Knowledge of the temperature of the ground in time and space as well as its thermal properties gives basic information about physical phenomena concerning the transfer and accumulation of heat in the ground. It can be also used for evaluation of the heating possibilities of heat pumps; to proper design the size of the ground exchangers and the depth, at which they should be installed. For this purpose, a mathematical model based on the heat balance equation on the ground surface was developed. The basis of the model is the Carslaw-Jaeger equation regarding the temperature profile in the ground. The model was verified using experimental results for two different locations (different climatic conditions, moderate and arid climate)—the standard deviation is equal 0.62 K and 0.92 K, respectively. In this work, the impact of several parameters on the ground temperature profiles and thermal fluxes was determined. It was found that among the examined parameters the amplitude of the daily average solar radiation flux strongly effects on the total amount of heat transferred between the ground and the environment during the year, wherein the other parameters have a negligible effect.

Methods for the calculation of the undisturbed ground temperature (UGT) are presented. Heat fluxes occurring on the surface of the ground and their influence on the UGT are described. Correlation equations for the calculation of the undisturbed ground temperature based on the meteorological data averaged in the yearly cycle are proposed. These equations are of a semi-empirical character and they are based on the heat flux balance. The determined coefficients of these equations, particularly the convection heat transfer coefficient, are consistent with the values specified by other methods.