"Green building" or "sustainable design" is now part of the standard of care that a landscape architect must deliver to the landscape architect's client. One reason for this: "Green building"/"sustainable design" is now encoded in the AIA typical contract between architect and the architect's client. This contract also typically governs most landscape architecture practiced in the USA because most landscape architectural design services are provided to the ultimate client via the architect - architects are usually the lead on projects.
Actually the phrase used in the contract is "environmentally responsible design" and it is repeated twice, including "environmentally responsible design approaches", "environmentally responsible design alternatives", and emphasizing "material choices and building orientation".
A landscape architect's aesthetic sensibility and approach is not something that the profession seeks to control. However as a regulated profession landscape architects are responsible to ensure safety, security, and human welfare. Lack of reasonable care (failure to perform) may result for example in personal injury or economic loss for which the non-performing landscape architect may be liable. This is worded differently in different sources, but this is the general idea.
