That thing in the living room is a rainwater storage tank. Water is so central to our lives, and Paul Morgan Architects make it central to this house. "Within the living room the ceiling wraps down to an internal water tank. The tank cools the ambient air temperature of the living room during summer, supplies rain water, and structurally carries the roof load. Excess water drains to an external tank, and is used for flushing toilets, irrigating the garden, washing wetsuits [it's near the coast in Victoria, Australia] and occasionally for drinking."
"During winter the tank is drained and wrapped in an insulating jacket. The tank also plays an important role in organizing the living area into four discrete zones: kitchen, living, eating and work."
"Wind scoops on the south elevation also act as a passive thermal device. These scoops trap cooling winds during summer whilst providing shading from the hot afternoon sun." ::Paul Morgan Architects via ::Materialicious