Council House 2
Melbourne’s Great Experiment: Technological ambition and daring-do provide a wealth of lessons for aspiring green designers
Melbourne’s Council House 2 is as much a political act as it is architecture. You don’t build what is widely considered Australia’s most sustainable building, routinely lavished with international awards and praise, and not expect at least some criticism, some hand-wringing, and perhaps some latent jealousy from designers, builders, and developers not involved in the project.
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“CH2 was designed as a lighthouse project for the future,” says Rob Adams, using the building’s nickname. Adams is Melbourne’s director of city design and urban environment and was the project’s earliest champion. After an original scheme to reuse the existing Council House 1 building (CH1) fell flat, Adams convened the design team for a non-stop, three-week charrette in 2003 to workshop the new building, which replaced a parking lot next to CH1. By the end of that intensive session they agreed to the design that was built and opened in 2006. “This whole sustainability thing can become a battle between art and science, as opposed to simple things like opening the windows,” he says.
The project’s architect, Mick Pearce, is not as diplomatic as Adams about the public reaction to the multiplicity of radical technologies deployed in the building. “A lot of what we did was clever engineering, and the architects hate it,” says Pearce, who designed the project in close collaboration with Adams’ staff at the city, engineers at Lincolne Scott’s Sydney office, and his own colleagues in DesignInc’s Melbourne office. “Architects in Melbourne think of architecture as a formal game, and I don’t go along with that.”
Instead, Pearce has developed an architectural application based on biomimicry, which is best known in the U.S. through the work of Janine Benyus including her book, Biomimicry: Innovation Inspired by Nature (1997). Biomimicry applies the rules and process of nature to design, not in a literal transcription, but in performative terms. Pearce hails from Zimbabwe, where he employed biomimicry on the design of the Eastgate office building in Harare in 1996. At Eastgate, Pearce mimicked the performance of an African termite mound by installing rock piles in the basement as thermal storage. Such a strategy couldn’t work at CH2, he says, because of space constraints on the tight central business district site.
For CH2, Pearce focused on how the 10-story office building mediates between the environment and the occupants. This is expressed most directly by each facade: The east is enclosed by a service core, the west opens and closes behind operable recycled timber shutters, and the north and south include operable windows and balconies down one side. Daylighting is minimized, in part due to the 70-foot-wide floor plate, but also to limit solar-heat gain. Work stations occupy central zones, leaving daylit areas as meetings and break-out spaces. Conditioned outside air is delivered through an underfloor displacement ventilation system, with controllable “twist” diffusers, supplemented by chilled panels integrated into pre-cast concrete ceiling modules that also hide lighting and cabling. One of the most effective features is never seen. Similar to the principles behind the rocks at Eastgate, the windows of CH2 automatically open to allow night air to cool exposed concrete surfaces. This stored energy dissipates through the morning hours. Adams, who works in the building, says the air-conditioning system rarely kicks in before late morning. He estimates this contributes to a 20 percent reduction in cooling demand. “Imagine if every building in Melbourne did that,” Adams says, happy to encourage others.
These occupied floors—or what Pearce calls a “better zoo”—have now been independently tested, the results of which were published in March 2008 in a post-occupancy report available on the city’s website (www.melbourne.vic.gov.au). Although occupants were somewhat dissatisfied with lighting levels and the acoustics of the open office, they rated thermal comfort and air quality high. The designers addressed the lighting by adding some indirect fixtures to wash the ceiling; the acoustics issue had more to do with the staff’s transition from cellular to open offices and the associated behavioral changes. More important to the city, however, the survey reported a 10-percent productivity improvement in comparison to CH1 and, Adams reports that absenteeism dropped from an average of 3.6 days to 1.5 per year. “This is equivalent to AU$2.4 million [US$1.7 million] per year,” he says of both statistics. “If you apply that to the AU$11 million [US$7.7 million] we spent on green technologies, the payback period is five years, and that’s as good as it gets.”
That cost premium for green technologies was the subject of some speculation in the Australian design community soon after the building opened. This especially related to the failure of the colorful rooftop wind turbines, which the design team admits were over-engineered due to safety concerns and are too heavy to spin under common wind conditions. Other scrutiny concerned the early problems with the black-water treatment plant in CH2’s basement. In reality, the plant worked fine, only the ceramic filters that would never have needed replacing did not work; order was restored once they were instead fitted with conventional fibrous filters. “We had an agreement with the subcontractor, so we weren’t out any money,” says Adams. The black-water plant relies on sewer mining—in simple terms, it removes raw sewage from the city’s pipes, treats it on-site, and reuses the clean water for non-potable needs like cooling towers and toilet flushing. Building-scale black-water plants remain a relatively experimental technology in Australia, since many city councils can be skeptical of water quality, not to mention the systems’ high energy use and capital cost. Pearce, for one, thinks the technology only makes sense when it’s sized to feed several buildings, a precaution they took in design, but haven’t used in practice, for CH2. A 60kW cogeneration plant—which generates electricity and usable heat, and also powers an absorption chiller—on the building’s roof is another piece of technology that Pearce wouldn’t use again, unless multiple buildings could benefit. “You end up with too much waste heat that you can’t use,” he says of the relatively small CH2.
Water plays a significant role at CH2, since the chilled panels provide a significant amount of cooling, helping to reduce fan energy and duct sizes for the air-side system. Che Wall, managing director of Lincolne Scott and its Advanced Environmental Concepts group in Sydney, promoted some of the more innovative features of the building’s mechanical system. “The chilled panels use chilled water produced by phase-change materials for 80 percent of the year; otherwise they rely on cooling towers,” he says. The phase-change materials, or PCMs, are saline-solution-filled balls in three large tanks in the basement; they freeze at a relatively high temperature (as high as 59 degrees Fahrenheit or more). By freezing the PCMs at night during off-peak hours, the building reduces its dependence on conventional chillers. “We found that by sizing the PCMs for nighttime use, we could afford the system,” Wall says. For the retail areas on the ground level, Wall developed a series of “shower towers” that provide cool water to temper the air supply. “They are basically an architectural cooling tower,” he says, and routinely stop pedestrian traffic along Little Collins Street.
CH2 remains very much a work in progress. Pearce notes the final commissioning report has yet to be completed, thus energy performance has yet to be formally quantified and shared with the public. Among his many civic duties, Adams is now at work putting together a brief for the redevelopment of CH1. In the three years since the Green Building Council of Australia awarded CH2 the country’s first-ever 6 Star Green Star rating—roughly equivalent to LEED Platinum—the building has moved the city to adopt minimum sustainability ratings for all projects over 50,000 square feet and inspired at least three other 6 Star projects. “We’ve gone past the discussion of whether or not we should be doing this,” says Adams. Pearce is even more sanguine, saying, “[Melbourne] has been an intellectual center for politics for some time, so I think history is on our side.”
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