Energy usage in buildings contributes significantly towards carbon dioxide emissions. A reduction in energy consumption by domestic premises alone would help to alleviate this problem. In the UK, while legislation has raised insulation standards, the traditional methods for home heating have remained largely unchanged. This paper describes a domestic heating system comprising a solar-assisted heat pump and thermal store in which the conventional tiled roof acts as the solar collector. The system is installed in a house near Basingstoke, UK, and has been monitored over a heating season. A validated energy flow analysis is presented, together with in-situ performance characteristics of the roof collector system and heat pump. It is shown that the test system in its present form saves 55% of the energy consumption of a gas-fired central heating system using a non-condensing boiler. Economic comparison in terms of present worth shows that a modified version of the test system would be better than electric storage heating and second only to gas central heating. A further-modified system is suggested with the potential to economically displace gas central heating as well as to provide energy savings for the consumer.