 71,700 kWh of the annual electricity consumption, while its ALCC was the lowest at 99,223 CNY, which was 8.1 % lower than the PVGSHP system. After optimization, the ALCC of the PVGSHP-ASHP system reached the minimized value of 91,158 CNY, with a reduction of 8.1 %. These findings can provide new ways to solve the load mismatch problem of GSHP systems while enhancing the system efficiency in the hot summer and cold winter zones of China.

Thermal performance analysis of an energy pile with triple helix ground heat exchanger

A Ground Source Heat Pump (GSHP) is a renewable energy-based HVAC system that extracts or supplies heat from/to the ground via a Ground Heat Exchanger (GHE). One of the most commonly used types of GHE in GSHP systems is the energy pile. In this realm, the GSHP system with a triple helix energy pile has become the focus of attention. To this aim, a comprehensive three-dimensional transient Computational Fluid Dynamics model of the energy pile with triple helix GHE and the surrounding soil is developed. The effect of several parameters, including helix pitch, helix diameter and pipe diameter, on the thermal performance of the system, is investigated. Simulated cases are chosen using the design of experiments methodology. To evaluate the thermal performance of GSHP, an objective parameter is defined as the ratio of the load provided to the load required by the building. The sensitivity of the objective parameter to the studied parameters and surface response curves are analyzed using the response surface model. Also, the optimization process was implemented to obtain the optimum system. It is demonstrated that, the tiple helix GHE enhance the objective parameter by 24% compared to conventional helix GHE. According to the obtained results, the helix pitch has the greatest impact on GSHP thermal performance. Furthermore, the pipe thermal interaction, in addition to the surface area between GHE pipes and the surrounding soil, plays an important role in thermal performance of GSHP.

Numerical simulations on potential application of ground source heat pumps with vertical ground heat exchangers in Bangkok and Hanoi

Southeast Asian countries have experienced fast economic growth for several decades. This rapid growth has been accompanied by an increased energy demand per capita. Ground source heat pumps could be a solution to improve energy efficiency. However, there are several concerns with the introduction of this technology. Unlike in four-season countries, where a seasonal balance between cooling and heating demand exists, the use of ground source heat pumps in Southeast Asia is primarily for cooling. The temperature difference between the ground and air is also small. In this paper, we evaluate the first thermal response test results ever performed in Southeast Asia at sites in Bangkok and Hanoi. Borehole heat exchanger models were established on the basis of the apparent thermal conductivities according to the thermal response test results. The borehole heat exchanger models were then used to evaluate the five-year performance of a ground source heat pump in a typical small-sized detached office building under specific climatic conditions. The increasing borehole heat exchanger temperature is unavoidable because of the absence of heat extraction. Consequently, the coefficient of performance decreasing, along with the increasing power consumption, over time. Yet, the results indicating that the ground source heat pump can still provide good thermal performance. We also evaluated the effect of the number of boreholes on the ground source heat pump performance. The results indicate that the maximum coefficient of performance can be relatively improved by 16.1% and 14.9% in Bangkok and Hanoi, respectively, using 10 instead of 6 boreholes.

Field study of heating performance of three ground-source heat pumps in Canadian single-family houses

This paper is the second part of a two-part study on the performance of ground-source heat pumps (GSHPs) in single-family detached houses in Canada. In Part I the cooling performance of two GSHPs was tested, analyzed and evaluated over one cooling season. In this paper, the heating performance of three vertical closed-loop water-to-air GSHP systems installed in three new single-family detached houses in Innisfil (80 km north of Toronto, Canada) is monitored, analyzed and evaluated over one heating season. Results show that GSHP A, GSHP B and GSHP C were able to meet the peak heating load without using the auxiliary heating element. The seasonal coefficient of performance of heat pump of GSHP A, GSHP B and GSHP C is 4.2, 4.0 and 3.4, respectively, whereas the seasonal coefficient of performance of the GSHP system of GSHP A, GSHP B and GSHP C is 3.8, 3.4 and 2.7, respectively. GSHP A has the highest COP mainly because it is equipped with a variable speed compressor while GSHP B and GSHP C are equipped with two-stage compressors. The average temperature of water leaving the ground loop of GSHP A, GSHP B and GSHP C is 3.9 °C, 3.1 °C and 2.7 °C, respectively, where the average temperature of water leaving the ground loop varied by up to 6.3 °C throughout the heating season. The total power consumption and operating cost of GSHP A, GSHP B and GSHP C are less than conventional air-source heat pumps by up to 46%, 40% and 24%, respectively. It is concluded that GSHPs operate at high COPs without operational problems even in very cold climates if designed, sized and installed correctly.

