Sustainable buildings are those that have a balance between building and the sustainable environment.  They are designed and may be built using natural materials that are available locally.  They are built to reduce the overall impact of the built environment on human health and the natural environment by efficient use of energy, water, and other resources, and to reduce waste and pollution.

Is it really sustainable?  I believe that it contribute to the sustainability of the environment, but the building itself will need maintenance, again using locally available materials, and so it has an advantage in terms of cost in its maintenance.

Sustainable buildings seek to optimize the use of natural resources to minimize environmental impact. But keep in mind that the zero impact of human activities there. A building capable of self-sufficient in electricity by using solar panels is reducing the environmental impact caused by electricity production in nuclear, thermal or hydroelectric plants, so it is a sustainable building.