In architecture, there are two kinds of sustainability: one simpler, smaller, and ethical in its relationship with the environment and with people; and another which is “fashionable”, used as a label in a speculative way, without an understanding of what it really means.

Cities, with their concentration of services, economic opportunity, mobility and social interaction, have proved endlessly attractive to humans.

Buildings stand at the epicentre of the climate change and sustainability debate, as discussions at the recent COP26 conference demonstrated.

In the world of invention, innovation and design, very little goes to waste. And in today’s ideas-hungry world, the achievements of decades past are all ripe for reimagination.

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.

The building sector has become much greener. To get such credentials it has adopted methods borrowed from other industries, such as life cycle analysis ( LCA ), which looks at the environmental impact of a building at every stage from its creation to its decommissioning.

Our future depends on energy, and as households and cars currently contribute to more than 50% of all energy consumption in the EU, new energy-efficient architecture can be an important approach to bring this percentage down.