Patterns of home heating demand during the day have significant implications for the design of energy networks and will be an important consideration in the introduction of low carbon heating systems such as heat pumps. In homes in the UK it is very common to operate space heating intermittently; the heating is usually switched off when the occupants are asleep at night and when they are out during the day. The strong association between heating operation and household routines leads to a morning peak in demand which, if it persists following electrification of heating, will require significant reinforcement of electricity supply networks. This paper examines factors that underlie current UK home heating practices. A unique dataset of heating controller settings from 337 UK homes with smart heating controllers allows investigation of how patterns of heating operation in individual homes contribute to daily patterns of space heating energy consumption at the group level. A mixed method approach is followed, combining quantitative analysis of data with interviews with householders, drawing on insights from social practice theory. The peak level of space heating demand is found to be higher in the morning than the evening. The concept of thermal routines is introduced, bringing a time dimension to the consideration of domestic thermal comfort and recognising that demand for space heating is linked to patterns of practices in the home, which are themselves linked to social routines, e.g. timing of work and school. The results from this study suggest that household thermal routines around 07:00 in the morning are a particularly important consideration for a transition to future energy systems with a high proportion of low carbon heat. Factors that currently limit flexibility of heating demand in the UK are identified and the implications for a transition to low carbon heating sources are discussed
