In shallow geothermal energy, the characterization of the thermal properties of rocks is fundamental in order to assess the ability of the ground to exchange heat for building conditioning.

In fact, the performance of Ground Source Heat Pump System (GSHP) depends on both heating/cooling building loads and site-related settings. For this reason, a reliable geological and hydrogeological characterization of the ground is required. Thermal conductivity is a key parameter to properly dimensioning low enthalpy geothermal systems by numerical modeling and a direct thermal measurement performed on representative specimens is necessary to give real data to planners, public administrations and operators involved in the geothermal sector.

Quality initiatives, such as ISO 17025, require apparatus calibration using certified and traceable reference materials. However, there are no certified reference materials for thermal effusivity. In this absence, an attempt is underway to obtain the” best available” thermal effusivity values for a series of reference materials using measurements of thermal conductivity, thermal effusivity, specific heat capacity, and density. Progress is reviewed by comparing the values obtain by two different methods.

The Modified Transient Plane Source (MTPS) method of thermal conductivity and thermal effusivity analysis is a method of transient thermal conductivity and thermal effusivity testing with growing popularity owing to its short test times and single-sided, interfacial configuration. Previously, work has been published detailing theoretical and experimental application of this method to thermal conductivity testing of liquids, powder uniformity, and other materials. This work expands upon the previous work. It includes details on the physical basis for the MTPS model, physical simulations to confirm fundamental assumptions about one-dimensional heat flow through test samples including foams, glasses, ceramics, and metals, and model and simulation validation with experimental data.