New energy retrofit concept: 'Renovation trains' for mass housing

A large operation is required to make Europe's existing housing stock more energy efficient, in terms of both demand reduction as well as the installation of local renewable energy technologies. The combination of overall (national) energy targets and the European Union's Energy Performance of Buildings Directive (EPBD) targets suggests the scale of this task involves the retrofitting of millions of houses. An example of a large-scale, rapid process is presented where a series of houses have been retrofitted using a standardized process. A pilot project exploring this strategy has been completed in Kerkrade, the Netherlands. Several innovations were introduced, tested and refined for the renovation of 150 houses: a serial retrofit process, a renovation time of ten days per house with the houses inhabited during the process, and responsibility for energy performance assigned to the construction team. The construction process is a renovation train moving from one house to the next. The experiences are now being used and developed for a follow-up project: a new concept can be used to scale up the process from 100 to 10 000 renovations a year.