The California Academy of Sciences can probably be viewed as the coup de grace of sustainable buildings with regards to water conservation.
Located in San Francisco, California, this natural history museum, amongst the largest of its type on the planet, covers 400,000 square feet, all topped by an undulating, green roof. As with project number three, the roof is key to the performance of this facility economy-wise.
Indeed, the roof prevents an estimated 3.6 million gallons of runoff from carrying pollutants into the ecosystem annually (roughly 98% of all storm water), whilst also significantly reducing potable water use. This is done via the use of reclaimed city water to flush toilets, the installation of low-flow fixtures, and the recycling of sea water to and from the Pacific Ocean for the aquarium systems.