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Council House 2

Coordinates: 37°48′51″S 144°57′59.8″E / 37.81417°S 144.966611°E / -37.81417; 144.966611
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Council House 2 (CH2)
Map
General information
TypeOffice
LocationMelbourne, Australia
Current tenantsCity of Melbourne
Construction started2004
Completed2006
OwnerCity of Melbourne
Technical details
Floor count10
Floor area12,536 m2 (134,940 sq ft)
Design and construction
Architect(s)City of Melbourne in association with Mick Pearce with DesignInc.
Structural engineerBonacci Group
Services engineerLincolne Scott
Civil engineerBonacci Group
Quantity surveyorDonald Cant Watts Corke
Main contractorHansen Yuncken

Council House 2 (also known as CH2), is an office building located on Little Collins Street in the CBD, in Melbourne, Australia. It is occupied by the City of Melbourne council, and in April, 2005, became the first purpose-built office building in Australia to achieve a maximum Six Green Star rating, certified by the Green Building Council of Australia. CH2 officially opened in August, 2006.[1]

Environmental features

Comparing to a building with a Five Green Star rating, CH2's emissions will be 64% lower. When compared to the existing Council House next door, it is expected to:

  • reduce electricity consumption by 85%
  • reduce gas consumption by 87%
  • produce only 13% of the emissions
  • reduce water mains supply by 72%

Features include new LCD computer monitors, which will consume 77% less energy, and new T5 light fittings which should consume 65% less energy. The building also houses 48 m2 of solar panels, which provide 60% of hot water, as well as a gas-fired cogeneration plant which provides 40% of the building's ovll electricity, with reduced carbon emissions.[2]

Of the total construction cost of $50 million, $12 million were invested in energy, water and waste innovation. The time for payback is expected to be less than ten years.[3]

Design

CH2 is meant to be a ‘lighthouse project’ for new building developments, aiming to influence future design to be more sustainable and efficient. Some objectives when designing the building were to be greenhouse neutral and improve the overall employee wellbeing. Different strategies were used when doing this but all were focused around a sustainability aspect.

Biomimicry was a large component in designing the building. The buildings principle design architect, Mick Pearce, incorporated a system previously and successfully used in the Eastgate Centre in Harare. The heating, ventilating, and cooling system (hvac) is designed with strategies taken from a termite mound. In the termite mound, the cool wind is drawn into the base of the mound, via channels and the ‘coolth’ is stored using we soil. As the air warms, it flows upwards and out of the mound via vents. This gives the mound the ability to keep a stable temperature. CH2 uses similar strategies with its system by effectively using natural convection, ventilation stacks, thermal mass, phase change material, and water for cooling. Another strategy used taken from nature is the skin system. The façade is composed of an epidermis (outer skin) and dermis (inner skin). The ‘dermis’ of the building consists of the outside zone to house the stairs, lifts, ducts, balconies, sunscreens and foliage with the inner line defining the extent of the ‘fire compartment’. The dermis was designed with lightweight constructing using a steel frame. The epidermis provides the micro-environment including the primary sun and glare control for the building while creating a semi enclosed micro-environment.

Ventilation stacks are implemented on the north and south façades of the building. These stacks are used to channel air. The north stacks receive more sun so they are black to absorb heat, which in turn encourages the warm air from the building to rise up out of the stacks. The south stacks are used to channel down cold air through the vents. These stacks also offer shading for office windows.

The ceilings are made from precast concrete, with a ‘wavy’ shape, to optimize surface area, which allows for an increase in thermal mass capacity. The thermal mass in the concrete is flushed at night, through a night purge, absorbing ‘coolth’ form the night air and allowing it to absorb heat from the space during the day. With the ‘wavy’ design, heated air is collected at ceiling height, and then channeled out of the building and into the ventilation stacks. Radiant cooling is also a strategy used by running chilled water through beans and ceiling panels. Chilled panels cool the rising warm air, which then drops, creating a natural convection current. Phase change material is used to cool the water for the chilled beams and panels. It efficiently helps to keep the water circulating through the beams and panels at a desired temperature. The phase change material is often referred to as the ‘battery’ of the building because of its purpose of storing the ‘coolth’.

Shower towers are used on the southern façade. These towers draw outside air from above street level and cools the air by evaporation form the shower of water. The cool air is then supplied to the retail spaces and the cool water is used to pre-cool the water coming from the chilled water panels.

The designers also used an innovative concept of design by using the same amount of foliage on the building as would have been present if the site was still in its original natural vegetated state. This is accomplished by using a roof garden, which also serves as a breakout and recreation space for staff. The northern façade also incorporates planter boxes situated east and west of each northern balcony.

Green Star Rating

Green Star rates the environmental performance of a building based, in this case, on its design. It is administrated by the Green Building Council of Australia (GBCA). The rating looks at the following aspects of the building process:

  • Building Input
  • Management
  • Indoor Environment Quality (IEQ)
  • Energy
  • Transport
  • Water
  • Materials
  • Land Use & Ecology
  • Emissions
  • Innovation

Each of these aspects are then broken up into smaller categories that cover a wide range of topics.

