Friedensreich Regentag Dunkelbunt Hundertwasser (December 15, 1928 – February 19, 2000) was an Austrian painter and architect. Born Friedrich Stowasser in Vienna, he became one of the best-known contemporary Austrian artists, although controversial, by the end of the 20th century. The heating plant in Spittelau Vienna is known to be very efficient and enviromentally friendly.