Sustainability in architecture is all about:

healthy buildings which are free from toxic emissions
airtight buildings which keep unwanted draughts out
superinsulation which keeps the building warm
breathable construction using natural materials which allows moisture to pass through the building fabric
solar shading using louvres and plants to reduce summer overheating
minimising water use by fitting low water demand appliances and taps
sourcing materials locally wherever possible
natural and renewable energy like wood for heating, and wind and sun for electricity generation
rainwater capture for use in the building (washing machines and wcs) and to irrigate gardens
reed beds to treat sewage on site
re-using buildings wherever possible to avoid waste
designing buildings so that they are easy to deconstruct using minimal energy and creating as little waste as possible

Clayhill Farm active systems and materials exploded diagram