Traditional building materials such as concrete, firebrick and petrochemical insulation produce a lot of greenhouse gas emissions. The team behind LIFE REUSING POSIDONIA took a natural approach to construction. They used dried Posidonia oceanica seagrass as an effective and inexpensive thermal insulation in 14 social housing units for poor and disadvantaged people on the Balearic island of Formentera. This local, traditional and environmentally friendly construction method reduced emissions by 60%, cut energy use by 75%, and water by another 60%. The approach can be used in other coastal areas that are home to the seagrass. 41 local jobs were created to carry out the work.