A Novel Data Management Methodology and Case Study for Monitoring and Performance Analysis of Large-Scale Ground Source Heat Pump (GSHP) and Borehole Thermal Energy Storage (BTES) System

Aalto New Campus Complex (ANCC) is a recently inaugurated educational facility at Aalto University, located in Otaniemi (Espoo), Finland. Within over 40,000 m2, it comprises two faculties, a shopping center, recreational areas, and a metro station. ANCC is also a large-scale application of Ground Source Heat Pump (GSHP)–Borehole Thermal Energy Storage (BTES) in Finland, comprising an irregular BTES field of 74 boreholes with an overall length of roughly 23 km and 4 million m3 of energy storage. Therefore, accurate monitoring of the GSHP–BTES energy system is crucial for sustainable and efficient long-term operation. Due to the fundamental issues affecting the accuracy of all thermal energy meters, a novel methodology adjusting for consistency of the measured data (in order to accomplish daily energy balance on both sides of the GSHP) is developed. The proposed methodology is used also in conjunction with reconstruction of missing relevant data before April/May 2020 by applying linear regression techniques. The developed data management is considered essential due to its capability to handle measured data with high uncertainty (thermal meters) by using highly accurate data regarding the GSHP power demand. Additionally, operational data and relevant GSHP performance indicators for the 18-month period starting from July 2019 is presented and analyzed.

Comparative costs of ground source heat pump systems against other forms of heating and cooling for different climatic conditions

Ground source heat pump (GSHP) systems can provide cost effective and sustainable heating and cooling for buildings while using considerably less fossil fuel than conventional heating and cooling systems. This benefit can be further enhanced by adopting hybrid GSHP (HGSHP) systems wherein the GSHP component provides the baseload thermal energy with the balance provided by conventional systems. This study compares the costs of GSHP and HGSHP systems against conventional systems under a variety of climatic conditions, exemplified by those encountered across Australia, but including conditions encountered elsewhere. The results indicate that the comparative performance of GSHP and HGSHP systems depend on many parameters including climatic conditions, ground conditions, drilling prices and prices of electricity and gas in the regions where the systems are installed. Here we show that in general, adopting GSHP or HGSHP systems over conventional systems allow property owners to pay lower lifetime costs under most climatic conditions and gas to electricity energy price ratios. The results also indicate that conventional systems may be preferred in highly heating or cooling dominant climates and at locations with high drilling costs or low energy prices. In contrast, GSHP and HGSHP systems are preferred in locations with a more balanced climate, lower drilling costs and/or higher energy prices. There is no “one size fits all” rule given the many factors that can influence the lifetime costs. The paper shows that climatic conditions, ground conditions, drilling and energy costs must all be carefully considered when assessing the most cost effective sustainable energy technologies for space heating and cooling.

