Ecolonia is a town expansion near Alphen aan de Rijn built in 1994 as a sustainable neighbourhood. It widely uses biological materials with a focus on the ease of recycling, and avoiding concrete wherever possible. Where concrete was used, it was made with recycled materials such as rubble. This approach makes it easier to replace and dispose of parts in the Ecolonia buildings. The complex also used further techniques to make the area more regenerative, such as nature-based water management systems and a focus on isolation and energy efficiency.