What makes a building a green building? Green buildings are designed with sustainability goals and fulfill specific criteria in their construction, maintenance, and life cycle — designated by certifications such as LEED® (Leadership in Energy and Environmental Design) from the U.S. Green Building Council or the DGNB System (Deutsches Gesellschaft für Nachhaltiges Bauen) from the German Sustainable Building Council. For those looking for entry points and a general understanding of how a building is actually a sustainable building though, it helps to consider models and look at details.  “The most sustainable building in the world” Earning a platinum certificate with the highest DGNB certification score achieved thus far, the building known as the Eisbärhaus (Polar Bear House) in Baden-Württemberg, Germany proffers many mindful details. These include: building material choices, such as using recycled concrete in the reinforced concrete-wood hybrid structure; energy efficiency solutions, such as a battery storage system for storing the electricity generated by a photovoltaic system — to use when needed; and a software system, which controls various features in response to current local weather conditions — and …