High Performing Buildings - Spring 2009 - (Page 46) treatment and recirculation system. Greywater from hand basins and showers is piped to the basement, where it is treated and stored for flushing toilets. Rainwater also is harvested and stored in the tanks for the same purpose. Ideally, the water storage tanks would have been located on the roof to gravity-feed the building’s requirements. However, it was found that the roof could not structurally support the tank — a limitation of working with an existing building. On the upside, housing the water storage tanks in the basement allowed for some of the building’s existing piping infrastructure to be reused. Bathrooms feature waterless urinals and sensor-operated hand basins, which supply water that has been premixed to 86°F. A solar heat- The roof was refurbished to house a range of features that enable the building to run efficiently. These features include a weather station, a gas-fired air-conditioning system, evacuated tube solar hot water and PV arrays. Also on the roof is an entertainment area with a deck and a barbecue grill, which is shaded by an amorphous PV array. The rear of the building features a large deck on level one, which sits above the car park. Large windows on each level allow natural light to enter the building. Since this photo was taken, a crystalline array has been installed to generate power and provide shading from the afternoon sun for staff working at the rear of level four. 46 HigH Performing ing system provides the domestic hot water (DHW). Water efficient taps, toilets and showerheads are used throughout the building. Blackwater harvesting was considered during the design phase, but was rejected on the basis that not enough space was available in the building for such a system, and also that it would lead to substantial recurring maintenance and licensing costs (operation of such systems in Melbourne requires a license from the local Environment Protection Authority). Pumping, filtration and monitoring equipment would also have added to the building’s energy consumption. Factors beyond the owner’s control have meant that water-saving initiatives haven’t been quite as effective as expected. Australia’s ongoing drought has meant that potable water is needed spring 2009 for toilet flushing. It was hoped that this function would be performed entirely by harvested greywater and rainwater. The amount of rainwater collected by the building has continued to fall, however, and in its second year of operation rainwater collection fell by 1,320 gallons. As a result 6,380 gallons of municipal water had to be used to supplement toilet flushing — 42.65% of the total amount used for this function. Some issues also were identified with the building’s greywater system, which were causing it to use more potable water than required. It was replaced in September 2007 with a new system which prescreens the water to remove coarse materials, removes contaminants and then applies an ultraviolet disinfection process to the water. The system is fully automated and has low maintenance requirements. Buildings
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