Today, approximately 80% of people in Europe live in buildings that are thirty years old or more. Around 50% of people live in houses that are fifty years old and more. The possible obsolescence of this housing stock is a critical issue – both across the continent of Europe and beyond. The reasons for this obsolescence are various: changing lifestyles leave old models of houses outdated; changed demographics mean more single occupiers and an increasingly aged population; in many instances the quality of construction and environmental standards have been superseded by a concern for fuel efficiency and reductions in carbon emissions. In other cases, the communities that once lived closely in old estates and neighbourhoods have crumbled – leaving people in isolation and lacking services.