LEARN-EER, “Mutual Learning for Energy Efficient Retrofitting” is a project addressed to the training of professionals of the building sector. The main objective is the development of an active learning platform for the building, energy and retrofitting sector’s professionals, aiming to improve Energy Efficiency in the Retrofitting of buildings (EER). The operating philosophy of the platform is based on the "peer to peer" or mutual learning methodology, i.e. the target groups may act as learners and trainers, sharing specific content through the platform.The platform is addressed to professionals and final-course students (future professionals) of the building, energy and retrofitting sector. In order to properly reach target agents, the necessities these groups manifest will be identified, as well as hindered barriers regarding the peer learning approach and the knowledge shared itself.Directly, project results will encourage a more attractive training model, with ICT and web based communication, in regional and transnational level. Users will be able to complement their training in first person and mature professionally towards 2 main skills: EER experts + EER trainers. Thus, being able to correctly assimilate contents and effectively communicate knowledge shared is the personal objective of the target group. After the downturn of the construction sector in many countries, especially in Spain, a large group of professionals of the sector have lost their jobs or at risk of losing it. Preparing them for an emergent sector, like retrofitting, which shows an increase on overall in Europe, and combined with the increased need and demand for energy efficient solutions, will allow them to be better catered for labour market demands, and reduce the risk of unemployment, and increase their employability.For the building, energy and retrofitting sector, this peer-learning methodology will result on a dynamic professional qualification model that will provide good practices and improve organizations know-how & philosophy towards the EU objectives.Regarding the building, energy and retrofitting market, the impact generated by improving the sector’s competitiveness and professional’s training quality, will conduct to overcome employment barriers, market needs and create a business society. New skills gained by target agents and a more confident market will return professionals motivation for a sector punished by economical crisis and weak energy performance standards.