A young growing family with toddlers and primary school age children commissioned Threadgold Architecture to design an energy efficient eco home on their 120 acre Yallingup property that embodied their ideals to live sustainably and off-grid.  The brief demanded the home be power self-sufficient and incorporate passive solar design principles to reduce energy consumption.   This south west architecture opitimizes sustainable design principles by being sited at elevation to take advantage of views, cooling breezes and is surrounded by citrus, nut and pomme fruit orchards set out to permaculture principles.  It achieves passive solar design through a large area of north facing glazing.  During the warmer south west days, the owners open the Breezeway glass louvres to the underside of roof eaves on the northern elevation to generate cross ventilation and cool the kitchen and living areas.  Throughout the colder days of a south west winter, the family closes the operable windows and louvres to enjoy direct sunlight across 85% of the living floor space.  The honed concrete floor to living areas captures the radiant heat from the direct sunlight during the daylight hours and releases the heat through cooler south-west evenings.  The specification for the house incorporates materials that have a low embodied energy with rammed limestone to the south elevation for heat retention and Corten cladding the west elevation.  The house boasts complete power self-sufficiency with a 5.5kw photovoltaic system discretely hidden from view behind the single lock standing seam anthra zinc clad parapet.  The house's sustainable design credentials are further endorsed through rainwater harvesting and a potable water storage capacity of 550 kilolitres.  The house's green building benefits are also enhanced through incorporating a 440 litre Solarhart solar hot water system boosted by a Chazelle wood fire box with Arte Domus tiles and Astra Walker tapware are specified throughout the wet areas.  The fitout has reduced the embodied energy of the build by utilising locally sourced recycled jarrah and sheoak hard wood species with a high natural resistance to white ants.  The landscaping surrounding the house to predominantly comprise of edible plant species such as dwarf coffee trees, feijoa, papaya, pineapple and tamarillo trees also laid out to permaculture principles.