Sustainability and knock down rebuild go hand in hand due to the new sustainability standard in the new home.  Water is a key area of saving with the Wels ratings system controlling water flow and ultimately saving water. The Average Australian homes uses 200,000 litres a year and with the new Wels system new homes use 110,000 litres which is approximately a 45% reduction in usage.  Larger savings can be made with the use of a plumbed to service water tank system.  With the addition to the new home build of the latest solar gas boosted hot water units solar energy can be harnessed.