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                    Water conservation

                    Close-up of CH2's shower towers
                    The water conservation design strategy for CH2 has established a water consumption total of less than 31 litres per day per person.

                    ​Water management measures implemented by CH2 fall into four categories:

                    • water efficiency
                    • water recycling by sewer mining
                    • water reuse – rainwater harvesting and fire sprinkler test water
                    • innovative water saving techniques.

                    CH2 has the following features:

                    • 'AAAA' fittings and fixtures throughout the building
                    • taps and showerheads of low water flow rate – approximately 2.5 litres per minute and nine litres per minute
                    • water flow to all hand basin taps controlled by electronic sensors
                    • four litre / three litre dual flush toilets and two litre flush urinals.

                    Water conservation measures

                    Water recycling and sewer mining

                    Central to the water reuse strategy in CH2 is the Blackwater Treatment Plant.

                    As well as treating both the blackwater (toilet) and greywater (showers and basins) waste produced by the building, the system is also treating sewerage ‘mined’ from the sewer in Little Collins Street, next to CH2.

                    Sewerage is usually made up of 95 per cent water. The system in CH2 is demonstrating that sewers can be a source of useable water.

                    Reuse of fire sprinkler test water

                    In CH2, the fire sprinkler test water is collected and reused for showers and taps. It has been calculated that, over one year, this will save approximately 9000 litres of water per week.

                    Most of this water is saved from the fire pump testing. The fire pumps are connected directly to mains water, so the discharge during testing is collected and placed into the potable water tank in the basement.

                    The water in the reticulated sprinkler pipes is considered to be potentially contaminated and this is collected and put through the Blackwater Treatment Plant.

                    Rainwater harvesting

                    The building has been designed for the total roof area to be used in capturing rainwater. The rainwater collected is used with the recycled water from the Blackwater Treatment Plant for toilet and urinal flushing, landscape watering, cooling towers and for off-site uses such as fountain top-up and street tree irrigation.

                    Vertical gardens watering system

                    A challenge for CH2 is to provide vegetation equivalent to that if the site was still in its natural state. This is achieved with both horizontal and vertical plantings: the roof landscape and the northern green facade of the building.

                    There are internal plantings in the office areas and on the summer and winter terraces at the west end. Recycled water is used to water the external plantings.

                    The challenge for CH2 was to get the water to the plants efficiently; the solution being a self-watering system in the recycled plastic planter boxes. This water-sufficiency based system provides the ideal wet-and-dry cycle required for healthy plants.

                    The system comprises a watering device and a soil additive. Each planter box is filled with Fytogen Flakes, a soil additive that looks like polystyrene flakes but acts like water crystals, storing water until the soil needs it. The planter box is also connected to a system functioning in a similar way to a toilet cistern, which is triggered to refill with water when the crystals dry out.

                    Shower towers and cooling towers

                    The shower and cooling tower systems use water as the cooling media, allowing for an energy-efficient cooling system. Recycled water is used in the cooling towers, while the shower towers use mains water.

                    This is a good example of how to improve the energy efficiency of a building while reducing greenhouse gas emissions.

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