Environmental sustainability has become a mainstream issue, with profound effect on the architectural profession. Many developers, those who support the financing of buildings, have become educated to encourage the facilitation of environmentally sustainable design, rather than solutions based primarily on immediate cost. Major examples of this can be found in Passive solar building design, greener roof designs, biodegradable materials, and more attention to a structure's energy usage. This major shift in architecture has also changed architecture schools to focus more on the environment. Sustainability in architecture was pioneered by Frank Lloyd Wright, in the 1960s by Buckminster Fuller and in the 1970s by architects such as Ian McHarg and Sim Van der Ryn in the US and Brenda and Robert Vale in the UK and New Zealand. There has been an acceleration in the number of buildings which seek to meet green building sustainable design principles. Sustainable practices that were at the core of vernacular architecture increasingly provide inspiration for environmentally and socially sustainable contemporary techniques. The U.S. Green Building Council's LEED (Leadership in Energy and Environmental Design) rating system has been instrumental in this.

Answer this question, if possible (if impossible, reply "unanswerable"): What organization's rating system discourages sustainability?
unanswerable