Berlin is full of so called “Brandmauern”, walls that have no windows because originally they had another house close to them. The war bombed them away, or the communists or Adenauer did, who knows. Fact is, it’s not going to change fast (of course in expensive neighborhoods, new houses are built) but in other sites, people will have to live with their ugly and overall badly isolated brandmauer (I believe in english it’s fire division wall).
So here’s the idea: Why not paint them with special materials or even grow plants on them to make everything cosier and prettier and less expensive? Brandmauer.de are a bunch of architects and artists that want to make Berlin a little less grey (and of course, run a fun business). Check it out on Brandmauer.de, especially if you want to have yours painted!