I want to know the answer to the following question:
What novel concept was introduced at the end of the 20th century?
All the background I'm provided with is that "To satisfy the contemporary ethos a building should be constructed in a manner which is environmentally friendly in terms of the production of its materials, its impact upon the natural and built environment of its surrounding area and the demands that it makes upon non-sustainable power sources for heating, cooling, water and waste management and lighting.". Is that enough to answer the question?
Answer: no