The design of energy and climate policy is usually seen as an ‘expert’ domain, relying on technical tools such as economic analysis. However, policy requires the support of politicians and citizens alike, through the democratic process. Many policies, such as reducing carbon emissions from homes and transport, also affect people’s lives directly. It is thus necessary to supplement technical analysis with methods that allow an exploration of people’s views, values and behaviours. One such method is codesign, whereby groups of citizens work with policy analysts to develop strategies informed by the lived experience of citizens, as well as the specialist knowledge of analysts. There is a history of co-design approaches in public services such as healthcare, but there have been few attempts to co-design public policy measures. This paper reports on a Citizens’ Panel, a representative group of people working with specialists to create co-designed policy recommendations for reducing carbon emissions from homes. The process revealed that policy co-design can provide detailed, viable proposals. In this case, panellists emphasised the necessity of leadership and support from government; tailored, consistent information; targeted regulation; and financial incentives. Finally, the wider potential role for policy co-design for energy and climate is addressed.