Residential energy use accounts for approximately 28% of total primary energy use in the UK: with consumption in this sector forecast to increase due partly to expanding numbers of households. Finding ways to reduce residential energy consumption must form a key part of the climate change strategies of the UK and all developed countries. In 1995, an innovative piece of legislation was passed in the UK, devolving residential energy efficiency responsibility to local government. Under 'The Home Energy Conservation Act' (HECA), local authorities are obliged to consider the energy efficiency of private as well as public housing stock. Authorities were given a duty to produce a strategy for improving residential energy efficiency in their area by 30% in the next 10-15 years. This paper describes the enormous variation in the quality of local authorities' strategies and discusses reasons for this variation. Based on a nationwide survey of HECA lead officers, it considers the opportunities and constraints facing local authorities, and what has been achieved to-date under the Act. It also examines how HECA fits into the UK's national energy policy and explains the roles of other institutions across the public, private and voluntary sector in facilitating implementation of the Act. Finally, the paper considers how other countries can learn from the UK's HECA experience and can use the Act as a template to apply the principle of subsidiarity to this area of environmental policy.