The building sector has a significant impact on the European economy and the environment. It represents about 9% of the EU’s gross domestic product (GDP) and provides 18 million direct jobs.

Restoring historic buildings and saving energy at the same time is now a reality. Passive house window expert Franz Freundorfer developed the heat-saver for the Waaghaus in Bolzano, a building from the 13th century .

A well-accepted measure for climate protection involves reducing greenhouse gas emissions . And buildings have the greatest energy saving potential, according to the official EU Energy Efficiency Plan 2011 .

Historical buildings and town quarters are an integral part of the European cultural heritage. However, such buildings are often not very energy efficient and thus contribute substantially to the emission of greenhouse gases.