CH2 reuses water, using less in the process. Find out more about:
Strategy for water efficiency
Water recycling and sewer mining
Re-use of fire sprinkler test water
Rainwater harvesting
Vertical garden watering systems
Shower towers and cooling towers
Strategy for water efficiency
The overall water conservation design strategy for CH2, including water saving impacts of the cooling and ventilation systems, has established a total water consumption design performance target of just under 31 litres per day per person. Water management measures implemented by CH2 fall primarily 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 of approximately 2.5 litres per minute and nine litres per minute respectively
- water flow to all hand basin taps is controlled by electronic sensors
- 4L/3L dual flush toilets and 2 litre flush urinals.
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Water recycling and sewer mining
Central to the water reuse strategy in CH2 is the Blackwater Treatment Plant located in Basement 3. 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, adjacent to CH2. Sewerage is usually made up of 95 per cent water and the system in CH2 is demonstrating that sewers can be a source of useable water.
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Re-use of fire sprinkler test water
The fire sprinkler system in the vast majority of buildings is connected to mains water and during the regular testing process the water is normally discharged to the sewer. In CH2, the fire sprinkler test water is collected and re-used, mostly in conjunction with mains water for showers and taps. It has been calculated that over one year this will save about 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.
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Rainwater harvesting
The building has been designed for the total roof area to be used for capturing rainwater. The rainwater collected is used in conjunction 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. A storage tank with a capacity for one week’s capture at 15 kilolitres is located in the basement.
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Vertical gardens watering system
Another concept in 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 façade of the building. In addition, 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, and the solution is 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.
This 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.
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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. These two features are a good example of the efficient use of a value added product, recycled water, to improve the energy efficiency of a building while reducing greenhouse gas emissions. This is a significant factor considering drought conditions and Melbourne’s current permanent water restrictions, where the use of a limited resource may not outweigh savings in energy use and greenhouse gas emissions.
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