The Irish demo case is to provide proven case studies and recommendations to guarantee that the building sector adopts a circular, decarbonised retrofit strategy and to lead policy changes. Built in 1911 and expanded to the back in the 1940s and 1960s, the building complex (see picture) is a protected campus owned by Limerick Clare Education and Training Board (LCETB). Over a thousand students get vocational training in the complex's many interconnected buildings, which take up the vast majority of the property. The demo site will test bio-based materials, using Mycelium and breathable adhesives to sequester carbon, as well as green roof testing with different waste products and green vegetation. Balancing cost, mechanical properties, and sustainability will be crucial in ensuring the success of the decarbonised retrofit. Bio-based fully recyclable composites and products in the form of Sandwich Insulation Panels developed by TUS will speed up the retrofit modular processes in a circular and cost-effective way for scalability for the construction industry. TUS with the support of FAB will establish practical retrofitting and circular guidelines for the construction industry and building owners to support the DeCO2 uptake of circularity exchange and use of materials. The Retrofit Guidelines will include approaches to audit the condition and performance of the buildings, decarbonisation approaches and address considerations such as implementing bio-based materials and carbon sequestration methods as well as strategically integrating renewable services (ventilation, heat pump and PV) to ensure healthy buildings, circularity and ease of dismantling in the future. The actions implemented will be recorded in a digital twin to establish a building passport for the future maintenance and operations and training purposes for the campus, will be done by CEMOSA.