Accessible, sustainable, and made in America. These three principles
create a building and landscape that mediates a sloping site, shields
itself from winter winds, and opens toward vistas of the surrounding
countryside. The tripartite goals are also reflected in three increasingly
visible masses: a green-roofed bedroom wing inset into the hillside; a
gable-roofed living area facing the street; and a sky lit tower commanding
views of the stream valley below.

http://www.dwell.com/houses-we-love/article/impressively-accessible-home-has-tower-can-be-reached-wheelchair#4