Green Star is a public method of demonstrating commitment to environmentally responsible building. It provides a standard language to discuss sustainability for buildings.

On March 22, 2005, CH2 building design was awarded a 6 Star rating under Green Star – Office Design v1. The following table presents the points possible, and points awarded for CH2 [4]

Category Points Available Points Awarded
Management 12 10
Indoor Environment Quality 26 20
Energy 24 16
Transport 11 9
Water 12 12
Materials 14 9
Land Use & Ecology 8 2
Emissions 13 9
Innovation (not included in total) (5) (5)
Total Points 120 87

Post-Occupancy Reports[5]

Note: Post-occupancy reports were recorded after one year of building use while the building was still going under adjustments.

Thermal Comfort: Thermal dissatisfaction ratings should be below 10% in most locations of the building. The perceived overall thermal comfort is also good but the airflow is perceived to be to low.

Air Quality:The air quality of CH2 is excellent in terms of measured pollutant levels. The occupants also perceive the air quality to be better. The formaldehyde concentrations are much lower than compared to common office buildings. The overall air quality is excellent due to the 100% fresh air intake and the use of low toxicity materials used in all furnishings and finishes as well as an extensive use of indoor plants.

Noise Levels: Ambient noise levels and reverberation times were considered ideal but the occupant satisfaction ratings for now were average to poor and were generally worse than benchmarks. This is due to the open floor layout, which improves communication between employees, but allows for unwanted interruptions. White noise increases satisfaction scores on one level compared to the rest of the building (10-18%).

Lighting: The background lighting levels are sufficient, and the recommended task illuminances could be achieved if personal task lighting was switched on. Occupant satisfaction for lighting is average to poor in CH2 and is worse than some Building Uses Studies benchmarks (BUS).

Perceived Productivity: Three quarters of CH2 occupants rate the building as having a positive or neutral effect on productivity, compared to 39% in the original Council House. CH2 is rated in the top 20% of Australian buildings for perceived productivity.

Perceived Worker Health: CH2 is rated very highly for perceived healthiness, and is considered to have low levels of occupant reported rates for building related health symptoms. Absenteeism and staff turnover has not changed but more time must pass to have conclusive data.

Overall: 80% of occupants prefer CH2 to their previous accomodation

Awards and Recognition

2004

  • Exemplar, Imagining the Future Award, Year of the Built Environment Awards, CRC Construction Innovation in association with DesignInc.

2005

  • Special Projects Initiative, Award of Excellence LG Pro Local Government Professionals
  • 6 Start Rating Certification, Green Start Rating Green Building Council of Australia
  • Green Building Award, World Environment Day Awards 2005 United Nations Association

2006

  • Greenhouse Expenditure Award, Eco-Buy Awards 2006
  • Recycled Expenditure Award, Eco-Buy Awards 2006
  • The Hey Big Spender Award, Eco-Buy Awards 2006
  • Environmental Planning or Conservation Award, Awards for Planning Excellence 2006, Planning Institute of Australia, Victoria Division

2007

  • Environment Planning or Conservation, National Awards for Planning Excellence, Planning Institute of Australia
  • President’s Award, National Awards for Planning Excellence, Planning Institute of Australia
  • Sustainable Architecture Award, 2007 Victorian Architecture Awards, Royal Australian Institute of Architects, Victorian Chapter in association with DesignInc.
  • President’s Award, 2007 Excellence in Property Awards, Australian Property Institute, Victorian Division
  • Sustainable Architecture Award, 2007 National Architecture Awards, Royal Australian Institute of Architects
  • Finalist, Sustainable Design, Global Innovator’s Awards 2007 CoreNet Global
  • Environment and Sustainability Award, Victorian Engineering Excellence Awards 2007, Engineers Australia, Victorian Division in association with Lincolne Scott and Bonacci Group
  • Sustainability Award, IDEA Excellence Awards 2007, (Inside) Australian Design Review in association with DesignInc.
  • Sire William Hudson Award, Australian Engineering Excellence Awards 2007 Engineers Australia in association with Lincolne Scott and Bonacci Group
  • Sustainability Building Award (projects under £25,000), Sustainable Building Services Awards UK Chartered Institution of Building Services Engineers (CIBSE) Awarded to Lincolne Scott

2010

  • 6 Star – As Built Rating Certification, Green Star Rating, Green Building Council of Australia
  • Detail of the shutters on the northern facade
    Detail of the shutters on the northern facade
  • Eastern side and rooftop turbines
    Eastern side and rooftop turbines

See also

References

  1. ^ Hansen Yuncken, retrieved 18 January 2010
  2. ^ City of Melbourne, retrieved 18 January 2010
  3. ^ Newman, Peter, et al.: Resilient cities : responding to peak oil and climate change, 2009
  4. ^ Hes, Dominique, et al.: Design snap shot 04: Green Star Rating - Office Design v1, 2008
  5. ^ Paevere, Philip & Brown, Stephen, et al.: Indoor Environment Quality and Occupant Productivity in the CH2 Building: Post-Occupancy Summary Report No. USP2007/23, 2008

37°48′51″S 144°57′59.8″E / 37.81417°S 144.966611°E / -37.81417; 144.966611


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