Training Manual for Designers of Shallow Geothermal Systems
About this book
The GeoTrainet Training Manual for Designers of Shallow Geothermal Systems, published in 2011 through the European GeoTrainet consortium funded under the Intelligent Energy — Europe programme, was developed as a structured educational resource to support the growing shallow geothermal heat pump sector across the European Union. The manual targets engineers, energy consultants, and geologists engaged in the feasibility assessment and detailed design of ground source heat pump (GSHP) installations, providing both the scientific underpinnings and practical calculation tools needed to plan, size, and optimize these low-carbon heating and cooling systems. Ground source heat pump systems exploit the thermal stability of the shallow ground—typically the upper 200 metres—to provide efficient space heating, cooling, and domestic hot water.
Unlike conventional boilers or chillers, a GSHP does not generate heat through combustion or direct electrical resistance; instead it moves thermal energy from the ground to the building (heating mode) or from the building to the ground (cooling mode) using a vapour-compression refrigeration cycle. The ratio of useful thermal energy delivered to the electrical energy consumed by the compressor defines the coefficient of performance (COP). The manual explains that instantaneous COP values for well-designed GSHP systems typically range from 3 to 5, meaning that for every unit of electricity consumed, three to five units of thermal energy are delivered.
The more meaningful indicator for seasonal performance is the Seasonal Performance Factor (SPF), which accounts for part-load operation, cycling losses, and pump energy, generally settling in the range of 3.0 to 4.0 for optimized systems. Borehole heat exchangers (BHEs) constitute the most widely used ground-coupling method described in the manual. A BHE consists of a U-tube or double U-tube of high-density polyethylene (HDPE) inserted into a drilled borehole, which is then grouted to ensure thermal contact between the pipe and surrounding formation.
Heat carrier fluid—typically a glycol-water mixture—circulates through the loop, exchanging thermal energy with the surrounding rock and soil. The thermal performance of a BHE depends strongly on the undisturbed ground temperature (which reflects the local climate and geothermal gradient), the thermal conductivity and heat capacity of the geological materials, and the thermal resistance of the borehole itself, which is influenced by grout conductivity, pipe diameter, and installation geometry. The manual dedicates substantial coverage to the characterization of ground thermal properties.
Thermal conductivity values vary widely, from below 1 W/(m·K) for dry unconsolidated sediments to above 4 W/(m·K) for crystalline rocks such as granite and quartzite. For smaller installations, tabulated values from geological surveys may suffice, but for larger systems the manual recommends performing a Thermal Response Test (TRT), in which the borehole is subjected to a controlled heat injection rate and the resulting temperature evolution is monitored and analyzed with analytical or numerical models to extract in-situ conductivity and thermal resistance values. Design methodology covered in the manual follows a progression from site assessment—including geological profiling, hydrogeological mapping, and identification of regulatory constraints—through thermal load calculation, borehole field sizing using established tools such as Earth Energy Designer (EED) or TRNSYS simulation packages, to system integration with the heat pump, distribution loop, and building controls.
The manual stresses that the ground thermal balance over the service life of the installation must be evaluated; imbalanced heating-dominated or cooling-dominated loads can cause progressive ground temperature drift that degrades long-term COP. The manual also devotes considerable space to the regulatory landscape across EU member states, which was notably fragmented at the time of publication. Requirements for drilling permits, groundwater protection, minimum setback distances between boreholes, and grouting standards varied markedly from one country to another.
The GeoTrainet project itself aimed partly to catalyze harmonization of training and certification requirements for designers and drillers, establishing a minimum competency framework that national professional bodies could adopt or adapt. The manual thus functions not only as a technical reference but as an advocacy document for raising professional standards across the European shallow geothermal market.