Is the organisation of ministerial portfolios associated with governments’ policy priorities? Specifically, do policies targeting energy efficiency in residential buildings vary depending on where the portfolios of Energy and Environment sit? Poorly insulated houses contribute significantly to countries’ CO2 footprint and lead to higher levels of energy poverty. Effective solutions remain evasive, at least in part because governments’ policy strategies are often uncoordinated. However, governments cannot formulate coordinated strategies unless they facilitate such coordination through the organisation and design of ministerial portfolios. Political agendas and preferences alone cannot fully explain policy choices; the organisational design is also critical (Hall 1996). This ‘political/policy game’ should have direct effects in policy continuity and effectiveness. Yet, it is under-studied and poorly understood. Using unique new data on the structure of ministerial portfolios in 15 European countries over thirty years, we test the hypothesis that when the departments of Energy and the Environment are major portfolios and have been in place for longer period of time (spanning government changes), they will be associated with a higher number of policy initiatives aiming at higher levels of energy efficiency. In contrast, when the department of Energy is a minor portfolio under Business or Economics, policies for improving energy efficiency are likely to be fewer and less ambitious.