A ground-to-air heat exchanger takes heat from a temperature-stable and widely available heat source - the ground and uses it for the preliminary preparation of air for needs of building ventilation. The exchanger itself is characterized by a simple design in the form of a pipe, through which the air flows and interacts with the ground through the pipe wall. During heating season, ground has a higher temperature than the air flowing through the exchanger, so heat is transferred from the ground to the pipe wall by conduction, and then by convection to the air flowing through the exchanger. For the purposes of analysing such an exchanger, a model was developed and implemented in MATLAB® computer program. The model domain consists of the soil, a pipe buried in the ground and air flowing through the pipe. Division of the domain into elements, the shape of which is adapted to the domain geometry, is done automatically according to a given number of elements and the size of the analysed soil domain. Each domain element is defined with its material’s physical and thermodynamic properties. Element volume, together with material properties, determines mass, thermal resistance, and thermal capacity of an element. These characteristic values, together with temperature, determine an element’s heat balance at every moment in time, and thus the heat transfer between neighbouring elements. In each time step, discretized earth-air exchanger element temperatures, in this model, are calculated using the backward finite difference method, by matrix multiplication of the inverse matrix of coefficients and the constants vector. Based on the analysis of the discretization parameters influence, a time step between 30 and 300 s and number of elements between 2000 and 4000 were determined for the parametric analysis of the exchanger and the simulation of its operation in a typical week, while taking into consideration the accuracy of the solution and the duration of the simulation. Heat exchanger pipe material is, from the point of view of heat exchange, a parameter that does not significantly affect heat transfer, since the heat exchanger pipe, as a rule, has a small resistance to heat transfer and smaller dimensions in relation to the domain, while from a technical and economic point of view, the choice of pipe material significantly affects other requirements that a system must meet, such as hygiene, durability and maintenance. Air flow speed in a pipe is directly related to building ventilation and thermal requirements for which a system is designed. Volumetric air flow is a given parameter, to which pipe dimensions and heat exchanger length must be adapted to achieve optimal heat transfer, considering installation and operation costs. Therefore, an exchanger is dimensioned for low air flow velocities, from 1 to 3 ms-1. Heat transfer from ground to air flowing through an exchanger depends on air flow speed, which determines the air heat transfer coefficient, and pipe size, i.e. heat exchange surface. These two values should be determined in such a way, to achieve the highest transferred heat value. Heat transfer can be effectively influenced by using a multi-pipe exchanger, where heat transfer is achieved with higher air flow speeds, while simultaneously increasing heat exchange surface. Installation of a multi-tube exchanger requires a larger available installation area, while at the same time the value of heat flow per meter of an exchanger tube decreases. By analysing a simulation of heat exchanger's operation with realistic characteristic boundary and initial conditions, length of the exchanger and air flow speed in an exchanger were shown to be the most important operating parameters. Length of an exchanger determines the maximum value of exchanged heat, and air flow speed determines the power consumption of a fan, which is the only component of the system in this configuration that consumes electricity.