This thesis presents a study for examining the viability of hybrid ground source heat pump (GSHP) systems that use solar thermal collectors as the supplemental component in heating dominated buildings. Loads for an actual house in the City of Milton near Toronto were estimated. TRNSYS, a system simulation software tool, was used to model the yearly performance of conventional GSHP as well as the proposed hybrid GSHP system.The house was equipped with a data monitoring system which was installed to read and record fluid flow, temperature and electricity consumption in different components of the system. The actual yearly data collected from the site was examined against the simulation results. In addition, a sensitivity analysis was carried out to determine the relationship between the solar collector area and the ground loop heat exchanger (GHX) length. It was shown that the ratio of GHX length reduction to solar panel area of 4.7 m/m2 results in the optimum ratio, which corresponds to 32 m GHX length reduction with a 6.81m2 solar collector area.This study demonstrates that a hybrid GSHP system, combined with solar thermal collectors, is a feasible choice for space conditioning for heating dominated houses. It was shown that the solar thermal energy storage in the ground could reduce a large amount of ground loop heat exchanger length. Combining three solar thermal collectors with a total area of 6.81m2 to the GSHP system will reduce GHX length by %15 (from 222 m to 188 m). System malfunctioning in the cooling season was also detected, and options for fixing the problem were presented. A sensitivity analysis was carried out on different cities in Canada, and results demonstrated that Vancouver, with the mildest climate compared to other cities, was the best candidate for the proposed solar hybrid GSHP system with 7.64 m/m2GHX length reduction to solar collector area ratio. Overall system economical viability was also evaluated using a 20-year life-cycle cost analysis. The analysis showed that there is a economic benefit in comparing to GSHP. The net present value of the proposed hybrid system and GSHP system were estimated to be $44,834 and $41,406, respectively.