The refurbishment of existing building stock demands solutions within single units. Interior insulation is a suitable technology. The challenge is to bring multiple demands (energy consumption, comfort, hygiene, ecology, sustainability, architecture, ...) and requirements (technical aspects, law, monument conservation, building physics, ...) together to create optimal solutions. Therefore it’s necessary to arrange individual system components (heating, ventilation, interior insulation,..) to form working exemplary refurbishment solutions. The development of such solutions is the aim of the project. Not only durability and quality is to be ensured but also user acceptance. As a result market penetration and energy efficiency in the existing building stock continues to rise. Increasing the rate of refurbishments is the overall aim of the project.