council house 2 melbourne

Council House 2, an administrative building for the City of Melbourne, is the first in the country to achieve the highest possible rating of six stars in Australia’s Green Star environmental accreditation. 

Every aspect of the building has been examined and rethought from first principles, evolving new precepts that are based in the desire to be as true as possible to the fundamental “laws of nature”. The design philosophy is concerned with developing appropriate architectural responses that are a direct and honest expression of the biodynamic relationships that nature uses in her own designs.

This has implications for the building’s architectural form and for all the very sophisticated engineering within it. The composition of this building – its skin, its bones, its very innards – has been subjected to rigorous reappraisal to attune it to natural processes. This acknowledges the reality that we, as a society, must develop more sustainable structures to live and work in, if we are to survive as a species

CH2’s public face is the tall facade overlooking Swanston Street, one of Melbourne’s public boulevards. It is entirely composed of timber vertical slats covering a fully glazed wall. These slats pivot vertically, opening and closing in response to the time of day and the angle of the sun.

The facade is thus animated in direct response to the external conditions. This is biomimicry at its very best – the building moving and becoming alive in response to the conditions surrounding it. 

The building’s crown houses another element that aptly announces the design philosophy. Six huge, bright yellow wind turbines are a fitting visual tribute to the way air moves around CH2’s interior, proclaiming way this building harnesses another powerful natural resource, wind. 

Council House 2 ( CH2 )
A Video Tour

Melbourne Council House 2 (CH2) is a multi-award winning and inspirational building that has reduced CO2 emissions by 87%, electricity consumption by 82%, gas by 87% and water by 72%. The building purges stale air at night and pulls in 100% fresh air during the day. The building exterior moves with the sun to reflect and collect heat, and turns sewage into usable water. The building has improved staff effectiveness by 4.9% and will pay for its sustainable features in a little over a decade..

Like Eastgate, CH2 is cooled by a timely management of the difference in temperature between night air and day air. In this case, a whole side of the building is opened up to direct air intake through automatic shutters made from recycled wood (left).

This “night purge” vents the warmer air directly from the office and shop spaces and cools down the overhead mass of concrete. The warm air rises up to openings in the ceiling and then travels through hollow floors to a vertical shaft and eventually to roof vents. This passive treatment alone is enough to keep the spaces comfortable for a part of the day. Cooled fresh air rises up through floor registers throughout the day.

CH2 also uses another temperature gradient of a fluid, water, to condition the air in the building. First, water is “mined” from the sewage supply of the city, triple filtered and then put to work flushing toilets, watering plants and conditioning the air. The AC water is run down the outside of the structure through five 15-meter “shower towers” (below) which create evaporatively cooled air for induction into the lower commercial spaces.

The remaining water is piped into basement storage where it is cooled through a phase change apparatus and distributed when needed. The phase change apparatus is made up of 10,000 stainless steel spheres containing salts with a high freezing point (15 degrees C) which are frozen at night and then used to chill the water for distribution during the day, much like ice cubes chill your drink as they melt. This newly cooled water is pumped from the basement to chilled beams at every level of the building. These beams are arrayed copper pipes that drop cool air down later in the day when the effects of the night purge have worn off.

This building also uses thermal mass to absorb heat, reduces heat gain by a strategic placement of glazing, and produces power and heat by photovoltaic and thermal solar panels and a gas-fired cogeneration plant. It also hosts an equivalent amount of plant leaf surface to the site (to replace what theoretically was lost by development of the land), which oxygenates the air indoors and out. The building receives a fresh air change every half hour, and the owner claims a 10.9 percent improvement in worker productivity as the biggest payback from the $11 million (Australian) ventilation system. This increased productivity is calculated to be worth over $2 million (AUD) a year in staff time and means that the investment will likely pay for itself in 5-6 years. 

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