How big is the carbon footprint of a building? How much grey energy is hidden in its four walls? If you want meaningful and honest answers, you need the right tools. The life cycle assessment (LCA) offers effective and tried-and-tested ways to ascertain the impact different construction techniques, energy concepts, building parts and materials have on the environment at every stage of the life cycle. The DGNB System was the first certification system in the world, that has taken the long-term environmental impacts of buildings into account.