The aim of this project is to determine how heat pumps, as technical objects, impact energy consumption in Norwegian homes. Much of the previous research on energy consumption has focused on what motivates users to reduce their energy use, for example better billing information or knowledge of the environmental benefits. This study approaches the question of domestic energy consumption by bringing the technology that actually uses the energy to the foreground. The study uses actor-network theory in conjunction with practice theory to examine the role of heat pumps in the network of household energy-using practices, with a particular focus on home-heating. The aim is to shed light on how these practices might be shaped by heat pump technology, and vice-versa. The study utilises key concepts from ANT, namely the concepts of technological scripts and agency, to conceptualise heat pump technology. This conceptualisation is then employed in an examination of the role of heat pumps in the network of household activities, which is approached from a practice theory perspective. Members from 15 households in the Oslo/Akershus area were interviewed about the use of their heat pump and the other methods used for heating their home. The research questions guiding these interviews were: How do heat pumps, as technical objects, influence the way people use them? Are heat pumps used in the ways intended by their design? And how do homes with heat pumps use other forms of heating? The interaction between the user and the heat pump is discussed with a focus on how the nature of this interaction affects energy consumption. The study also incorporates an examination of the wider context of this energy use, namely the heating related practices taking place in the households studied.