Editorial

The existing housing stock has a major energy saving potential and is mostly considered to be the sector in which energy efficiency most cost effectively can be achieved. About 30% of all energy use is consumed in the housing stock. The European union formulates saving targets, policies and regulations that have to be implemented by the member states and a considerable share of the EU budget for research and innovation is dedicated to this challenge. In recent years many policies, investment programmes, technical innovations and process innovations have been developed and been put into practice. However, it appears to be very difficult to realise massive renovation programmes in the existing housing stock and really make a step forward towards the energy efficiency goals. This special issue presents an overview of actual insights of the perspectives of energy efficiency in the housing stock based on several research projects and analyses and discussions about how the current policies will work out and which are the barriers that still have to be taken. We focus on the policies, the processes and the people.