Techno-economic feasibility of retrofitting solar combisystems to houses in the Canadian housing stock (CHS) is investigated using the Canadian Hybrid Residential End-Use Energy and Emissions Model (CHREM). Solar combisystem architecture and sizing is based on the systems and guidelines provided by the International Energy Agency (IEA) Solar Heating and Cooling (SHC) Programme Task 26. Houses with sufficient roof area facing south, south-east or south-west, and a basement or mechanical room to contain solar combisystem components, including the thermal storage tank, auxiliary boiler and pumps, are considered eligible to receive the retrofit. A hydronic heat delivery system is used to supply heat to the thermal zones. Solar collector area is sized to match the nominal capacity of the existing heating system in each house. Reductions in energy consumption and greenhouse gas (GHG) emissions are evaluated. Results show that close to 40% of houses in the CHS are eligible for solar combisystem retrofit, and if all eligible houses are retrofitted, the annual energy consumption and GHG emissions of the CHS would be reduced by about 19%. The tolerable capital cost varies significantly amongst provinces, and governmental subsidies or incentive programs may be required to promote solar combisystems in some provinces. (C) 2015 Elsevier Ltd. All rights reserved.