Optimization of Energy Pile Grids during Unbalanced Heating and Cooling Operations


Shallow geothermal energy systems (SGES) are becoming more common due to their ability to assist in efficient heating and cooling of buildings. These heat exchanger systems can also be integrated within building foundations, thus creating energy geostructures, which do not require the additional installation costs of a borehole field. Despite the popularity of SGES, several challenges remain. One challenge is subjecting SGES to unbalanced heating and cooling loads during the year. If more energy is required for either heating or cooling, the in situ ground temperature could potentially change over time, thus negatively affecting the efficiency of the system. This is especially challenging in heating or cooling dominated climates such as Chicago, Miami, or Houston, and when energy demand profiles are such that they only require energy for heating, such as bridge deck deicing or grain drying. Furthermore, energy foundations cannot be optimized with respect to geometry for heat exchange with the ground as the design is primarily governed by geotechnical design. This paper explores selective utilization of energy piles within a typical energy pile grid to minimize the amount of energy lost in the ground. The study utilizes a calibrated numerical model to investigate different combinations of heat injection and extraction alternatives. The findings from the analyses are evaluated to establish a practical solution to the problem that would not require an advanced control system or significant oversight from a system operator.

Meeting Name

Geo-Congress 2020: Modeling, Geomaterials, and Site Characterization (2020: Feb. 25-28, Minneapolis, MN)


Civil, Architectural and Environmental Engineering

Keywords and Phrases

Cooling Systems; Energy Efficiency; Geothermal Energy; Heat Exchangers; Heating; Soil Mechanics; Structural Design, Advanced Control Systems; Building Foundations; Geotechnical Designs; Heating and Cooling; Heating and Cooling Loads; Heating and Cooling of Buildings; Practical Solutions; Shallow Geothermal Energies, Piles

International Standard Serial Number (ISSN)


Document Type

Article - Conference proceedings

Document Version


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© 2020 American Society of Civil Engineers (ASCE), All rights reserved.

Publication Date

01 Feb 2020