In February 2018 Wikispaces.com announced that it would be shutting down. The scheduled closure of services is: "Classroom and Free Wikis end of service: 31st July 2018; Plus and Super Wikis end of service: 30th September 2018; Private Label Wikis end of service: 31st January 2019" Appropedia could serve as a new home for the content currently hosted on sustainability-related wikis on Wikispaces. Below is a list of relevant wikis.
Admins can export their wikis' data by following these instructions.