An increasing number of installations with underground heat storage have determined the development of new, more accurate and quicker calculation techniques. Therefore, this article shows a numerical model for a single vertical borehole heat exchanger working with underground heat storage. Emphasis has been put on developing a finite element which describes the process of heat exchange. A one-dimensional element with multiple degrees of freedom was used in this work. The changes of grout temperature affect the temperature of the circulating fluid, thus it is necessary to apply a suitable model. The grout area has been divided into three zones, and each one corresponds to a different temperature. Such an attempt allows to determine a more accurate temperature of the fluid. The results obtained for temperature distribution were compared to a model created with the use of Ansys commercial numerical software. (c) 2013 Elsevier Ltd. All rights reserved.