This paper reports the results of a study of the effectiveness of using low-grade ground heat for heat pump systems in the climatic conditions throughout Russia. The study was performed using the software package "INSOLAR.GSHP.12", which simulates the non-stationary thermal conditions of ground source heat pumps (GSHPs) over several years of operation. The impact of long-duration ground heat collection on soil thermal conditions and the impact of phase transitions of ground moisture on the effectiveness of GSHP operation were taken into consideration during the simulation. The GSHP energy conversion factor (COP, the ratio of useable thermal energy produced by the GSHP to the energy expended to operate the GSHP) average for the 5th year of operation was used as a criterion of to make efficiency zones of Russia. The results of the zonation study are maps of the territory of Russia with contours reflecting the coefficients of energy conversion and unit cost of energy consumption for GSHP operation with vertical and horizontal systems for the collection of low-grade geothermal heat and assigned to 1 m(2) of heated area of a building. (C) 2016 Elsevier Ltd. All rights reserved.