This paper presents measurement results of a heating system equipped with a vapour compressor heat pump supplying a Polish single-family house with heat. The heat pump lower heat source is the rock mass where a vertical U-tube ground heat exchanger was installed. The measurements presented herein were performed between October 2011 and September 2013. The example measurement results illustrate the changes in the temperature of the medium at the ground heat exchanger inlet and outlet, the variability in the temperatures of the surroundings, as well as the variability in the heat pump operation time and electricity consumption in selected periods. The measurements made it possible to determine the analyzed system driving electric energy consumption throughout two heating seasons of identical duration in two subsequent years. The results allowed an analysis of the cumulated energy consumption in the periods mentioned above. The analysis was comparative in nature by relating to other selected heat sources. (C) 2015 Elsevier B.V. All rights reserved.