Performance evaluation of ground source heat pump using linear and nonlinear regressions and artificial neural networks

Ground source heat pump (GSHP) systems have been widely used in both Northern Europe and China and have received a large amount of research attention due to their role in heat exchange of heating and cooling indoor temperature. Previous investigations have demonstrated that numerous design parameters have remarkable influences on the heat transfer performance of GSHP. Moreover, it is found that the design-ordinated provisions are not available for the direct prediction of the heat transfer performance of GSHP. To this end, this paper presents three numerical approaches (i.e., linear regression, nonlinear regression and artificial neural networks) to evaluate the heat transfer rate of GSHP regarding the fixed variables. An experimental database of GSHP applied in China is first collected containing 79 test results measured by authors and 33 experimental measurements from available literatures. Aiming to obtain the prediction models with high accuracy, the extensive and important variables (i.e., soil thermal conductivity, vertical well depth, well diameter, U-tube thickness, water flow rate and water temperature difference) reported in all test programs of the compiled experimental database are then set as the input parameters in the numerical approaches. The results show that the developed artificial neural networks (ANN) can provide more accurate predictions on the tested heat transfer rate of GSHP compared to the linear and nonlinear regressions. Finally, the trained ANN model is employed to conduct the parameter study to predict the influence of the input variables on the heat transfer rate and heat transfer rate variation of GSHP. The evaluation results demonstrate that increasing the well diameter and the U-tube thickness can lead to decrease the heat transfer rate of GSHP, whilst other variables (i.e., soil thermal conductivity, vertical well depth, water flow rate and water temperature difference) have an improvement in the heat transfer rate of GSHP.

Performance assessment and techno-economic optimization of ground source heat pump for residential heating and cooling: A case study of Nanjing, China

This study implemented the performance assessment and techno-economic optimization of residential ground source heat pump (GSHP). First, a detailed numerical model integrating the ground heat exchanger and heat pump and economic model considering economic indicators were developed to analyze the thermal and economic efficiency of residential GSHP. Then, Taguchi method was proposed to investigate the impacts of five parameters on the thermal and economic performance of GSHP and obtain the optimal parameters set. After that, the sensitivity of optimal parameter to the drilling costs, pipe prices, and interest rate were performed. Lastly, the analysis of variance approach was implemented to find out the relative significance of parameters. Results revealing that the superiority of individual GSHP can be maintained in the vast majority of time and the capital investments are relatively high within the range of 13034.4 to 18199.2 CNY. The optimal parameters combination was of great discrepancies when taking the economic indicators into account. The most economical choice of pipe size remains unchanged, despite the optimization objectives and varying pipe prices. The relative importance of fluid velocity, borehole depth, and pipe material towards the variation of economic efficiency largely depends on the drilling costs, pipe prices, and the interest rate.

Novel Experimental Device to Monitor the Ground Thermal Exchange in a Borehole Heat Exchanger

Ground source heat pump (GSHP) systems are becoming popular in space heating and cooling applications. Despite this fact, in most countries, the role of this energy is not as important as it should be nowadays according to its capabilities for energy generation without CO2 emissions, mainly due to the lack of technical knowledge about GSHP performance. The analysis of the physical processes that take part in the geothermal exchanges is necessary to allow the optimal exploitation of the geothermal resources. For all the above, an experimental geothermal device was built in the laboratory to control the phenomena that take place in a borehole heat exchanger (BHE). A 1-m high single-U heat exchanger was inserted in the center of a polyethylene container which also included granular material (surrounding ground) and the grouting material. Temperature sensors were situated in different positions of the experimental setup. Physical processes are evaluated to finally validate the model. Numerous applications can be developed from the experimental BHE. In this research, the determination of the thermal conductivity of the material used as medium was carried out. Results of this parameter were also compared with the ones obtained from the use of the KD2 Pro device.

Evaluation of thermal imbalance of ground source heat pump systems in residential buildings in China

