The residential sector accounts for a third of energy use in the UK (DECC, 2014b) and generates fifteen percent of greenhouse gas emissions (DECC, 2014c). Lowenergy housing is therefore critical to meeting climate change mitigation targets (DECC, 2011). New homes are required to be carbon-neutral by 2016, presenting a considerable challenge to the housing industry (DCLG, 2006). Addressing this ambition remains shaped by the ‘techno-rational paradigm’, where energy savings rely on optimal design, technological diffusion and ‘correct’ use. In contrast, this thesis understands technologies and ‘behaviours’ as connected through social practices, which interrelate in dynamic ‘systems of practice’. Housing policy, newly built homes, and domestic practices are critical to governing low-energy housing transformations, yet initiatives consistently fail to account for inter-connections between these different practices. Whilst interventions are attempted, they frequently go awry, or operate in unexpected ways. Developing a systems of practice analysis, this thesis analyses implementation of the Code for Sustainable Homes (CSH) - a building energy performance standard introduced to drive ‘a step-change in sustainable home building practice’ (DCLG, 2006). A Norfolkbased affordable housing scheme, accredited as carbon-neutral, forms the focus of this mixed-methods case-study. The research identifies that householders incorporate energy-efficient building materials and renewable technologies in ways that frequently fail to mesh with designers’ assumptions. Housing professionals also struggle to modify ingrained ‘ways of doing’. Importantly, these actors and their practices are enabled, or constrained, by connections within and across broader practice systems. This has important governance implications. Research and policy should therefore: (i) conceptually map the housing system delimiting the network of involved actors and agents, and identifying pivotal links for target practices or interventions, (ii) generate multi-actor and multi-pronged interventions and join up distributed sources of evidence, and (iii) attend to how interventions generate reactions, interactions and resistances across the practice system.