Hundertwasser's comment on the work

As the street is largely ruled out for planting trees due to the traffic and subterranean conduits, roof greenery mostly takes on a penthouse nature and remains invisible to the man on the street and is often unfeasible for constructional reasons, the vertical building façades are an alternative for establishing a forest in the city.
Here are just some of the advantages:
1. Tree tenants, trees growing out of the windows, are visible from afar and benefit many people.
2. Tree tenants produce oxygen.
3. Tree tenants improve the urban and residential climate considerably by mitigating the humid-dry and warm-cold contrasts. Fewer headaches - more well-being.
4. Tree tenants are a perfect dust-absorbing and dust-filtering system. In particular, the fine, toxic dust which even vacuum cleaners cannot suck up is largely neutralised and removed in the area of tree tenants. The housewife will have less dust in her apartment.
5. Street noise is significantly reduced, as the echo effect of the vertical canyons of buildings is muffled.
6. Tree tenants form a partial screen and produce a sense of security.
7. Since the tree tenants must make do with a few cubic metres of earth, they cannot develop into big trees. Their capacity for furnishing shade will thus remain very limited. So sun and light easily reach the windows the tree tenants are growing out of, too, particularly in the winter, when the leaves have fallen.
8. No trouble from spiders and ants, as they do not live in trees. But hopefully butterflies and birds will come.
9. In this way beauty and a living source of joy will be restored in a co-existence with a piece of nature in one's own house.
(excerpt from: To the Occupants of a Building on Alserbachstrasse in Vienna, 1980, translation from: Hundertwasser Architecture, Cologne, 1997, p. 82)