The thermal comfort level of Chinese residents in the hot-summer and cold-winter zone is increasing with economic development in recent years. More district heating and cooling systems were installed in these areas. Supported by the government, ground source heat pump (GSHP) is used as a common environmentally friendly district heating and cooling system in many residential communities. However, the evaluation of the real performance of GSHP is limited, especially limited understanding of the common issue of thermal imbalance of GSHP systems over several years—the mismatch between heat extraction from and rejection to the ground. Performance of GSHP systems can deteriorate over years if the thermal imbalance is significant and not addressed. For GSHP in the hot-summer and cold-winter climate zone, there are few thermal imbalance studies based on real field data and modeling. To address this gap, this paper proposes an integrated simulation model to evaluate thermal imbalance of GSHP systems considering key influencing factors including occupant behavior and heat pump performance. A case study was conducted to simulate and analyze the actual operation of GSHP in Chinese residential buildings. The indoor comfort temperature setting and flexibility of residents’ control on indoor terminal air-conditioning units determine the actual heating and cooling demand in residential buildings, which resulted in differences in thermal imbalance for GSHP systems. It was found that GSHP systems with radiant floor only for heating lead to the most severe thermal imbalance, while GSHP systems with fan coil units or radiant ceiling for cooling and/or heating achieved much better thermal balance. The proposed thermal imbalance ratio is an important indicator that can be used to evaluate thermal imbalance of GSHP systems and thus inform their design and operation for energy efficiency.

Performance of heat pump system for water heating in European climate

A performance of air-to-water and brine-to-water heat pump for domestic hot water preparation was analyzed in different climates of Europe. Air-source heat pumps are widely used energy source for domestic applications with low operation costs. Their system SPF was found at level of 3.0 for domestic hot water preparation for medium latitudes in Europe. Investigations on the ground-source heat pump performance show their average SPF are close to air-source technology.

In-field performance evaluation and economic analysis of residential ground source heat pumps in heating operation

The objective of this study is to investigate the field performance, economic benefits, and environmental impact of ground source heat pumps (GSHPs) for residential space heating compared with conventional natural gas furnaces in a severely cold climate. A total of 32 residential houses with 16 vertical and 16 horizontal loop GSHPs in Iowa, U.S. were included in this study. The required heating energy in each house was estimated by using the heating degree-day (HDD) method and the building characteristics obtained during the on-site energy audits. The monthly GSHP electricity use in each house was collected over two consecutive heating seasons. Based on the estimated heating energy and the monthly GSHP electricity consumption, the coefficient of performance (COP) was derived for each unit on a monthly basis over the dominant heating period. Results showed that the median values in the calculated COP were 2.8 for both horizontal and vertical loop systems. The calculated COPs were found to be 30%–124% of the nominal values for horizontal systems and 46%–110% for vertical systems, with an average being 80% of the nominal value for both horizontal and vertical systems. In addition, 28 out of 32 GSHPs showed lower calculated COPs compared with the nominal values. The economic analysis showed 44–86% savings in energy expenses as a result of using GSHPs in place of conventional natural gas furnaces, with median savings being 70–77% depending on the electricity rates. The environmental analysis showed 23%–61% CO2 emission reduction with a median of 45% compared with natural gas furnaces. These results quantified the economic and environmental benefits of using GSHPs in Iowa, U.S., which provided essential information for policy making and incentive program development. Also, the developed analytical approach to determining the field performance of GSHPs is suitable for large-scale, long-term GSHP performance evaluation given its minimum requirement on field measurements and readily available utility data.

Comparative performance analysis of building foundation Ground heat exchanger

The aim of this work is to improve the performance of Ground-Source Heat Pumps (GSHPs) by placing the heat exchanger pipes in the soil under the building foundation and in the building foundation reconstructed in Turkey. In this scope, firstly, experimental studies have been performed on horizontal parallel pipes buried in soil under the foundation of the 2400 m2 Central Laboratory building, which was newly built at Yıldız Technical University. A comparison between the results of the experimental and newly developed numerical model is presented. Then, a full-scale numerical model for a shopping mall is developed based on the pipe location (soil and concrete layer), Numbers of Parallel Tube (NPTs) and different condensation temperatures in the heating season. The results show that the COP of GSHP when the pipes are buried in the soil under the building foundation is greater than when the pipes are buried in the building foundation. Furthermore, considering capital investment and operational costs, a reference function is defined as an optimization parameter. The effects of the pipe location, increasing rates in electricity prices and NPTs on reference function are investigated. For higher NPT values, locating the pipes in the foundation gives higher values of the reference function while for lower NPT values it is vice versa.