Sustainable development, according to Bruntland, is development that provides for the needs of today without compromising the needs of future generations.
For any individual development, whether existing or new, that means taking into account the effect of that development not just on its own requirements to function satisfactorily today, but its long term consequent performance in itself and in its affect on others for ever.
Perhaps the most direct way to assess the sustainability of a development is by measuring the waste it produces. The less waste the more sustainable the development. The ideal in deed would be to produce no waste at all and with some existing developments, such as the Kalundsberg eco town in Denmark, that does not appear to be a vain aspiration.
Breaking the waste producing linear throw away life style and entering the virtuous circle of recycling, repair and reuse one time waste become new resource and the only actual loss is the labour to effect the lifestyle, which there is no reason to find unpleasurable. Self-sufficiency is after all the most basic aspiration and if it can be comfortably achieved most desirable.
The modern, high-tech way to self sufficiency, through the appliance of science is from now on the mainstream industry to which all education, trade and industry and way of life needs to be directed.