The world's first city hotel with a zero-energy balance

Boutiquehotel Stadthalle in Vienna is the world’s first city hotel with a zero-energy balance. Sun-facing walls are covered with solar panels and interior walls covered with green ivy. In addition, they water their plants and flush their toilets with their own well water.

https://www.hotelstadthalle.at/en/sustainability/zero-energy-balanc…