DOI: 10.7764/RDLC.17.2.250The Balearic Islands’ Housing Institute (Instituto Balear de la Vivienda-IBAVI), in collaboration with the Directorate General of Nature, Environmental Education, and Climate Change of the government of the Balearic Islands, has received a European grant worth €754,012 from the LIFE+2012 program to carry out the building and monitoring of 14 public housing units in Sant Ferran, Formentera. The main objective of the project is to contribute to the development of technologies, methods, and innovative instruments in the field of nature conservation, climate change, environmental policy, the production of information, and communication on environmental issues in all EU member states. This paper, a collaborative effort between the University of the Balearic Islands and the IBAVI, presents the results obtained for the determination of the bulk density of a layer of Posidonia oceanica used as an insulating material, and which complied with the limitations of thermal conductivity for a thermal insulation solution in a flat roof.