This document discusses how practice theory can inform governance and policymaking for a post-carbon world. It argues that policies across government shape energy demand through their influence on practices like working, digitalization, housing, and more. Interview data highlights challenges to coordinating policies between departments and overcoming legacy policies. The authors argue for reflexive governance where all policies address energy use and a post-carbon transition, rather than isolated efficiency efforts. Coordinating policies to transform conventions of need could better achieve emissions reductions. However, interviews revealed barriers like departments prioritizing their own objectives and resistance to change from policies perceived to benefit citizens.