| Phase: |
Theme |
| Theme: | Geothermal (T05) |
| Status: | Active |
| Start Date: | 2024-04-01 |
| End Date: | 2026-06-30 |
| Principal Investigator |
| Koohi, Seama |
Project Overview
Ground-source heat pumps (GSHPs) are potentially a more efficient technology to provide heating and cooling to buildings compared to conventional systems. However, their large cost, often due to large cost of ground drilling for installation of vertical ground heat exchangers (GHEs), is a major limitation to their wider adoption. Inaccurate engineering design results in oversizing GHEs and an opportunity exists in reducing the system cost by properly sizing GHEs and optimizing their layout within the borefield. This requires developing advanced mathematical models that allow simulation of heat flows in the ground surrounding GHEs and ultimately optimization of GHEs. The objective of this project is to address this issue.
Outputs
| Title |
Category |
Date |
Authors |
| Techno-Economic Assessment of Dual-Source Heat Pump Systems: Borehole Size Reduction and Life-Cycle Cost Analysis Across Three Cities in CanadaDual-source heat pumps (DSHPs) mitigate high upfront costs of ground-source systems (GSHPs) in by dynamically switching between air and ground sources. This study evaluates DSHP performance and economic feasibility across three Canadian cities (Edmonton, Toronto, and Montreal) through semi-analytical dynamic simulations of DSHP system and life-cycle cost analysis. Lowering the outdoor air temperature set points (0°C, -5°C, -10°C) —above which the heat pump operates in air-source mode and below which it switches to ground-source mode during heating mode—reduces borehole lengths by 4.5–42%, with Toronto achieving the highest savings (42% borehole reduction, 24% capital cost reduction, and 14% net present value (NPV) of costs reduction at -10°C) due to milder climate. University of Alberta | Publication | 2025-05-25 | Nima Mahmoudi Majdabadi, Koohi, S. |
| Optimization of Borehole Layouts in Ground Source Heat Pump Systems Using Metaheuristic AlgorithmsGround Source Heat Pump (GSHP) systems that are connected to vertical ground heat exchangers (GHEs), also called boreholes, are a sustainable option for heating and cooling buildings, as they make use of the stable temperature of the ground and deliver heating and cooling efficiently. However, the high initial cost, mainly due to drilling boreholes, remains a major challenge. One of the most practical ways to reduce this cost is by decreasing the total length and number of boreholes while still meeting GSHP system requirements. The goal of this work is to find practical and efficient ways to design GHE layouts that are more affordable and easier to implement in larger projects without affecting system performance. This is done by keeping the borehole running fluid temperature that is in connection with the GSHP within acceptable limits during both heating and cooling, and ensuring that borehole lengths do not exceed a set limit, here 250 meters (820 ft). An optimization procedure is proposed based on a regular arrangement of boreholes to determine the required borehole numbers following current design practice. Then, a genetic algorithm is applied to rearrange the positions of these boreholes to further reduce the total borehole (and drilling) length. It was concluded that optimizing the layout with fewer boreholes than in the base case yielded better results, with the algorithm achieving a 6% reduction in total drilling length. University of Alberta | Activity | 2025-10-06 | Farzad Dadbakhsh, Koohi, S. |
| A review of environmental assessments of ground-source heat pumpsGround source heat pumps (GSHPs) are considered to be a promising technology to improve the energy efficiency of heating and cooling in buildings. However, sustainability of heat pump technologies and in particular GSHPs can sometimes be questioned. Detailed investigation of the environmental impacts of GSHPs over all stages of their life is needed to evaluate their sustainability. In this article, studies focused partially or in full on the environmental impact assessment of GSHPs, and their integrations with other systems, are reviewed. The focus of the review is on the main findings of such studies to provide a clearer picture of their status, but a summary of data input and methodologies that are used in such studies is also provided to ensure meaningful comparisons can be made among results of various studies, and to guide new studies on environmental assessment of GSHPs. It is found through this review that the main life stage contributing to environmental impacts of GSHPs is operation stage and the main contributor during this stage is electricity generation mix. Improvements in electricity generation source seem to be the most important factor to be considered if a wider adoption of GSHPs is sought. University of Alberta | Publication | 2024-12-08 | Koohi, S. |
| A Semi-Analytical Dynamic Model for Ground Source Heat Pump Systems: Addressing Medium- to Long-Term Performance Under Ground Temperature VariationsAs the demand for sustainable heating, ventilation, and air conditioning
(HVAC) solutions increases due to climate change and energy efficiency concerns,
Ground-Source Heat Pumps (GSHPs) have emerged as a promising technology.
However, GSHP performance is significantly influenced by temperature variations under
the ground. The overall objective of this study is to evaluate the impact of ground
temperature dynamics 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, enabling accurate predictions of system performance over extended periods.
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. University of Alberta | Publication | 2025-06-11 | Nima Mahmoudi Majdabadi, Koohi, S. |
