Researchers at Ontario Tech University are collaborating with McClymont and Rak geotechnical engineers to develop a new sustainable thermal storage technology that addresses the main challenges that have prevented geothermal heating and cooling systems from being adopted in a meaningful way in Ontario. An innovative storage medium, based on a construction slurry, will be developed and used in the underground thermal storage, and coupled to a geothermal heat pump to provide high-efficiency and clean building heating and cooling. This new, inexpensive technology will be able to be effectively integrated with solar heating, making it more cost competitive with natural gas, and leading to increased adoption and considerable CO2 emissions reduction in the building sector.